Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: gootie on July 10, 2010, 12:56:04 pm
Title: Retard feature pros and cons
Post by: gootie on July 10, 2010, 12:56:04 pm
As a new member and actually a Foretravel admirer for years(I don't have one yet) I'm curious to know not how this system works but how well it is liked compared to other systems you more experienced?
Thanks Gootie Madison,WI
Title: Re: Retard feature pros and cons
Post by: Rudy on July 10, 2010, 01:22:32 pm
Gootie,
I love my retarder system and use it all the time. Here is how I understand the systems work.
The adequate but least powerful system is the exhaust brake found on most diesel motorhomes. It is either on or off. When on, it will slow the coach down on most hills such that you will need to turn it on and off as you descend to maintain the speed you want.
The Jake engine brake in some higher end motorhomes turns the engine into a compressor and is more powerful in slowing the coach than the exhaust brake and may have two levels of operation instead of just one. This is the system used on big trucks and is the one cities post signs saying no engine brake to stop citizens from hearing the noise they create.
The transmission retarder is the most powerful of the three and needs good cooling for the transmission fluid as it will heat up when retard is in operation and is why big trucks do not prefer it.
My Foretravel has always dissipated the heat as they apparently planned for it when designing the cooling system.
It is armed to work when you turn the retard switch on. As you step on the brake, the first pressure engages 30% of the retarder ability. Additional pressure will engage 60% and even harder pressure will bring on 100% retard.
If you have the joy stick and the retard switch on, there are six levels of retard available without stepping on the brake. This allows you to vary the retard to match the steepness of the hill to hold speed where you want it.
Stepping on the brake with the retard switch on works the same with or without a joy stick.
With the joy stick full forward the coach will coast with the accelerator at idle. With the joy stick back from full forward, the retarder will engage at the set retard level anytime the accelerator is at idle,i.e. your foot off of the accelerator. If you are on the accelerator asking for power the retarder is off.
If I have erred here or missed something, I am sure one of the others with help out. It sure works good for me.
Title: Re: Retard feature pros and cons
Post by: Tim Fiedler on July 10, 2010, 01:25:56 pm
Gootie,
My first Foretravel (36' 1989 OREG or Oshkosh Rear Engine Gas) had no retarder or exhaust brake. It didn't stop so well, but I guess I didn't notice it because I had nothing to compare it to. I have since had a 1999 36' U-270 and currently own a 2000 U-320 40' (4010 or single slide unit).
Both those coaches have the retarder and I absolutely would not ever have a large coach now that didn't have a retarder.
Pro's
Incredible stopping power
Smooth engagement
No Noise
Adjustable with Joystick and can be used independent of brakes
Con's
Expensive if purchased as an option (actually expensive to build into the price of a Foretravel too...)
Transmission Temps need to be monitored during prolonged use (going down a grade for a substantial distances in the mountains)
I have inadvertently hit the joystick and put one notch of "retard" into use while going down the road. Found it because cruise control kept disengaging, Guess you could say both the transmission and the driver were
"retards"....
My good friend Dave Head can fill you in on the pluses of exhaust brakes, he has had two Foretravels with them installed, but I believe given a choice he would much prefer the retarder.
Tim Fiedler 2000 4010
Quote
On 7/10/10 11:56 AM, "gootie" As a new member and actually a Foretravel admirer for years(I don't have one yet) I'm curious to know not how this system works but how well it is liked compared to other systems you more experienced?
Thanks Gootie Madison,WI
Title: Re: Retard feature pros and cons
Post by: gootie on July 10, 2010, 01:32:46 pm
Thanks guys I had road tested a new 40 footer at factory in 2000 and was much in awe of the Foretravel . My day is coming
Gootie
Title: Re: Retard feature pros and cons
Post by: George Stoltz on July 10, 2010, 02:09:41 pm
Another pro to having a retarder is that your brake pads will last a whole lot longer.
Another pro is faster stopping in emergency situations.
We are so pleased and fortunate to have bought a coach with a retarder. It offers a great sense of safety to us.
Title: Re: Retard feature pros and cons
Post by: Russell on July 10, 2010, 02:42:29 pm
We have nothing to compare it to. We just know the Allison Retarder works great. While traversing the Rockies last year, we crossed the continental divide 8 different times. It was not only a breeze with the retarder, it offered a real sense of security going down some of the long grades.
Title: Re: Retard feature pros and cons
Post by: gootie on July 10, 2010, 03:02:40 pm
So now that a few members have included their very helpful responses I have to ask about the trans temps in heavy use. Do most Foretravels have trans fluid temp gages? Seems like the only way to tell if some limits are being approached. Again, I really appreciate this info as we will be "pulling the trigger" someday and this brand of motor coach is the desired home
Thanks Gootie
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 10, 2010, 03:20:18 pm
Yes, all diesel Foretravels have transmission temperature gauges.
The typical diesel instrument cluster will have this gauge as well as the usuall suspects as fuel, water (coolant temp), oil pressure, Front & rear air tank pressure (psi)[these are needed for the air operated brakes as well as the air spring suspension].
Many owners either have added additional gauges such as a pyrometer (measures turbo temperatures of the exhaust gasses used to drive the turbine) as well as turbo boost (measures the current vacuum levels at the turbine providing the pressurized air for combustion and horsepower enhansement); or have added aftermarket monitoring systems availabe for the electronically controlled diesel engines. Anexample of such a monitoring system is the SilverLeaf brand.
Title: Re: Retard feature pros and cons
Post by: Jon Twork on July 10, 2010, 03:51:34 pm
I actually haven't met anyone who does not like the Allison retarder on
Foretravels.
It was one of the MAJOR reasons I purchased a Foretravel as I pull a trailer and I like the redundancy as it concerns stopping my rig.
It works amazingly well and would most likely only be out performed by an electric retarder.
I can tell you that if you get a Foretravel and it has a retarder on it, you should use CAUTION in applying it in a panic stop. It will, along with your brakes, STOP YOU NOW.
Title: Re: Retard feature pros and cons
Post by: Gerry Vicha on July 10, 2010, 04:21:57 pm
Hi Gootie, I have a Detroit 6V92 350 H.P. with the "Jake Brake" system, with two levels of braking power. Previously I had a "Bluebird" with transmission retarder. Both work well, The braking power of the retarder is stronger, however heat is created. The Jake Brake does use engine compression to slow the vehicle, this does no harm to the engine nor does it create any additional heat. The "Noise" created is well muffled by the motor home exhaust system. With the S.O.B. (some other brand) coach I did have a heat dissipation problem... :(
Title: Re: Retard feature pros and cons
Post by: Gayland Baasch on July 10, 2010, 10:37:14 pm
My 96 U270 has the button. I read somewhere in the literature that it only costs $400 to convert it to the joy stick. Does that sound right? Is it worth it (does the joy stick work that much better?)
Is there any reason not to have it "engaged" under "normal" driving conditions. I had an incident driving through Albuquerque, rush hour traffic, needing to change lanes so looking for an opening, looked up and my lane was a parking lot. I did get it stopped in time, but it would have been nice to have the retarder helping.
Title: Re: Retard feature pros and cons
Post by: George Stoltz on July 10, 2010, 11:27:45 pm
Gayland,
You keep giving us more opportunities to spend your money. I think the major difference between the button and the joystick is that you have greater flexibility in choosing the degree of retardation. When driving in heavy traffic (which I try to avoid at all cost) I keep my retarder pulled back 3 notches. That way as soon as I let up off the accelerator I get some immediate slowing down.
Title: Re: Retard feature pros and cons
Post by: Barry & Cindy on July 11, 2010, 12:00:49 am
On our coach the dash transmission temperature gauge was OEM connected to temperature sender screwed into the large diameter elbow on the transmission fluid returning from transmission fluid heat exchanger.
So our gauge used to read the hot fluid AFTER it was cooled down.
I moved the sender to the hot out-flow (going to the exchanger) on the back on the transmission.
Now, when under full-retard, transmission temperature gauge climbs pretty steady up toward 300 degrees on a long downhill mountain run.
And drops back to 180 degrees like stone when we reach the bottom of the hill where we turn retarder off.
The sender has a 1/8" pipe thread male fitting.
Title: Re: Retard feature pros and cons
Post by: Jim Monk on July 11, 2010, 12:05:51 am
Gootie, we just got back from our first trip to the Rockies in our 1997 U 270. Left S.E. Texas & went to Silverton, Colorado. about 1200 miles, crossing Raton Pass, N.M., La Veta Pass, Co. Wolf Creek Pass, Co. Coal Bank Pass, Co. and Molas Pass, Co. Not knowing what to expect I didn't even bring a tow car. It was a breeze both pulling the hills and going downhill thanks to the retarder. This is our first motorhome so I can't compare it to not havng one. The only problem I had was a heat alarm for a short while, but not sure why. The alarm went off after a short while.
Jim Monk 1997 U270
Title: Re: Retard feature pros and cons
Post by: J. D. Stevens on July 11, 2010, 08:38:24 am
Gayland,
Expect about $600 to have the joy stick installed. We recently added it to a 1997 U295. About $375 for the parts and $240 for labor.
We haven't used it much in Texas, but expect to use it on our trip to Montana. We made a similar trip in a 37' "other brand" and used the exhaust brake a few times. I expect better control and greater comfort with the retarder controlled by the joy stick.
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 11, 2010, 09:26:03 am
Quote
My 96 U270 has the button. I read somewhere in the literature that it only costs $400 to convert it to the joy stick. Does that sound right? Is it worth it (does the joy stick work that much better?)
Some additional information on installing a joystick. http://beamalarm.com/Documents/installing_joy_stick_retarder_control.htm (http://beamalarm.com/Documents/installing_joy_stick_retarder_control.htm)
Title: Re: Retard feature pros and cons
Post by: gootie on July 11, 2010, 09:37:44 am
Gootie, we just got back from our first trip to the Rockies in our 1997 U 270. Left S.E. Texas & went to Silverton, Colorado. about 1200 miles, crossing Raton Pass, N.M., La Veta Pass, Co. Wolf Creek Pass, Co. Coal Bank Pass, Co. and Molas Pass, Co. Not knowing what to expect I didn't even bring a tow car. It was a breeze both pulling the hills and going downhill thanks to the retarder. This is our first motorhome so I can't compare it to not havng one. The only problem I had was a heat alarm for a short while, but not sure why. The alarm went off after a short while.
Jim Monk 1997 U270
This is the type of comment that I was looking for and I now have to ask are you using synthetic tranny fluid? It sounds as though we all should be monitoring the outlet temp as I understand the tranny fluid life expectancy is shortend by higher temps. Does the use of synthetic change the lubrication capabilities under these extremes?
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 11, 2010, 10:09:39 am
Gayland, I do not use long life trans fluid but rather change the std fluid at required intervals. I drive about 8,000 miles in two years, so I change it and the filter every two years. I use the retarder 100% of the time. I leave the rocker switch on...period. Then whenever I use the service brakes, the reatrder helps stop the vehicle according to the 33%, 66%, 100% based on depth of pedal application. I also use the joy stick to slow down the coach even of flat roads to slow down any time I have to. This serves to reduce the amount on wear on the service brakes.
Title: Re: Retard feature pros and cons
Post by: Gayland Baasch on July 11, 2010, 10:21:25 am
Great information - it was actually gootie that asked about the synthetic oil, but only because he beat me to it. I see that the PO used synthetic so I'll probably stick with it.
Barry, do you think your temp unit was installed by mistake, or are they all installed after the cooler? Maybe their theory was/is as long as you're supplying cool oil to the tranny, there's nothing to worry about???
George - money not a problem, I'm setting up a site so you all can contribute, cause I know you all want me to be happy ;D
Title: Re: Retard feature pros and cons
Post by: gootie on July 11, 2010, 10:55:40 am
Gents This question of where to monitor tranny fluid temp could be answered by an Allison rep?
Title: Re: Retard feature pros and cons
Post by: Tom Lang on July 11, 2010, 11:24:20 am
I see only pros no cons. The transmission retarder was the number one reason (followed by 99+ more) for my chosing Foretravel.
Living in Los Angeles, it use the retarder a lot. When traffic slows, i reach for the joystick even before my foot hits the brake pedal. I sometimes make it all way down the Grapevine, the Baker Grade, and truck-restricted sections of Highway 49 without using the foot brake. And I do watch the transmission temperature, but have never seen an appreciable rise.
Tom
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 11, 2010, 11:27:54 am
Quote
On our coach the dash transmission temperature gauge was OEM connected to temperature sender screwed into the large diameter elbow on the transmission fluid returning from transmission fluid heat exchanger.
I had asked James Triana some time ago: Is the sensor monitoring the output of retarder (350 degrees max) or sump pump (250 degrees maximum) He told me that our Gauge monitors the sump temperature (250 degrees max).
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 11, 2010, 11:34:31 am
Barry, that makes sense to me as if the available fluid is already at 250 at the sump, that would indicate that the amount of heat absorption by this temp fluid is near its max when exiting the retarder with all those additional BTU's. It would also indicate if the trans cooler is performing its duties of discipating those BTU's back into the atmosphere.
Title: Re: Retard feature pros and cons
Post by: Raymond Jordan on July 11, 2010, 11:37:44 am
Hi Gayland, I added the joystick control to my 1997 U 320. It was a unplug, plug, tie wrap, type of installation. It is the BEST modification I have done to the coach. A can't leave home without it deal.
Title: Re: Retard feature pros and cons
Post by: George Hatfield on July 11, 2010, 12:47:23 pm
We have Silverleaf and I have seen the trans temp increase to as high as 240 degrees on long hills. Is the max temp 250 degrees?
Also, I read somewhere that one should not use the retarder in the rain? Reason?
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 11, 2010, 01:13:25 pm
Quote
We have Silverleaf and I have seen the trans temp increase to as high as 240 degrees on long hills. Is the max temp 250 degrees?
At 250 degrees the (beeper/buzzer) should come on. You should not let it get to that temperature. On long steep grades I find I need to downshift to 4th or 3rd gear & use brakes more because of rising retarder Temp.
Quote
Also, I read somewhere that one should not use the retarder in the rain? Reason?
It affects the ABS system from functioning properly.
Title: Re: Retard feature pros and cons
Post by: George Stoltz on July 11, 2010, 01:18:54 pm
Great information - it was actually gootie that asked about the synthetic oil, but only because he beat me to it. I see that the PO used synthetic so I'll probably stick with it.
Barry, do you think your temp unit was installed by mistake, or are they all installed after the cooler? Maybe their theory was/is as long as you're supplying cool oil to the tranny, there's nothing to worry about???
George - money not a problem, I'm setting up a site so you all can contribute, cause I know you all want me to be happy ;D
Gayland -- I've already given my 2 cents :)
Title: Re: Retard feature pros and cons
Post by: D.H. Spoor on July 11, 2010, 01:20:56 pm
Temperatures:
A few years ago at an FMCA Seminar on Allison, and in the Q&A session, I learned following -
a. Allison provides two temperature outputs, one in the sump, the other in the retarder section. Foretravel uses the sump sender, perhaps because the temperature swings are much faster and higher, and could cause unnecessary alarm and/or concern.
b. At about 300 degrees in the retarder, the software starts "load shedding", and at about 330 degrees, the "shedding" is close to 100%, meaning the retarder has shut down "retarding".
c. The Senior Allison Rep advised that 250 degrees in the sump is equivalent to 300 degrees in the retarder section.
My conclusion and current practice is to use 200 degrees (sump) as a "Yellow" or "caution" zone and 250 degrees is my "Red Light" limit where I pull over and high-idle in Neutral until the temp is down. Being conservative, chicken and slow on a mountain down-hill, we have toured the Rockies about 5 times over the years and I have never seen 250 degrees.
Parenthetical anecdote: our first coach was a 1988 U-280 with no retarder and I worried about transmission temps because, in Colorado, it wasn't unusual to hit 250 degrees and I would back off. Met an RV'er in a park who had been a Fire Truck salesman for 20 years. and he scoffed at my concern. He said that at a fire, pumpers were "locked" at wide-open throttle for 8 hour at a time and were always at 250 degrees in the transmission (Allison 4-speed).
Title: Re: Retard feature pros and cons
Post by: LynnD on July 11, 2010, 01:48:47 pm
Hi Peter, The retarder is supposed to be wired to the braking system. It is supposed to work on the 1/3, 2/3, full on, sequence, controlled by the braking system, even if the retarder is manually turned off. This was a safety feature originally designed into it, although I am not sure whether this started with day one or not.
Good luck, LynnD '01 GV
Title: Re: Retard feature pros and cons
Post by: J. D. Stevens on July 11, 2010, 01:59:05 pm
On our 1997 U295, the retarder will not activate from the brake pedal if the manual switch is off. In slick conditions you may wish to have the retarder off in order to have finer control of the wheels with the pedal and ABS.
JDS
Quote
On Jul 11, 2010, at 12:48 PM, "LynnD" Hi Peter, The retarder is supposed to be wired to the braking system. It is supposed to work on the 1/3, 2/3, full on, sequence, controlled by the braking system, even if the retarder is manually turned off. This was a safety feature originally designed into it, although I am not sure whether this started with day one or not.
Good luck, LynnD '01 GV
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 11, 2010, 02:06:30 pm
Quote
On our 1997 U295, the retarder will not activate from the brake pedal if the manual switch is off. In slick conditions you may wish to have the retarder off in order to have finer control of the wheels with the pedal and ABS.
That is the way mine works also. If the retarder switch is OFF than I have no retarder use.
Title: Re: Retard feature pros and cons
Post by: Dave M (RIP) on July 11, 2010, 02:41:32 pm
George, Rain or snow, what ever makes for a slick road. Always remember when driving a rear engine vehicle, the most weight is at the rear and if you get it sliding you will most likely find the vehicle has swapped ends. When road get slick, Retarders, Jake brakes get turned off. When rain first starts, it brings the oil in/on the road to surface = slick road until it gets washed off. FWIW Dave M
Title: Re: Retard feature pros and cons
Post by: John S on July 11, 2010, 03:19:22 pm
Another pro to having a retarder is that your brake pads will last a whole lot longer.
George, your are correct that it does not wear out the brake pads but if you use only the retarder your calipers will stick and you will be replacing the pads on both sides and a rotor too. It is expensive. The issue is lack of use not too much use because of the retarder. Use your brakes to make the final stop. You will thank me later.
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 11, 2010, 04:54:29 pm
Quote
The issue is lack of use not too much use because of the retarder.
James Triana mentioned after starting the coach, you should push the brake pedal all the way down periodically to keep the slide pin from sticking. Because as John says, it is lack of use that is the issue.
Title: Re: Retard feature pros and cons
Post by: Paul Smith on July 11, 2010, 06:12:26 pm
My new SilverLeaf VMS 240 CL does not agree. It displays temperatures in the Retarder and Transmission. Typically, the Transmission temperature will be about 180-190 and Retarder 100 or so if Retarder is not being exercised.
I have yet to see the Retarder temperature go to 180 even on long, steep downhills. I don't know if this is real or some typo in the VMS setup, etc. best, paul
___
'Thriving not Surviving'
Quote
a. Allison provides two temperature outputs, one in the sump, the other in the retarder section. Foretravel uses the sump sender, perhaps because the temperature swings are much faster and higher, and could cause unnecessary > alarm and/or concern.
b. At about 300 degrees in the retarder, the software starts "load shedding", and at about 330 degrees, the "shedding" is close to 100%, meaning the retarder has shut down "retarding".
c. The Senior Allison Rep advised that 250 degrees in the sump is equivalent to 300 degrees in the retarder section.
Title: Re: Retard feature pros and cons
Post by: Paul Wildenstein on July 11, 2010, 06:54:43 pm
" George, your are correct that it does not wear out the brake pads but if you use only the retarder your calipers will stick and you will be replacing the pads on both sides and a rotor too. It is expensive. The issue is lack of use not too much use because of the retarder. Use your brakes to make the final stop. You will thank me later."
John is absolutely right about this. I pulled into a rally a couple years ago and everyone came over to see what was on fire. It was my left front caliper and it had not slid back after a brake application somewhere back down the road. I got parked, but had to have a road service come to me and he spent over two hours freeing the caliper so that I could drive home. Our next trip was to Nacogdoches so I had all the brakes serviced. Fortunately
I had not yet damaged any pads or the rotor.
Paul 36' 2000 U320
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 11, 2010, 07:11:41 pm
Paul W, Do you attribute the stuck caliper to your mode of using the retarder too much and not the brakes enough?
Title: Re: Retard feature pros and cons
Post by: Paul Wildenstein on July 11, 2010, 09:12:41 pm
Peter,
Yes I do. I love that retarder and used it almost all the time, mostly using the joystick. I might drive all day long and just about never touch the brakes except for that final 10 - 0 to come to a complete stop. Since my incident I still use the joystick a whole lot, but I make it a point to push those brakes on good and hard on a regular basis. Gotta remember too, that just using the brakes to slow down on the highway may not exercise those calipers one bit. You have to either turn off the retarder or make sure you get past the retarder points on the brake pedal.
One other point I might make. Those very shiny steel pins on which the calipers slide (two per corner) cost over a hundred bucks each. Six of my eight needed to be replaced.
Paul 36' 2000 U320
Title: Re: Retard feature pros and cons
Post by: Brian on July 11, 2010, 09:28:58 pm
I have a 1995 U240 (cat 3116 engine) with retard and it has not been engaged in a very long time. Is there something to check or maintain before it is used?
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 11, 2010, 09:44:19 pm
Brian, use your judgemt. If you've serviced the transmission on a regular basis, there should be no problem using the retarder. Use that retarder, it is a great safety feature. (Assuming you have an Allison Transmission retarder)
Paul, I heed the warning. I will make sure that the service brakes are fully engaged more often. I have not noticed any changes in braking performance or overheating of the wheels at this point. I'll also make it a point to disengage the retarder once every trip for a few miles to make sure I have to use those expensive brakes.
Title: Re: Retard feature pros and cons
Post by: Barry & Cindy on July 11, 2010, 10:18:28 pm
Retarder will not come on with brake pedal, when side panel electrical retarder switch is off. This switch is NOT the joy stick. Check it out by watching light in switch.
Title: Re: Retard feature pros and cons
Post by: Paul Smith on July 12, 2010, 11:11:04 pm
SilverLeaf tells me the VMS data is accurate and that the Allison rep probably mis-spoke best, paul
Quote
On Sunday, July 11, 2010, Paul Smith Sr wrote:
My new SilverLeaf VMS 240 CL does not agree. It displays temperatures in the Retarder and Transmission. Typically, the Transmission temperature will be about 180-190 and Retarder 100 or so if Retarder is not beingexercised. I have yet to see the Retarder temperature go to 180 even onlong, steep downhills. I don't know if this is real or some typo in the VMS setup, etc. best, paul
___
'Thriving not Surviving'
Quote
a. Allison provides two temperature outputs, one in the sump, the other in the retarder section. Foretravel uses the sump sender, perhaps because the temperature swings are much faster and higher, and could cause unnecessary alarm and/or concern.
b. At about 300 degrees in the retarder, the software starts "load shedding", and at about 330 degrees, the "shedding" is close to 100%, meaning the retarder has shut down "retarding".
c. The Senior Allison Rep advised that 250 degrees in the sump is equivalent to 300 degrees in the retarder section.
Title: Re: Retard feature pros and cons
Post by: PatC on July 13, 2010, 12:20:41 pm
SilverLeaf tells me the VMS data is accurate and that the Allison rep probably mis-spoke best, paul
Paul, Your SilverLeaf may be accurate, but will only read the temps where the sending sensor is located in the system. And exactly where that sensor is located can cause the temperature to vary greatly.
Title: Re: Retard feature pros and cons
Post by: Paul Smith on July 13, 2010, 02:28:30 pm
I'm not sure what to do about this. Please advise. best, paul
___
'Thriving not Surviving'
Quote
Your SilverLeaf may be accurate, but will only read the temps where the sending sensor is located in the system. And exactly where that sensor is located can cause the temperature to vary greatly.
Title: Re: Retard feature pros and cons
Post by: Tom Lang on July 13, 2010, 05:01:45 pm
Regarding rain and other slippery conditions -- The ABS system does not take the retarder into account. If the ABS senses a wheel locking up and releases the air brakes to that wheel, the retarder is not playing along. This not only negates the ABS system, it also throws the entire braking system into imbalance -- not good. Even without ABS, applying braking only at one end (or more at the rear end) in slippery conditions will cause that end to slip and slide more than the other end -- also not good.
I do not always turn off the retarder in light rain, but I do keep the location of the red switch in mind, just in case I want to turn it off in a hurry.
Another retarder point (and Foretravel feature discovery too) is that the transmission will automatically downshift when going down a grade with the retarder engaged if you fall below a certain speed. This downshift makes the task easier for the retarder (and less heat into the transmission fluid), and also multiplies the amount of retarding you have selected via the joystick.
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 13, 2010, 05:37:17 pm
I do not have ABS in the U270 but realize it is a great safety feature when driving in slippery conditions such as ice, snow & heavy rain. As I undestand, the coach brakes function the opposite of automobile brakes, that is, the rear brakes do most of the braking. Otherwise the amount of plunging of the front end would create unstable conditions when a greater portion of the GVW is at the rear end on busses & DP's, and the front brakes would wear out much before the rear brakes.
Notice that with this confuguration for coach braking, the retarder applies braking equally to both sides of the drive axle only. Then, the ABS being independent of the retarder should apply its intermittent application of the service brakes to any slipping wheels including the drive axle wheels. I assume that coaches with tag axles also have ABS on that axle's wheels (I don't know). As Tom indicates, if slipping the ABS pulsating service brakes may have erratic effects as the retarder is still applying "braking force (not friction as in service brakes)" while applying the service brakes.
Bottom line is, when driving under slippery conditions, whether you have ABS or not, turn the retarder off and SLOW DOWN to safe speeds for your braking capability and load w/o the retarder.
Title: Re: Retard feature pros and cons
Post by: Raymond Jordan on July 13, 2010, 06:13:01 pm
Hi Peter, Your last sentence says it all. It seems the best action is to turn the retarder off when the roads are wet. I hope I hope I never experience a retarder slide. Getting to old for that stuff.
Title: Re: Retard feature pros and cons
Post by: Gary Bouland (RIP) on July 14, 2010, 09:25:02 am
Tom, & others, My 95 GV DOES have ABS and it is connected to the retarder. I found this out when I was trouble shooting the system. I would be really surprised if a 97 did not have ABS. On mine the ECU for the ABS is wired into the Retarder, when slip is detected retarder is deactivated. HOWEVER my system is obsolete and I had to defeat the retard feature. IF you have a light in your dash that says BRAKE you will find that it is an indication that ABS is either working or has failed.
Title: Re: Retard feature pros and cons
Post by: PatC on July 14, 2010, 10:39:17 am
Bottom line is, when driving under slippery conditions, whether you have ABS or not, turn the retarder off and SLOW DOWN to safe speeds for your braking capability and load w/o the retarder.
I also think this is excellent advise. I don't know a lot about the retarder yet, but I know Jake (exhaust) brakes well. When the roads were slippery, I always turned off the Jake brake. And yes, I have experienced engine stall caused by the Jake brake. It was not fun.
And on the ABS topic, I do not believe that ABS will work well on black ice. One night I was traveling down a secondary highway and going down a small hill. Was traveling about 55 mph and I let off the accelerator. Everything went still and I looked at the tach and it showed about 700 rpm and the speedometer was bounceing between 10 and 15 mph, but I had not slowed down one bit, was on black ice. I really do not believe that ABS would have helped me under these conditions. I got back down on the accelerator and gradually slowed myself down to a stop. Had I hit the brakes, who knows where the rig would have gone. It was a empty petroleum transport (tractor trailer) and they are like skate boards on ice. They go about 5000 lbs lighter than the normal tractor trailer and when empty the brakes just lock up, often even on dry roads. But ABS is great on ordinary wet, snow covered and slippery roads.
Title: Re: Retard feature pros and cons
Post by: PatC on July 14, 2010, 04:21:49 pm
Met an RV'er in a park who had been a Fire Truck salesman for 20 years. and he scoffed at my concern. He said that at a fire, pumpers were "locked" at wide-open throttle for 8 hour at a time and were always at 250 degrees in the transmission (Allison 4-speed).
Dan got me thinking when he stated the above. It is true that a fire engine pumper transmission is locked in high gear at wide open throttle when pumping. My son is a paramedic/firefighter and I asked him about this. He was in NYC right after 9-11 and told me that the NYFD Seagraves pumpers were sitting connected to fire hydrants and pumping at full throttle, un-manned, for several days. maybe even weeks, at a time. They had fuel tankers going around to fill them up. He was there over a week and said the ones he saw were already hooked up and running when he arrived and were still there hooked up and running when he left a week later. It was not ideal conditions cause everything was covered with layers dust. I think this speaks well of the conditions an Allison transmission can operate under.
Thank you Dan for bringing this to light!
Title: Re: Retard feature pros and cons
Post by: Jerry Whiteaker on July 21, 2010, 04:14:10 pm
Yes, it is recommended that the retarder not be used on slippery roads such as when it is raining or snowing. The retarder only brakes the rear drive wheels and the braking effect increases with speed. It can't lock up the rear wheels like the service brakes can, but the combination of service brake and retarder can cause locked rear wheels sooner on a slick road. Most likely this will be happen at high speed at the worst time. With the rear wheels slipping the rear part of the coach may stop following the front of the coach and suddenly its not pointed in the desired direction. Most likely this is followed up with a panic brake application making the situation even worse. It would take a real cool driver to release the brakes and reach over and turn off the retarder while going sideways down the road. Also it is going to take a few seconds for the fluid to empty out of the retarder chamber and cease retarding. The ABS (for those who have it) can not release a sliding wheel when it is caused solely by the retarder. ABS could help though if foot braking is being applied as it should release the service brake on a sliding wheel.
For new owners, I would suggest that you drive with the retarder off until you become familiar with how the coach drives and handles. In the beginning you have enough to keep you busy without operating a joy stick and brake applications that may be more than expected. On steep downgrades, one also needs to downshift as necessary to keep the retarder from overheating the transmission fluid. Personally, I like to keep it below 250, but higher might be acceptable, and some might like to keep it lower than 250. Also I think the retarder should be turned off occasionally just to check that the regular service brakes are operating properly and can stop the coach quickly. I also leave the retarder off for a few stops after the coach has been in storage just to check the brakes and to quickly remove rust from the rotors. It is a wonderful device for extending brake life and descending mountains.
Jerry Whiteaker 96 U270 36'
Title: Re: Retard feature pros and cons
Post by: John Cooper on July 25, 2010, 05:09:56 pm
Racing drivers call the ratio of front to rear braking force brake bias. Too much front bias and the car will no longer steer, too much rear bias and the car will spin. Think of the retarder as adding to the rear brake bias. Turn off the retarder and SLOW DOWN. I would think pulling a toad would make things worse. Most Foretravels have the engine in the rear. Once a rear engine vehicle start to spin they are very hard to correct because of the all that rear weight, just ask Porsche 911 drivers!
Title: Re: Retard feature pros and cons
Post by: Jerry Galliart on July 25, 2010, 08:05:37 pm
Can someone tell me how the retarder effects the use of brakes or what are the best on the toad. It looks like any type that uses signals of the tail lights would cause the toad to brake the coach. What is everyone using? Any problem burning up toad brakes?
Title: Re: Retard feature pros and cons
Post by: Barry Beam on July 25, 2010, 08:16:19 pm
Quote
Can someone tell me how the retarder effects the use of brakes or what are the best on the toad.
An Allison transmission retarder provides secondary vehicle braking via the transmission. The retarder does not operate any Toad Brakes you may have.
Title: Re: Retard feature pros and cons
Post by: J. D. Stevens on July 25, 2010, 08:37:50 pm
Last week we descended from the Eisenhower Tunnel to Golden, CO, without using the brakes until it was time to exit I-70. Gear selection and retarder setting via joystick allowed us to control the speed of the 32,000 pound combination without raising the transmission temperature above about 200F (per dash gauge).
My traveling/driving partner was pleased to see how well the coach handled the mountains. When we began our ascent, we saw an 18-wheeler coming down with copious smoke coming from all wheels except on the steering axle. I suggested that we would be able make a safer descent, and indeed we did.
The Grand Cherokee in tow behind the U295 has electric brakes that only activate under hard braking. They are activated by an inertial sensor in a control box near the driver's position. The activation point is adjustable. I had adjusted the brakes to activate on what I consider to be a hard stop. The brakes never activated during the descent along I-70. The brake system is a VIP-Tow-Brake that was part of the coach/toad combination that we bought. The system works well with the retarder, and only actuates on a hard stop or a breakaway of the toad.
The joy stick for the retarder was an addition to the 1997 coach after we bought it in April, 2010. It was a welcome and useful improvement for driving in the mountains of Wyoming, and Colorado.
Title: Re: Retard feature pros and cons
Post by: Jerry Whiteaker on July 25, 2010, 09:28:11 pm
Regards Jerry Galliart's question about what kind of toad brakes everyone is using. Don't know what others are using, but I have the Roadmaster Brakemaster http://www.roadmasterinc.com/products/braking/brakemaster/brake_m.html (http://www.roadmasterinc.com/products/braking/brakemaster/brake_m.html) . I'm happy with it although you have to install and remove it each time the toad is towed. Takes a couple of minutes to install and < a minute to remove. It uses air from the brakes on the coach. I tried US Gear's Unified Brake on a SOB about 10 years ago and didn't like it. http://www.usgear.cc/unified_tow_brake.htm (http://www.usgear.cc/unified_tow_brake.htm) It was supposed to provide proportional braking, but it didn't do that, it was either on or off. It kept jerking the tow bar so much that I set up a camcorder in the toad to see what was happening. It's still being sold, and people say they like it, so I may have had a defective one. I bought it from Camping World and they refunded my money. The retarder is supposed to turn on the coach brake lights, so if a toad supplemental brake system uses that as a signal, it could overheat the toad brakes.
Jerry Whiteaker 96 U270
Title: Re: Retard feature pros and cons
Post by: Dave Head on July 25, 2010, 11:13:27 pm
Cool! Now I can describe my Foretravel as 'just a larger version 911 turbo'...
Quote from: John Cooper
Racing drivers call the ratio of front to rear braking force brake bias. Too much front bias and the car will no longer steer, too much rear bias and the car will spin. Think of the retarder as adding to the rear brake bias. Turn off the retarder and SLOW DOWN. I would think pulling a toad would make things worse. Most Foretravels have the engine in the rear. Once a rear engine vehicle start to spin they are very hard to correct because of the all that rear weight, just ask Porsche 911 drivers! John Cooper 91 GV 36' Oshkosh chassis Cat 3208T 300HP
Title: Re: Retard feature pros and cons
Post by: Bill & Kim on July 30, 2010, 02:19:04 pm
When driving in heavy traffic (which I try to avoid at all cost) I keep my retarder pulled back 3 notches. That way as soon as I let up off the accelerator I get some immediate slowing down.
Absolutely agree. The Retarder is a very useful tool when driving in stop & go traffic in a city. Besides helping to reduce your brake wear, it adds additional braking force when needed. Had to make a 'panic' stop on the interstate here in Austin one time and after hitting the brakes & pulling the retarder to 6, the coach stopped like a charm and actually did so significantly more smoothly than if I hadn't had the retarder.
I'm a believer and would not want to be without it.
Title: Re: Retard feature pros and cons
Post by: Dave M (RIP) on July 30, 2010, 03:47:21 pm
Just think of the poor Newell with a Jake brake, at 55K + lbs and drum brakes or a 1965 Pontiac Station Wagon trying to stop behind you in a panic stop. Your FT is gonna get creamed I bet. I also have played with a simulated panic stop on a dry road, I started laughing, it stops like a car, not a bus or truck. MO Dave
Title: Re: Retard feature pros and cons
Post by: Peter & Beth on July 30, 2010, 04:40:37 pm
Yup, Dave...I did the same panic stop test on my little 34 footer. Not what I had anticipated. Next time I try that I'll make sure to glue everything down inside the cabinets. Thankfully I was alone driving, otherwise I would have had to glue down Charlie & Cokie, too (Yorkies, 5 lbs each). :)) The coach's dry weight is about 25,000 lbs. and has the same chassis components as a 36' (I think).
Title: Re: Retard feature pros and cons
Post by: Tom Lang on July 30, 2010, 06:55:57 pm
I too had one of those panic stops, but it was unplanned. Driving on one of those four lane almost-freeway highways with a 65MPH speed limit and stop lights. One turned red at the absolute worst time, and I had to slam on the brakes. The joystick was halfway back, reducing some of the latency on retard activation when I hit the brake pedal. It stopped much quicker than expected, and easily short of the intersection. Everything not nailed or glued down slid forward.
Title: Re: Retard feature pros and cons
Post by: PatC on July 31, 2010, 10:43:25 am
I heard this from the previous owner of my coach. Kind of laughed to my self having driven class 8s for a very long time. Have not used the retarder yet. Guess I will have to try it out. Mine is on the 4 speed and just on and off. Pat
Title: Re: Retard feature pros and cons
Post by: Dave M (RIP) on July 31, 2010, 10:14:38 pm
One small point, I feel the retarder is too aggressive with light brake application. When I only want to slow just a little, I only use the joy stick 1 click as with brake pedal, even very light application the retarder over brakes with the 1/3 setting, think that is 2psi on brakes or 1st step. Just wonder if anyone ever had the transmission reprogrammed for 1/6th in first step. ? Wondering Dave
Title: Re: Retard feature pros and cons
Post by: Rod O on September 15, 2010, 08:43:26 pm
In a nut shell there are only two kind of RV owners, those that have a retarder and those that want one. ;D
Title: Re: Retard feature pros and cons
Post by: LBoyd on September 15, 2010, 10:55:55 pm
We just did I-70 from Grand Junction to Denver. When we planned the trip I was very worried about that section as it was my first experience with the FT in mountains. Three 10k passes and many lesser grades. I'm now a total believer in the retarder (it was dry) for highway driving. I think you can over do it, particularly in stop and go.
Title: Re: Retard feature pros and cons
Post by: Chad and Judy on September 16, 2010, 04:14:27 pm
Not sure about the "over-do-it". I use the retarder on every deceleration / stop, thou I do leave the lever fully forward when not in-use to avoid auto actuation. (As did the first owner of this coach.) As-of 90K miles my brakes are at roughly 70% remaining.
Best regards!
Chad and Judy '98 U320 - Wickenburg, AZ
Title: Re: Transmission temp gauge questions??
Post by: Chris on November 26, 2010, 04:37:08 pm
Hey folks,
I was hoping for some input. I noticed on my last trip that my transmission temp gauge did not seem to be registering a temp, the retarder was off as I was going down very icy grades in the Oregon Mtn passes. The temp outside was around 20 degree's...I recently had the engine oil changed, they checked the tranny oil as well but did not require replacement fluid...I am just wondering if it was so cold or because the retarder was turned off that the temp was not registering ..thoughts?
Chris Reiter 98 U270
Title: Re: Retard feature pros and cons
Post by: George Stoltz on November 26, 2010, 04:54:06 pm
Chris,
You are bringing up not only a timely topic, but a very controversial one as well. I have been told not to use the retarder on icy roads. My solution is to not drive on icy mountain roads. Period. Others will chime in.
Title: Re: Retard feature pros and cons
Post by: amos.harrison on November 27, 2010, 08:37:48 am
Chris,
At cold temps without retarder use you likely won't see the trans temp gauge register. Looks normal to me. Wait and check it when you can use the retarder again.
Title: Re: Retard feature pros and cons
Post by: Chris on November 27, 2010, 08:59:28 pm
Bret,
Thanks for your reply...when I take out my coach and put the retarder in use I will be sure to look at the tranny temp gauge..ideally it will register. Happy Holidays...