Retard feature pros and cons

Topic: Retard feature pros and cons (Read 4675 times) previous topic - next topic

Re: Retard feature pros and cons

Reply #25 – July 11, 2010, 01:13:25 pm

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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.

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Also, I read somewhere that one should not use the retarder in the rain? Reason?

It affects the ABS system from functioning properly.

Re: Retard feature pros and cons

Reply #26 – July 11, 2010, 01:18:54 pm

Quote from: old_nodaker – 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

Gayland -- I've already given my 2 cents

Re: Retard feature pros and cons

Reply #27 – 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).

Re: Retard feature pros and cons

Reply #28 – 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

Re: Retard feature pros and cons

Reply #29 – 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

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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

Re: Retard feature pros and cons

Reply #30 – July 11, 2010, 02:06:30 pm

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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.

Re: Retard feature pros and cons

Reply #31 – 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

Re: Retard feature pros and cons

Reply #32 – July 11, 2010, 03:19:22 pm

Quote from: George Stoltz – July 10, 2010, 02:09:41 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.

Re: Retard feature pros and cons

Reply #33 – July 11, 2010, 04:54:29 pm

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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.

Re: Retard feature pros and cons

Reply #34 – 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'

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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.

Re: Retard feature pros and cons

Reply #35 – 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

Re: Retard feature pros and cons

Reply #36 – 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?

Re: Retard feature pros and cons

Reply #37 – 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

Re: Retard feature pros and cons

Reply #38 – 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?

Re: Retard feature pros and cons

Reply #39 – 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.

Re: Retard feature pros and cons

Reply #40 – 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.

Re: Retard feature pros and cons

Reply #41 – 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

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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'
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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.

Re: Retard feature pros and cons

Reply #42 – July 13, 2010, 12:20:41 pm

Quote from: Paul Smith – 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 from: Paul Smith – 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

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.

Re: Retard feature pros and cons

Reply #43 – July 13, 2010, 02:28:30 pm

I'm not sure what to do about this. Please advise.
best, paul

___

'Thriving not Surviving'

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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.

Re: Retard feature pros and cons

Reply #44 – 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.

Re: Retard feature pros and cons

Reply #45 – 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.

Re: Retard feature pros and cons

Reply #46 – 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.

Re: Retard feature pros and cons

Reply #47 – 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.

Re: Retard feature pros and cons

Reply #48 – July 14, 2010, 10:39:17 am

Quote from: Peter B. Martin – July 13, 2010, 05:37:17 pm

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.

Re: Retard feature pros and cons

Reply #49 – July 14, 2010, 04:21:49 pm

Quote from: D.H. Spoor – July 11, 2010, 01:20:56 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!

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