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 #50 – 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'

Re: Retard feature pros and cons

Reply #51 – 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!

Re: Retard feature pros and cons

Reply #52 – 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?

Re: Retard feature pros and cons

Reply #53 – 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.

Re: Retard feature pros and cons

Reply #54 – 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.

Re: Retard feature pros and cons

Reply #55 – 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 . 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 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

Re: Retard feature pros and cons

Reply #56 – 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

Re: Retard feature pros and cons

Reply #57 – July 30, 2010, 02:19:04 pm

Quote from: George Stoltz – July 10, 2010, 11:27:45 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.

Re: Retard feature pros and cons

Reply #58 – 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

Re: Retard feature pros and cons

Reply #59 – 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).

Re: Retard feature pros and cons

Reply #60 – 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.

Re: Retard feature pros and cons

Reply #61 – July 31, 2010, 10:43:25 am

Quote from: Dave M – July 30, 2010, 03:47:21 pm

it stops like a car, not a bus or truck.

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

Re: Retard feature pros and cons

Reply #62 – 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

Re: Retard feature pros and cons

Reply #63 – 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.

Re: Retard feature pros and cons

Reply #64 – 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.

Re: Retard feature pros and cons

Reply #65 – 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

Re: Transmission temp gauge questions??

Reply #66 – 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

Re: Retard feature pros and cons

Reply #67 – 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.

Re: Retard feature pros and cons

Reply #68 – 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.

Re: Retard feature pros and cons

Reply #69 – 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...

Chris

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