exhaust brakes on allison/duramax

[raja402]

Does anyone have an exhaust brake on their
Chevy Duramax equipped with an Allison Automatic transmission?
Have you had problems with or any ideas? Somewhere I read that they were not compatible. Would like any ideas or comments.

Thanks. I really like this forum, I'm a newby to Montana and 5th wheeling,but I love it.

Randy, Jackie and Gabe Sweek
2002 Chevy Duramax 2500 Crew-cab
2004 3575RL Montana
Oregon based

[DHenry]

I do not feel that you would need one on the Duramax with the Allison. Also I think I heard that if you installed one that it would void your warranty, not sure, but would check before installing one.

[BillyRay]

I don't have the answer for you, but I know the one would work off the transmission, and the other I believe would work with the exhaust...so I don't know if you could or would want to use both

[ken]

I was told not to install a exhaust break on the Duramax if you have the automatiic trans. It is not worth the expense. This came from a large engineering firm that does all of the add ons from Banks exhausts to snow plows here in Virginia.
Ken and Velda
Dahlgren Va
2005 3475 Montana
2005 2500HD GMC 4x4 Crew cab, Duramax with edge and attitude, and 45 gal transfer-flo fuel tank.

[Glenn and Lorraine]

Welcome Randy and Jackie to the MOC.

I have been hauling my Montana around for 2 years. I started hauling it with an '03 Silverado and now I am using an 05 GMC. Both were the Duramax/Allison combination and at no time did I ever feel I needed any additional help stopping this rig. I have hauled through the mountains of New York, Penna, Virginia and most recently Tennessee and North Carolina with no problems at all.
When I first bought my '03 I spoke to the Banks Factory Rep at the RV Show in Harrisburg, Pa and he said that any additional add on braking was a waste of money. He felt the Tow/Haul Mode built into the Allison was all that was needed. When the FACTORY Rep says you don't need it who ya gonna believe? However he indicated that if I did go ahead and add any after market items the odds are it would void the manufacturers warranties on both the engine and transmission. That's a gamble I would not want to take for something the Banks Factory rep feels would be a waste of money.
As this subject has come up in the past I know you will be getting information to the contrary. If there is any doubt in what I am saying I would suggest you contact GM or Allison for verification.

[Dave e Victoria]

Actually, the new Duramax (LBZ) for 2006 changed some aspects of the turbo so it would work better with the exhaust brake. It apparantly spools up faster after idling. Also note that exhaust braking is offered as a factory option on C4500 trucks using the Duramax Allison combination

Here is the basic difference. The tow haul mode on the Allison depends on engine friction to hold back the load. There is no exhaust restriction so the engine is not restricted. Exhaust breaks puts a partial restriction in the exhaust system so that the engine has to push air out the exhaust. The exhaust stroke of the engine thereby holds back or brakes the turning motion of the engine. This restriction helps brake the whole load. It helps the tow haul mode by offering more engine braking and relieving the service brakes on the truck and trailer.

To be sure, here are good exhaust brakes and bad ones. Two variables make the difference. A good brake does not entirely stop up the exhaust. Rather, it is a partial restriction to relieve some of the pressure and temperature buildup. Second, less expensive exhaust brakes are activated by a simple switch in the throttle linkage of teh truck. More expensive and elaborate systems monitor truck speed and temperatures among other variables to help decide when and how much braking to apply.

Banks has one of the better exhaust brake systems and a very excellent tech writeup on their website. It convinced me. I plan to install one on our new 3500 GMC D/A when it arrives.

Also, it is important to note that exbhaust brakes are NOT the same as the old time Jake brake. Modern exhaust brakes are relatively less noisy. There should be no effect on your warranty provided you use a responsible aftermarket supplier.

[ols1932]

quote:Originally posted by Dave e Victoria

Banks has one of the better exhaust brake systems and a very excellent tech writeup on their website. It convinced me. I plan to install one on our new 3500 GMC D/A when it arrives.

I've had the Banks exhaust brake on my Ford since March 2002 and wouldn't be without it. It definitely helps slow the rig down and going down hill it is very good.

[Dave e Victoria]

I wanted to add a thought to this. We tow a lot in the mountains. Leaving Phoenix toward Flagstaff, there are several Long 6% downgrades including the descent into the Verde Valley. This is a long run -- maybe eight miles or so. It has banked curves and only one or two runaway off ramps. Returning to Phoenix, it is the same thing with the descent from Sunset Point thru a long winding drop into the valley. About once every other trip we see sombody with a trailer in the ditch along with the resuting backups.

These runs were scary in our old diesel pusher motor home. Scary when we pulled a travel trailer, scary when we had our Big Sky 3295 and scary with the Cambridge. Believe me, the tow haul mode is not adequate by itself. I approach these downhills at 45 watching idiots in four wheelers blast past at 75 or more. I find I have to develop a pattern of pumping the service brakes as we descend or speed will develope rapidly. While I thank GM for tow haul mode, I am definitely looking for anything to save the life of my service Brakes. It is true that I have almost 70,000 on factory original brakes with lots of life left but, even new brakes give up a lot of stopping power when hot. Therefore, if even a 20 or 50 % improvement is available with exhaust braking assist, I am all for it. I'm with Orv on this one. I'll have one on the new GMC.

[Ormee and Ginette]

I have found that the TOW/HAUL mode of the transmission is not sufficient in slowing the truck and trailer down... The service brakes must be used in order to get the vehicles to a slower speed in order for the Allision to down shift... The Allision will not down shift if the speed is to high for the next lower gear and will put the engine in an over rev situation... The exhaust brake is where this comes on very handy... I have installed a BD Engine Retarder about one month ago and thus far it has proved to be worth every cent spent...

[raja402]

thanks for the replys and info regarding exhaust brakes,still contemplatting. I really think however I am going to get them installed. Not sure which brand. Any help? Any ideas? Just got back from a nice trip, hope everyone else had a good weekend.

[Dave e Victoria]

I screwed up in an earlier post on this topic. The turbo charger on new 2006 Duramax does not necessarily assit exhaust brakes, it is an exhaust brake if engaged. It has a variable vane teechnology that can be engaged to restrict the exhaust.

Also, I said tow haul mode braking depended on engine friction. In fact, it also depends on the exhuast breaking existing in tyhe engine design due to the fact that there is naturakl restriction in the stock exhaust pipes and mufflers.

Ok, got that clarification off my chest. I suggest you go to the Banks website and read the material on exhaust brakes. It has a very clear description of how exhaust brakes work. Of course, they also promote the Banks version as one would expect. But, you will be armed with good info on which to base your opinion.

BTW, I applaud your decision to ge one. let us know what you decide and how you like it.
Dave

[sreigle]

I read that the new Duramax will have the variable vane geometry in the turbo like the Ford 6.0 has had since 2003. That will close the vanes under no throttle conditions, creating an exhaust backpressure. I find in the Ford the tow/haul and turbo initiated backpressure creates outstanding downgrade braking control on grades to 8% towing a Montana weighing 14,360 lbs. I would expect the newest Duramax with similar turbo technology will have similar grade braking performance. Also, when solo and NOT in tow/haul I find this diesel with that backpressure goes down grades just about the same as our 1999 V10 gasser did. Just my nickel's worth but wanted to point out the turbo change makes a big improvement in grade braking, along the lines of an exhaust brake. I'm not sure if that version of the Duramax is what is currently being sold or is to be available after the first of they year. I've heard both.

[Dave e Victoria]

Steve,
This is what GM Media has to say in their press release.

Another new feature of the Duramax 6600's turbo system is the capability of the variable-geometry turbocharger to provide exhaust braking. This function is available on some medium-duty truck models and can replace add-on exhaust brake hardware. With the new system, braking is controlled by a signal from the engine controller and can be activated by the driver.

This statement is confused even more so by the fact that the order sheet for the 4500 has a place where one can select an exhaust brake oprtion. This option is not available on the 2500HD or 3500. While the 4500 has the an upgraded LLY engine and the others have the LBZ engine, the turbos are suppossedly identical.

I've been asking the experts on the Dieselpage for a clarification but have not gotton one so far. If I get an answer, i will post it here. I'm most curious as I have a new 3500 DRW on order and wonder if I need to order an after market device. So Far, Banks is mum on the deal.