48RE + Exhaust Brake: Current Status

[MojaveJoe]

Thanks Carlton

Keep us posted on any new developments you hear of. Your input, though not always what I wish I was hearing, is useful for relieving my stress over whether I will be installing an aftermarket e-brake, or waiting on D/C. For now, looks like a few years until I reach my 70K. So until then I think I will just keep my 5'er service brakes in top shape, and use 2nd gear when necessary



Regards,

Joe

 

[dandlwiley]

Carlton, thanks for your continuing input. You sure can't get this info from DC! Joe, you think you have stress wondering if you should add a Jake Brake--how about us folks who have one--dealer-installed--and are almost afraid to use it! We long for the days of the standard transmission and Pac Brake--we used that combo all the time. I still think that those of us who have the "bad" combination of e brake and transmission--dealer installed--should have some recourse from DC, other than just taking the brake off. You have a lot more weight to stop than we do. We'd go to the 6 speed in a heartbeat if we could.

 

[ACerf]

Exhaust Brake

What upsets me is the fact that the 48RE was suppose to be able to handle the E-Brake. Now it is okay for the later model 48 because it has a ECM and the earlier ones have a PCM. It would seem to me that when they were engineering the trans, they would have taken the E-Brake into consideration!

 

[Carlton Bale]

Re: Exhaust Brake

Originally posted by ACerf

Now it is okay for the later model 48 because it has a ECM and the earlier ones have a PCM.

The 48RE with ECM control has still not been warranty-approved for use with the exhaust brake. There will be thrust washer changes (at a minimum) required before official approval is given.

It would seem to me that when they were engineering the trans, they would have taken the E-Brake into consideration!

I understand. The exhaust brake caused warranty concerns and DaimlerChrysler didn't want to hold-up the release of the 48RE. DaimlerChrysler and Cummins are working together to address the issues that keep surfacing now. We're going to try to make sure exhaust brake compatibility is not an issue if different transmissions are released in the future.

 

[Rosco]

Carlton,



I have a 2004 Cummins/48re so I will assume that my truck is using the ECM to control the trans. Now, is this thrust washer buried deep in the trans or is it easily replaced? Also, can my trans even accept the upgraded washer?

 

[Carlton Bale]

Originally posted by Rosco

I have a 2004 Cummins/48re so I will assume that my truck is using the ECM to control the trans. Now, is this thrust washer buried deep in the trans or is it easily replaced? Also, can my trans even accept the upgraded washer?

Rosco,



The thrust washer is not easily accessible. I've never taken a 48RE apart but based on the schematic I saw, it is not an easy swap. I believe it is backwards compatible. One of the changes being addressed is high speed second gear reverse torque.



Keep in mind, I'm not a DaimlerChrysler employee and I don't have any athourity on the transmission or warranty.

 

[Rosco]

Thank's Carlton.

 

[ACerf]

Exhaust Brake

I can understand that DC didn't want to hold up release the of the 48RE. But, it appears they should have done more testing before doing so. All to often manufactures want to get a product on the street before it is really tested, and than the consumer pays the price of testing it for them! In this case DC did half the job, which leaves the early model 48RE owners holding the bag! I am glad that it is a better trans, because frankly I did not want the 47RE. But on same token it should have been "THE" trans to have! Not to mention it should have been a 5-Speed. But I guess I am asking for to much! But thanks for the help Carlton, it isn't your fault.

 

[Carlton Bale]

I'm disappointed to be giving another update that does not announce exhaust brake compatibility with the 48RE. DaimlerChrysler and Cummins are still working to validate it for warranty-approved exhaust brake application. There has been substantial dyno and vehicle testing over the past few months and some issues have been identified.



I still hope that we can get the exhaust brake warranty approved for the 48RE. At this point, it may be MY05 or later. If the approval is backwards-compatible for previous model years, I'll be sure the let everyone know.



Bulletproof reliability is the objective and we're still working to achieve that before releasing the product.

 

[JRG]

I would think that if it were back wards compatible, there would still be a programming issue, esp on an 03. 5. Also I bet DC would see their warranty claims go up... ... a little bit



JRG

 

[brillmtb]

Perhaps they should have gone for the 6 speed Mercedes transmission?



Also, I have a friend who was able to speak with a DC engineer who stated that only problem with using an exhaust brake on the 03 48re is that the driver can select modes where there is no lockup, not that the transmission cant handle it. Since it is a driver dependent issue they didnot not feel comfortable approving it.



I think thats why all the effort/rumors are directed towards making a sustem where the diver cannot manually select a mode using the gearshift or OD button such that the exhaust brake would be engaged and the TC is not locked.



None of this helps us poor 03 owners who wish not to void our warrenty.



Damm shame, I think DC owes us big time!

 

[brillmtb]

Perhaps they should have gone for the 6 speed Mercedes transmission?



Also, I have a friend who was able to speak with a DC engineer who stated that only problem with using an exhaust brake on the 03 48re is that the driver can select modes where there is no lockup, not that the transmission cant handle it. Since it is a driver dependent issue they didnot not feel comfortable approving it.



I think thats why all the effort/rumors are directed towards making a sustem where the diver cannot manually select a mode using the gearshift or OD button such that the exhaust brake would be engaged and the TC is not locked.



None of this helps us poor 03 owners who wish not to void our warrenty.



Damm shame, I think DC owes us big time!

 

[Carlton Bale]

Originally posted by brillmtb

... only problem with using an exhaust brake on the 03 48re is that the driver can select modes where there is no lockup, not that the transmission cant handle it. Since it is a driver dependent issue they didnot not feel comfortable approving it.

Originally, that was the case but additional hardware modifications have since been identified. One or two internal changes to trans hardware are being considered and then more testing to make sure everything is OK.



You're right about 03 vehicles, it's unfortunate that the software changes are not backwards compatible but it looks like there will be trans hardware changes anyway.

 

[dandlwiley]

brillmth: We are with you on the statement that DC owes the 2003 owners big time! We are pretty steamed about this, and not happy with the way the Jake works with the 48RE. We DO have a written DEALER warranty (which we trust) that covers the use of the Jake with the transmission, but at the end of that warranty (70K miles) we are back to rebuilding with an after-market, I guess. We didn't tow much this year after getting the new truck and Jake, but when we did we really were aware of lock up and did a lot of manual shifting, which is OK with us. We don't tow in OD.



Those of us in this situation need a name and address at DC to register our complaints. Anyone willing to spearhead this project? I currently don't have the time. Having DC reply with something like "take the Jake off" isn't a solution--we would not have purchased the 48RE knowing it wasn't e brake compatible.

 

[JRG]

Carlton,



I have a couple of problems with the "excuese" that have been given as to why I am not "approved" to have an exhaust brake on my truck.

• If I am in gear, exhaust brake engaged, how is this any dirrerent than the same situation with a gas engines compression braking? The transmission doesn't care.
  
• If the converter is unlocked, how does this put stress on the transmission? Fluid shear doesn't make sense, as there is no change in rpm on decelerate with the brake engaged or not (700 rpm) The converter doesn't care what motor is in front.
  

My bottom line is that I don't see the difference in a Cummins with an exhaust brake and the natural compression braking of a gas motor.

Just ticked that DC is backpedaling this issue. Lots of people purchased because of the 48re, me included. It should be made right. What good is it to have a Cummings if you can't use it safely? Ford and Chevy got it done.



JRG

 

[Carlton Bale]

JRG,



I'm hesitant to respond because I don't want this to be confrontational in any way. The reason I started this thread was so that users interested in using an exhaust brake with the 48RE would be informed of the progress. Communication changes were requested by owners and this is one small way I'm trying to help. If I'm hurting more than helping, I may need to rethink the approach.



The failures are real. I saw some parts last week that came out a test truck that had only 5,000 miles on it. The thrust washer in question is loaded only when the exhaust brake is engaged and there was substantial wear.



There are several differences between an exhaust brake on a diesel and intake-throttle braking on a gasoline engine. First of all, the compression ratio is much higher on a diesel, resulting in more braking force at the flywheel in certain situations. Secondly, and much more importantly, a throttle on the intake side produces vacuum during the piston's downward intake stroke and max possible vacuum is 14 psi below atmosphere (10 psi manifold vacuum pressure is more likely).



On the other hand, an exhaust brake causes extra force during the piston's upward exhaust stoke. The maximum pressure is designed to be around 60 psi above atmospheric conditions. With a retarding pressure that is up to 6 times higher (in absolute terms), the diesel brake is noticeably different from a gas throttle. The result is much more reverse torque being transmitted through the trans.



As I mentioned in a previous post, when the torque converter is unlocked and it is trying to re-lock during exhaust braking, all fluid is recirculated internally to try to build pressure. When this happens, the trans fluid does not pass through the trans cooler and there is a lot of fluid shearing going on. This is acceptable for short periods of time. However, during exhaust braking only, this condition can exist for the entire downhill run. This can result in very high trans fluid temperatures inside the converter but still normal temperatures in the trans pan where the temp sensor is located. Overheated trans fluid, as I'm sure you know, is never a good thing.



Hopefully this has helped answer your questions. Since I have no official involvement with the transmission or warranty, there is not much I can do other than try to keep everyone informed of what I know from an exhaust brake perspective. I hope I'm helping.

 

[RankRam]

Carlton don't think we have any ill feelings toward you.



We all appreciate your knowledge and input in this matter but as an 03 48RE owner that once had 99 5 speed with a Jacobs E-Brake I wish I never purchased this auto. The auto is nice but without the E-Brake available it will be my last auto and I don't care how great the next auto is I will have a 6-speed come heck or high water!

 

[TCDiesel]

Brake

Mr Bale,Don"t shrink back because someone express a opinion on the subject,I and you have disagree on the exhaust brake. I would put more effort into a engine brake. Cummins already has one for the ISL motor. I like your post ,Please continue sharing the updates.

 

[Dean Upson]

Carlton,



Your input has been extremely helpful and it is appreciated by all of us. Thanks.



Dean

 

[crabjoe]

Carlton.. Thanks for the update!

Only problem with the news Carlton is giving is that this is bad news for the '04 48RE owners also.



If the thrust washer can't pass as it is currently installed, I'm out of luck.



Man, I waited for the '04 because I thought the issue was that DCX's PCM couldn't control the 48RE correctly to keep it locked. Knowing that DCX replaced the control module by using the Cummins ECM, I thought they would have figured it out with a programming fix.



Why can't Dodge and Cummins get together to just make sure that the transmission can lock in all gears for the exhust brake? Wouldn't that fix the problem????