: AWD Drivetrain Lash: Any True Fixes?



onewhippedpuppy
07-11-07, 07:20 PM
I've done plenty of reading on this forum, enough to find that drivetrain lash on AWD V8 models is a pretty common problem. What I haven't found is people who have had it really fixed.

At some point it seems that there was a "fix" that involved reprogramming the transmission ECU, and detuning the motor. Not really what I am looking for, but thanks for playing. I also saw mention of a "low-lash" transfer case.

I have a bit of a clunk at 42k, just enough to be noticable. With 8k on the factory warranty, I'd like to have it addressed, but only if the dealership actually has a fix for it. I have no desire for them to kill my power and MPG.

So, anyone actually had this problem fixed? If so, how?

Smokin' SRX
07-11-07, 09:15 PM
Well, here it is. I had my truck "re-flashed" in such a way that the RPM's throttle up slightly, while braking, to keep some downshift pressure on the drivetrain. NO engine power loss occurred! I may be wearing the brakes a bit extra, but I can't notice/feel it! I am satisfied. 21K miles. 18K when done.
Talk to your dealer. I don't have the re-flash #. They should know:bigroll:

King3244
07-11-07, 10:26 PM
I don't think there is a fix or at least none that Cadillac is prepared to do. If you look up technical service bulletins there is one there about the problem and like the famous oil usage in the old N*s it falls under "acceptable parameters".

Nice little catch phrase that! Sort of like catch 22 if you have read that old book or seen the movie.

john d
07-11-07, 10:37 PM
I've done plenty of reading on this forum, enough to find that drivetrain lash on AWD V8 models is a pretty common problem. What I haven't found is people who have had it really fixed.

At some point it seems that there was a "fix" that involved reprogramming the transmission ECU, and detuning the motor. Not really what I am looking for, but thanks for playing. I also saw mention of a "low-lash" transfer case.

I have a bit of a clunk at 42k, just enough to be noticable. With 8k on the factory warranty, I'd like to have it addressed, but only if the dealership actually has a fix for it. I have no desire for them to kill my power and MPG.

So, anyone actually had this problem fixed? If so, how?
Yes there is a fix...it involves replacing the transfer case with a "low lash" case. I think it's a Borg Warner.
Mine was replaced under warranty.
I got re-flashed before the TC was replaced and performance is ruined forever.
If your SRX is in the "yellow top" bulletin "most wanted list" the dealer is under some kind of mandate to re-flash your computer if your SRX is in the shop for ANYTHING. Once it's done there's no recovery.

john d
07-11-07, 10:54 PM
Yes there is a fix...it involves replacing the transfer case with a "low lash" case. I think it's a Borg Warner.
Mine was replaced under warranty.
I got re-flashed before the TC was replaced and performance is ruined forever.
If your SRX is in the "yellow top" bulletin "most wanted list" the dealer is under some kind of mandate to re-flash your computer if your SRX is in the shop for ANYTHING. Once it's done there's no recovery.
If your SRX was built before 5/14/04 (Look at the last six digits of your VIN if it's less than 192515) REPLACE TRANSFER CASE WITH LOW LASH DESIGN
(BELIEVE PART NUMBER IS 24233827 NOT 2423387 )
Let us know how it works out for you. Cadillac furnished me with a rental car while work was done.

onewhippedpuppy
07-12-07, 08:41 AM
john d, any TSB to support that? I like to have ammo when I go into a dealership. Did it fix your issues?

john d
07-12-07, 11:18 AM
john d, any TSB to support that? I like to have ammo when I go into a dealership. Did it fix your issues?
I'm aware of no TSB. It took a zone manager (or higher manager) to approve.
Don't get the TSB re-flash for the computer as the following thread discusses...get the new style TC.
I'll be unable to respond for the next week or so so hope this info is enough for now.
http://www.cadillacforums.com/forums/cadillac-srx-forum/31533-drive-train-backlash-clunk.html?highlight=10cars

avatards
07-12-07, 03:03 PM
I wonder if this problem is likely to occur on the new CTS 2008 AWD since they supposedly share AWD design with the SRX...

onewhippedpuppy
08-07-07, 12:23 PM
Update: The SRX is at the dealership. They seem aware of the issue, and are planning to replace the transfer case. Hopefully it will go smoothly, and without issue. Too bad they gave me a loaner 2007 Impala.:( What a POS. I can't believe people actually buy these.

ArcticAir
08-07-07, 06:12 PM
Off topic but when i put my 07 v6 SRX in for service GM paid for the rental and I got a 07 DTS V8. After driving the DTS for 2 days i really missed the SRX ! Theres no comparing the 2 cars SRX blows the DTS away! The DTS was like a boat on water ! A couple of things i did like about the DTS was AC SEATS & HEATED STEERING WHEEL and the SUPER SOFT SEATS!

john d
08-07-07, 09:50 PM
Update: The SRX is at the dealership. They seem aware of the issue, and are planning to replace the transfer case. Hopefully it will go smoothly, and without issue. Too bad they gave me a loaner 2007 Impala.:( What a POS. I can't believe people actually buy these.
OWP - That's great news!
You won't believe the difference especially if they don't do a detuning reflash.
It's like a different vehicle that's better.:)
Let us know what you think when you get your baby back.

terryk
08-08-07, 12:46 AM
Are you folks sure they are really detuning the engine or just changing the torque management on shifts, slightly higher idle and keeping the idle float higher during braking?

Did they actually remove timing at WOT? I seriously doubt it, but maybe ....

john d
08-08-07, 01:44 AM
Are you folks sure they are really detuning the engine or just changing the torque management on shifts, slightly higher idle and keeping the idle float higher during braking?

Did they actually remove timing at WOT? I seriously doubt it, but maybe ....
What "they" did was delay the WOT command from the accelerator to the throttle plate at the ECM. Plus they delayed throttle closure when the accelerator pedal returned to a power off position.
GM/Cadillac admitted the detuning in my mediation hearing calling it a design change.
Mediator said it wasn't a "lemon" or safety issue since it was a design change and he couldn't rule against GM/Cadillac.

onewhippedpuppy
08-08-07, 08:39 AM
Well, I didn't get a new transfer case, but they did fix the issue. At some point in the past, the ECU reflash was done on my Northstar, but not the TCU reflash. According to the service manager, that probably made the issue worse, because the programming in the ECU and TCU was different, and not designed to work together.

Impressions after one day: no more clunk. I can't duplicate it, previously it was easy. Transmission shifts more naturally now. Before it seemed to up and downshift at somewhat odd times, but now it is quite good. Idle is maybe 100 RPM higher now, and I did notice the throttle "hanging" when I let off of the gas. Both of my past BMWs used to do this too. There is no noticable change in engine response, and keeping an eye on the avg and instant MPG in the computer there seems to be no change in MPG. If anything, it is now more fun to drive, because the engine and transmission are on the same page. I will be watching it all very closely, but for now, I'm happy.

A tip though, for anyone who may have this same issue. My dealer did not know there was a TSB. After I gave him the number he determined that the ECU had been reflashed, but not the TCU. If I had not done my homework, they would not have done a thing. Make sure you take the numbers in with you, don't rely on your dealer to know.

onewhippedpuppy
08-13-07, 11:45 AM
Another update, the problem is NOT fixed. The transmission shifts much better, the car is more pleasant to drive, but it is not fixed. The clunk is less pronounced, but still there. It is at it's worst when coasting at highway speeds, then getting back onto the gas. Headed back to the dealer this afternoon, this time I will push for the transfer case replacement.