NHTSA investigating Rear Diff Issues

MescalVto · #1 (**permalink**) 02-06-08, 11:52 AM

"My name is Stephen McHenry; I am an investigator with the National Highway Traffic Safety Administration of the US Department of Transportation. I am interested in the report you filed with us in April 2006 regarding your Cadillac rear differential.
Did you ever experience “wheel-hop” problems with your CTS-V?"

I just received the above message today. I think I reported leakage issues, interesting question . . . any one else getting this? What do you guys think I should say; wondering if answering yes to hop means they discount the issues experienced to potential "owner abuse" or if they are actually concerned about hop being an issue in itself?

onebadcad · #2 (**permalink**) 02-06-08, 12:11 PM

Wow, only took 21+ months to contact you. The Gov is sure getting more efficient.

There was a sticky for the NHTSA interest over six months ago, nothing ever came of it. You can reply if you chose, but do not expect much action.

rand49er · #3 (**permalink**) 02-06-08, 12:51 PM

I'd very honestly tell him the facts:

"Yes, I experience wheelhop if I try to accelerate very hard. Because I do not want to over stress the differential, I try to avoid inducing wheelhop. I wish I did not have to be so careful about that."

BrianTX · #4 (**permalink**) 02-06-08, 12:56 PM

Right right, I agree with being honest. Whatever the problem is giving misleading information or leaving out key parts will only serve to dilute the issue and drag out the process even more (if that is possible dealing with the federal government!). And you don't want to be the baseball player called up to testify that you didn't do steroids, right? LOL

**The Tony Show** · #5 (**permalink**) 02-06-08, 02:14 PM

I'm concerned about some "up and comer" trying to make a name for himself by turning wheelhop in a CTS-V into a horrific safety issue, ignorant of the fact that wheelhop can happen in just about any car.

atdeneve · #6 (**permalink**) 02-06-08, 02:18 PM

Quote:

Originally Posted by rand49er

I'd very honestly tell him the facts:

"Yes, I experience wheelhop if I try to accelerate very hard. Because I do not want to over stress the differential, I try to avoid inducing wheelhop. I wish I did not have to be so careful about that."

I would further explicate the conditions under which you would experience wheel hop because, honestly, I don't think you have to attempt a brutal launch in order to induce wheel hop.

From a roll in first gear (no clutch involvement), if you get deep in the throttle, wheel hop is very much a reality. I don't believe matting the throttle from a roll can be construed as abuse. There really is no shock to the drivetrain imparted by such behavior - normally.

Unfortunately, in such circumstances, we do happen to experience substantial shock in our drivetrain - specifically, the rear differential - due to wheel hop. To categorize any normally non-abusive behavior as abusive, simply due to a design defect that precipitates an unintended and ostensibly detrimental behavior - namely wheel hop - is harshabarsha.

Of course, after having learned the threshold point at which wheel hop is most likely to rattle ya rear, one would have to be an idiot to continue to knowingly induce wheel hop. Yes, that would be wrong. It would also be equally wrong, if not more so, for such a problem to be left unaddressed, knowing full well the inevitable damages that would result.

Furthermore, bring light to the fact that this behavior is emphasized in rainy / wet weather conditions, such that even an attempt to moderately accelerate in a simple everyday situation, such as entering a standing on-ramp, will leave you going nowhere. Could be quite dangerous in some situations. Perhaps just a nuisance in others (eg, having a long line of people honking behind you as you leisurely pull away from the light). Regardless, it's unacceptable.

Jyah, you should say that. You're not only being honest, but you're also further providing them with a wealth of helpful information for their research (jou shud get like a eagle skowht meddul or sumting). And they can't discount the differential issues as owner abuse. Bueno? Help them help us.

JBCTSV · #7 (**permalink**) 02-06-08, 02:19 PM

The real issue is a weak differential due to poor design. A recall on the diff is what is needed, A new diff that is designed and tested to take the 400+ lb ft of torque produced by the V car. Corvette and Camaro never had serious issues, Cadillac should setup up.

**The Tony Show** · #8 (**permalink**) 02-06-08, 02:34 PM

Quote:

Originally Posted by JBCTSV

Corvette and Camaro never had serious issues, Cadillac should setup up.

There's plenty of Corvettes with broken diffs from wheelhop, and Vipers, and Porsches, etc, etc.....heck- a forum member posted up recently about his FWD Saturn wheelhopping like a sonuvabitch!

Do a search on any Corvette or Camaro forum for "wheel hop" and you'll get 10 pages of threads.

atdeneve · #9 (**permalink**) 02-06-08, 02:40 PM

I like wheel hop. Wheel hop rocks.

NormV · #10 (**permalink**) 02-06-08, 03:41 PM

Probably a lawyer! I'd close the thread rather than deface the forum.

Norm

TrazzNJ · #11 (**permalink**) 02-06-08, 05:10 PM

Stephen McHenry is an investigator at the NHTSA and I will be talking to him shortly. My opinion is that if the car is going to wheel hop, the diff should be able to handle it. I have driven thru tire shake in a drag car that was so bad I couldn't see but the rear didn't break. I know......these are not drag cars but I think you would all agree that the rear diff in our cars is extremely under-engineered for the power and weight of a V.
I'll let you all know what he has to say.

WheelHop · #12 (**permalink**) 02-06-08, 06:03 PM

Quote:

Originally Posted by atdeneve

I like wheel hop. Wheel hop rocks.

Thanks man! You, too!!

lasstss · #13 (**permalink**) 02-06-08, 09:26 PM

Quote:

Originally Posted by TrazzNJ

Stephen McHenry is an investigator at the NHTSA and I will be talking to him shortly. My opinion is that if the car is going to wheel hop, the diff should be able to handle it. I have driven thru tire shake in a drag car that was so bad I couldn't see but the rear didn't break. I know......these are not drag cars but I think you would all agree that the rear diff in our cars is extremely under-engineered for the power and weight of a V.
I'll let you all know what he has to say.

I mailed a bunch of photos, documents e mails etc to these guys. No response although I did talk to them briefly.

STAGEUP · #14 (**permalink**) 02-07-08, 12:00 AM

Hmm, I dont see anything wrong with having a diff designed for the power of the base model CTS in a CTS-V. Unless you decide to drive the CTS-V with that diff.

TrazzNJ · #15 (**permalink**) 02-07-08, 11:49 AM

I spoke to Stephen for about 45 minutes this morning. He is testing and 04,05, and 06 I believe next week at one of GM's proving grounds. I told him what he could do to make the car "wheel Hop" as GM is saying the rears only break from abuse.
He seemed like a straight up guy that was just trying to do the right thing. It is more about a saftey issue than anything else. If you are pulling out into traffic and you blow the rear diff and get hit by a bus...kind of stuff.
All I would say is anyone who didn't report their rear end failure, do it now. The data base needs to be filled in order for us to have any chance at a recall fix.

WWW.Safercar.com
Do It !!!