Help: Transmission or diff failure

[Jacob_Seattle]

Hello All,

I am hoping someone can help me with a recent failure I had with my 1999 NSX. The car has 37k miles and high boost comptech supercharger. It has Comptech 4.55 gearing and was most likely never driven hard. I am pretty sure it was never tracked (verified at Autowave last month as well as the info from the previous two owners). The upgrades have been on the car since 2003 and a little over 20k miles. It is a six speed manual and all work was done by Autowave in Huntington Beach, SoCal.

I just recently picked up the car and drove it 1200 miles. I took it to the track for possibly the first time in the car's history (very plausible claim). I had some all season tires on and it was not very planted around the turns as I would have liked. As a result I was probably driving the car at 6/10 rather than my normal 8/10. I had six laps in and I hear a very loud BOOM. I thought I dropped the drive shaft and it dug into the ground. I slowed down and coasted to the side of the track. On the way to a stop, there was a loud boom and kink in the drive train every wheel rotation. Once the track was cleared, I had the car towed (flat bed) to my garage and pushed it to my lift. It was probably pushed 5 car lengths and had the pop/boom sound every wheel rotation. The CV joints are good. The sound seems to be coming from the transmission and I would guess some of the gears broke off and are loose inside. However, this is my question for everyone. Is it my transmission or diff? It is not favoring one side or the other. Please view the movie:

http://www.youtube.com/watch?v=t_BXR_Qomic&feature=youtu.be

My theory, since the car is such low miles and has not appeared to have been pushed hard, is that Autowave's tech did not put in the gears properly. It was all ok until it was under some strain. I was not pushing too hard, again I was about 6/10 due to my tires and for me to get used to this car. I was fairly aggressive on my gearing as I was trying to find out what gear to be in at the different locations on the tracks. But again, 6 laps and less than 10 miles of actual track time. Please let me know what you guys think. I am also searching for the parts to replace what is broken. Thank you all very much in advance.

Jacob

 

[usafdarkhorse]

I'm sadly not familiar enough with the NSX's transmission and diff, but if there's a way you can pull the shaft from the tranny to the diff and spin the wheels, you might be able to single out whether it's the diff or not.

I had a diff blow up in my old Z (yes R200s do go boom). Was a fun experience. A pin let loose and chewed up the pinion gear. Sounded like a "clack" about every rotation. I would probably start suspecting the diff since alot of guys track their NSXs and don't have any transmission problems, and since the diff is not OEM.

 

[Jacob_Seattle]

I'm sadly not familiar enough with the NSX's transmission and diff, but if there's a way you can pull the shaft from the tranny to the diff and spin the wheels, you might be able to single out whether it's the diff or not.

I had a diff blow up in my old Z (yes R200s do go boom). Was a fun experience. A pin let loose and chewed up the pinion gear. Sounded like a "clack" about every rotation. I would probably start suspecting the diff since alot of guys track their NSXs and don't have any transmission problems, and since the diff is not OEM.

Thanks for the input. I also had the same thought, these transmissions are very robust. This should be especially true since I have only 37k on the clock. I tried to get the stethoscope out and try to hear where the sounds are coming from. I am not sure how to pull these two apart and test individually. Thus, I am hoping something happened that is more of a "typical" failure. Thanks again.

Jacob

 

[Mac Attack]

... The car has 37k miles and high boost comptech supercharger. It has Comptech 4.55 gearing and was most likely never driven hard.

Are you kidding me? So you're assuming a 13YO NSX with a high boost SC and aftermarket rear end has never been driven hard?

You bought a 13YO sports car that has been extensively modified. Sounds like you're trying to place the blame for it failing in someone else's hands. Sorry it happened, but unless it came with a warranty, buyer beware.

A quick search brings up this thread:
http://nsxprime.com/forum/showthread.php?t=100290

This is a great forum with a lot of good information. I highly recommend you do some searches on the mods your car has just to become a little better informed.

Good luck with the fix.

Dave

 

[Mac Attack]

Also, if you're going to track it in the future, read up on the engine oiling issues and spun bearings. A baffled oil pan is a must. An Accusump is even better. While the engine oil pan is out, put a bung in so you can monitor oil temps.

 

[shawn110975]

my opinion on cars that previous owners put SuperChargers on is for the whole reason to track it.

when you do finally get the transmission out
your tech will know if it has been tracked.
I am sure there are signs.

and I have heard of some guys that take the instrument cluster out and unplug the miles clock only on track days.

yes its illegal but I have heard them doing it. to keep the miles down.

seller says " heres the reciept when i got the super charger installed 30K miles, now look at the instrument cluster see 32K miles so its not been driven alot as you can see it only has 2K miles more "
Buyer says " wow your right its a low mile NSX "

thats another reason why I stay away from any NSX that has been modded like this and another reason why people revert back to stock when tring to sell the car.

one thing you can check is the 2 screws above the instrument cluster bezel, do the screws look like they have been removed before? as the paint/coating will be scraped off from the screwdriver.

Im not saying your car has this just sayin its an easy check.

 

[Honcho]

How do you know the CV joints are good? You would not know they blew by looking at them- you would have to take off the boot and look at the joint itself. This sounds like a CV gone bad. I would inspect them before spending the time and $ cracking open the trans.

 

[usafdarkhorse]

^^^ this

Easiest first I suppose.

I figured the tranny and R&P were all housed in the same case, so my suggestion may not be possible, at least not so without cracking open the case.

Good luck and let us know what you find.

 

[Jacob_Seattle]

Thanks for the info and replies thus far.

I want to clarify that my 13 year old car is bound to have some issues. I am not disappointed in the performance of my NSX. I am certainly not under the illusion that everything will always be great and not fail. My intention of this post is to seek help from knowledgeable owners whom may have had a similar issue and can point me in the right direction.

I have searched and have seen what possible failures exist. I have seen that the 4.55 gearing "can" break. I have read that some transmissions fail. And of course CV joints fail. My question is from my video and information, can someone help identify my specific issue? I have good leads and of course the only way to know for certain is to open up everything. It just would be great to become more informed before the gloves come on (that is rubber gloves).

I am thinking that the CV joints are OK as the vibration and noises seem to be coming from the trans/diff. They could be transferred to one of these components and have an appearance of or an enhancement of sound propagated through into these components. Thus, it could be the CV joints. But then again, I would also assume that the CV joint failure would tend to be more prevalent on one side (ie the side that failed). Am I wrong in my understanding of this or with my logic?

I am still very appreciative of all input. Thanks again,

Jacob

 

[Jacob_Seattle]

my opinion on cars that previous owners put SuperChargers on is for the whole reason to track it.

when you do finally get the transmission out
your tech will know if it has been tracked.
I am sure there are signs.

and I have heard of some guys that take the instrument cluster out and unplug the miles clock only on track days.

yes its illegal but I have heard them doing it. to keep the miles down.

seller says " heres the reciept when i got the super charger installed 30K miles, now look at the instrument cluster see 32K miles so its not been driven alot as you can see it only has 2K miles more "
Buyer says " wow your right its a low mile NSX "

thats another reason why I stay away from any NSX that has been modded like this and another reason why people revert back to stock when tring to sell the car.

one thing you can check is the 2 screws above the instrument cluster bezel, do the screws look like they have been removed before? as the paint/coating will be scraped off from the screwdriver.

Im not saying your car has this just sayin its an easy check.

Good point and good issue to look out for. I guess there are quite a few guys out there that are not shy to cut corners. This would not be a positive prior issue to have.

 

[TyraNSX]

Have you drained the oil using a strainer or gone through it with a magnet to look for chunks?

 

[davidf]

Get out your wallet.:frown:

 

[SFNSXguy]

As the owner of a Comptech 4.55 R&P I suggest that is the failure. These R&P are marginal at best and are only recommended (needed) on a NA engine. When the 4.55 was used by Peter Cunningham there were several failures, enough for them to stop using them.
I love the 4.55, but my engine is stock -- you're producing a lot more HP.
Sorry for your pain, but you should talk to Chris at SoS about R&P repair and options.
Good luck with this (and I hope I'm wrong and that it's something a lot cheaper).

 

[EdinKali]

I'd put my money on it being the 4.55 R&P as well. Known issues with that product.