08 350z, 60k miles..

Was sitting at a stoplight, started out in 1st hear and car started shaking a little then stop, but when I started to roll I heard this weird noise that sounds like its with rotation.. So immediately pulled over into a parking lot.

Looked under car, and didn't see anything that had fallen or come loose so I just started slowly going in a circle and this is the noise I have:

http://www.youtube.com/watch?v=BkTD8cZV7Ro

I just recently replaced a wheel bearing and all has been fine for about 4 days now. The day after I replaced the wheel bearing I took the car to the dragstrip but that has been 2 days now and never had any problems until now.

Car handles fine and feels fine just has that horrible noise, so something is obviously wrong.

Just looking for some pointers while I'm at work, when I get off I'm going to get it up in the air.

Thanks!

 

Its a radar detector







Sorry couldn't resist. Sound like it's coming from your rear end. Didn't you say that it was a little noisy before because they didn't shim it correctly? Sounds like its getting loose and wearing out. V V V

 

Yep, that's correct. I bought pumpkin with the gears already installed for a steal. CIN Motorsports told me, after they installed the pumpkin, that it has a whine and whoever set them the first time didn't do it 100% correct. But it has been doing it for ~8k miles now with no problems.. but maybe it is going out..

Either way, I could not get the noise to happen again today, drove it 3 1/2 hours to the beach and didnt have a single problem... So maybe it was something stuck in my caliper or tire tread

oh well...

 

Well I guess that mystery has been solved, you gonna look for another one or go back to the stock ratio?

 

Yep.. may as well update this thread as well.. My diff failed or something tonight.. started making the same noise as in the video in the OP.

Was just sitting at a stoplight, went to take off in 1st and just heard a very loud "metal to metal" pop, so pulled over immediately and looked under my car to see this:




I haven't been able to get under the car to see what exactly happened... but after talking to a couple knowledgeable people, I think either the stub shaft popped out due to inproper installation or internal failure in the diff itself (spider gears or w/e).

SR71, I will be picking up a used 3.5 VLSD in a pumpkin already, will put it in, and on the side, over time, going to have some 4.08s thrown into this one if it its fukced.

 

Sorry to hear, I know you like the 4.08's.

 

I did.... I wonder that, them being set incorrect, if I was getting the full benefit of the 4.083 final drive though?

 

Sorry to see all of this, big hassle. I hope that you get it all taken care of soon! I don't think the 4.08's had anything to do with this; I'll bet that the installer did a poor job getting the correct shims/tolerances; maybe even bearings. Getting the correct shims and/or combo of them is critical to doing a fair job or if it's done correct. That is why no shims come with the kits; it's different with every car and a good mechanic will put it together, check the tolerances and take apart and adjust accordingly. That's why they sell such a long list of shims (about $18 per), but it's worth it to buy extra ones even if they don't get used, so the installer can get it spot on. Plenty of guys get new fd gears and throw them together using the existing shims and call it good. Check your bearings too; not cheap for new ones, but gives you peace of mind with all new. Good luck with all of this!

 

Got the rear end out and opened her up... here's what i see

the pumpkin and diff cover are cracked:




Missing 2 bolts out of the (ring gear?):




Basically all of the bolts are loose:


Found 1 bolt just laying in the pumpkin, other one probably just got ate up i guess? see all the metal shavings on the inside:







So here is my guess.. the bolts came out, got lodged between the ring gear and the inside of the pumpkin and when it spun, it just cracked the pumpkin/diff cover?