WHenever i get to around 104, my rear creates this hum/vibration feeling. It seems like it originates from the passenger rear tire area. When i let off at over 100, it gets a little worse till it gets down to like 90 then goes away. My thoughts are bearings. What are y'alls thought?

john

 

tires would be first place i looked

 

air pressure and tires are good (i work part time to Express Tire).

Other thoughts?

john

 

how much gear oil is in the diff?

 

i replaced it about 2 months ago, hummed before and after. Filled it up to the fill hole on top on a level surface.

john

 

sounds like it's time to actually take a look at the bearings and gears.

 

yup...


or you could just keep it under 100....

 

wheres the fun in keeping it under 100?

john

 

living to drive it another day

 

what he said or not killing someone else while you're having your stupid fun, not having insurance rates higher than mine.

 

**thinks about this**


OOOOOH.. KagA152 and ede... THATS why you guys are so slow at the dragstrip and why you never show for trackdays..... you're afraid going faster then two digits will cause the car to spontaneously combust.




heh, rather then judge his useage of the car, lets stay on the topic of diagnosing it.

 

i have absolutely no problem endangering my own life at the strip, but not on the streets where there are other drivers and no ambulances standing by.

anyways, whens the last time the bearings were replaced, if ever?

 

I have not replaced the bearings, and i have owned the car for 2 years.

WHen i am hitting speeds at over 100, it is in a certain area that is all privately owned by people i know, they let me have fun with my car there and beat it up a little, and there are not other people around to injure. If i hurt myself, so what, but i do not wish to endanger the life of someone else.

 

silly question....is it your driveshaft?

 

should i take it to get balanced somewhere? where would i even begin to look for a place that does that?

 

If its not an aluminum shaft ill bet thats the problem. Get a nice aluminum one and see what happens.

 

Yep...Go to a junkyard and try to pick up a real nice LS1 driveshaft in good condition.

 

dont waste time or money on balancing the one you got, goto a bone yard and find either an alum 3rd gen, or any v8 4th gen one. they are aluminum and dont have the ballance issues that we have. If you still have the problem after that....also, when was the last time you had your tires balanced? try swapping the rear 2 wheels (only if your tires are bi-directional) and see if the issues moves with the wheel (DO NOT try and swap the front and rear though).

Hope this helps man

 

Here is another one for the driveshaft - I was wondering when someone would say that magic word. You could be really extravagant and get an $800.00 carbon fiber driveshaft

I would be so afraid of that unraveling from a rock hit or something.

 

tires are balance and rotated about once a month, i work for a tire shop part time, so tires aren't a problem right now.



I will try to find an aluminum driveshaft then. What years and models were they available on the third gen?

john

 

Hi,

I have exactly the same problem and bought an alum. driveshaft. It moved the hum further up the speedo range (110mph) but is still there. I think it has to be bearings or something back there. Good thing is that it's an incentive not to go over 100, which can only be a good thing

Good luck & let me know if you track it down!

Felix

 

Hopefully i got the problem solver in my garage, A new rear end compliments of Z28Dude. Now i need to find an aluminum drieshaft to help too.
I want to think about what you said though, put a lighter driveshaft on and the hum didn't happen till higher speeds. So the weight up the driveshaft spinning, vibrating on the rear end, hum. less weight, less vibrational force... are you running a manual too? where might the viberation be originating?

john

 

Hi,

No mine is a 700r4. I'm guessing that because the alum. shaft is smoother- it masks the problem?? I would go the new rear end route but mine is a Borg Warner with the nice brakes so I want to try and solve it.

I still think the hum is coming from the wheel bearings or one wheel is out of true and shaking slightly- and it isn't my tire.

It's a problem that is livable with... just!

Thanks,
Felix

 

I have the same problem, I'll tell you what it is when I find it . Please do the same with a reply to this thread.

 

I started getting a funny noise/?vibration at around 105-115mph after one of the adhesive balancing weights on my rear drivers side wheel fell off. So I'm betting that's the problem. The good thing is that it doesn't reappear the whole way up to over 140mph!

What kind of shop would you ask about balancing a driveshaft? Can that be taken care of by the same kind of machine shop that does does rebores etc for engine rebuilds?

ZZ42Fast:- Have you tried to find any parts/suppliers for the 9-bolt rear over here in the UK? Are you getting the new cover for it which is coming up?

 

well, this post has been down for a while, did a search and thought that i would post about my vibe now.
Got an aluminum drive shaft from a 98 ss, now my 105 mph hum is gone, well, i can't get the car up high enough too hear it anymore. my new driveshaft is highly out of balance, vibes very bad up to 60, then calms till 65 and gets increasingly worse. I will be taking it over to a driveline shop to be balanced, hope that works.

john

 

from what I understand most driveshafts will make a vibration like above stated when the shaft reaches 1/2 the critical speed. Diameter, balance and a few others variables affect the critical speed of the shaft. Things like rear gear and tire diameter affect how fast the shaft has to turn to get the vehicle up to speed.

i.e. The same shaft that had a vibration at set speed with a low numerical gear like a 3.08, 2.73 will cause the same vibration at a lower vehicle speed like with a gear like a 3.73 or 4.10 . by installing a better shaft you have raised the critical speed therefore the vibration that comes aproximatley at 1/2 the shafts critical speed will be raised.

driveline shops that build driveshafts can more effectivly balance your drive shaft than the factory did. They can even build you a custom d/s.

This is just what I understand from what I have reasearched. I thought I would share it with the board. If I am wrong let me know.