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Odd rearend noise

Old 03-02-05, 12:09 PM
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Odd rearend noise

I recently went to drivers school in Savannah, GA with my FB IT7 car. Throughout the duration of the weekened i noticed a hum coming from the rearened of the car. Towards the end of the weekened i noticed the noise had gotten slightly louder so i decided i better look at it when i got home. Upon pulling the 4:88 LS i didnt notice any probs with the clutch plates or anything the rearned appears to be in great condition. I also examined the rear axels and bearings and couldnt find any problems. Anyone ever have a similar prob or know what this might be?
Thankx!
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Old 03-02-05, 02:00 PM
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A couple thoughts:

Did you check the bearings in the diff? or just the on the axles?
Did you check the backlash on the diff gears?
Any vibration, or just a humming?

Marcus
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Old 03-02-05, 02:07 PM
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Did you check the u-joints closely for looseness, or binding ?

You mean you can actually hear your rear end over your rotary exhaust system ?
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Old 03-02-05, 02:11 PM
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the noise is just a humming. U joints are fine, as well as the bearings. Still kinda lost. Haha yes the noise was somewhat audible but definitely didnt drown on the 98db i blew.
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Old 03-02-05, 07:05 PM
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Hmmmm, did the hum only happen while on track ? Did the hum change speeds with the motor/car speed ? Could it have been the aftermarket fuel pump? I have a Holly red mounted near where the OEM pump was & it hums......... If it was a more rattle & you have a large a$$ exhaust system going over the axle it could be doing a number on something. I have 3 inch going over the axle & things are close. If you have a 3rd link is the drive shaft hitting the body mounting point ? If you have a 3rd link are the OEM upper control links bushings removed & replaced with some soft foam ? Let us know what you find please. We all like to learn.

Have Fun ; )
David
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Old 03-02-05, 07:16 PM
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What kind of bushings are you using in the rear? If you have spherical bearings it could just be the normal gear noise coming through. You can't hear it with all the rubber or urethane. It might have been louder because you were focused on it in later sessions!!
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Old 03-02-05, 07:32 PM
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My car is doing the same thing and its probably the wheel bearing but I'm not 100% sure. The wheel is not loose but something is definitely noisey on the right side and it wasn't before I started tracking the car.

http://fritz.sysadmin-racing.com/

clich on the link and download either video with the title beginning NASA VIR Full 2.05

Notice the humming is constant but when the right side is loaded it's considerably worse.
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Old 03-02-05, 11:52 PM
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I cant believe nobody suggested TIRES! It is amazing how loud a performance tire can get as it ages and gets harder. My Yokohama AVS ES100's started out completely silent, got old and with it loud as hell. I just replaced them with the same thing and back to no noise at all.
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Old 03-03-05, 09:26 PM
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humming

I recently installed AWR s solid bearings,sub frame mounts, and diff mounts in the rear of my car and I now hear a humming (really a whining ) noise which I did not here before. I hope jgrewe is right cause I really do not want to drop the subframe and diff again. Does any one else have the same noise with solid mounts and spherical bearings for bushings? Before the swap the car ran flawlessly with no noises at Buttonwillow for a 2 day HPDE. And After dropping it down from the stands I could here it as soon as I hit 25 mph. I am going to CA Speedway with NASA next weekend and really do not have the time to drop it and change out the diff as a precaution. I have had it on Jack stands in 3rd gear at 2500 rpm several times trying to hear where it is coming from the noise is quieter under the car than it is inside the car that is why I thought it was the solid mounts. Any insight would be appreciated. I really don't think I could muster the ***** on the oval portion of CS knowing the diff could lock up. The car is a S4 TII. Sorry if I hijacked your thread,but this seemed like the same problem we are having.
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Old 03-04-05, 04:01 PM
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when you hear the noise will help rule stuff out. does it get louder on in gear decel? accel? coast? turning like fritz said?
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Old 03-04-05, 05:26 PM
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noise

Mine does not get louder with engine rpm or speed it does change pitch though. It is definetly directly related to speed. It also does it coasting. There is no change in picth when going from in gear to neutral until the car starts to slow down. no change when turning

Last edited by Flynbryn; 03-04-05 at 05:28 PM. Reason: forgot somthing
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Old 03-04-05, 10:51 PM
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solid mounts on anything transfer a ton of noise and vibration
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Old 03-05-05, 08:29 PM
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My 88 TII whines between 30-45 mph on throttle only. No whine at any other speeds on or off throttle. Noise is the same whether maintaining speed (light load) or on full boost. I recently changed the rear lube out, and the whine got better for a while.

Anybody??? Friend says bearings.
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Old 03-27-05, 11:54 AM
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There is the slight possibility that what you are hearing is an increase in the lash between ring and pinion caused by the increased wear resulting from track use. I had the same thing happen to my se rear end on my first gen after the second track event I did with car. I had just replaced the 170k rear end with one from a 90k car. I used redline MT90 gear oil. After the second track event (200+ miles of track time per weekend) the whine coming from the rear end had become much louder. I will try to rememdy the problem by checking the lash between the ring and pinion to see if it is within specifications. Hopefully this will help.

Evita
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Old 03-28-05, 09:45 AM
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It sounds like i have the exact same problem as you. I feel it is either wheel bearings or my old *** bald as hell yokohama A032R tires (already known for tire noise when new). This is on my 3rd gen btw. It is definately directly proportional to vehicle speed, not engine speed or anything else. I hear it right from about i would say 5-10 mph and it gets to a possibly louder howl/whisstle (could just be pitch) as speed increases. I have new set of tires for the car, now. I am hoping this fixes the problem. If i remember, i will let you know if bad tires was the cause of MY problem. Maybe it will be the same thing.

Adam
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Old 03-30-05, 06:09 AM
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Well, i got the rear tires mounted. The tires had nothing to do with the whining noise coming from the rear end . I guess I am going to have to go with another angle on this problem. Maybe its the kaaz rear end I have in there.

Adam
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