tbl01

Hello All,

I finally purchased a 1989 s4 car form a Former rennlister/PCA member back in July of this year.. Car is in original condition, metallic grey, auto 92k orginal miles Nice. I immediately had new accessory belts, rebuilt ac compressor/drier(car was converted to r134a early this year) installed. Everything works on the car with the exception of the side markerlights, and just recently a small issue with interior lights above the rear view mirror.( have to search on that issue)

With all the projects around the house, and a newborn due any day now, I havent had much time to allot to my new toy. I am about to embark on doing the inner cv boots (myself)that are ripped almost all the way around. I have all the write ups form various sites so I shouldnt have too many problems with install.


I have used the search feature, and I have a question hopefully someone can chime in and advise me on regarding the cv boots/joints......

There is a low humming noise that emantes from the rear after about 40mph and gets louder with speed. No clicking noises form cv joints. Can bad cv joints cause this kind of noise?? I would tend to think it is wheel bearings, but from all that I have read on this forum is seems inconclusive.

I can pick up two axles in good shape for 90/piece. I would rather just do the boots, but definetly dont want to do the job twice.

Any additional advice on this subject which has been discussed before would be a great help.

Greg

littleball_s4

Welcome, greg.

Check tranny levels.

If you have access to a lift, ask a friend take a virtual ride in D while you try to locate the sound from behind. He can also brake gently and briefly to load the tranny. Luckily you would spot the noise.

If not, I would take the shafts out, take a look and spin the wheels by hand. If you can still say nothing about the sound, then put the other shafts in (you said you trust them).

If the sound is gone, you hitted it.

If not, install 4 new boots in your old shafts and ebay them as "in good shape, 92k, r&r" or keep 'em as spare as you continue looking for your sound.

PD: no, I don't need them

ROG100

Tires

Charley B

If the car sat for some time before your purchase the tires could have well flat spotted. the symptoms for this can be all over the map depending on the type of tire, amount of pressure in them, how long stationary etc. Sometimes just putting some miles on them will "true" them up, but maybe not. Max out the pressure and see if the sound goes away or appears at a higher mph. Do you feel a slight vibration in wheel or seat as you hear the noise? There are lots of possibilities back there but I agree with Roger, a noise or vibration that starts at speed is most often tires.

littleball_s4

Agree, tires are also suspicious, I forgot that one.

You'll have to change the boots anyway, and I suggest you do it asap. However, a little tire pressure test won't hurt. Go for it, perhaps you save the $.

tbl01

Thank you for all replies. I didn't think about tires; however they are about 4 years old (good year F1 I think)Tires have little wear on them. Car was closer to daily driver then show queen.
Ill have to check tire rack for deals... But then were talking rims....mods... must resist.

No vibrations that I can feel in seat or steering wheel. Having owned a 2001 cobra with the notorious vibe problems, I have been around vibe issues and then some.

rixter

I had a similar problem on my 88 and it turned out to be the wheel bearing...
put the car on a lift remove the wheels, put it in gear and push the gas, with someone outside the car at the back you should hear if it's the bearings... if you don't hear the sound I'd suspect the tires, especially at 4 yrs old

Bill Ball

Tire noise changes with the road surface, such as at transitions from asphalt to concrete. Bearing noise does not.

At $90, if the used axles have good boots and tight CVs, I'd far rather change them than change the boots.

mpesik

T.T

IcemanG17

Easiest thing to check is wheel balance or tire flat spots......if that doesn't fix it....then check the tranny fluid level.....still not it.....then I'm thinking torque tube or wheel bearings......try this.....put the car in neutral & rev the engine.....does it still make the sound?? If so then its the TT.......if not & it only happens when the car is moving and gets worse with actual speed (not RPM)....then its gotta be wheel bearing or axles?

AO

Is it speed dependent or RPM dependent? If RPM, it could he heat shields around the exhaust system Just something else to look at..

tbl01

The torque tube was replaced at about 40k miles with diff bearings. The noise is more speed dependent. much louder above the legal limit then 40. Tranny does seep, but level checked at PPI ok. I am going to check tires first, replace the axles outright with good used units.( probably easier to do then the cv boots, thathave been ripped it looks for quite some time.) probably should do rear wheel bearings at same time if not too expensive. . Thank you all for the responses and guidance.