Possible Rear Differential issue??Need some Help!!

[EuroxS4]

So I recently replaced my rear wheels bearings and checked the fronts and so on. I hear humming or high pitched noise at certain speeds. normally between 55 and 81mph. Anything below or above is quiet. I gonna guess the rear differential is the culprit. Question is should I bother changing the rear diff fluid to see if the noise goes away??? Also is there a heavier weight fluid that I can use to get rid of the high pitched noise???? Any Information at this point would be very helpful. Thanks guys!!!

[The_Jerbel]

Are you running the stock rear diff mount?

[Raacerx]

Depending on the mileage, a diff fluid change would be a good idea anyways. Worth it before you go swapping the entire thing out. You can go up in viscosity, but I would try stock since the new fluid will be considerably heavier due to it not having been broke down so much.

I would think the noise was more likely your driveshaft from the tranny to the diff. But yeah, if you have an Apikol rear diff mount or Stern power ring, then you aren't alone in whining around 60-70mph.

[Audi S4 Turbo]

I have a rear diff I am selling if that's the case.

[Congratulati0ns]

same noise right here too, i have apikol diff mounts and the stern ring thing, and it started whining after those mods, but as long as i know its nothing thats broken and its only the gear noise being transfered due to the stiff mounts, i really couldnt care less=]

[EuroxS4]

The whole car is all bone stock.

[The_Jerbel]

Change the oil and see what happens. You may have done something wrong if the noise started only after you replaced your rear CV's.

[Dimcorner]

I had this problem on mine and someone at AW went to a dealership to diagnose. It turns out it was a bearing on the rear diff (inside horn where drive shaft connects to rear diff). I have the part numbers that he changed if anything but I don't think the car will fall apart. I noticed that if I have the DTS connected the noise is much more noticeable so I think it's an alignment issue between the tranny and the rear diff. Humming is definitely from the rear diff since I had the car up on a lift and they got it up to 60mph and they used to probe to verify noise. It only happens on load as well.

[EuroxS4]

Kool thanks for confirming.Do you have those part numbers of the bearing and other parts that i assume have to be replaced as well handy? ?If you have the part number of the bearing in question please post.Thanks

[EuroxS4]

Pic Attached From Etka.I believe this is what I need just a matter of which part failed and what else has to be replaced.

[Dimcorner]

... Yeah that's gotta suck to install...

[EuroxS4]

Do you have those part numbers of what needs to be replaced by any chance?? If you do please post. Thanks

[Scotty@Advanced]

If you replace that pinion bearing you need a bunch of other stuff. It's cheaper and easier to get a used diff.

[EuroxS4]

Does Anyone have a list of parts that need to be replaced?? Or a link??? Any information that would be helpful to me.

[Congratulati0ns]

Does Anyone have a list of parts that need to be replaced?? Or a link??? Any information that would be helpful to me.

Honestly if its the bearing problem like you guys are saying, i wouldnt even bother changing that, theres plenty of s4 part outs in the classifieds and you can pick up a good rear diff for about 150-300

[Dimcorner]

(P/N's 01E 311 235A and 01H 525 193) is what the guy at AW changed and stopped his noise.

[EuroxS4]

Thank you for the part numbers. I think ill take a look into it and see if it can be done over a weekend of something. Thank you once again!!

[EuroxS4]

Ok so I realized how much of a pain it would be to replace those bearings. So my next question is this. My car has a DQA rear diff. Would a DAK rear diff work in my car???I check the the ratios are the same. Part numbers vary by prefix one has is a L other is a K. So would I be able to use either or??? Or do I need a DQA for sure???

[Dimcorner]

Thank you for the part numbers. I think ill take a look into it and see if it can be done over a weekend of something. Thank you once again!!

Yeah the guy said it had to be pressed out and and in.

[EuroxS4]

Yeah not only that but according to the repair manual it needs to be heated to be removed as well. At this point I need to figure out if a DAK rear will work or if I need a DQA that I have in my carm

[haus4]

I dont know the different codes for rear ends off the top of my head, but if you have a 6sp then you can only use a 6sp rear and vice versa for a auto.

[EuroxS4]

I believe DQA and DAK are found in a4 and s4 cars it doesnt matter wether the car is automatic of stick shift. Can anyone confirm and or tell me the difference if a DAK rear diff will work in my car even though its a DQA originally???

[lotusgardener]

I have a 6 speed 4.11 geared rear diff available for 275 shipped or a 3.889 rear diff for an automatic for 275 shipped also.

[EuroxS4]

Sorry I already found a replacement for cheaper.Just need to know if DAK is gonna work with my car.

[sfored]

Sorry I already found a replacement for cheaper.Just need to know if DAK is gonna work with my car.

ever find an answer to this ?

[EuroxS4]

Yes DAK rear differential will work as far as is know.I have a DAK coming hopefully this thursday or friday. I will let you know once i have it in the car.But i know it has the same final drive as a DQA. Same internally etka confirmed this as well. Only thying that is different is the axle shaft flanges also confirmed by etka. Will post info once its in the car. Thanks for looking.

[Congratulati0ns]

please let us know if you have an update on this, this humming is killing me

[EuroxS4]

Got my diff today just got it maybe 35mins ago. Unfortunately I wount have any updates till next week thursday. I believe the diff I received might be incomplete. i will have to take a look into it and make sure its all there.As of right now the neck part of the rear diff is not there I am trying to work out this issue with a seller.Looks identical to the one in my car If anyone want i can definitely takes some pics for what its worth. But i believe the problem bearing is in the neck part on the rear diff which i did not recieve. I will keep you guys posted till next week.

I feel your pain my high pitched noise is killing me to especial on highway.

P.S Make sure you dont have a bad wheel bearing. My diff only make the high pitched noise under load coasting its fine no noise.

[Congratulati0ns]

im confused man, wheel bearings are tight and checked 3 times already, and the reason im confused is because mine whines/humms under load a little and especially coasting, wheather im in neutral or in gear=[ any ideas? support bearing?

[EuroxS4]

Could be the bearing in the driveshaft that goes from the trans to the rear diff of the torsen diff in the rear of the trans. Normally if the dirveshaft bearing is no good you can look at it see its dry or check it for play side to side.

[EuroxS4]

If you have aftermarket diff mounts they will transfer the frequency to the car and you'll hear a whine at all times.

[Congratulati0ns]

yea i do have aftermarket mounts but its gotten louder since ive done them, ill check that support bearing...its this one your talking about right..

http://www.jhmotorsports.com/shop/ca...products_id=48

[EuroxS4]

yeah thats it.I know for a fact if you have the apikol rear diff mounts you will have a whine. So far alot of the guys that put them in have said they have a whine, i'm not sure if all but i recall there being another thread similar to mine where its was discussed that after apikol mounts were installed they noticed a whine.

[EuroxS4]

Ok So Its been a while. No Solution yet as I did not put in the rear diff as of yet.I should be getting the other part of the rear diff that I didnt recieve the first time around. So Hopefully this Thursday Ill have it.

[EuroxS4]

Just want to give everyone an update. I finally installed the DAK rear diff into my S4. My car came with a DQA rear diff. So Its confirmed that a DAK rear diff is a swap for the DQA you just have to swap the drive flanges for the rear driveshafts. Also It does not matter wether the diff came from a manual or automatic car as its the rear diff.

Most important things to remember is to always make sure that the diff has the same final drive ratio as the diff in your car in my case 4.11. So with that being said I had the diff in my car almost a week now and I couldn't be happier the car is finally nice and quiet. ETKA Also was very helpful as it will tell you the if there is any differences between internals of the rear diff.

It also doesnt matter from what car the diff came from.Its doesnt have to be from a s4. The rear diff i installed came out of a 99 audi a4 2.8 v6 automatic. Audi used the same diffs in the a4 cars and s4 cars. Only differences I found was the driveshaft flanges are different and the final driver ratio on the DQA and DAK rear diffs is 4.11.

I hope this info helps anyone that was contemplating this swap. I myself looked for an answer to this and couldnt get a straight answer and wasnt sure wether all the facts were true. In previously seen posts everyone has said that the rear diff has to be from a s4 and from a automatic if your car is an automatic or a stick shift if your car is a stick shift.

This is not the case as the rear diff also known as the final drive does not know what engine or transmission is driving the drive shaft that bolts up to the rear diff. Just wanted to clear that up as a few people sent me questions pertaining to this.

I hope this if of use to most of you if you ever need to Swap the rear diff out if you have a noise.

[EuroxS4]

Still have the same rear diff installed and going strong without issues guys!!

[rob]

I have a whine now, too. Also have vibs at 60 to 70 and a clunk on accel from 50 to 80. I tried the apikol to get rid of the clunk. It did not work and started the whine. Now, I'm going to try single piece drive shaft to eliminate the bearing. Thanks for the info on your diff, may try that later.

[Jesper P.]

My rear diff is noisy too, in addition, I have much play in the right side, I want to renew the position 4 and 6, but how to measure the thickness of the adjustment washer? can I use the targets from the original washer?

[Jesper P.]

I Got it fixed!

[Vespe]

Did you need to shims the bearing or changed only the bearings.
I assume shims was done when manufactured and change to new bearing do not change the fit of shims