Rear gear whine...opinions

Mintsick · Sep 22, 2011

I just got done swapping in an 8.8" with an auburn lsd and 3.55 gears that I got used into my 93. I added SVE upper and lower control arms and a Drake musclecars aluminum girdle with the bearing load bolts. Granted this is the first time running the car with this rear & gear setup but yesterday I took it to work and noticed a bit of whine at highway speeds (45-55 and 70+). I know for a fact the gears are not OEM Ford, I want to say they are US Gear...BUT if I had torqued the bearing load bolts on the cover too much could this cause the gears to whine? I know it's entirely possible that some gears just aren't as quiet as others, and of course I know that maybe they were not setup properly to begin with.

Kdubslugga · Sep 22, 2011

So you just swapped out the whole rear end, you didnt install the gears yourself? 9 times out of 10 the reason for whine is to much backlash "play between the ring and pinion gear". Gears should be measured with a micrometer and the play should be between 8-15 thousandths. If not this will cause the whine your talking about. Is the whine most notable on the highway when you let off the gas pedal?

Mintsick · Sep 22, 2011

That's right, I bought the entire rear end housing with the gears already installed. The whine actually only seems to be present with acceleration or constant speed, not while coasting on the highway. I've researched a ton about setting up gears properly but I just do not have the proper tools or location to check them out myself. I have heard of certain gears being noisier than others even when setup correctly but coming from a stock set of 2.73's and never hearing much of anything I guess I'm not sure what is "acceptable" or not. I will likely have a professional check the setup out to see what is up.

PhillyVert · Sep 22, 2011

Not to jack the thread,but my i got my rear rebuilt about 1000 miles ago.I got it totally rebuilt w/frpp 4.10's installed.I Mine whines at lower speeds though around 20-40mph.Ive been wondering what the noise is too.

90lxcoupe · Sep 23, 2011

you can check backlash with about 50 dollars worth of tools, you need a dial indicator, and a magnetic base. Just get them at harbor frieght, the chinese indicators work, and are accurate. There not as smooth or durable as american ones but no reason to spend over $100 on something you will only use a few times. I believe acceptable backlash is between .007" and .011" Its not hard to check, and IMO not worth paying someone $75-100 to check it.

Mintsick · Sep 23, 2011

That's a good point, it won't hurt to check it myself and I acquire another tool to add to the collection I could probably even adjust it if only the carrier side shims needed to be adjusted, I won't mess with removing and setting the pinion with 1 foot of working space on my back under the car though. Just ordered a dial indicator and the magnetic mount from HF, less than $25 combined.

90lxcoupe · Sep 23, 2011

Cool, there are some good writeups on the internet about setting up the rear when you get the tools in.

03ghoststang · Sep 23, 2011

if you r gonna re check the backlash and adjust here is a write up i did, i originally posted it on the 4.6L tech cause i had a 03'GT...but the actual gear swap was done on my 5.0L here is a link to it............

http://www.stangnet.com/mustang-forums/631757-little-how-install-gears-pretty-long.html

Mintsick · Sep 26, 2011

^ Sweet man thanks for the write up!

Rear gear whine...opinions

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