Noise From The Rear Diff

[stangman11]

Hey guys so when I bought my car I automatically heard that the bearings in the rear diff were bad. No biggie I had a set of 3.73 I had plans to put in anyway. So long story short I took it to a local guy I know well to put the gears in and now its the third time back at his shop for a sever whinning noise when turning. Everything has been changed in this rear including, new axle bearings, carrier and pinion bearings and even axles and the noise still persists. The only thing I can think of at this point is possibly the clutches or the axles were machines wrong. Just wanted to throw it out there to see if anyone had any input.

 

[MFE92]

What kind of car and what kind of axle, with what kind of brakes, are we even talking about?

 

[stangman11]

87 GT stock drums all just redone with new shoes spring kit and wheel cylinders with factory ford axles

 

[Gearbanger 101]

When you say "took it to a local guy I know", is that to say took it to a reputable guy, or just a guy with a reputation for doing inexpensive work. If you don't shim up the rear end properly, it'll howl. If he just threw in the gears without taking proper measurement, it's not going to matter how many times he pulls them in and out.....it's going to make noise. This could very well be your issue.

 

[pissedoff92]

also if he mixed up the shims and left even a tiny one out the ring gear could move side to side enough to growl whine or worse overheat or break teeth. ask him what the specs were, such as backlash bearing preload what the gear pattern looked like. so on and so forth. my money is on improper shims

 

[ratio411]

Yeah, it's hard enough to diagnose something like this online when the original poster did the work himself.
We are hearing from the 'middleman' on the work, and it really is impossible to do anything more than guess.
If you had done it yourself, we could get specific answers.

I will say that I had a rear end go totally out on a vehicle, and took it to a shop to just be replaced with a junkyard rear. Well, after they couldn't find a match in the area, and had the van all tore apart, I went ahead and gave them the 'go' to rebuild the rear. The guy claimed that he had built hundreds of rears, and knew what he was doing. I bought all new parts... gears, bearings, install kit, diff, etc... He did the labor.

Needless to say, he was full of crap. He broke parts installing them, the rear made terrible noises, and after he had it in his shop several times to try and fix it (and didn't), I just got my own junkyard rear and installed it myself. I should have known when he opened the install kit and complained that there was no crush sleeve provided... The Dana 60 doesn't use a crush sleeve!

 

[ratio411]

He could have messed up:
Pinion shims
Carrier shims
Crush sleeve setting (pinion bearing preload)

You could have messed up:
Break-in procedure

Also, if you have a Traction Lock diff, you need the 'friction modifier' additive along with correct oil.
The diff can make noise on turns if you use the wrong lube, or too much/too little friction modifier additive.
After a proper break-in, you MUST change the lube. The gears wear heavily on break-in, and leave all sorts of nastys in the lube.

Learn how to do a gear. It's not black magic.
I used to think it was. Now I do them myself, and was surprised how easy it is.

 

[krazedstang]

He could have messed up:
Pinion shims
Carrier shims
Crush sleeve setting (pinion bearing preload)

You could have messed up:
Break-in procedure

Also, if you have a Traction Lock diff, you need the 'friction modifier' additive along with correct oil.
The diff can make noise on turns if you use the wrong lube, or too much/too little friction modifier additive.
After a proper break-in, you MUST change the lube. The gears wear heavily on break-in, and leave all sorts of nastys in the lube.

Learn how to do a gear. It's not black magic.
I used to think it was. Now I do them myself, and was surprised how easy it is.

I too am one who thinks it's black magic. I'd like to do my own gear but am afraid of messing it up.

 

[ratio411]

There are 2 tricks to doing a gear.

1: Keep track of ALL shims.
The shim thickness that is used stock almost always works perfectly for the new gear set.
If any changes are needed, they are very slight. So just remember that whatever shims it has stock, make a great starting point.

2: After you remove your pinion bearings, take a die grinder and gently remove some of their ID. Just enough that they slip onto the new pinion gear without getting stuck. This way you can just slide the bearings on and off as you adjust pinion shim thickness. Having to press them on and off each time is a bear, plus can damage the bearings. When you are done, keep the modified pinion bearings in your tool box for future 8.8 gear changes. After you get the shims right with the modified checking bearings, you then press the new ones on.

You don't have to do this with the carrier bearings on an 8.8 as the shims are outside the bearings.

Keep the old crush sleeve too. When checking setup, you just snug the pinion nut to the old crush bearing.
Don't install the new crush sleeve until the very end, during final assembly.

Another tip... The threaded retaining pin for the cross pin, in the diff.... Be very careful with it. It can snap the head off when tightening or loosening. I opened the rear in my F150, and the head was gone from the retainer. Luckily the pin and threads stayed in place for who knows how long. I have snapped one as well... So just be careful with it. All it does is keep the cross pin from moving, nothing too taxing.

Edit:
I should mention the fact that if you are going to do this, you do need some specialty tools. A dial indicator is a must, as is a torque wrench. You should also have a way to press the bearings on and off, or at least have a shop that will do it for you.

The hardest part for me is 'reading' the paint when looking for the wear pattern. It is not real obvious as one would hope. I tried the paint on the ring at first, but putting it on the pinion and letting it transfer to the ring seemed easier to read for me anyway.

 

[pissedoff92]

also dial-type in/lb torque wrench for pinion preload is very helpful. also a dial caliper for shim measurement

 

[stangman11]

Hey guys sorry for being MIA. The guy that is doing the work on the car for me is a friend of mine that works at a local shop. I to am a technician but was to nervous to attempt doing the rear end myself so I have been working with him. After many long nights in the shop I beleive we figured it out.

When the axles slide into the side gears into the pumpkin we noticed that they still had some lateral movement. Pulled the entire pumpkin out and disassembled it. With simply the gears only at the end of the axle shaft we found that instead of being tight on the splines it actually was able to rock side to side which would explain the noise while turning when everything we have new bearing throughout the entire diff. So at this point I am awaiting a new ford racing gear set to be installed and pray that this is the end.

 

[Gearbanger 101]

Some lateral movement in the rear end is normal though. How much are we talking here?

 

[stangman11]

You are able to put the gear on the end of the axle while it is out of the car and rock it back and forth on the splines quite a bit i dont have a measurement but I assumed it should be tight on the splines.

 

[MFE92]

No, it has to have some play to account for misalignment and flex in the axle tubes.

 

[stangman11]

Really? I spoke to other guys in the business that are familiar with the 8.8 and I was told they should be tight.

 

[MFE92]

I'm not in the business of rear ends, all I know is there has to be some axial tolerance because there are variances in axle housing straightness, in fact it would be extremely rare to find a rear end whose axle tubes are in perfect alignment. Then again, what I'm envisioning by "rock it back and forth" might be different than what you're actually trying to communicate.

 

[pissedoff92]

Yea it shouldnt be press fit but it should slide relatively easily on the splines

 

[ratio411]

I agree, there is plenty of slack in the axle movement.
Has to be when it's cold. It's just like wheel bearings, relatively loose when cold, so that when they get hot, they can expand without seizing up.

Edit:
Oh, wait, I think I see what you are saying...

Axle out of the car, you slide a spider gear on the axle, and it rocks?
Like you put on a ring, and it's too big for your finger?

Did you use a 31 spline diff on 28 spline axles?
(I don't even know if the 31 would slide onto a 28, but it is substantially larger, so maybe?)
I doubt the spider gear is supposed to rock much. Again, it could be a cold thing, for heat expansion, but rocking on the splines doesn't sound right to me. ???

 

[pissedoff92]

I guess it all depends on how much hes talking. I can see it having a few thousanths of play to keep heat down and compensate for axial movement but I have no clue what the spec would be