symptoms of a breaking GM ten bolt rear end

[qwik219d9]

symptoms of a breaking GM ten bolt rear end

I think my GM ten bolt rear end is going south I don’t abuse it much like burnouts and real hard launches, car has 125K miles recently I started hearing a fluttering noise only when rolling the faster the speed the louder/quicker the flutter noise (not a whine like when backing up a import) this noise has progressively gotton louder.

What I have done so far,
1.checked if diff. had fuild it was full.
2.jacked the pass. Side rear wheel off the ground ( I believe this is where the noise is coming from) w/ trans in park I grabbed the wheel at 6 oclock and 12 oclock and checked wheel bearings hubs seams intact.

Next I plan to drain/stain fuild looking for metal chips ect.

I have a TA girdle I think it has a magnet inside or will small pieces of metal still drain out?

If I remove the diff. cover if there is something broke or cracked will I be able to observe from the back ? or doe’s the diff. have to be removed for full inspection?

The car still moves however it won’t accelerate as it usalley doe’s seams to have lost a lot of power.

for the expense and added wieght I don’t plan on a ford 9” or a GM 12 bolt as a replacement I would concider a ford 8.8 if there are torque arm kits available and the TCS isn’t a major issue, otherwise I will most likely rebuild any suggestions on a good replacement diff.

edit: my ring and pinion is a Richmond 3.23 stock ratio.
edit: I’m not sure what size diff my 99 WS6 has 7.5” or 7.8” can this be found out on the door lable of codes?

Any tips is appreciated.

[SMWS6TA]

Here are a couple of areas you can check.

Check the U joints on the drive shaft. Excess play?
Remove the drive shaft. Next try moving the pinon side to side up and down. Any movement and pinon bearing is shot.
Drain fluid - look for metal. Any = bearings going out.



If you are looking at a 8.8 you need to check out my thread to see exactly what you're in for (see signature). There is a lot of issues you need to address that is not for the average DIY'er. Welding requires special skills and technique that most welders have forgotten or haven't learned. Took me 8 months to find one in my area. Making mine to be honest I spent close to 12 bolt or 9 in. Reason why is I used upgraded parts over the stock pieces because I knew I was going to be abusing it. Biggest expense is going to be Custom Moser axles (About $500 with bearings for 9" housing ends).

Hawks 3rd Gen is offering 8.8's but they again are close to 12 bolts & 9" rears in pricing.

[qwik219d9]

I crawled under the car grabbed the drive shaft and was able to twist it about a 1/8"
is this excessive?
would draining and staining the diff. fuild be the next step?

Thanks

[pajeff02]

You need to check the u-joints for lateral movement. Up/down and side to side. You probably felt driveline play.

[raynor139]

When my pinion bearing went it was a louder noise at slow speeds almost like a grinding/clunking noise depending on direction I was going.

If you don't wanna spend alot of money a used 10 bolt is alot of the times cheaper then rebuilding.

I know strange was saying a price increase was coming for the s60 but last I saw it had not. May wanna give that a look. I went with that since the car is mostly a cruiser. It will hold alot of power for a good bit cheaper then some other options. Downside is it is a bit heavier then something like the 9 inch.

[qwik219d9]

I could'nt move the driveshaft up or down or side to side.
1.so when I was twisting it the 1/8" was this normalle?

I'll try again to move the DS up/down side/to side, if it still stays steadie (not move)
2. whats the next step drain/strain the diff. fuild?

3.if the pinion bearing is ruined doe's this mean that it's broken pieces of metal shredded the diff?
the car still drives however not as it should major lose of power.

this problem just seamed to happed all of a sudden I wasn't beating on the car and this was the result.

Raynor I'll be on the lookout for a used 10 bolt what all cars or trucks ten bolt can be swapped into the 99 TA

any tips on finding a used ten bolt these cars are not usalley in the junk yards.

and
4.what is the door lable code for my gear ratio of 3.23

thanks.

[qwik219d9]

if I find a used rear end how can I test it to know if it's not worn out?

[SMWS6TA]

see if it spins freely and see if any bearing material in fluid. Also try to match it to your rear. A4's have different gear ratio than M6's.

[pajeff02]

Pull the rear cover and visually inspect everything inside the differential. While it is open, give everything a spin and check for excessive backlash. You can also throw a dial indicator on it and take a reading.

[2002ssslp]

Pull the rear cover first and swipe it with an extendable magnet to see what is in the gear lube. Look for any unusual wear patterns in the ring gear and see if there is a clunking sound when you rotate the R&P. You got 16 years and 125k out of an overmatched 10 bolt rear so I would not think about rebuilding it. You said something about weight and an 8.8 rear. A 12 bolt is not much heavier and it will bolt right in without any trouble. Good luck.

[Firebirdjones]

I've never had a broken rearend give me the feeling of any loss of power. There might be semething else going on causing that.

If you did hear noises from the rear, I certainly pull off the cover and inspect things. If you've never changed the gear oil, it's overdue anyway, so if nothing is found to be wrong, you just knocked some maintanance out of the way

If something is found broken or abnormal, I wouldn't bother rebuilding. Much cheaper to find a good used rear and toss it in. If you want a permanent fix and never have to worry about it again, especially if you plan to keep the car, I'd take the plunge and stick a 12 bolt or 9 inch in it and be done. Money well spent in the long run. Not enough weight difference to even worry about, besides it's in the rear where the car needs it. I'd give up a few lbs for bullet proof operation any day of the week.

[kingls1]

As someone who just installed a Strange S60 that would be where I would spend my money again if I were wanting a quality piece. I was completely 100% satisfied with my decision on going with the S60. And yes the price did go up but now it is in line with most 12 bolts as well as some 8.8's you can buy and IMO a much stronger piece.

[qwik219d9]

I drained the diff. fuild into a paint strainer funnel did'nt see any small grinded up metal shavings

I stuck my hand in bottom of case and found a few small chunks and one larger chunk not sure where these chunks come from

the exposed ring appears to be intact will jack wheels off ground rotate and look at unexposed side of ring later.
thanks

[SMWS6TA]

pics?

[qwik219d9]

seams 2 images each 120k has exceeded my quota

[SMWS6TA]

need to upload to photobucket than capture & paste the url

[pajeff02]

I do not see anything amiss in the pics. Get a flashlight and roll everything over several times while you check it out. Pay attention to the helical gears in the posi unit as well (as best you can).

[kingls1]

I'm guessing something from the center section. Look at the pinion gear also. I know this much you are in for a rebuild or replace so I would start looking and figuring out prices and where your money is best spent.

[2002ssslp]

While the car is in the air you can have a buddy start it up and put it in drive and release the brake, listen for any unusual sounds. The gears have enough lube on them for a good 15 second spin at idle.

[RONS98TA]

Those are some pretty hefty chunks of metal. They came from something in there. Changing the fluid wont fix the issue. Its really hard to tell from the picts where the chunks came from. You need to put the car in neutral and spin the gears using the tire and find out where the gears are broken.