neveret

iTrader: (1)

I've had my V about a year now and it's a daily driver. To preface my question I'd like to note that I already have the following items:

cs diff bushing and block
old school sub frame bushing inserts (the poly type that sandwich the oem bushing)
voodoo chicken driveshaft
cs engine and trans mounts
ls7 clutch

All of that and of course I still have the clunk when taking off from a stop and in between low gear shifts if I don't feather the clutch and throttle perfectly.

I understand that it is the opinion of some that this noise is created by slop (excessive backlash) between the ring and pinion. Since I'll be doing some deeper maintenance in a couple of weeks to correct shifter slop, I'll get a dial indicator in there and test for backlash to see if it is indeed out of spec. The typical amount on most diffs is somewhere between .005 and .010 and if it's in that range I don't see how that could be the cause of the clunk. I should also note that my diff is still relatively quiet so I'd assume that pinion depth is good.

My question is: If the backlash is excessive, has anyone attempted to adjust the shims to move the carrier to the right to bring the backlash back into acceptable range? I've rebuilt diffs before and I have enough tooling to accomplish the task. I don't have the cash or desire to change to an 8.8 and my stock unit is working fine for daily use. I'm looking for a low cost alternative to further eliminate the clunk so I can continue to enjoy this car.

ls1247

iTrader: (2)

Can't recall any reports of successful lash adjustment on the Gertrag but that doesn't mean it can't be done. Finding someone willing, able and affordable might be a challenge as parts info is sketchy at best and a new diff is in the $1400 range so most mechanics just haven't bothered with it.

I've got an 8.8 in mine at it clunks but not as bad as the Gertrag.

Gus_Mahn

iTrader: (1)

The shims to adjust backlash are behind the carrier races. Special tools are required to pull the races.

Naf

iTrader: (1)

Ask rpm transmissions

neveret

iTrader: (1)

I've got a getrag service kit for the vette diffs, so if needed I have the tools and facilities. I'm just curious if anyone has measured the backlash on a clunker. I'd like to know how bad it actually is.

1BADCTS

iTrader: (17)

It's been a while since I was inside one of these, but doesn't the side cover hold the carrier in place? if it does, how would you even check backlash?

neveret

iTrader: (1)

might have to make a fixture with an axle, a worm clamp, and a piece of sheet metal. McGyver style. I'll figure something out.

G-Body

iTrader: (4)

I never tried it but these are the specs I found.

neveret

iTrader: (1)

that helps, thanks. .008 - .013 seems pretty loose. If my diff is on the high side of that, I'll definitely tighten it up and report the results.

voodoochikin04

iTrader: (3)

There are several places that shims are added or removed.. On either side of the carrier inside the diff and on the pinion.. You can order all the shims from nalley gmc & Buick. They range up in .05mm increments if I recall. I can also verify that the internals are similar to the vette diffs. Same carrier bearings, lsd clutch disks, and such.

Gus_Mahn

iTrader: (1)

I don't have a clunker, but I do have a new unused 3.91 geared diff sitting on the shelf.

neveret

iTrader: (1)

I got the diff out and cleaned up. However, whoever/where ever I read that the V diff uses the same carrier bearings and side cover seals as the corvette diffs was erroneous. The v carrier bearings are smaller so the issue is - some of the tooling in my vette diff tool kit wont work (are too big). I wasn't willing to be denied though, so I did a little modifying on the bearing race removal tool and made it work. Another difference between the vette diff and v diff is that on the vette there is a shim stack (3 shims) under the side cover races and on the v there is only a single shim per side. This means it's not as easy as swapping thicker shims from one side for thinner on the other to move the carrier to eliminate excessive backlash. I've got 4 shims on order that will give me .004 or .008 adjustment and I'm fairly confident that will get me really close to perfect. I'll update again next week after I get the shims in the mail and get this thing tightened up.

BudRacing

iTrader: (3)

Nice work. The driveline slop has always been a huge issue on these cars and this seems to be the last item that nobody has messed with (or at least posted about). Looking forward to the results. Any pics or instructions would be a big help too.

bmylez

iTrader: (3)

You mean him. ^^^


(Not calling you out Matt, just clarifying!)

neveret

iTrader: (1)

I think I read it somewhere else as well, but it was definitely a little deflating. I tried to put the race remover in and it didn't fit. I said to myself, well this just got more difficult than I wanted it to be. Kind of like what I say every time I dig in to something like this.

bmylez

iTrader: (3)

If it makes you feel better, I'm on hour 26 or 27 in my lifter replacement project. Heads had oil all over the place, so I've been cleaning and cleaning and cleaning...just now getting around to bolting one of the heads on. Kill me.

voodoochikin04

iTrader: (3)

I never said the side cover seals were the same.. I listed the diff carrier bearings and shims as the same because when I researched it I found interchangeable part numbers.. But I can see that obvious isn't working here.. However.. I know 100% sure the lsd clutch discs are the same because I assisted a client in using them in his V-Diff... Apologies for any I formation that was not quite correct, perfect example why it pays to either get hands on or do you're own research.