lets talk about diff backlash
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lets talk about diff backlash
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.
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.
#2
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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.
I've got an 8.8 in mine at it clunks but not as bad as the Gertrag.
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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.
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#10
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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.
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a little update
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.
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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.
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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.