Manual Trans. Thud when shifting

[JuRuKi]

So are there 6MT's out there that dont have the thud?
When i bought my car I knew about the problem and all 3 of the GT PP's the dealer had on the lot had the thudding.

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[duke107628]

Roger.

Are you the guy that tried the bushing. At first the noise went away and then came back?

 

[Genxer]

I have diff bushings and a trans insert. The diff bushings may have dampened the sound a little, but the thud is still there. Nearly 12k miles and mine is not any worse than when it was new. It hasn't been bad enough for me to take it to the dealer.

I noticed this diff is unusual in that I feel something ever so slight as I turn corners. I have assumed this is the nature of the Torsen design. It's always been there as well as the slight thud. Neither have gotten worse. I just figured that it's not momma's soccer van and have chalked it up to driving a high hp machine.

 

[duke107628]

I have diff bushings and a trans insert. The diff bushings may have dampened the sound a little, but the thud is still there. Nearly 12k miles and mine is not any worse than when it was new. It hasn't been bad enough for me to take it to the dealer.

I noticed this diff is unusual in that I feel something ever so slight as I turn corners. I have assumed this is the nature of the Torsen design. It's always been there as well as the slight thud. Neither have gotten worse. I just figured that it's not momma's soccer van and have chalked it up to driving a high hp machine.

Good to know. Thanks.

 

[Bonafide]

For what it's worth, I had a slight thud from the beginning 1-2 and very faint 2-3. Installed Steeda differential bushings and swapped diff and trans fluid to BG and 2-3 thud disappeared and 1-2 thud only sometimes. Installed MGW shifter a few hundred miles ago and since new shifter, no thud at all, ever

 

[JuRuKi]

Mine isnt slight nor faint. Its a loud thud and it can be felt in the whole car. So maybe yours went away because it was slight/faint to begin with.
Should i try installing differential bushings? It doesnt bother me much but i would love to lessen the thudding a little.

 

[duke107628]

Mine isnt slight nor faint. Its a loud thud and it can be felt in the whole car. So maybe yours went away because it was slight/faint to begin with.
Should i try installing differential bushings? It doesnt bother me much but i would love to lessen the thudding a little.

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[Bonafide]

Mine isnt slight nor faint. Its a loud thud and it can be felt in the whole car. So maybe yours went away because it was slight/faint to begin with.
Should i try installing differential bushings? It doesnt bother me much but i would love to lessen the thudding a little.

Based on my experience. I would give it a try, especially because the cost is low. I tried it only after hearing about the success others were having with it. Fair warning, if you have a stock exhaust you might notice an increase in gear whine (I was stock at the time). But the trade offs (decrease in thud and helped with wheel hop) were worth it for me. Good luck to you.

Edit: Gear whine improved after fluid swap.

 

[daltron]

I think mine is gone. I don't want to post what I think did it before I double check tonight but either way I will let ya'll know.

 

[wildcatgoal]

U tried the diff bushing and does not work right?

Like I've said elsewhere on this forum, the diff bushings do not reduce this noise. If anything, they'll increase it (if your car is prone to the noise). It is play within and between the transmission and differential, not the differential moving. I had a super similar (probably same) issue with a Chevy truck. Ultimately replacing the differential solved it. I was no longer able to literally, by hand, twist the drive shaft left and right a pretty significant distance and hear the exact clunk I heard in the truck. Guess what my drive shaft does? And it isn't the driveshaft itself that has play when twisted. It's what it is connected to.

 

[fogus]

Still following this. Still willing to organize my "thud day" in the North East USA where we hit a dealer with 5+ reports in a single day so they freak out and do some investigation

daltron, I'd love to hear how your test went.

We should probably summarize all the "fixes" everyone has used and had success with at some point.

 

[Genxer]

Like I've said elsewhere on this forum, the diff bushings do not reduce this noise. If anything, they'll increase it (if your car is prone to the noise). It is play within and between the transmission and differential, not the differential moving. I had a super similar (probably same) issue with a Chevy truck. Ultimately replacing the differential solved it. I was no longer able to literally, by hand, twist the drive shaft left and right a pretty significant distance and hear the exact clunk I heard in the truck. Guess what my drive shaft does? And it isn't the driveshaft itself that has play when twisted. It's what it is connected to.

It may be that our diffs have a fair amount of gear lash. I would interested to see if anyone has compared clearances on their gears to factory specs. Or, do these Torsen diffs have a looser spec?

The main reason I did the diff bushings was for more stability and it did that for me. Tightened things up a bit.

 

[daltron]

Still following this. Still willing to organize my "thud day" in the North East USA where we hit a dealer with 5+ reports in a single day so they freak out and do some investigation

daltron, I'd love to hear how your test went.

We should probably summarize all the "fixes" everyone has used and had success with at some point.

My thud is now gone. I can only assume it was the driveshaft.

These are all my drivetrain related mods/fluids. The nice thing is that they were all done over time so I definitely think it was the driveshaft. What I bolded is what was the last install, with what I assume fixed it was the driveshaft. I have a PP with the stock 3.73 rear end with the Torsen.

Steeda Tri-Ax
DSS Aluminum Driveshaft
UPR Driveshaft Safety Loop
McLeod RXT
McLeod Steel Flywheel
DSS 1400HP Halfshafts
RP Synchromax
AMSOIL Severe Gear 75W-90
Steeda IRS Subframe Bushings
Steeda IRS Subframe Alignment kit
Steeda Differential Race Aluminum Bushings

 

[EXP Jawa]

It may be that our diffs have a fair amount of gear lash. I would interested to see if anyone has compared clearances on their gears to factory specs. Or, do these Torsen diffs have a looser spec?

I pointed this out a while back, but it bears repeating. The Torsen internal gearing lash is actually quite good, but the lack of a preload spring (which a clutch diff needs to load the clutch) means that the lash it does have isn't masked like it is in a clutch diff.

Also, by checking lash at the pinion, what you feel is the diff lash, multiplied by the gear ratio, plus the r&p lash. So, when you have a 3.73:1 gear set versus 3.31 or 3.55, the apparent lash is amplified more.

And of course, the 3.73 gears and the Torsen are bundled together on these cars. So, combined together it makes it seem even worse.

 

[Rustang]

So are there 6MT's out there that dont have the thud?
When i bought my car I knew about the problem and all 3 of the GT PP's the dealer had on the lot had the thudding.

Right here, no thud whatsoever. I have heard one with the thud too so I know what it sounds like.

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