thesource

iTrader: (60)

What Tremec says or suggest has almost no influence on my decisions when building transmissions. I'll take my 15 years of experience from building all sorts of manual transmissions over what Tremec suggest.

If Tremec was on top of things, there would be no reason for people to develop after market upgrades for the T56. It would be perfect from the factory and never give issues which would be bad for my business.

Mikey 97Z M6

iTrader: (37)

Because Tremec likes to sell replacement parts. All joking aside, they have a variety of factors to consider.

A) How many will be pushed to the hp/tq limits
B) What kind of warranty issues can they afford to deal with
C) How skilled are the factory techs (GM Dealers etc..) that are rebuilding them under warranty
D) How difficult is a loose spec compared to a preload (time/money etc..)
E) How many miles of expected use
F) Probably a plethora of other considerations but you get the idea...

It's not all about what is the "correct" way to do things. Auto manufactures often make these same decisions based on how many law suits they anticipate from a bad design.

Borg Warner originally engineered/designed/produced the T56, that's why sometimes you'll see the tighter preload specifications. Some auto manufactures might be looking at the specs and changing them to their own specs as well. If BW thought is was ok, I'm sure we're good.

Mike

wrd1972

iTrader: (12)

Good discussion guys. This was my first transmission rebuild so I have to rely on reference material and other folks experiences. The thought to put about .002" preload on the mainshaft occurred to me but I figure with my experience, I would trust the manufacturer. All in all I am just glad the vibe is fixed and its a bit stronger in a few areas, is also more quiet and it works as well as the day it was new. I chased this damn problem for three yearsand I am confident it actually started long before that but it took the 4.10 gears to reveal the problem.

Tobias05

iTrader: (1)

WRD, about how many miles did you have on your transmission?

I noticed today at 70mph in 4th gear my car does not shake like it does in 5th or 6th. It also seems a little worse when the transmission is colder.

Seems to be like a pulsating, comes and goes over 2-3 seconds kind of vibration.

wrd1972

iTrader: (12)

I went after the problem around 80K but I am convinced it started long long before that and it just got worse. It seemed to have different paterns at different time. Sometimes it was a steady vibe and others it fade in then out in a rythmic kind of way.

The easiset way to diagnose is to drive to about 90 in 3rd if you can then 4th and note if there is a vibe. If no vibes in 3rd and 4th, drive to 90 in 5th and then sixth. On mine is was totally obvious there were vibes in 5th and 6th. I mainly really felt the vibe in the seat of the pants and very little in the shifter. It is entirely speed related, RPMs have nothing to do with it.

If you tear the tranny down and can slip the 5/6 gear off without a puller. IMO you have the same problem I did.

wrd1972

iTrader: (12)

Just wanted to report that its nearly one year later and the rebuilt T56 is still totally vibe free in all gears.

jimbos'ss

iTrader: (6)

subscribing

slowpoke96z28

iTrader: (2)

maybe now is the chance to see how much endplay has to do with the situation like the other two said. i would venture to say measure the endplay before repair, and if its bad, only fix the end play. if the endplay is good, set that **** to the exact same as it was measured after you do the mainshaft and 5/6 replacement. that'll be the most scientific way i think.

wrd1972

iTrader: (12)

I have talked to many transmission experts over the last year including a former mechanical engineer who worked for Borg Warner (now owns a transmission repair shop locally), and all said that if the mainshaft preload being loose solely caused the 5th/6th gear vibe issue, then it would have likely vibrated in the other gears as well, which it never, ever did. That said I dont think anyone in this thread, who solely blames the preload, has hypothesized on how it could only vibrate in 5th and sixth but not 1st through 4th.

Without even first mentioning what I found about the gear, many said that since it was localized to the 5th/6th drive-line only inside the tranny, there must be a specific component in that drive-line that is failing or has failed. When I explained what I found with the mainshaft and the 5/6 driven gear and showed them this thread, they then said bingo.

This one was better explained to me as well. When the 5/6 gear started wobbling on the mainshaft creating the vibe, that vibe was transmitted to the driveshaft. The vibe went down the driveshaft and into the 9" rear end and ultimately into the chassis (poly bushings BTW) and thats why I felt the vibe much more in the seat as opposed to the shifter. I also remember swapping out a pair of perfectly blanced driveshafts, one aluminum and the other chromeoly. The chromeoly one transmitted more vibes which were felt in the seat than the aluminum one. Swap the aluminum one back in, the vibes were fewer but still there so this confirms that vibes from the tranny will certainly being transferred to the driveshaft. By the way after the tranny repair, both driveshafts were tested yet again and no vibes were detected like before the tranny repair.

I agree that it would be nice to know the real root problem but it might likely result in someone installing/pulling the tranny several times to scientifically determine. I agree there are variables in play but to dismiss the 5th/6th gear and worn mainshaft, considering the facts I have put forth from the jump in this thread, is just not logical IMO. Also IIRC, I only added .002" more shim than what came originally. I just cant see .002" alone causing this kind of trouble I had before the rebuild.

sjsingle1

iTrader: (1)

vid not working

wrd1972

iTrader: (12)

I just checked it and its working just fine.

TDP

iTrader: (23)

Just read your posts in this thread from 12/3 to now. Glad to hear the "repair" has held up. I've been using this method for 3+ years now and am still batting 1000 Unfortunately most builders don't have the means to perform this upgrade/repair. It's simply a poor design from the factory and would have cost Tremec way too much money to go back & re-design it. It's a perfect example of a given design working out just fine on paper, but did not standing the test of time. In the TR6060 transmissions (2008 & up), they made this section of the mainshaft 100% splined & press-fit. So it's no longer an issue on the newer transmissions.
I get this done on about 70% the T56s that come through the shop. I'm only adding about 0.003" to the journals, but that's all it takes.. Most others will replace the mainshaft with a new one and/or replace the 5-6 cluster gear ($450 in parts), just to wind up having the same problem down the road.
What I find interesting is that about 95% of these cars don't have any vibration issues, even with the mainshaft journals and splines worn out. It seems completely random when a vibration is present. However, if a car is vibrating due to the worn mainshaft, this repair has always fixed it.

Hans Grüber

iTrader: (2)

How much does it cost to repair the mainshaft?

From your experience when rebuilding T56's, how common is it that the 5/6 gear can be easily pulled off the mainshaft with just your hands.

I have my trans disassembled right now and I was able to just pull it off with my hands. I bought mine used so I'm not sure if it had this vibration issue. Do you think this is a sure bet that I'll have this problem? Also is this vibration issue common?

xx_ED_xx

iTrader: (17)

I would buy a dial caliper and measure it. I just measured mine even though I never felt any vibrations. and I get the same hole size as his gear set but my mainshaft is 1.501. mine has a tight fit on the splines as well so probably why I havent had an issue yet. But i can pull mine off by hand

Jvmun

iTrader: (1)

Awesome

HioSSilver

iTrader: (8)

good thread. I've been having a similar vibration.

wantsum410

iTrader: (5)

I had struggled with this same issue for a few years ....5 & 6th gear Vibration. After finding this thread & Jason @ T D P ,he fixed the shaft issue & some other stuff the last guy missed .
After getting my trans back I must say WOW it is super tight with NO issues shifting,vibrations ,ect.Oh ye the shaft fix was only $100 .....not $800 in parts alone that everyone else wanted to do to fix the problem .
Thanks Jason for a Great Job on my Trans !

jimbos'ss

iTrader: (6)

my trans will be coming to you in a few months for this fix jason. BTW that diamond stage 2 you sent me was by far the best clutch I have installed so far. The pedal feel is same as stock, but it takes the abuse nicely! already have 15 passes on it without missing a beat and getting locked out of third or limp pedal issue. Best money I've spent on the car next to the 25 bucks I gave Pat G to spec my cam.

STEEPSS

iTrader: (30)

What does it cost to fix this if I were to just send you my main shaft and 5/6 gear (if you need it)?

JonneyRocket

I recently purchased a 1997 Firebird formula WS6 with a Rockland Standard Gear (son of transzilla)T56 6 speed transmission.Soon after buying car I realized it had a 5th and 6th gear vibration.I stumbled across this thread and it made sence to me so I called up Rockland to bring this to their attention.You figure after spending 3000.00 on a transmission rebuild they would at least listen to whae I have to say,guess again.They totally denied that this vibration could be a problem with the transmission.They said it was the 4 10 gears in the Moser rear that was causing it.What a bunch of arrogant over priced jerks.After calling them back and not getting a return phone call I decieded to call Jason at Texas Driveline performance.After talking to Jason I decieded to send the trans to them for the repair.They did the mainshaft repair and fixed a couple of other things that Rockland apairently missed.I got the trans back and put it back in car yesterday.I took car out for a ride today and guess what ,the vibration is gone.If anyone else has this problem stop wasting your time on other things and send it to Jason.I want to thank LS1 Tech and especially Texas Driveline Performance for fixing this annoying problem.And thanks for nothing Rockland Standard Gear.