wrd1972

iTrader: (12)

Update.
Got the T56 95% back together. The new 5/6 driven gear fits extremely snug on the repaired shaft liked I hoped it would. However the mainshaft endplay is going to have to be reset with this repaired shaft because now its too tight. I am going to need some more shims to accomplish that.

Went ahead and replaced the blockers and installed a steel 3/4 fork as well as 3/4 billet keys. The 1/2 syncro had some minor wear so it got replaced too.

Finally determined that there was as much as .010" of 5/6 driven gear clearance and wobble on the original mainshaft. Obviously that cant be good for anything. Hope this fixes the vibe.

slowpoke96z28

iTrader: (2)

any new word?

wrd1972

iTrader: (12)

The repaired mainshaft is wanting to be shimmed .002" more loose. I am waiting for the new shim to arive from TDP which might be here on Friday or Saturday. Once I have the shim, the tranny will be completely finished and ready to install in about a half hour.

Not looking good that I will get it back in the car on new years. Anyone wanna guess why? Maybe I can get it back in Sunday or Monday.

Kevin97ss

you'll be so drunk that you will wonder out into the yard and hold on to the grass to keep from spinning off the planet? Thats my plan as well

slowpoke96z28

iTrader: (2)

or, you'll want to drive it and hope none of the drunks hit you.

wrd1972

iTrader: (12)

The transmission is completely back together and seems to be operating exactly like it should at least on the bench. It turns very smoothly and all gears easily engage and disengage.

I have now noticed that after this rebuild, the input shaft does not have the up and down slop that it used to. Before the rebuild, the thing definitely moved a noticeable amount most likely as a result of things loosening up during the last 16 years of use. I now have it shimmed it to exactly to what Tremac calls for and that is resulting in a tighter input shaft. Hell maybe this will also result in less (not excessive) noise and whine coming from the transmission.

Funny thing is about a year ago, I had a pilot bushing wear completely out and got the harshness, vibes and scuffing noises between shifts. The bushing had opened up enough that the input shaft was not very well secure and once the new bushing was in, all was well. I never really gave much though to a sloppy input shaft. I am now thinking that the old sloppy input shaft contributed to that pilot bushing failure so there is another potential serious issue I can check off the list.

Well the transmission is back in the car and bolted up but I am not going any further till I do a few tests to make sure that I dont have the infamous "incomplete clutch release" problem that has plagued me before when installing a new clutch, in this case a Competition Clutch stage 2. Probably around 2 hours from test driving it to see if the 80MPH 5th/6th gear vibes are history. Gosh I sure hope so.

TDP

iTrader: (23)

Good luck and I'm looking forward to hearing your feedback after the test drive. Finally the moment of truth has come

wrd1972

iTrader: (12)

Ran out of energy to go any further tonight plus "helper" was out with the kids. Gonna be another day or two it looks like.

85MikeTPI

iTrader: (9)

That was your problem all along... You just wasted time and money throwing parts at a mis-shimmed unit..

wrd1972

iTrader: (12)

If this were the case, why were there no vibes in 1st - 4th and rather bad vibes in 5th and 6th only? You honestly believe that the 5/6 cluster gear that is supposed to be tight press fit on the mainshaft that in reality had .010" of slop fit did not contribute to the issue? Again this thing was wobbling on the shaft enough to ctually wear the shaft away along with the ID of the gear. We will just agree to disagree on this one.

Again there was a clear and obvious failure with the 5/6 drive line and in contrast all of the 1st - 4th driveline was spot on and tight the way it should be. I dont consider it wasted time and money considering it is now closer to Tremac spec than what it was and no amount of shimming would have corrected the root problem.

TDP

iTrader: (23)

Your T56 surely needed to be freshened up, and I'm sure it will have a whole new feel to it. At a minimum, it was preventative maintenance, in addition to addressing the issues that you had going on.

85MikeTPI

iTrader: (9)

I completely believe that. If the shimming was that far off on the input, you can bet the extension shaft was that and more causing your vibration. Reassemble it with your original mainshaft with proper shimming and prove me wrong..


This is still your contention, measuring the shaft in the wrong place and comparing a stock shaft to a modified one.. There is no clear and obvious failure other than the one you've created in your mind.

You have a placebo, and I'm sure your vibration will be gone when you get it all together..

wrd1972

iTrader: (12)

I cant even be sure how far off it was. I stated above it moved a noticeable amount and everybody's definition of this will be different. I took no measurements so in all fairness it could have been off a little (within acceptable tolerances) or a lot. I do know that the last pilot bushing I pulled had no no abnormal wear and could have been reused. It would be counterproductive to reuse the old shaft to prove you wrong anyway. One it has severe wear where the 5/6 gear goes and even a brand new in box 5/6 gear fits extremely loose (not within Tremac spec) and two you wont believe me even if the input pre-load were ruled out.

Also I will state that the shim pack used is the shim pack that Tremac installed when the unit was new. I will give them the benefit of the doubt that they did not screw up th shim pack.

With all do respect, you are simply ignoring the facts of the "obvious failure" in question. I even posted a video to back them up.

1. When the T56 left Tremac, the 5/6 gear was tightly press fitted on the mainshaft using the splines and some of the journal. Before the rebuild, the 5/6 gear had .010" of clearance to the main shaft and could be pulled off by hand again as seen in the video

2. When the T56 left Tremac, the splines that drive and capture the 5/6 gear were intact. Before the rebuild, the splines under the gear were ~20% thinner as a result of the gear wearing them away due to fluttering and loss of press fit. You even said yourself in post #4, "In the OEM setup, the splines themselves support the cluster. When they wear, the cluster press fit will suffer". I will take this as an obvious failure.

3. When the T56 left Tremac, the journal under the 5/6 gear (a couple inches in length) measured 1.498" and I know this because there is a 1/4" area that never makes contact with the 5/6 gear so the measurement was taken there. The area of this journal at the least worn, is 1.496" and at worst worn, is 1.494". This indicates that up to .004" of metal is gone and there is also a leathery texture supporting this. The repaired shaft measures 1.5005" on the full length of the journal.

4. When the T56 left Tremac, the ID of the new 5/6 gear measured 1.498". I know this because I measured the brand new in box gear. Before the rebuild the ID of the worn 5/6 gear measured 1.505". The gears ID enlarged .007" as a result of it fluttering around on the mainshaft. There is also a leathery texture supporting this.

5. The new T56's no longer use the 5/6 cluster gear and small spline contact points like in our f-bodies. Tremac obviously recognized this to be a problem and made the needed revisions starting with the 03 Cobras.

The above points clearly indicate an "obvious failure" on two parts that is not just made up in my mind as you assert. This is not that hard to figure out.

Addressing the "obvious failure" described above and whether or not it resolves the 80MPH vibe can be debated since the new mainshaft/input endplay in general was tightened up as well. I can look at it objectively and admit that three issues were addressed at the same time, those being the mainshaft, the 5/6 gear and the input/mainshaft end-play. But at the end of the day, I am still leaning toward the mainshaft and the 5/6 gear as the heart of the problem.

TDP

iTrader: (23)

Dam, what gotten into you Mike? lol Leave the guy alone
His tranny is now going to be in the best possible condition, and thats all that matters.
FWIW, the difference in the shim thickness could be due to the fact that the mainshaft was replaced. Also when the journal repair is done, the shaft does tend to "grow" and shrink some.

wrd1972

iTrader: (12)

Update:
Finally after all these years, I can honestly claim some real progress at resolving the high speed vibes. I got the car all back together and went for a test drive for about 10 miles on the interstate. During the drive, I detected absolutely no vibrations at all at speeds up to 90MPH. Before the vibes started at 80MPH and quickly got more intense at 85MPH. Everything felt smooth as silk in 5th and 6th gears plus the car just sounded differently overall due to the absence of the noise and rumble that was produced when the vibrations were occuring.

Their is definitely a lot less "clunking" now especially in 5th and 6th gears plus all the gears engage and switch buttery smooth just like when the car was new.

Anyone that seems to have this problem I have illustrated in this thread ought to look at the 5/6 driven gear and the main shaft for wear. I think its safe to say that the new 5/6 driven gear is attached to the repaired main shaft much better and tighter than when the tranny rolled off of the assembly line. I really want to give a big time thanks to Jason at TDP (Texas Drive train Performance) for all the assistance.

Just to be on the safe side, I want to get some more miles on it before calling it 100% fixed. But as of right now, its looking very likely that it is.

TDP

iTrader: (23)

Awesome! I figured that would do the trick. Thanks for the good words and I'm very glad to hear that your vibration issue is fixed!

96lt4c4

iTrader: (5)

When you say clunk in 5th and 6th, do you still have some clunking? My car clunks in 5th and 6th gear pretty bad. I replaced the tail shaft bushing thinking it would help that but it didnt. My vibratinon is better than it was but I still have something going on. I think mine needs to come out.

wrd1972

iTrader: (12)

It does not make any of the clunking noises any longer I assume due to the 5/6 gear now fitting tightly to the mainshaft. Before the rebuild, the old worn 5/6 fluttered at certain speeds and could also shift front to rear on the shaft. Also tightening up the end-play may have played a roll in making it more quiet as well. The clunking was not very loud, just a little annoying.

wrd1972

iTrader: (12)

Success.
I will now call it officially fixed. After more road testing, there is not even a hint of the 85MPH vibration in 5th or 6th gears. Smooth at 100MPH as well.

hulm333

i have this 6th gear issue in my 05 cts-v 46k on it. only 6th and between 55-85, immediately after 85 it goes away and its good for cruising above 85. what and how are the best ways to diagnose whether its 6th gear or a drive line or a rear diff..... thanks jesse