wrd1972

iTrader: (12)

Are you surprised? Why would big player like Rockland trust what some "internet pro" like myself with regards to troubleshooting something as complicated as a T56 tranny. I mean seriously, this is the first time I ever looked inside a manual transmission but even I can tell when things don't look right such as intended press fit parts that remove by hand, parts that rock on their respective shafts and have clearances up to .005". Oh, and worn chafed areas of the shaft too and worn away areas of the splines. I also had a another well know T56 rebuild sponsor on this board tell me years ago on the phone that this supposed loose fitting 5/6 gear is a non-issue.

But what do I know other than to say that 2.5 years later, its still totally vibe free.

Shameless plug for TDP.

jmd

iTrader: (4)

If it's isolated to 5th/6th and the miles on the car are enough for the issue to have developed, it's worth the time to pull it and check.

re: the driveshaft connected, a gearset that's not under load (because of being up on stands,) will show different harmonics than loaded (same gear, same car, same rpm, same mph but on the freeway.)

The 5-6 cluster gear is on the mainshaft (output shaft.) What happens if you let it go long enough is it will junk the bearing on 6th on the countershaft and the countershaft. And the 5-6 cluster gear will push the reverse synchro back on the mainshaft and junk the reverse gear bearing too. And on that note, you can better understand the importance of the first paragraph in this post.

Phillipm

iTrader: (2)

I pulled my T56 last night to tear into it as well. I've been fighting the same vibrations for 6 years. Like others I've tried a million things and found nothing. Everything points to the same problem as the OP so here it goes. BTW, this is how Rockland delivered the trans to me.. They didn't even take the time to trim off the output shaft.

wrd1972

iTrader: (12)

OP here. I ran the car up to 80MPH on jackstands and felt nothing abnormal. There must be load applied for the vibes to occur. Hand on the case when at speed proved nothing also. I still have the damn 5/6 cluster gear hanging on my wall as a reminder that if you replace everything, it will eventually be fixed.

FTR, now being years and years later, T56 is still smooth as silk.

wrd1972

iTrader: (12)

...another two years. Still smooth as silk.

flintwrench69

iTrader: (11)

So I've got mine apart going through it & installing a Level 2 kit & all the bearings. Remember seeing a puller is needed for removing synchros & for removing the 5-6 cluster gear. The synchros needed a puller & press, the 5-6 cluster gear came off kinda easy but it seemed like it fit good & tight on the mainshaft. I didn't need a puller, just slipped off. I've noticed the vibration at higher speeds in these 2 gears also. Will a new cluster gear take care of it?

flintwrench69

iTrader: (11)

Ok I read a lil more & see the 5-6 cluster gear & the mainshaft need replaced they both wear. Or have the shaft repaired. I slid the gear back on & rocked it on the splines you can feel it move back & forth. I went ahead & ordered both parts. I'm feeling good about this higher speed vibration being gone!

jmd

iTrader: (4)

You need to measure. The factory interference fit eventually fails. The interference fit suggested here might be just about achieveable with the repaired mainshaft.

jmd

iTrader: (4)

You need to measure. The factory interference fit eventually fails. The interference fit suggested here might be just about achieveable with the repaired mainshaft.

HioSSilver

iTrader: (8)

I had my trans apart recently. It was wore pretty bad. I reclocked the 5/6 gear on the shaft. That tightened it up but who knows how long that will last.

WS6wanted

Wrd1972 super impressive rebuild man! I read this thead from top to bottom. I had a hard enough time with my rear end rebuild, I don't think I would attempt a t56. I have a vibe at 70+, im hoping it is not my t56.

wrd1972

iTrader: (12)

Annual bump for those with 5/6 vibes.

Texaswino

I'm having vibration problems in my 37 Ford with Lt1,T56. Vibes start about 70 in 5 and 6th. I feel no vibes in 4th or when slipping in neutral at speed. I have changed rear ends (4:10-8.8), drive shaft twice (balancing 3 times) and tail shaft bushings. This post leads me to believe the problems is in the tranny although I had it rebuilt before installation. Any other test I can perform before removing t56 and taking to TDS?

Thanks in advance
Dave

jmd

iTrader: (4)

Your next step is to pull it.

HioSSilver

iTrader: (8)

Finally took the car for a ride and the vibration was bad from 60ish to over 70 then seemed to go away about 80. It's odd to.....it almost sounds like padels slapping at one point.

onebadbowtie86

iTrader: (13)

After chasing a high speed vibration for a couple years, and replacing about every other part on my car, I rebuilt my t56 myself this past winter and had the main shaft repair done. no more vibes for me!