01Sidewinder

iTrader: (1)

Yesterday I was at the drag strip. I just made my pass and am coming up the return road. I tried to down shift, but I couldn't get it out of fourth. I finally forced it out and got it into third. After that it shifted into first through third fine. I went back to the pits. While holding the clutch in, I put the shifter into first through fourth. When I got it into fourth it would not come out for anything. I pushed the shifter forward as hard as I could, hitting it even, and it would not move out of fourth. Infact I'm still stuck in fourth. I had to drive a hour and a half home with only fourth!
Now what could have caused this? What is wrong with this crappy transmission? I just had third gear and the syncro replaced a couple months ago. Any help is greatly appreciated!

Camaroholic

iTrader: (1)

Well, odds are good that the little keys in the 3-4 slider gear have become dislodged from the slider, and are blocking you pulling the gear back in to neutral. I've seen a couple of trannies with these keys broken.

Here are some pictures.

http://www.akmcables.com/T56-1.jpg

This is the 4th gear assembly. Input shaft, a synchro, the 3-4 slider assembly, and a shift fork.

This is it assembled:

http://www.akmcables.com/T56-2.jpg

The slider gear moves back and forth to select 3rd or 4th. In the position above, it's in neutral.

Here is 4th gear engaged.

http://www.akmcables.com/T56-3.jpg

Note the black plastic pads on the shift fork. It's pretty common to see those broken. You can bend this aluminum fork when attempting to disengage the gear when it's stuck.

Now, here's the culprit. These little POS slider keys. They help keep the synchro in place, but they do like to pop out. Note this one - is popped out (I made it do that).

http://www.akmcables.com/T56-4.jpg

And finally, here are the little evil bastards, along with their springs that hold them in the slider gears.

http://www.akmcables.com/T56-5.jpg

Hope that helps.

Andrew

Jason99T/A

iTrader: (21)

I couldn't have said that better myself Andrew.

Jason99T/A

iTrader: (21)

I would also add a severely damaged syncro can cause those problems as well. I actually had a defective syncro from Tremec in my last T56 rebuild right out of the box. The syncro would slide on the the driven gear, but would not come off without some prying. (you could shift into 2nd, but could not pull the shifter out of this gear) I swapped the syncro out and all was well.

Jason

01Sidewinder

iTrader: (1)

Very informative! Thanks a lot Camaroholic and Jason99T/A. I went ahead and took all of the nitrous out last night. I dropped it off at the dealership this morning to get it fixed under warranty. Hopefully it won't take them too long to get back to me. I'll post when I find out exactly what went wrong. Thanks again!

buschman

Yeah seriously. Great explanation Andrew.

Vents

iTrader: (9)

http://www.akmcables.com/T56-4.jpg

man i hate those..

Jason99T/A

iTrader: (21)

That's what broke in my original 30k miles stock tranny.

Camaroholic

iTrader: (1)

Heh, yeah, I just happened to have a parts T56 laying around out in the shop, so I grabbed the pieces and the digital camera. You know what the problem was with this parts T56 in the first place? Yep. Broken slider keys in the 3-4 gear slider. I have rebuilt a few T56's, so I had some extra slider keys laying around from those rebuilds. My own spare T56 also had broken 3-4 slider keys when I picked it up.

My personal least favorite part is the outside ring of the slider gear itself. They could've built that out of a harder metal. Those teeth get chewed up too easily, and at $125-$150 a pop to replace, they aren't cheap. And you can't buy just the ring, you have to buy the whole gear.

On my ST-10 (in the 79Z), the slider rings are $38 each, and the *entire* rebuild kit, including all bearings, races, synchros, gaskets, seals, new countershaft, etc was $150. But it was a bit tougher to rebuild. There were 88 needle bearings on the countershaft that you had to insert... one at a time... And hope they didn't fall out of the hole...

-Anderw

needle bearings

qs9999

Sorry to hear about your Trans. I am a pontiac tech who ends up working on all the Firebirds that roll in the door ( I just got good at taking them apart) there is a tsb for those 6 speeds for the problem you guys are having. TSB #01-07-29-003A the discription is for: Transmission Jumps Out of 3rd Gear (Replace 3-4 Shift Fork, 3-4 Synchronizer Assembly, 3rd Gear Blocker Ring and 3rd Speed Gear, but I have found it also cause the 4th gear sticking, the parts need for the car are:


12523207 3-4 Shift Fork
12523078 3/4 Synchronizer Assembly
12523186 3rd Gear Blocker Ring
12523077 3rd Speed Gear

I have done this for cars under warrenty and have never seen the cars in for the problem again, if you get your trans redone you should replace the 3-4 shift fork even if you don't have problems shifting. the new fork is new and does not lok like the pictures poted here. I don't have pics of the new fork or i would upload them. GM says the problem starts cause the fork bends. the trans them selfs are very strong but when the fork is bent 4th gear is engaded to far and 3rd gear is not enouf. thats what causes the problem. this is the only weak area I have found with these transmissions and wish you all well.

Ken

Joe Kizzire

And put the shift stops back in the shifter. I don't care what anybody says about internal stops you need the stops on the shifter.

blkmgc1

iTrader: (11)

check it out first post sweet. anyway all i wanted to say was that my trans is in the shop right now for the same reason that this post was started.my trans went in the middle of my first pass at about the 1000 ft mark or just there after. went through the traps and was stuck in 4th. did the same thing you did pried on it for awile and it poped out the only thing is i fried what i thought was third and come to find out i fried all except 6th.oops. f it i'm goin with a 350 turbo.this will be the 2nd time in 13 mo it's been rebuilt.good luck man.

qs9999

blkmgc1,
when they rebuilt your trans did they replace the 3-4 shift fork?. It seams to be a weak point of the MM6 trans.

Ken

blkmgc1

iTrader: (11)

as far as i know yes.replaced 2nd 3rd and 4th syncros and all shift forks.i don't think GM planned accordingly when they made that trans and put it behind a relitivly beefy motor.no time to wait for the gears to mesh just hammer it they'll go .always was a fan of automatics anyway more consistant and no where near the hassle.

pimpmaro

Huh, from my understanding the T56 is a pretty stout little tranny... maybe that's only if it's built up though...

blkmgc1

iTrader: (11)

from what iv'e heard they are however i think i'm a little harder on them then most.however you are correct they can be upgraded to titanium gears and other junk as well(a tranny gut i'm not) but even then guys back home here still break stuff in them.little easier to fix though cause ya just brake 1 part not the whole thing.

qs9999

GM does not build the trans, its made by TTC and as they state "Currently, the TREMEC T-56 is being used on the Dodge Viper, Chevy Corvette Z06, Ford SVT Mustang Cobra, Aston Martin DB7 Vantage and V12 Vanquish, and Holden Commodore and Monaro."

but don't take my word for it here's a link to there web sight, and for those intrested they include and pdf for rebuilding the trans


it is the same thing you get when you buy it on ebay. and its free web page

good luck

blkmgc1

iTrader: (11)

hey man i don't doubt it matter of fact your right i was talking to friend and the viper does have it.only one difference the internals are bulletproof.or better than the camaros.he had said that the insides were titanium.don't know a whole lot about tranys but i know titanium is stonger than what we have for that torque monster viper.

qs9999

if you look at the web page you can see the y make differnt trans with different torqe ranges witch I'm sure are for differnt applications. so i'm sure the Viper, Z-06 and SVT have titanium gears.

I don't have a problem with that or the torqe differance but the problem are not from the gears blowing up. it's from shifter/ syncro problem, thease part are alu. and brass. so titanium is not need it a stock or slightly beefed up F body.

I've got guys with stock cars still under warrenty beating the crap out of these syncros and bending shift forks. but not braking, chipping or cracking gears.

Ken

Camaroholic

iTrader: (1)

I don't know where you guys are getting your information, but my BS-o-meter is on "PEGGED" for titanium internals on a Viper T56.

You can change the 'torque rating' of a transmission simply by changing the cut of the gear and the gear ratio itself. No need to change the metal. The 1993 F-body T56 had a lower torque rating than the 1994+, because of the different gearing. Not because of component strength.

AFAIK the only major differences are the steel 3-4 shift fork, and the carbon fiber synchro pad material. The input shaft and main shaft are likely different materials (and a different cut), but nothing is titanium from anything I've ever seen, heard, or read.

And titanium isn't necessarily stronger than a good steel. It's just lighter. It's used in valvetrain components to reduce weight. Not for strength. In fact, titanium valves are a bit softer than their stainless steel counterparts.

So again, sounds like a bunch of hear-say "I know a guy who told me" type info being passed around here. Post up facts, not "I think".

-Andrew