FreakZ

Another post I just read has prompted me to post this for everyones public knowledge as this problem seems to be growing more and more increasing.

I can't believe no tranny shop or builder has caught this yet! I know EXACTLY what it is, as it took me 4 times of rebuilding my own to find out what was going on. I really think that Tremic needs to release a technical bulletin on this. Anyhow, here is the problem....

PROBLEM
Tranny gets stuck in 4th gear, or 3rd gear, and/or is really hard to move around in neutral.

DESCRIPTION
If you use a shifter with no shifter stops, then you are relying on the guide plate inside the transmission to limit your throw into each gear. Normally, this would not be a problem. You can take each slider and put it in every gear as far as possible (until it rests against the gear), and the keys stay in, and everything is hunky dory. HOWEVER, if you take the slider and try to put it into 4th gear as far as possible, you will notice that the keys will try and pop out. When they pop out, they pop out twords 3rd gear, and actually get locked on the 3rd gear blocking ring, and cause it to semi "engage" 3rd at the same time. Once this happens, and you have two gears engaged at the same time, the weakest part goes, being the syncro keys in this case. They shred in half. When this happens, it makes it almost impossible to get it out of 4th gear, as the half sheared keys left act like a wall and catch on the slider.
NOW, the reason this doesn't happen to everyone, and usually takes a while to happen is simple. The ball on the guide for the gears actually stops on the tranny case for 2nd, 4th, and 6th. It is the case that stops you from going "too far" into 4th. What happens is simple, after many hard shifts into 4th, you begin to dent the aluminum case, which allows it to go into 4th "too far". Like I said before, you can't go "too far" into ANY gear and cause a problem EXCEPT for 4th. The reason 4th is this way is because of the design of the gear and the distance between the input shaft and output shaft.

SOLUTION
The solution is VERY simple, use a shifter with stops, and adjust them correctly!! I know, sounds simple, but often the hardest problems require the most simple solutions! After 4 rebuilds of getting 50 miles each rebuild before getting stuck in 4th, I discovered this, and adjusted my shifter stops correctly. Guess what?!? 10K miles now!!

I have rebuilt over 50 T56's here locally. I have run into two other T56's so far with this exact same problem. Each time using a shifter with stops has solved it.

akaceril

Glad I used my shifter stops

felton316

The ball doesn't stop the shifter. The ball should not even be touching anything while the tranny is in gear. It is the shift detent assembly and it just provides the 'notchhyness' between 1-2 & 3-4 & 5-6. The 'maze' looking like piece (shift guide plate) is what does the internally stopping of the shifter. It limits the front offset lever from moving too far. Now you may be on to something about the keys popping out, but a shifter with stops is not going to prevent that. It will only prevent the shifter from not fully engaging the gear. If you are denting the aluminium case, then you might have a problem with the shifter it self. Neither my stock shifter or my Hurst billet Pro allow any contact with the tranny case. Now I might have misread your post or not got the jist of it, but an external stops won't provide anymore protection than the internal stops. Just my two cents

FreakZ

You would think that. However I can promise that the ball actually makes contact with the case before the notch touches the end of the plate. Of the three T-56's I have worked on that have had this problem, the case was dented in all 3.

felton316

Well, I just checked mine again, since its sitting in my garage in the middle of a rebuild. I have atleast 1.5 cm before anything even touches the case. My tranny is a 98, so I don't know if that matters, but I am rebuilding it due to the 4th gear problem. I don't have it torn down all the way yet, but I am expecting to see a bent 3/4 shift fork, which would cause those little synchronizer keys to pop out. I'm currently replacing it with the Viper shift fork and all new synchros while I'm in there. Hopefully something can be found to fix this problem of T56's being to weak. Which shifter are you using? I wonder if that is playing a role in the damaged trannys.......

FreakZ

My shifter was an old style ripper that I wasn't using stops with. Another one was a stock shifter, and another one was a pro 5.0 with no stops.

When your checking for clearance in 4th, are you able to see the ball? It is very difficult to see the contact. Check to see if you see a slight indentation on the casing.

FreakZ

I'm actually in the process of building a STRONG T-56.

1) Cryo Treated
2) Custom Solid Steel Syncro Keys
3) Carbon Kevlar Blocking Rings
4) Steel 3/4 Fork

felton316

I've got numbers 3 & 4, where did you get the custom keys from?

FreakZ

I designed them, and had my friend at a machine shop CNC them.

OldSchoolSS

How much are theys keys if you buy them seperate to rebuild your own trans?

Fresca4u2

I've rebuilt my 1996 TA MM6 Tranny once already now and just last night I'm right back to square one again. 3/4 syncro keepers are sheared again. And yes, there are people that sell rebuilt T56's that are supposed to be bulletproof, with solid steel keeper keys. I'm going to go the route of FreakZ and just draw the MasterCam NC file so I can machinel them with one of our CNC mills at work. I'm going to check it over for the ball detent problem that FreakZ is talking about. I hope this is the case, if so I'll get a shifter with stops and maybe be able to get more than 20k miles out of it this time.

SidewayzOZ

iTrader: (11)

Pulled this one up from the ground eh?...talk to bugsqauwsher (or however you spell his name) before you put those stops in....he is a tranny rebuilder and is highly against stops. If you ever saw videos of FreakZ's runs, he was pretty hard on transmissions, and that car had some serious power. He ran 6.9/10.9's off the first stage, never saw numbers when the second stage was used, but I imagine he used it on the street. I think he was more on the verge of the transmissions limits than stops can prevent.

My90Iroc

iTrader: (26)

How does the Pro 5.0 fit in to this problem? Does it have stops on the shifter? Thanks.

Mrplow

The steel slider keys might sound like a great idea, but if you have seen what happens to the aluminum ones if they come out and go through the gears then you can see why the steel ones might be a bad idea. I know you think the steel ones are going to be "bullet proof" and not fail, but think of what will happen if they do. Now instead of just needing new slider keys and being stuck in gear, you will be replacing a few if not all of the gears. When the aluminum ones go through the tranny and go through the gears they get chewed up and spit out as a metalic paste. But a piece of steel trying to go between the gears would be a disaster. It will grenade the entire tranny. But that is just my opinion and can't prove it just yet, because I don't want to destroy my tranny. So hopefully the people running these will proove me wrong.

Fresca4u2

I'm not sure if they are using Aluminum in keys in the newer T56's but I know for a fact that the pieces stuck to the magnets in the bottom mine lets me know they were steel. It's a cheap stamped steel part that is prone to being broken after being stress hardened after thousands of shifts. Also, if the solid keeper keys do their job, there won't be a chance of them going through the gears and being ground up.