T56 locked in 4th

Got the 5.3 into Burned Orange (formerly Orange Crush). Had it on the dyno this morning, and it made 260/305 - so that's great!

What's not great is that while on the dyno the trans decided it liked 4th gear the very best, and refuses to use any of the other gears. Going to snatch it out over the next few days - planning on being at Cresson for Friday practice.

Anyone have suggestions on what parts I might need to order? Internet suggests it's the 3/4 keys or maybe the shift fork. Both seem to be common problems with the T56.

- Josh

Suggest taking to a reputable builder instead of monkeying around with it yourself. (understand I used to own a transmission shop) In Houstion there used to be six speeds inc. with a guy named Honeycut but word awhile back on ls1tech was they may have stiffed several people. Search ls1tech for a good builder. There has to be some in Houston. There are several up here in DFW (Standard Transmission and Gear, Texas Drivetrain Performance) This is who several racers (Patterson) have used recently with excellent results-he has also built an AI car which you can see on their website so I would just call them. Tell them you are a racer and see what they can do to help you. Ship it to them and pick it up here or have someone pick it up to install at the track.
http://www.dederichsmotorsports.com/

Nice dyno!

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Originally Posted by Sook

Got the 5.3 into Burned Orange (formerly Orange Crush). Had it on the dyno this morning, and it made 260/305 - so that's great!

What's not great is that while on the dyno the trans decided it liked 4th gear the very best, and refuses to use any of the other gears. Going to snatch it out over the next few days - planning on being at Cresson for Friday practice.

Anyone have suggestions on what parts I might need to order? Internet suggests it's the 3/4 keys or maybe the shift fork. Both seem to be common problems with the T56.

- Josh

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Is that the one we swapped LT/LS input shafts on at the Orange is Fast shop?

So far every T56 with shifting issues we've taken apart traced back to worn out
blocker rings. (One of the early ones may have had a bent fork, I've slept since
then and I'm old so memory is fuzzy on that.) When the blocker rings are worn
out the gear select slider can over travel which lets the keys move too far which
locks the trans in that gear. The 3/4 slider seems to be the most vulnerable to
this wear. The other thing we (Scott, Sean, David) have struggled with is the
main shaft preload. It isn't hard, just kind of fiddly. It is REALLY IMPORTANT
to marinade the blocker rings in trans fluid before you put them in. Otherwise
the clutch material on cone wears off really fast, or so we believe. David can tell
you more than you want to know.

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Originally Posted by 39PitCrew

Is that the one we swapped LT/LS input shafts on at the Orange is Fast shop?

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No that was me! Still shifts great so far, no issues.

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Originally Posted by Pranav

No that was me! Still shifts great so far, no issues.

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Haha, we did this one with the OIF guys as well - local T56 experts! I had this trans on track as MSR-H for a couple of sessions before the engine went. Not sure what happened, but the dyno tech somehow got it stuck in 4th on the dyno. I'll do some reading on these blocker rings. Don't have a solid forward plan yet.

Mack's standards here in town has a great reputation. 713-738-1555

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Originally Posted by Sook

Haha, we did this one with the OIF guys as well - local T56 experts! I had this trans on track as MSR-H for a couple of sessions before the engine went. Not sure what happened, but the dyno tech somehow got it stuck in 4th on the dyno. I'll do some reading on these blocker rings. Don't have a solid forward plan yet.

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Will be interested to hear what the postmortem is on it.
Did the 3/4 syncro have stamped or billet keys?
We had one eat a set of billet keys before we figured out
where the problem was.

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Originally Posted by 39PitCrew

Will be interested to hear what the postmortem is on it.
Did the 3/4 syncro have stamped or billet keys?
We had one eat a set of billet keys before we figured out
where the problem was.

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I don't remember what keys were in it. It had been professionally rebuilt after it had become locked in 4th last year at Cresson (go figure!). I think they used fancy parts to prevent that problem from happening again.

The only thing I distinctly remember from the last time it was open (@ OIF) was that the 1st gear synchro wasn't looking happy, but I decided to proceed at risk.

Update: got it apart today. The "dirty" way since one of the guide pins had the head already broken off. ALL the 1/2 keys were out of the slider assembly and the 3/4 keys that weren't broken came out when the slider came apart.

Looks like all stamped keys to me and right now I would tell you the stock aluminum 3/4 fork. Did not notice any bearing issues from a super quick look.

I think plan A is to cobble together something from spares Monday night so Josh can make an attempt at Cresson.

What's your take on the billet keys? I have no idea what's inside the red dragon's box, but it was rebuilt before I got my dirty mitts on it.

On my T-5, I swapped to billet keys in the 3/4 slider and haven't had any issues since breaking the stamped stock keys back in 2011.

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Originally Posted by Supercharged111

What's your take on the billet keys? I have no idea what's inside the red dragon's box, but it was rebuilt before I got my dirty mitts on it.

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At this point we believe in billet keys for sure 3/4 and a steel fork. We've been using stock plastic fork pads based on all the reading we've done. Also believe in somewhat smaller tolerance in the shim pack.

We also watch for 3/4 blocker wear since we believe that coupled with mainshaft "nose" bearing opens up the room for it to get stuck in 4th.