Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

LT1 T56 blows reverse

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Old Feb 9, 2013 | 01:14 PM
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Default LT1 T56 blows reverse

Short version: Shifter slides into reverse gate with ease and nothing happens

I was having a problem where my reverse lockout wasn't working, on 4-5 occasions when I was shifting fast from 4-5 I'd hit reverse and grind since I bought the car in August. Well the last time it happened was 2 weeks ago and ever since reverse would pop out 90% of the time and be pretty hard to engage and grind when it wouldn't. (I'd never try to hold it in and keep it grinding and force it).

Well we had a snow storm last night as those of you in the northeast know, I dug the T/A out and was rocking it very gently to loosen it and for once reverse wasn't even grinding or being difficult . Well after 2x engaging it, it just quit . Now it slides into the gate with zero resistance, I can release the clutch and nothing.

I did some research and saw some posts talking about removing a plate in the back of the trans and servicing it in the car/ replacing the gear and shift fork. I'd assume the blocker ring is gone? I've read conflicting posts on whether there is a synchro on reverse or not.

I haven't had a chance to check the fluid level yet but would low fluid impact reverse first? Seems strange that it just slides in so easily.

I'd really appreciate any advice, the timing is very bad for me to be pulling the trans and sending it off for a rebuild.. Hell I don't even know if I could do it safely on the street where I do all my work, thanks guys.
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Old Feb 10, 2013 | 08:10 AM
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Reverse is fully synchronized in a stock T56.
Sounds like your box was repeatedly clash-shifted.....they will all give up after enough of this. You wore the clutching teeth down so far that the sleeve cannot engage the gear. This was after the blocking ring lining was worn down...too. I do not support repairs with the trans hanging in the car. You will likely need most of the reverse parts: gear ,sync,fork&pads,friction ring and a good flushing out.
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Old Feb 10, 2013 | 02:55 PM
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Originally Posted by calhoon
Reverse is fully synchronized in a stock T56.
Sounds like your box was repeatedly clash-shifted.....they will all give up after enough of this. You wore the clutching teeth down so far that the sleeve cannot engage the gear. This was after the blocking ring lining was worn down...too. I do not support repairs with the trans hanging in the car. You will likely need most of the reverse parts: gear ,sync,fork&pads,friction ring and a good flushing out.
I'm sure the PO must have done it a good few times because after the first time it happened to me, I started having difficulty with reverse. It would engage fine and as I'd be reversing it would feel like something would bind up and it would pop out of gear.

I've done some more research since and rebuilding the T56 seems easier than I was expecting. I'll be looking for a donor trans to build, or worse case scenario the car will be down for a while as I rebuild it. My main concern is how I'll go about doing this on the street with jack stands or ramps. I should have enough clearance to drop the trans down and slide it out of the car, can't wait until it warms up so I can start this project

Isnt the gear and synchro an integrated unit for reverse? At leasts thats what I got from my reading. The rest of those parts come in a standard rebuild kit apart from the fork I believe as well.

*Also I might as well ask about this.. At very low speeds (under 10mph) when in first I'd be getting a rattle, like a light grinding. Is it possible that first lost it's press fit? When I had it up on the lift last time, I rotated the drive shaft and it would rotate about a good 1/2" and something in the trans would clank. Any input?

Thank you!
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