TurboGibbs

iTrader: (6)

I have been building manuals for years but I am about to attempt my first T56 rebuild. The question I ask is about removal of the 3 detent keys (dogs i've always know them by) on the inner slider hub that help hold the outer hub in the neutral position. These are a common breaking problem on abused muncie 4 speed tranny's and i've always just removed them since the internal linkage controls slider position anyway. I've also heard of T56's having the same problem and they make tool steel keys to remedy this. What I want to know has anyone just removed them all together and if so have you had any problems by doing this? The main purpose that I can tell they are for is to keep the sliders from vibrating and causing more tranny noise. It makes a tranny shift much smoother without them.

calhoon

iTrader: (6)

You can remove them altogether but you must leave the friction rings in place to complete the stack up . Of course, this will make a crash box out of it - that is it will clash-shift every shift because the synchronizing function is defeated.

TurboGibbs

iTrader: (6)

I guess I will see when I tear into it. An old muncie's syncros will work just fine without the dogs. Thanks.

calhoon

iTrader: (6)

working fine is relative. If you are adept at speed matching, no synchros are needed. Most cannot do this and the synchronizer is required for street driving.
BTW I forgot to say leave the hoop springs out with the struts/ dogs/inserts/keys

TurboGibbs

iTrader: (6)

Removing the hoop spring is a given. The muncie tranny's I have done in the past shifted like stock with the keys removed. They weren't a crash box. I have a Liberty pro-shifted M22 muncie that is a real crash box. I was unsure about the multiple piece synchro operation in the T56, the Muncie's are a one piece. I guess I will find out when I tear into it. If it's like you said I guess I will be leaving them in there.

87Fake

I sheared mine pretty good. I don't see why you would want them out. The resistance they cause to shifting isn't that much. you can operate the slider by hand even with them in place. Mine felt horrible going into gear without the keys, I guess it was like butter, but no positive "pop" in and out, even with the spring loaded ball on the shifter rail. The keys really help the in/out of gear feel.

TurboGibbs

iTrader: (6)

When you say sheared are you talking about the speed teeth on the syncro you sheared due to them being out? I do understand more load on the synchro speed teeth do to it having to line up with the hub in order to engage. I like the feel of it falling into gear though. That is a plus for me. Of course I love racing with my Liberty M22 but on the road it gets old.

calhoon

iTrader: (6)

I think he is talking about sheared struts.

bowtieman81

iTrader: (35)

I would not take the keys out. They are the main force that holds the tranny in gear. The detent ball at the shifter is really not very strong for holding gears.

I would just put some billet keys in, thats what I did when I rebuilt mine.

TurboGibbs

iTrader: (6)

I think that would just be the best thing to do. I believe you are right about the detent ball not holding tight enough to be safe. The detent system in the old Muncie's was tight. Thanks.

bowtieman81

iTrader: (35)

Yep the muncies had a stronger setup for holding gears. I have reubilt a few M21/M22 trans. You won't have much trouble with the T56

TurboGibbs

iTrader: (6)

Thanks

87Fake

I sheared the synchro keys on the 3/4 synchro. It was caused by overshifting 4th gear. I think this happens because the slider extends too far and the keys get caught between the inner and outer hubs wich are momentarilly not at the same speed. basically they get cut in half rather nicely and end up stuck to the magnets. I learned not to slam 4th too hard.

GTA Man

Sorry for pulling this thread out it's tomb, but did you managed to test the T56 without the keys??

I have an S1 Sequential shifter so keeping the gear in place is not a problem, I just want to know if removing the keys work.

Thanks

calhoon

iTrader: (6)

The shifter is not what holds you in gear. It’s the design of the clutching teeth of the synchronizer sleeve and how it mates to the clutch teeth on the gear.
struts are what move the friction cones to match sleeve speed to gear speed....synchronize.
leaving the struts an hoop springs out defeats the synchronizer. To shift , You clash the clutching teeth of the sleeve and gear until they mesh. This is what dog boxes do but they use heavier dog tooth designs so the don’t clash-off so readily.

GTA Man

Thanks for the input 👍