Blowing 1-2 Synchro (again!)
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Joined: Dec 2004
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From: K-W, Ontario
Blowing 1-2 Synchro (again!) Need some tips, advice on rebuilding my T-56
Long story short, my transmission can't seem to support the power from
the engine and conitnues to destroy the 1-2 synchro.
The symptoms are: tough going into 1st gear. will not go into 2nd unless
at high RPM, or grinding at slow speeds. Once in 2nd gear, it will hold fine.
When I rebuilt the first time, I used stock synchro's with brass blockers,
a stronger fork, and new bearings. The shifter is a Pro 5.0 with Lou's short
stick and adjusted as per spec.
Power is about 413 tq. @ 4800, 440 hp. @ 6300
http://procision-auto.com/ProAuto/SS/ss_track_tune.jpg
What sort of things have you done to support the power?
Is there anything available as replacement parts, or do I need to think about
a new transmission?
Thanks for all of your help!
Long story short, my transmission can't seem to support the power from
the engine and conitnues to destroy the 1-2 synchro.
The symptoms are: tough going into 1st gear. will not go into 2nd unless
at high RPM, or grinding at slow speeds. Once in 2nd gear, it will hold fine.
When I rebuilt the first time, I used stock synchro's with brass blockers,
a stronger fork, and new bearings. The shifter is a Pro 5.0 with Lou's short
stick and adjusted as per spec.
Power is about 413 tq. @ 4800, 440 hp. @ 6300
http://procision-auto.com/ProAuto/SS/ss_track_tune.jpg
What sort of things have you done to support the power?
Is there anything available as replacement parts, or do I need to think about
a new transmission?
Thanks for all of your help!
Was the slider replaced during the rebuild? I see it in the pic but is it new? You certainly aren't pushing more power than a t56 can hold. What is the clutch setup? Is is disengaging properly?
Thread Starter
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Joined: Dec 2004
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From: K-W, Ontario
No, the slider was not replaced.
The clutch is a McLeod 800, newer slave, adjustable master.
I don't have the TX specs handy, however clearances seem fine and
the pedal release action is also setup well.
Are you suggesting that I may need more clearance when engaging the
clutch?
The clutch is a McLeod 800, newer slave, adjustable master.
I don't have the TX specs handy, however clearances seem fine and
the pedal release action is also setup well.
Are you suggesting that I may need more clearance when engaging the
clutch?
An easy check for the clutch is to put the car in gear on level ground and with the clutch on the floor bring the rpms up to about 5500. If the car moves forward the clutch is not disengaging fully. If it doesn't move we can look back to the transmission for your problem.
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I would sugest ditching the Lou's short stick. Just got done writing a PM to someone asking on how they can increase their shift speed.
Honestly, simple physics, short stick sucks for rapid shifts. This could be throwing off your timing and hurting your trans because otherwise I see no reason why a T56 can't hold 440hp. As posted before in this section and on this site, my stock T56 held over 500hp with 7000rpm shifts and launches and is still not broken 400+ passes later. 100 of those with over 500hp and 7000rpm, the others with anything from stock to 396hp H/C to 396HP H/C and 75 wet shot to 450HP H/C.
You should not be hurting that trans unless you are making mistakes. Sorry to sound like a pompus ***.
Honestly, simple physics, short stick sucks for rapid shifts. This could be throwing off your timing and hurting your trans because otherwise I see no reason why a T56 can't hold 440hp. As posted before in this section and on this site, my stock T56 held over 500hp with 7000rpm shifts and launches and is still not broken 400+ passes later. 100 of those with over 500hp and 7000rpm, the others with anything from stock to 396hp H/C to 396HP H/C and 75 wet shot to 450HP H/C.
You should not be hurting that trans unless you are making mistakes. Sorry to sound like a pompus ***.
Thread Starter
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Joined: Dec 2004
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From: K-W, Ontario
Awesome replies everyone. Thanks for all the help with this.
The clutch is definitely disengaging with the pedal down, no question;
I even tried a 6K rev on level ground today - no roll.
The drill mod is done:
What sort of 'mistakes' could I be making?
Do you think the Pro 5.0 is not setup correctly? What I did was engage
the gear shift into 2nd, then adjusted the set screw until it touched the
back of the lever (with 0.010" clearance). The screw is locked in that position.
Same procedure done with 3rd gear since those are the two most abused
when power shifting.
I was hoping to read something to the effect of upgrading parts, but it
seems the stock T-56 is fine. Is it possible some of the aftermarket parts
failed?
IE: the synchro assembly
The clutch is definitely disengaging with the pedal down, no question;
I even tried a 6K rev on level ground today - no roll.
The drill mod is done:
What sort of 'mistakes' could I be making?
Do you think the Pro 5.0 is not setup correctly? What I did was engage
the gear shift into 2nd, then adjusted the set screw until it touched the
back of the lever (with 0.010" clearance). The screw is locked in that position.
Same procedure done with 3rd gear since those are the two most abused
when power shifting.
I was hoping to read something to the effect of upgrading parts, but it
seems the stock T-56 is fine. Is it possible some of the aftermarket parts
failed?
IE: the synchro assembly
Need some tips, advice on rebuilding my T-56
Long story short, my transmission can't seem to support the power from
the engine and conitnues to destroy the 1-2 synchro.
The symptoms are: tough going into 1st gear. will not go into 2nd unless
at high RPM, or grinding at slow speeds. Once in 2nd gear, it will hold fine.
When I rebuilt the first time, I used stock synchro's with brass blockers,
a stronger fork, and new bearings. The shifter is a Pro 5.0 with Lou's short
stick and adjusted as per spec.
Power is about 413 tq. @ 4800, 440 hp. @ 6300
http://procision-auto.com/ProAuto/SS/ss_track_tune.jpg
What sort of things have you done to support the power?
Is there anything available as replacement parts, or do I need to think about
a new transmission?
Thanks for all of your help!
Long story short, my transmission can't seem to support the power from
the engine and conitnues to destroy the 1-2 synchro.
The symptoms are: tough going into 1st gear. will not go into 2nd unless
at high RPM, or grinding at slow speeds. Once in 2nd gear, it will hold fine.
When I rebuilt the first time, I used stock synchro's with brass blockers,
a stronger fork, and new bearings. The shifter is a Pro 5.0 with Lou's short
stick and adjusted as per spec.
Power is about 413 tq. @ 4800, 440 hp. @ 6300
http://procision-auto.com/ProAuto/SS/ss_track_tune.jpg
What sort of things have you done to support the power?
Is there anything available as replacement parts, or do I need to think about
a new transmission?
Thanks for all of your help!
What do you mean by destroying the synchro?
Are you eating the engagement teeth on the blockers/gears/sliders?
Did you disassemble the entire trans to set the shims for main/counter shafts?
Please post the pictures of the damaged parts so we can help you better.
Thread Starter
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Joined: Dec 2004
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From: K-W, Ontario
What do you mean by destroying the synchro?
play with the clutch and shifter sometimes before 1st gear will engage.
Will not go into 2nd and low RPM/speeds. I'm still able to power shift
into 2nd when racing (6000+RPM and smooth entrt)
Once in 2nd gear, it will hold fine and disengage no problem.
Are you eating the engagement teeth on the blockers/gears/sliders?
was the case (shaved/damaged teeth). The difference for the first time
was second gear would not engage, and if it did, it would pop out (especially
at high RPM/Speed when power shifting).
After a year of the rebuild (under my posession), things are going bad again.
Did you disassemble the entire trans to set the shims for main/counter shafts?
damage, but all the new pieces were installed by a trans. tech.
Please post the pictures of the damaged parts so we can help you better.
jmd I'd like to think I'm shifting properly, however there's always a
chance the clutch isn't coming apart fast/far enough during the 1-2 shift,
or I'm early on the 'pull'.
Keep in mind the previous owner also had similar issues so it's either a lemon
t-56, we both suck at driving, the transmission shop messed up, or a part
may have failed.
I'd just hate to replace the 1-2 assembly with stock parts and have it
fail again...but everyone seems to have great results.
The Pro 5.0 instructions say to set the screw against the lever while in
gear, then back off 1 turn. I went with 0.010" as it was a closer stop point.
Is that partially the problem? I can't see it...but at this point, I have to
question everything.
So did you replace the:
1-2 slider (also known as synchro) and hub
blocking rings with cones (double cone)
1st gear assembly
2nd gear assembly
If not how does the engagement teeth look on the gears/slider ring/blockers?
1-2 slider (also known as synchro) and hub
blocking rings with cones (double cone)
1st gear assembly
2nd gear assembly
If not how does the engagement teeth look on the gears/slider ring/blockers?
On second thought, did you happen to check to see if the blocker rings on each gear had the proper clearances when they were seated on the cone of the gear? If I remember, with the blocker seated on the gear, there should be clearance of something like .020 between the rear face of the blocker and the front face of the gear. I'm wondering if there was a problem with the assem. from the get go.
Thread Starter
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From: K-W, Ontario
as well as bearings, and the gears for the 1st and 2nd shaft which engage
with the 'slider' (synchro)
If not how does the engagement teeth look on the gears/slider ring/blockers?
apart.
It's still in the car and I'm driving it. At the moment I'm shifting from 1st to
3rd until I can figure out which route to take.
The pictures you see in the first post were taken after I bought the car
and during the 1st rebuild.
To clarify:
Bought the car 3 years ago
Had an issue with engaging and staying in 2nd gear
Replaced all the parts you see above.
Car was fine for about one year. Raced it, street driven, etc.
Now once again I'm having troubles with 2nd gear engaging (as explained
above). Don't know why it's failing for a second time.
Hope that clears everything up (I suck at the internet sometimes
)