[h0trod389]

hay guys, im runnin a pontiac 389.030 over. she makes great power... the problem is that i keep eating muncie transmissions... ive rebuilt a early m-20 w/ 1" countershaft, about 3 times now, all new guts, n gears...
the problem is that 1st gear dont last too long. mabe this is why people put chevys in pontiacs... they dont like torque!
68 TEMPEST, 389 CI 3.55POSI @ 3800 LBS

WHAT KIND OF MANUAL TRANS ARE OTHER GUYS RUNNIN WITH PONTIACS?

[OneMoreTime]

Check your bell housing for runout..sometimes they are not as good as they should be..takes a dial indicator to do it..eyeball is not good enough..

Eating trannies can be caused by that..and there are alot of Pontiacs running Muncies with no big difficulty..

Just my best guess..

Sam

[428ho]

I've run M21's behind some fairly potent Pontiac engines with only one failure over the years. But I run a 4:11 gear.

On the link below notice the first gear ratio on the M20. Drop the hammer to hard and she will give up. M22 would be even better, but they're pricey.

http://www.nastyz28.com/transid.html

3:55 is kind of mild if your dumpng a load of torque into it off the line. Not really a good grunt gear off the line which is where most transmission damage occurs getting a heavy car moving. A 68 Tempest ain't exactly light.

I've heard you can beef up an M20, but unless you're trying to stay matching number or something I'd go close ratio M21.
But a change in rear gear should help you a lot.

[h0trod389]

Originally Posted by OneMoreTime

Check your bell housing for runout..sometimes they are not as good as they should be..takes a dial indicator to do it..eyeball is not good enough..

Eating trannies can be caused by that..and there are alot of Pontiacs running Muncies with no big difficulty..

Just my best guess..

Sam

im using a lakewood scatter sheild, i had to dial it in and use diffrent pins, .003 TIR, good enough eay?

i didnt want to go lower rear gears because i see freeway action constantly.
right now it has a th350 in it for the tim being. mabe a shorter gear is the answer...

thanks guys
B

[kain13]

try an m22 there is one in this boards classifieds