Join Date: Nov 1999
Location: Central California, USA
Guess I was wrong in stating no bigblocks came with the M20. Thanks for correcting me. I'm learning a lot here too.
The main point I was trying to convey is there is a greater risk of breaking an M20 compared to a M21.
I've read where the really high output bigblocks were paired with the M21 only, not the M20 because of the added torque multiplication of the lower first gear of the M20.I don't recall exactly but maybe it refered to the 454 engines, not the smaller 396 bigblocks used in the first gen camaros.
I'll take your word for it that firstgen Camaros were equiped with the wide ratio trans. I'm certanly no expert.
The M20 and M21 trannys are the same inside except for tooth count.
But the lower first gear of the wide ratio trans multiplies the torque and lowers the manufacturers max torque rating of the trans.
Example of a 454 making 450 ft lbs of torque:
450ft lbs X 2.20=990ft lbs.
450ft lbs X 2.56=1152ft lbs.
Big block engines are harder on manual transmissions because they make more torque and they have a heavier rotating assembly. The crank, rods , pistons, flywheel, and damper all weigh a lot more than a small block and when you get all that mass spinning and dump the clutch, that's a big load.
That shock load can be several times the rated torque of the engine.
Multiply that times the first gear ratio and you have a huge loading compared to a small block.
My Richmond 5 speed catalog lists three first gear versions of the SAME transmission.
ratio-mfr torque rating.
It looks to me that they are de rating the trans because the lower first gear ratios apply more torque to the rest of the trans, so they have to lower the input torque rating to keep output torque within design limits.
So using my reasioning, a wide ratio trans would be slightly weaker (15% to 20%) than a close ratio trans, WHILE IN FIRST GEAR.
If you don't have much traction, then that becomes the torque limiter on the drive train. But if your car really hooks up then at least in theory, the wide ratio would go BANG before the close ratio tranny.
I had the wide ratio in my 67 and I liked the low first gear but in the 3rd to 4th shift the revs really dropped.
The older I get, the faster I was!
[This message has been edited by davidpozzi (edited 06-22-2000).]