If this is your first visit, be sure to check out the FAQ You must be an NCRS member before you can post: click the Join NCRS link above to join. To start viewing messages,
select the forum that you want to visit from the selection below. If you have trouble logging in you can clear your cookies here!
Re: what is typically more desired the m20 or m21?
Neither the T-10 nor Muncie four-speeds have very good ratio sets for modern driving conditions, but they were developed back before interstate highways allowed cruising speeds in the 70-80 MPH range.
The CR versions require a short axle ratio for good around town performance, but they turn excessive revs at modern freeway cruising speeds. A tall axle yields decent highway cruising revs, but around town it's like a five-speed with no first gear.
The WR versions were created with the expedient of a shorter countershaft ratio, which shortened first second and third, but resulted in a HUGE gap between third and fourth.
Many 300HP/WR owners skip second gear because the engine is so torquey, second is not really necessary. First, third, and fourth are about the same ratios as the three speed.
The later Super T-10 CR (2.43/1.61/1.23/1.00:1)and WR (2.64/1.75/1.34/1.00:1) transmissions have much more sensible gearing for a road car with the biggest gap between first and second where it belongs. A flexible road gearbox should have progressively shorter inter-gear ratios as you go up through the gears and the Super T-10 does so. I believe a Super T-10 can be swapped into earlier T-10 and Muncie applications with a minimum of modifications.
I've worked out some even better ratios, but it would take some tooling investment to make this happen.
The two ratio sets, as with the T-10 and Muncie, are achieved with different countershaft ratios. The "Highway Cruise" axles would probably be best for how most of us use vintage Corvettes, today, but even with these tall axles, burnouts would be no problem.
Comment