vettecor

I presently have a '77 with TH-350. I am running 3:08 rear. My mechanic said I could go with a 3:70, (Richmond). I thought the next step up from a 3:55 would be 3:73! I put on about 3000 miles per year, including some trips out of state. Would this 3:70 be OK for highway driving of 70 MPH for 4 hours straight? Would it cause any damage to any existing part? ( I just had the transmission rebuilt).

Thanks
Larry :seeya

C3 Shark Tank

Before I did a trans swap to the 700r4 I had the TH350 and 3.54 gears, at 70 mph I believe the rpm's were about 3400 and I hated highway driving. With 3.70 gears at 70mph for 4 hours.....no thanks.

78Vette-SA

I'd agree with C3 ST. I've got the 3.55's and Turbo 350 and at 70 she's pushing well over 3k.

bence13_33

vettecor:
Corvette gears are 3.70, Richmond does offer 3.73s but not for the Corvette. I had a set of 3.70s in my car a while back with a 1:1 forth gear and 215/70/15 tires I was taching about 3000 @ 65mph. You could probably get away with a constant 70mph with the 3.70 gears but it's going to be hard on your engine. 3.55s would be a better choice (IMO).

fauxrs

I've got 3.70's in my 78 L-82 and have done very long trips (6-8 hours on the road) at 70 or greater. The L-82 is of course more inclined to higher rpms but I seriously dount you are going to see any damage done to your car - Rpm's are about 35-3800 if memory serves - My car is down with a rear suspension rebuild and its been awhile.

I'm driving up to Monterey this year for the historical races there - thats about 4-5 hours from me here in San diego minimum. not worried.