I have a 71 chevelle 402 Stock motor. I currently run 17" 275 40 tires I have a 69 M20 Muncie & 4:11 Posi 10bolt my problem is im tacking way to much RPM coming threw the gear and this car will be driven alot when it is driven maybe twice a week and also im planning a 2 1/2 hour drive in it too. Basically what is my choices on droping down the RPM im looking to run low RPM at high way speed but still able to burn the tires. And not sacrifice my fast take off. But also try to have a max speed of atleast 90-100mph just in case i find a race. I have about a $1000 budget. Should i change the trans & the rear end.

3.42-3.55 gear would be perfect.
You don't need 4.11's with a stock or even a mild 402

A lot of the M20's even came with 3.31's.

given your desire to stay within $1,000, i would change rear gear to 3.55. I have heard of guys having two rear gear set ups that can be switched out relatively quickly. perhaps that is something that would work for you

A lot of the M20's even came with 3.31's.


I agree with the 3.42s or 3.55s...

3.31's are a good choice too, BUT, I don't think anyone makes them "new"... So you'd have to find a good used set...

For $1000, rear gears are your best choice (going to be $2K+ to go overdrive)...

Nows the time to consider a different rearend, maybe a 12-bolt... They will cost the same for labor and parts, just the extra cost of the housing (and axles)... Figure roughly $1100+ for all the parts and labor for 12-bolt posi (assuming new axles and new posi unit, bearings, gears)... Of course, you should be able to get new gears in yours for $400+ (and use your old posi/axles) If you can find a bare housing at a swap meet, etc, or even something with decent axles, might not be too much above that $1000 budget... Might find a nice usuable 12-bolt posi for $600+, but make sure its good...

I'd just hate to spend $400+, and then have the rear blow down the road because it couldn't handle the 402/manual combo...


I originally ran 4.10s with an M20 behind my 396 (295/50 tires)... Too much... I swapped to 3.42s, and it made the freeway cruise more enjoyable, but the 396 still hd the power to launch the car well... Actually managed 16 MPG on the freeway with the 3.42s...

I have 3.55's behind a th400 and a 427 BBC with 26 inch tall tires. I love that combo! Its just fine on the highway cruising at normal speeds and does just fine at the track!

Daniel

The 3.42 would be your best bet for a new gear. The 3.55 is more expensive and I think the 3.42 would be better for the driving that you plan to do. If you are interested in a 3.31 send me an email. I used the 3.31 in my '67 SS396 Chevelle with a Powerglide and my '72 SS454 Chevelle with a Muncie 4 speed. Both were great fro driving and still had good performance.