Lock-up v. Non Lock-up Transmissions

[skink4president]

Apologize if this has been discussed before I read something recently about lock-up transmissions and rear end gearing. For a while I've been considering a 350 turbo to 700R4 swap ( I do a lot of highway driving). What's the rule of thumb regarding gearing and non-lockup/lockup trannys or overdrive/non-overdrive? (Right now I'm running a Turbo 350 w/ 3.08 gears front and back in my '73 k5.)

Thanks!

 

[beastofablaze]

Not really any rule of thumb...but since you have OD you can afford to gear big and not pay a big price in mpg.

One rule of thumb when regearing is match the gears to your tire size... more important than anything else.

What size tires are you running?

 

[Hogback Fabrication]

Hopefully 31's with 3.08's!

 

[skink4president]

Yeah, I'm running 31's. The 3.08s are stock. I thought most all 73's were at least 3.55s or more but I've counted, they're 3.08s. I plan on adding about 2-3" of lift and eventually going with 32 or 33" tires. What's the equation to determine ideal gearing for specific tire sizes. Isn't there a calculator out there for this?

Thanks.

 

[89GMCSuburban]

If you are doing a 700R4 with 33's, I'd run 4.10 gears. I had 33's and 4.10's for the move up here and it worked great....13 MPG great.