Main IndexAuto Repair Home Search Posts SEARCH
Who's Online WHO'S
Log in LOG

Search Auto Parts

Diff ratio for a LSA

  Email This Post

New User

Mar 9, 2023, 1:24 AM

Post #1 of 3 (162 views)
Diff ratio for a LSA Sign In

Hey everyone,

I’m building a 59 chev truck with a Lsa, Tremec 6 speed manual, Ford 9” diff and I’m trying to get some advice with what diff ratio to install.
I look into what ratio the vf HSV run and it is a 3.73:1
Would it be better if I’m running the same engine and gear box to run the same diff ratio or would it be better to install a ration like 3.50:1
The truck will be a cruiser with a bit of freeway driving

Any information will be much appreciated

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 9, 2023, 6:15 AM

Post #2 of 3 (137 views)
Re: Diff ratio for a LSA Sign In

You'll have to decide like a favorite flavor? How much power does so called "same" engine have in torque + HP @ what RPMs?

Factor you still have to decide is what you want for rear wheels and tires. The end all choice tires should state how far they go per revolution or measured that way also changes ratio.

IDK it's not my game but bet you want it all and look nice so more choices - all yours. Just factor wheel and tires also you've got everything else IDK engine IDK if you do? It all matters,

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 9, 2023, 9:52 AM

Post #3 of 3 (131 views)
Re: Diff ratio for a LSA Sign In

That is determined by what your goals are with the final product and the tire size you are using.

Using a taller tire changes the gear ratio so you have to account for that.

The lower the gear ratio ie; higher number gives you more torque at lower speeds and more acceleration but makes the RPMs run higher and decreases fuel mileage, increases cruising RPM and reduces top speed.

The higher gear ratio (lower numbers) gives you slower take off but better cruising fuel mileage.

3.71:1 means the driveshaft turns 3.71 (3 3/4) times for each revolution of the rear tires.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

  Email This Post

Feed Button

Search for (options) Privacy Sitemap