JackF

If you were picking a diff...

12 posts in this topic Last Reply

Recommended Posts

for a 72 with 32/36, 292, OD5, what would it be. I have never looked at the receipts for the cars (there lies madness mate), but have just started sorting them (there lies madness mate) to get a better detail on all the components on the turbo motor.

Anyway I ran across Korman's invoice for a lsd diff I bought. The guy who ordered it never picked it up and so I bought it right. I thought it was a 3:90, but according to the invoice it has a new 4:10 gear set. Seems a tad much for a driver. what do you all prefer and why?

Share this post


Link to post
Share on other sites

Jack- I've run both on my tii (similar hp to your setup.) It all comes down to what kind of roads your going to be driving on. The 390 was great around town and on the highway but I switched out for the 410 and the acceleration out of corners was much better. If your going to be on the highway for long periods of time I'd go with the 390.

Pete

Share this post


Link to post
Share on other sites

Jack, I think the 3.90 is pretty much perfect with a 5spd. It's a nice choice between the 4.10 which is a little quicker and the 3.64 which is a tad slow for my taste. If you want to sell the 4.10, I have a hotrod that could use it. Tim Jones tljonesco@aol.com

Share this post


Link to post
Share on other sites

I installed a 5 speed at the same time I rebuilt my engine--only has a 284 cam so not as powerful as yours, but I stuck with the original 3.64...it accelerates as well in 5th as the old engine did in 4th, and on the highway 74 mph is only 3200 rpm, as opposed to 4000 with the 4 speed.

My vote goes for a 3.64 if you're gonna do a lot of highway driving--like to events outside your area or daily commutes that aren't on twisty back roads (I wish!).

A 3.90 or 4.11 will give improved acceleration over the 3.64, but won't help highway cruising--you'll still be up around 4000 rpm at 70--ish in 5th. In my dotage I prefer a more relaxed cruising mode.

cheers

mike

Share this post


Link to post
Share on other sites

I'd love to add something useful that hasn't already been said, but I can't.

That said, 4.55's in a hot rodded MG Midget is a bit much. Like what Mr. Egan said, "hyperkinetic fury"

John

Share this post


Link to post
Share on other sites

I'm wondering the same thing. Eventually I will have a turbo and 5 speed and want the best ratio for hwy and light track use.

What do you all think I should go for?

Share this post


Link to post
Share on other sites
I'm wondering the same thing. Eventually I will have a turbo and 5 speed and want the best ratio for hwy and light track use.

What do you all think I should go for?

Stay with the 3.64 if you are going turbo, Hell I'd like something even taller, 1st and 2nd are just so short.

Share this post


Link to post
Share on other sites

I wouldn't mess with the 4.11 until I got the turbo up and running.

Jenn's car has a 3.64 and a bone- stock motor, and it's a bit doggy

versus my 3.91 and stock motor.

I really like the 4.11 in the race car- so much that I'm all excited

about the 4.44

t

Share this post


Link to post
Share on other sites

I think the 3.91 is the best over all diff.

I have one in my DD 320is and it's great. In town I never leave 4th, and even then, it will happily go up to 100kph in 4th, at a reasonable noise level.

A 4.1 would still be a good diff with a 5speed, but buzzy as hell with a 4speed. I wouldn't go 3.64 unless you've got a turbo, or something that has a power band that you'd want each gear strung out more.

-Andrew Poon

Share this post


Link to post
Share on other sites

"I'm wondering the same thing. Eventually I will have a turbo and 5 speed and want the best ratio for hwy and light track use.

What do you all think I should go for?"

I'm currently running an open 3:45 on my turbo and it is great. The turbo can pick it up. I've sourced a 3:36 lsd which is being rebuilt and will be installing that. I'm running 6.9:, 8-8.5# with a small IC. Not sure what you are planning for specs, but I'm very pleased with the 3:45.

Share this post


Link to post
Share on other sites
"I'm wondering the same thing. Eventually I will have a turbo and 5 speed and want the best ratio for hwy and light track use.

What do you all think I should go for?"

I'm currently running an open 3:45 on my turbo and it is great. The turbo can pick it up. I've sourced a 3:36 lsd which is being rebuilt and will be installing that. I'm running 6.9:, 8-8.5# with a small IC. Not sure what you are planning for specs, but I'm very pleased with the 3:45.

Where the hell did you find those?

Share this post


Link to post
Share on other sites

The 3:45 came on the car. I thought all turbos came with 3:36's until I saw Richard Sterns article last year which said there were actually a few offered. Dominic from Portland (the western version) had the 3:36 and the whole turbo rear end which I bought. Nice almost new 250mm rears. They work real well and will fit the 72 nicely.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now