I've been driving my electric fiero for a couple weeks now, and it is running well. However, the final drive ratio is too high for this motor. For best efficiency, I need to cruise at 65 mph in 4th gear at 3800 rpm, but its currently at 2500 rpm. This getrag 5spd has a 3.61 rear gear ratio, but it looks like I really need 4.56 gears. Is it possible to change? Where can I get the replacements?

thx and here is a link to my project:

www.evalbum.com/1590

What about using an 84 4-spd with 4.10 final drive?

Edit: Sorry just read your website.

So if you are noticing the best efficiency with the getrag in 4th gear @ 65MPH why don't you just drive in that gear instead of trying to change the final drive?

[This message has been edited by Jefrysuko (edited 05-06-2008).]

I would like the final 3800 rpm at 65 mph in 4th to reserve the other gears for slower intown driving. it just provides me more options. I thought about smaller tires but I would have to move to 14 wheels to get any benefit. the car sits too low already. I need to do a coilover conversion, and still looking at options.

Cool project!

Assuming 24.6" diameter tires, 3800 RPM will get you:

67.5mph in 3rd gear with the 3.32 84 4 speed.
61.4 in 3rd w/ 3.65 85-86 4 speed
57.22 in 3rd w/ Isuzu 5 speed
55.8 in 3rd w/ fiero 3.61 getrag
51.12 in 3rd w/ 3.94 getrag (and 75.05 in 4th)

quote Originally posted by 88formfactor: I would like the final 3800 rpm at 65 mph in 4th to reserve the other gears for slower intown driving.

Ok, I think I understand now.

Looks like your best option would be the 3.32 4-spd but good luck finding one. I have been looking for one for quite some time now for a V8 swap.

BTW: My 4.10 4-spd recomendation would be a horrible choice. It would be a lower speed than any which Guru mentioned in 3rd gear and would be at 92.9 mph in 4th. That is if I did my math right.

I think that Guru gave you your answer though...

quote Originally posted by fieroguru: 51.12 in 3rd w/ 3.94 getrag (and 75.05 in 4th)

Just drive 75 MPH!!!

What's wrong with using the 3.94 final drive ratio and short 1.03 4th gear as opposed to the .94 and 3.61 you have now?

The shorter gears are found in High Output Quad4 Getrags and the internals should be swappable.

quote Originally posted by 88formfactor: I would like the final 3800 rpm at 65 mph in 4th to reserve the other gears for slower intown driving. it just provides me more options. I thought about smaller tires but I would have to move to 14 wheels to get any benefit. the car sits too low already. I need to do a coilover conversion, and still looking at options.

That doesn't make any sense at all.