What parts need to be modified in order to fit a 4.88 ring and pinion (from a 1st gen?) into a 2nd gen rear diff?

 

thatz a good question bumpity bump bump
and also would that be a good gear for bottom end on the fc or jus top end?

 

I do believe that the final drive of 3.90 would be better for things such as drag racing, and a gear like your 4.88 would be better for top speed.
It could be the other way around... its late and I cant think straight

 

other way around......numerically higher gears make you accelerate faster, but limit top end. Lower slows acceleration, but give more top end.

I wouldnt imagine you would have to go higher than the 4.30s. If this is in an NA car, get the T2 trans and the 4.30 gears, do some lightening mods, and be on par with the GTUs.
If this is on a turbo car, just stay with the 4.11s if you like to highway race and see speeds of 130 a lot. If not, go with the 4.30s as you will benefit from quicker acceleration, and not need to worry about topping off at say 160ish

 

I don't know about 4.88, but I know that Agent_D has a 5.12. Not sure where he got it though

 

Joe's right that lower ratio number=higher top speed (aka taller gear). A shorter gear (higher ratio number) will improve acceleration.

4.88s require splicing the longer pinion shaft of the 2nd gen, to the 4.88 pinion gear. That's welding, and not something that you can just take to the local drivetrain shop and ask them to do, serious liabilities if it breaks, etc etc.

Speed Source in Florida is the only shop I can think of, off the top of my head, that will do this. I know there are a few others, I just can't remember who.

I think that would be a great mod for a SERIOUS drag racer, but for most people, 4.88s are way too much. 80mph would be almost 4000 RPM, and you'd be shifting a LOT.

PaulC

 

Thanks Silkworm. That's exactly the information I was looking for.

 

Yip, if your car is mainly a competition car and the tracks and events etc that you do dont see speeds over 130 or 140mph then a 4.8:1 diff ratio will improve your times, at an autocross a 4.8 diff will see you faster, more acceleration, allows you to be in the peak HP.torque range alot more etc etc etc

 

Mazda Trix makes an adapter for this (at least they used too), no welding needed. And the GTUs does NOT have a turbo tranny.Its n/a 100% with revised 5th gear ratio.