Not that I consider my FD a race car...
Currenty 320hp . Soon to be 400+ when motor gets a rebuild.

Im trying to get out of dragging the car, and want to start doing autocross.
Should I keep the 4.1 or drop down to the 3.90? Or is it to small of a change to make a difference? Maybe a different ratio? Any suggestions would be great..

Thanks..

 

just leave the 4.10's The 3.9 's would give you less rpm out of the generally tight corners in auto cross and bog you down. I have tried both and the only time you would want to go to a 3.9 or smaller if you have so much power that you just spin the tires when the car revs up. or the shifts come up too quickly.

 

Serious autocrossers run a 4.77

 

Who offers the 4.77?

 

+1

Going to finish up re-installing the suspension today so I can break in the Carbonetic diff with KG 4.77 gears. First autox with the new setup is Sunday.

4.10 gears for autox are really lame coming out of slow corners. I can only imagine how frustrating 3.90 would be.

Were I to do it again I would probably buy the 4.77 RX-8 gears from MazdaMotorsports.

The deal on the KG gears was too good to pass up though as it came with all the seals and bearings.

A good compromise might be 4.44 gears (also RX-8) if you didn't want to go as extreme as 4.77.

 

Well I would be serious if I had the time.. Realistically I will be able to track the car 2-3 times a year, if Im lucky.
4.77 might be to aggressive for me.
The 4.44/ 4.30 gears where what I started looking into. Since I still ran the 1/4 mile at the time, I was worried about traction issues.. Now that I am done with 1/4mile, I will look into those gear ratios.

Since I will be changing rearend gears, I was thinking about adding the brace to go with it. I have seen a couple of them on the vender's websites. Banzai, A-spec rx7store..ect... Do you guys recommend any of them?

 

I'm pretty happy with the 4:10 on track, but with the short 5th gear, which I think is more important. I worried I wouldn't like the car on the street with both a 4:33 and the short 5th.

 

4.77 with a 6 gear tranny =]

Jk

 

I ended up staying with the stock 4.10 gears.. Cant beat a free rear diff.. Since it was free, i did have the bearings replaced and upgraded to the Greddy pan, and banzai rear diff mount.....
Just some random pictures of the damaged, and the rebuilt rear differential...


I noticed this.. It almost punched its way threw...

More damage

Im guessing this is what did the damage... but who knows

New set up.. Greddy Cover with Banzai diff mount.

Installed

Better look at the diff mount.

 

Looks good. I like the greddy cover