Soma

From the inside of an NA diff it looks like the 4.30 gears simply bolt up.
Is there any type of calibration that needs to be done when installing these?

Some people say they feel a difference upgrading from the 4.10's, some say not.
I'm reading there is relatively a 5% increase in acceleration.
Anyone know what this amounts to in the quarter mile??
I'm curious as to what the "real" difference would be on the track.

Thanks YO!

Turbonut

iTrader: (1)

4.33 will give better acceleration, but is it worth the cost? The R & P go for around $400, and yes they need to be installed properly with proper pitch. I assume with new bearings, washers and labor $600/$700 just for the R & P installation.

I was contemplating changing my TII to 4.33's because of the larger rear tires, but just thought the performance increase wouldn't justify the cost.

GTUs 0-60 7.4 1/4 mile 15.8 @88 VLSD/ 4.3
GXL 0-60 7.8 1/4 mile 16.2 @86.4

Is .4 of a second in the quarter worth the price?

JasonS

iTrader: (62)

A TII is only 15.2, so what do you expect?
If you're able to do it right and not spend hundreds and hundreds I'd say it's worth it. I drove a GTUs a few years back and what a hoot! I'd say the fun would be worth $500!

Soma

Thanks for the info Turbonut.
Yes, the upgrade has the potential of being expensive, but I wouldn't mind experimenting with it if I could pick up a R&P at a good price.

Is .4 of a second in the quarter worth the price?
The dollar to quartermile time ratio is probably not justifable considering you could invest in setting up a small shot of nos instead but I'm just really curious as to how much potential my s5 has.

micah

600/700 for R/P installation? Are you out of your mind!? Where the **** do you go to get your gears installed? Geeze.. *ANY* mom and pop shop or even offroad shop can install them for 150-300. If you buy yourself a couple expensive tools (probably no more than 300 bucks), you could do it yourself. Then, all you would need is the shim kit for the RX-7 diff. Its not THAT hard to do yourself if you know what you are looking for.

micah

Also.. an R/P change of 4.1 --> 4.3 or 4.33 is a somewhat big change on cars as small as ours. Expecially with how small of a tire size change is possible.

Keep in mind that if you change your gears, it will change your speedo accuracy as well.

Furb

iTrader: (2)

and mileage

micah

Eh... nobody buys RX-7's for their awesome fuel economy anyways...

drft_180sx

^ are you joking? i only have to fill up like twice a year. my motor just blows after that...pretty good fuel economy in some sense?

micah

Interesting concept... my rx-7's usually last years with constant abuse.... but... I guess thats just me?

NZConvertible

5% is 5% no matter how big or small the car is. Nobody would expect a huge performance increase from adding 5% more power or removing 5% of the car's weight, so you shouldn't expect a "big change" from a 5% shorter diff ratio.

Personally I'd only bother if I could get the gears cheap and I actually had to take the diff out for some reason.

Asterisk

iTrader: (3)

well, take an NA with a T2 tranny, and miata torsen diff/ GTUs R/P and that is a great package right there. althrough u need a custom shaft.

Turbonut

iTrader: (1)

Don't get your underwear all twisted up. You must ge one great guy with wording like this. What has this site become!!!!!!!!!!!!

My post was not worded correctly, as it was meant to be $600/$700 for the total bill including the price of the R & P.

What a JERk!!!!!!!!!!!!