Madrx7racer

Hey everyone......I have a question for you guys. what happens if you install a GTUs diff and half-shafts into a regular N/A? does it matter that the N/A doesn't have a GTUs tranny?

SonicRaT

iTrader: (6)

Throws the speedo off is about it. The tranny is the same except for the gearing (which won't matter)

Madrx7racer

can you elaborate? what do u mean throw it off?

SonicRaT

iTrader: (6)

The speedometer won't be accurate any longer unless you swap the gear on the end of the cable that runs into the tranny. The only other difference is it uses the same gear ratio for 5th gear as the Turbo II (.756 where-as standard N/A is .711)

Madrx7racer

ah......Anyone else? What would happen tho....RPM wise? I'm not doubting you SonicRat...but I need multiple answers........I sold my GTUs diff. and the owner needs proof that it is a GTUs diff and I have no way to prove it besides the fact that it came off my GTUs which had/has the turbo brakes and suspension.

rx7power

The 80mph in 5th gear at 4000rpm is ONLY with the GTUs transmission which has a shorter 5th gear ratio. If you want something to judge it off of then go to this site. Note, when looking at this site, it's the 4.30 gears with the non-GTUs transmission.

http://rx7.com/store/rx7/fcdrivetrain_rearend.html

hope this helps some.

Also I orginally have done this swap w/o the GTUs transmission and my 5th gear at 80mph was at about 3400-3500 rpm, then after I got the GTUs tranny rebuilt (which I had on the side for a bit) and put in, then everthing read normal like a real GTUs.

Have fun!

SonicRaT

iTrader: (6)

It'll have a viscous LSD tag on the bolt, he can take it apart and count it all up. As for RPM's, it's hard to say considering the 5th gears are different, but his rpm's should be higher relative speed compared to the 4.1, I know in my GTUs 5th gear is around 3000rpm for 60, 4k for 80, and etc. Couple this with the fact that his wheels are probably different sizes than stock, and it's going to be hard to prove short of the viscous tag and taking it apart.

<^>(-_-)<^>

ya it is a weird situation, the subframe looked like it came out of the gtus it had the brakes. However before i purchased the diff i tested my one leg 4.1 and at 80mph i was aroud 3400 and at 60 2500 now it is at very close (within 50rpm) of what it used to be. RX7power can you elaborate on how it felt after you did the swap before the tranny maybe it will help. By the way the car is bone stock (stock rims/tires) mazdarx7racer can vouch he saw the car.

rx7power

The 1st - 4th gears between the regular NA's and the GTUs is the same. Anyways, after I did the swap, I didn't notice much in terms of acceleration maybe it felt a smidge faster. It's not gonna make you faster in the 1/4 mile if that's what youre lookin for. It's better if you race road course or auto-x because you'll be in the powerband more often to help u thru turns and corners. The LSD was a nice addition tho. The cool thing about having the GTUs tranny is that 5th gear actually accelerates. It's not like an overdrive. I live in hawaii and have to go over a mountain everytime i want to go to town and this new 5th gear is nice cuz i don't have to downshift (unless i'm in a big rush)

<^>(-_-)<^>

my concern is that it isn't a gtus diff i am seeing absolutly no change in rpms in 5th gear with regards to mph as compared to the stock 4.1 open diff. Is this normal?? Keep in mind that my car is bone stock, stock tires and rims. nothing has been changed except for the diff.

SonicRaT

iTrader: (6)

Which means your speedometer is off, as I mentioned previously, so you can't use it to accurately gauge anythin.

Icemark

its pretty easy to check the gearing, by simply marking the tire and diff drive shaft mounting flange.

Mark both with a single white line pointing down, and then turn the driveshaft/diff flange.

should take about 4.3 turns of the drive shaft to get the wheel to spin all the way around once.

A 3.9 geared rear end will spin less than 4 times, while a 4.1 rear end will spin just a hair past 4 times.

DelSlow

iTrader: (2)

i dont know about it not making a big differnce, when i swaped in a T2 tranney and diff, it felt alot slower through 1st and 2nd, didnt just rip the tires free like it used too. i also lost the lightwheight flywheel i had for a stock T2 flywheel, so that might have made a differnce as well. i have a GTUs tranny i dont need anymore, but i think the 5th gear fork is bent, because i couldnt get the shifter into the gate. $50 plus shipping, or i can just take the 5th gear out for you.

Madrx7racer

thanks for the info you guys....

tt1320flyer

so my speedo is off and it will read like the 4.1 gearing no matter whhat gears i have in it??