Angry Earl

iTrader: (19)

I know this sounds retarded as ****, but I want LONGER gears in my TII.


Anyone ever put a 3.9 ring and pinion out of an S5 auto rear end, into a TII pumpkin?


Is this possible?


How much longer were your gears increased by (rev's to mph)?


I wanna be drifting in 2nd, at like, 70mph.


I ******* hate shifting, and I wanna be cruising on the highway at, like, 1500 RPM's instead of 3400.


****, even anything in the 3.70's out of like a mazda truck would sound awesome too.

sadrmmr04

iTrader: (1)

if you're keeping your pumpkin, then it would have to be an ring for an 8in, aren't the autos 7in? or maybe im wrong....

CrackHeadMel

iTrader: (2)

i think auto's are 7" aswell

does the miata have a viscious limited slip available? if so do miata's have 3.90s or taller available, i belive you can swap them into a 7" fc housing

sadrmmr04

iTrader: (1)

but i think earl's is an 8in, well i would assume so, i believe his car is a TII

Derek 357i

This has been researched and discussed much on that V8 place (www.v8rx7forum.com) and your only real options are a complete rear end swap. Andrew has (had) a group buy going for another mustang cobra diff cradle swap. You are looking at 2K plus for that swap. The other option, albeit not a good one, is a mustang live rear axle swap from grannys speed shop.

Angry Earl

iTrader: (19)

ok, so short answer = "No."



thanks anyways dudes.

TweakGames

iTrader: (3)

It look you can get a 3.9 FD pumpkin with the FC clutch type diff in it, since you wanted to use it for drifting.

http://www.v8rx7forum.com/parts-ever...ap-13-bbk.html

Sojin

well i did some rd work on it because i want to get a 3.9 in my NA diff because the i have a T2 motor and trany and i want higher gearing and no u can not with out changing the punkin only one NAs u can just change out the ring and pino to a 3.9

ps to find out the speed at rpm the math thing for it is (tire outer dia X RPM) / (rear acle ratio X trany gear ratio X 1056)

jgrewe

iTrader: (1)

You can't just lower the RPM you are running at highway speeds without figuring out how much power you need. The reason the factory picked the ratio it did was to put the engine at the spot that is economical and lets you run up to top HP at top speed. So the question would be does your engine make enough power at 1500rpm to keep the car rolling at highway speeds?

My diesel truck with over 500ftlbs of torque stock spins about 1700 at 70 mph. Unloaded it probably makes enough power to run that speed at idle. You probably need about 100 ftlbs of torque for an FC at 70 mph. I'm sure you could find the formulas to figure it out pretty closely with some digging on the web.

Sojin

Thats true but in some case like mine i have more then enof and when i run it at higher speeds 70 plus its at mid to upper 3 and it builds bost by then

BLUE TII

iTrader: (9)

I believe the Japanese Auto RX-7s had 3:90 gears as well. There is definitely a source for the 3:90 gears for the TII rear end, it would just be alot cheaper to get them used...


I have also wanted to do the swap to 3:90 gears as 1st is useless traction wise even on DOT Rs and I have to shift into 3rd on Auto X sometimes.

You wouldn't be turning 1,500 rpm at freeway speeds, just a bit less than the normal 3,500 rpm.

Even if it were 1,500 rpm, a decently responsive turbo would just spool up to provide the torque. For instance my car can accelerate from 1,000 rpm (idle) in 5th as it spools up to ~2psi boost as it goes from 1,000 rpm to 2,000 rpm.

03/08/87

what's up with this FC. THe FA Sa's torque curve was low and ran high, Now this FC has grunt but not as much of a top end rush as I remember in the 85

03/08/87

this may be actual help

Instead of trying to get more speed per rpm which requires more power or else you become a slug and lug a dug.

It has been said that the rotary like to rotate, orbit or spin and I think it so balanced that it doesn't "float the valves" so why not find a way to increase your usable rpms?

I bet if you do, there will not only have additional rpm band for you to increase your top speed. Only drawback is the possibility of a lifted powerband.....meaning you will bog down low

nvrdone

.

Rotary_Rocket_87

WTF? Does this make sense to anyone?

TweakGames

iTrader: (3)

Nope, another person posting drunk/high. I THINK maybe he was saying, why don't you make your redline higher so you could stay in the same gear. Getting your internal balanced, competition bearings, and ceramic apex seals would allow a safe higher redline. But you will not be making as much power, and it might even stop your drift. I think Earl is looking for this on a drift car, not really a daily driver freeway car, but I could be wrong. Either way the larger rear wouldn't drop freeway speeds to 1,500 rpm.

sadrmmr04

iTrader: (1)

i know that a friend of mine had talked to a company that made all the brackets to make a ford 9in work on a hatchi, so yes, you CAN get the gearing that you want. i just all depends on how much money you are willing to throw at it to make it work

junito1

I tired of seeing my motor at 4,000 rpms at 75 mph. I see why he would want a 3.90 rear end. But the money and the difference its going ot make its just ridiculous to try and waste ur money.

And 2 gears for drifting is not logical. Short gears is needed for the variety of courses/corners you will run into. For example. When you drift rpms are higher than your true speed. SO 70 mph in second gear your car would be capable off would only be 50 mph sideways. SO what do you do when you really have to do a 70mph drift that your 3rd gear cant push anymore because of boost lag/power.

Red_Rabbit86

what about just swaping over the tranny ds and rear end to na spec it wouldnt be that expensive i see them all of the time used. i would think that the t2 lsd is much better then the na but it does work i would try that

ericgrau

iTrader: (1)

If you don't care about acceleration why do you have a turbo?

BLUE TII

iTrader: (9)

Wheel spin doesn't help acceleration....

coxxoc

iTrader: (3)

Because Earl is a drifter. He needs the power to break traction. That being said, if you go to 3.9 in one way or another, you will need to up the torque on your engine to still get similar power to the ground response. I don't know what boost you are running right now, but you would either need to up it or upgrade the compressor.

Josh

Angry Earl

iTrader: (19)

FINAL ANSWER:



Boost UP

Shift UP






thank you rx7club.com for the usual awesomeness.

Wezzmo

FDs have 3.9 gears
http://page.auctions.yahoo.co.jp/jp/auction/105370890

surely you can do some mix and match work to get it togethor..

sadrmmr04

iTrader: (1)

that's a good way of thinking about it