I have an 84 GSL - SE that I have transplanted an 87 T II motor into. I am not sure if the transmission/differential are original. I do know that I am contantly shifting and am almost wound out at 80 mph on the freeway. Not cool.

What i need to know is how to figure out if my gearing is stock. How do I figure this out by turning the driveshaft and counting the wheel turns? Do I multiply the rear end ratio by the first gear size and this should be the number of times the wheel turns with one driveshaft revolution?

Brian

 

Count the driveshaft revolutions in relation to the wheel. Mark the tire and see how many turns of the driveshaft to bring it around to that mark again. The tranny doesn't matter at this point. It will take about 4 turns if its stock, any more and you have a different rear end gear. If you have a truck box in there your final drive (5th) will be only a couple hundred rpm different than stock at highway speeds. Most likely you have a different rear gear if its that noticable.

 

cruising at 60 in 5th how many rpm's are you at. I know the my gsl-se has a stocker in the rear and I cruise at 3k at 60mph.

Hope this helps,
~Z

 

So, Jgrewe, what you are saying is that if I turn my wheel one complete revolution, I should get 4.1 revolutions from my drive shaft?

I haven't had the car out yet this summer (and damn, it's August already) but I seem to remember that 100 mph would be damn near impossible. I think it was around 3500 RPMs at 60 mph.

All I know is shooting of the line, I am running through the gears to fourth almost as fast as I can shift. With the T II engine in it, I want taller gearing. I just want to know what I need to replace on my car. What the heck is it going to be like when I actually start upgrading?

Brian

 

Other way around. 4 driveshaft roations = 1 wheel rotation.

Stock rear end should be 4.1 or something like that.

Keep in mind that your speedo could be off.

This might help:

https://www.rx7club.com/showthread.p...ght=check+math

And this too:

http://www.geocities.com/MotorCity/S.../firstgen.html

If you need a walk through on the calculations, let me know.

EDIT: Or just use this:

http://www.race-technology.com/WebPa...lculation.html

 

Feds and you said the same thing different ways. Its just easier to turn the driveshaft and watch the wheel. Its kind of hard to see the difference between a 3.9 and a 4.1 rear when turning the driveshaft. Its when you get to a 4.6 or a 4.88 or even a 5.12 that its easy to spot.

 

****, I just re-read it. Stupid mild case of dislexia!

You could also turn your drive shaft 10 or 20 times and count wheel rotations. Would make a more accurate guess at ratio.

 

I will get my *** on it one of these nights. Like a guy doesn't have enough to do. I just need to find out what my winter project is going to be on this car.

I once upon a time had an 83 GSL that I don't seem to recall being this low geared. Damn, I wish I still had that car. It got towed from outside my house and I was a poor college kid...no biggie, I bought it at a Goodwill auction for $200 though.

If I have any more Q's I will let you guys know.

Thanx.

Brian

 

is there any other rear ends u can use on a first gen besides the gsl? I heard people using the lsd's from 2nd gens. I dunno what the hell i'm askin i just wanna spin both wheels at autocrosses instead of one.

 

I forget which diff fits which housing but I know you can do something with a miata torsen. Do a search and it will probably show up somewhere.


Hey Feds, you hear about the dyslexic atheist.... he didn't believe in Dog.