Confirming front diff gear ratios?

[ghost]

I know the rears have that lovely sticker, is there anything like that in the front or do i have to mark and count the axles turns somehow?

 

The previous owner had the engine and tranny swapped and I both wanted to make sure I needed to swap the diff out (im super paranoid), and i wanted a possible way to check any future transmissions i see in junkyard and what not.

[bheinen74]

in 1995 and after, the stickers are no longer used.

[ghost]

Ah, forgot to say its an '87 GL turbo. Should the tranny have a sticker then? I havent crawled under and checked it out thoroughly (has some grime and dirtyness all under the bottom of the tranny)

 

And by swapped i mean swapped for another EA82 and tranny, no EJ or new combos like that.

[ruparts]

hi,

the 87 gl turbo would have had a 3.7 i think , if it was a manual trans. the "new" doner trans probably is too, most all of them were in those model years. the xt6 manual trans had a 3.9 front diff. i have never seen a sticker on any trans to say what ratio diff they have.

if it's an automatic it might be 3.9

[ghost]

That info IS why i was curious to figure it out... Paul (moosens) had the engine replaced with a jdm unit and tranny. He claims it was the wrong spline count on the "new" tranny in there, so he had to modify it to fit. In doing this I THINK that means the tranny could be the non-turbo single range tranny BUT im not positive. Being behind a turbo engine wont make it explode will it? It isnt THAT big a difference in power right? Maybe moosen can chime in and confirm. If it is indeed not a turbo tranny, but a normal single range that means it is the 3.9 correct?

 

Edit: I was gandering at this chart but it seems incomplete... The only S/R listed obviously isnt the one i have, i can count all 5 of the gears in mine =]

http://www.numbchuxconversions.com/Files/Gear%20ratios.JPG

Edited November 28, 2010 by ghost

[MilesFox]

if your donor trans is indeed a non turbo 5mt, with 23 spline stubs, it will be a 3.900 gear.

[ghost]

Ok, that answers that! I know for a fact he had spline issues with the tranny he got. They weren't the normal 25 i dont think.

 

NOW, 2 questions:

- will the turbo put enough power through it to make it go boom quicker than normal or are they fairly stout? (yes i know the turbo GL is stupidly slow, only like an extra 25 HP, but im worrisome)

- if i lift it and put on some nice 205/75/r15's or close to that, the higher gears being there works out perfectly doesnt it? Keeping it the way it is now means its going to accelerate faster and have a lower top speed than a stock turbo one right? I think i understand the difference in the gears being higher...

 

If this is true just confirm it for me: I should swap in my 3.9 for the rear and not worry about anything because it wont truly matter. The tranny wont boom, I'm worrying myself too much. Correct?

Edited November 28, 2010 by ghost

[Gloyale]

Okay. What rear diff ratio is in it?

 

Easy test is go to a parking lot.

 

Put car is 4wd and drive straight.

 

If you can drive straight, basically at all without hoping and chirping of tires, your ratios match.

 

It's harder to tell with the automatics because it's a hydraulic connection, but the manuals are all gears and will bind within feet of driving with the wrong ratio diffs.

 

 

My guess is that if Moosens did the install, he probably got it right.

 

If you're 4wd works without binding you have correct diffs.

[ghost]

The rear is still the stock 3.7, but Paul gave me a spare 3.9 he had to swap. He tested the 4 wheel drive and it didnt bind but i do beleive it is a 23 spline 5 speed single range tranny (meaning 3.9 from everything ive gathered now) He did have to do some swapping on the axles because the stock tranny was a 25 spline 3.7 i beleive. Because of these i think axles stubs needed swapped to get it working right.

 

Anybody have a nifty chart of this stuff? Id love to print it out for junkyard trips =] I found this \/ which is fairly good, but i think lacks the harder to find stuff. Or am i mistaken, are 3.7 or 3.9 the only options for EA series?

http://www.indysworld.com/80s/general/USRM/SOAMANUALSCANS/gear85fsm.jpg

[GeneralDisorder]

Drain the gear oil and count the ring gear teeth. It's pretty simple with a flashlight.....

 

GD

[bheinen74]

Drain the gear oil and count the ring gear teeth. It's pretty simple with a flashlight.....

 

GD

 

yes do this; or look for the stamping on the ring.

37 teeth its a 3.7

39 teeth its a 3.9

41 teeth its a 4.1

etcetcetc

but for sure its stamped onto the ring when you look at one.

[Gloyale]

yes do this; or look for the stamping on the ring.

37 teeth its a 3.7

39 teeth its a 3.9

41 teeth its a 4.1

etcetcetc

but for sure its stamped onto the ring when you look at one.

 

Not quite correct

 

this is Subaru gear ratios.

 

38 ring w/11 tooth pinion = 3.454

 

37 ring w/10 tooth pinion = 3.7

 

39 ring w/10 tooth pinion = 3.9

 

37 ring w/ 9 tooth pinion = 4.11

 

40 ring w/ 9 tooth pinion = 4.44

 

 

So you see, a 37 ring could be either a 3.7 or a 4.11. Youd have to count pinion teeth too.

 

IN this case, the trans is almost certainly not 4.11 (not offered in any EA) so if it's 37, it'd be a 3.7, if it's 39....it's a 3.9

[moosens]

Rob, as stated , its a 3.90 front and a 3.70 in the rear. You need to swap the rear diff I gave you.

 

These guys weren't the ones dealing with it so trust me,please. Throw out that chart and all .... it's a single range elect. operated 4WD which came in both 25 spline for turbo and 23 spline for N/A cars. My Factory Parts Manual will show you my info is correct.

 

That was Charlie that test drove it for a few second over gravel. Didn't have time to bind nor the solid traction so no worries on either end.

 

Talk to you soon.

[ghost]

So that confirms it was 23 spline in there, thanks Paul! I honestly wasnt sure but i remembered an old topic by you i found wayyy back in the archives of this board where you were trying to figure out spline issues and swapping axle pieces to work. I honestly couldnt recall which spline you swapped to though, hence why i was unsure about the original ratio compared to whats in there now. I think i also figured out everything i need to ID junkyard units too, that was my other purpose with this topic, because i would love to find a junkyard special dual range. I was just all confused with which ones are which based on splines and what not.

 

So this arises: what splines are the XT and XT6 rear units? I know where theres a few of both of those in yard here. Any chance of finding an LSD unit in those?