3.7 or 3.9 front diff? how do you know?

[subarubuddy]

i have a 5-speed dual range tranny already out of a car, but i don't know what car it came from. maybe a turbo maybe not. 85 or later DL/GL(-10)/loyale/turbo(??who knows??) thats all i know about it...so the problem is i have a 3.9:1 open rear diff in my loyale now, and i want to put the d/r tranny in. but how do i even know if it's a 3.7 or 3.9:1 ratio? i don't want to put it in and then tear it apart when i go to see if 4WD works. and obviously it wouldn't help to change the rear diff either because i don't know if i need to. thanks for all your help.

[Subarian]

I remember that the splines on the transmission input shaft are different on the turbo/non-turbo, but I don't remember the count. Someone here probably does, or your friendly neighborhood parts guy might have the info.

[mcbrat]

I remember that the splines on the transmission input shaft are different on the turbo/non-turbo, but I don't remember the count. Someone here probably does, or your friendly neighborhood parts guy might have the info.

 

correct.

 

do you have a spare non-turbo front axle laying around. if it fits on the stub shafts, it's a 3.90......

[mcbrat]

correct.

 

do you have a spare non-turbo front axle laying around. if it fits on the stub shafts, it's a 3.90......

 

or, if you have a spare main driveshaft to the rear, you can stick it in the end of the tranny, put the tranny in 4WD. have someone count the number of revolutions of the stub shaft when you spin the rear shaft 10 times...

 

(I think this will work....)

[MilesFox]

3.9 gear. the only other dual range tranny for a turbo was the full time, which would have a vacuum diaphragm on the side for the diff lock

[TROGDOR!]

Not quite... 85-86 RX's (and some very rare non-RX turbo cars) had a 3.7 part time 4WD dual range.

 

Popping an axle onto one of the stubs is the easiest and quickest way to tell.

[All_talk]

Yep, what he said ^

 

I have a '86 turbo coupe parts car with 3.7:1 dual range.

 

Gary

[redskin]

Yep, l'll third it, l have a 3.7 d/r 5 speed out of an early RX in my shed, the later ones, (post 87, l think), were 3.9.

[TROGDOR!]

To clear things up- ALL nonturbo cars were 3.9, ALL turbo cars were 3.7.

 

The ONLY dual ranges available in the EA82 were:

 

-Nonturbo, 3.9 ratio part time 4WD dual range (85-89)

-Turbo, 3.7 ratio part time 4WD dual range, same as above but with 3.7 final drive (85-86)

-Turbo, 3.7 full time 4WD dual range, differen than the other two (87-89)

 

That's all.

 

All turbo 5 speeds take 25 spline axles, all nonturbos take 23 spline. If your nonturbo axle fits, it's a 3.9 dual range. That's it.

[89hatch]

Thanks Trogdor, that's the post I was waiting for.

[subarubuddy]

Thanks Trogdor, that's the post I was waiting for.

yes thank you...that is exactly what i need to know!!