Any AWD transmission gurus ? Question about just using the rwd section

[pro4]

I have been planning this build for awhile but this just occured to me . I am just using the rear drive of a awd trans and was going to leave the fwd axles just free spinning . Would this cause excessive slippage (power to the drive wheels ) ? Or an this trans is it going direct to the rear drive ? 

[idosubaru]

It's been done before and works just fine in MTs and I'd guess ATs too.

 

It's going to be weaker but holds fine for average daily driver use applications.

 

In ATs with torque bind the rear hub can shear off with excessive binding and stress. If you're making a RWD drag car or doing burnouts and drifting I'd imagine that's where you'll see failures.

 

You might want to investigate wether VTD or MPT is more robust. Two different styles that transmit power differently. The VTD originally came in H6 vehicles so it has the opportunity (not saying I know that to be true) to be beefier from a design standpoint. Which would be ideal if you're turning your trans into a PTO. Lol

[Numbchux]

What transmission? Subaru transmissions all have different center diff/transfer gears...

 

Rule of thumb is, though, virtually all of them will need to be opened up and center diff modified (welded) to transfer 100% of the power, and the transfer gears behind the center diff rarely can hold up to much abuse. So depending what you're doing with it, that may not be the best option.

 

Aftermarket, stronger, transfer gears exist for many modern Subaru 5-speeds. There's a guy who makes an adapter bellhousing to use a Toyota RWD/4WD transmission. Or the Subaru BRZ/Toyota 86/Scion FRS 6-speed should theoretically bolt up. (These all ASSume an EJ/EG/EZ engine...)

[idosubaru]

Here's your big unknown:

 

 So depending what you're doing with it, that may not be the best option.)

 

you can find someone ditching their old failed VLSD unit or trans if it's a VLSD 5 speed and run that in this fashion. 

[pro4]

Sorry been out of town . The trans I have is a MT from a 96 legacy AWD .

[pro4]

This will be a circle track asphalt car 

[Subaru Scott]

You will have to take it apart and weld, or otherwise lock the center diff.

[idosubaru]

duplicate

Edited May 8, 2017 by grossgary

[idosubaru]

Sorry been out of town . The trans I have is a MT from a 96 legacy AWD .

Then you have a VLSD center diff:

you can find someone ditching their old failed VLSD unit or trans if it's a VLSD 5 speed and run that in this fashion.

Find a failed VLSD and swap that into your car. People replace the VLSD's or transmissions and throw the old failed ones away.

 

They fail to the "permanently locked" state, so what is typically a throw away failed VLSD could be free/cheap and give you RWD once you remove the front axles.

 

Or:

will need to be opened up and center diff modified (welded)

Edited May 8, 2017 by grossgary

[Numbchux]

I don't believe anyone makes a RWD coupler for the phase 1 center diff, so yea, you'll have to weld it.

 

Then you'll want to get some spare transfer gears, and get good at changing them. Or convert to a phase 2 center and get some beefier transfer gears, although it might be cheaper to go to a real RWD transmission.

[idosubaru]

I don't believe anyone makes a RWD coupler for the phase 1 center diff, so yea, you'll have to weld it.

 

Then you'll want to get some spare transfer gears, and get good at changing them. Or convert to a phase 2 center and get some beefier transfer gears, although it might be cheaper to go to a real RWD transmission.

 

 

...Says the guy who has been around racing...very valuable to pay attention to this!

 

my suggestions regarding failed "locked" VLSD's should be taken no more than light use daily drivers. 

[pro4]

So... just weld the spider gears like you would in a normal rear axle? Thanks appreciate  all the replys. I tried to download a picture of my project but it said the file was too large.

[Numbchux]

Yea, you can do that. Due to the design of the center diff, there are a couple places where you can safely weld it up. But yea, just like a "Lincoln Locker"