rear differential questions

[glcoupeguy]

i have a FWD 87 threedoor L-series. im swapping in an EJ20 and i want to know how difficult it is to install a rear diff. can i pull on off an RX or XT and pop it in? is it compatible with a newer trans?

 

..or should i get a newer diff off a legacy? will either have to be welded onto the frame? do i need to get the drive shaft shortened? :-\

 

also: can i run without the rear axles? i have drums in the back right now that im obviously planning on pulling but this might happen later on in the project.

Edited December 27, 2009 by glcoupeguy

[idosubaru]

hmm a couple folks (mr. radon and legacy777 i think) have done FWD to AWD conversions but it's stretching my memory.

 

the center carrier bearing for the driveshaft needed the holes drilled and tapped but that's easy and some FWD have had them before. either way the boss is there even if they aren't drilled, so simple.

 

as for the rear diff. there's a bolt up top and the two in the rear mustache bar - those attachment points are needed but shouldn't require welding. you'll want the mustache bar from a 4WD for a direct bolt on swap. not sure if you can drill the FWD bar or what they look like. but given that work needed to mount the rear diff and the need to convert the rear hub assemblies to AWD in order to except the rear axles - i'd just plan on getting almost an entire rear end from an EA vehicle (or XT6 if you want to do 5 lug at the same time).

 

EJ20 - so i guess you're going to an EJ trans too or retaining EA? probably better to go EJ if you have a choice.

[glcoupeguy]

sounds good. will it be able to handle the extra horsepower? and i need to make sure it works with the newer trans. (yes im getting a newer one, probably getting one from legacy though i dont know the model numbers)

 

and i will be going 5 lug but its a lower priority

Edited December 27, 2009 by glcoupeguy

[glcoupeguy]

i forgot to add: i know ill need to swap the hubs but i might not be doing that right away so i was wondering if i can run without rear axles for a while

[idosubaru]

If you insall everything but the rear axles, that's FWD.

 

With an EA trans it's totally possible to run FWD just lock it in 4WD and you have FWD because the rear isn't there. But an EJ20 with spirited use is going to trash an EA trans particularly in a configuration like that. But then you need an adapter plate to make it work too.

 

An EJ manual trans can't run FWD due to the nature of the viscous center diff, the auto's can.

 

If you can find an EJ trans with torque bind, it's essentially "locked" in 4WD for good, you could use that and run it in FWD. I know someone doing that right now and they've been pushing more hp than your EJ20 for while through it.