Replacing driveshafts with an eye toward GD wide swap

[Ghost]

Howdy Gents,

I have a 91SS that sits as follows.

1. Stock suspension
2. Car has been driven with ripped front axle boots for 12+ months, so both axles need to be replaced.
3. Throw out bearing went so I need to drop the transmission.
4. RS 6 spokes, tires rub on rear strut housings when new, doing this once was enough for me.

Time for upgrades! Where I want to go with the drivetrain and suspension...

1. GD wide track links
2. Performance absorbers of some kind. I almost pulled the trigger on some GC8 JRZs but I didn't want them to have trouble with GD uprights, or the wider GD track.
3. Eventually I want to go with 5x144 STI uprights. I'd like to leave them out of this project because of the cost associated with new wheels/tires.

I only have a chance to work on the car for about 6 hours a week, and I need to get out of my current DD, so I don't have too much time to tinker. I'm hoping to get some help building a proven plan that I can execute.

Edit: from http://bbs.legacycentral.org/viewtopic. ... 9&start=25 LucyFords posts seem to indicate I have to switch over to a GD diff (and transmission for the 4.11 diff) to use GD axles. Is there a way to do this with out replacing everything?

[Legacy777]

I haven't seen any other info besides what Lucyford posted, so hopefully some others can chime in.

[Ghost]

Did more homework and got my answer (it's funny how that works).

This post from rs25 sums up the cluster F

http://www.rs25.com/forums/f128/3000186-post7.html

Basically the front is easy. But the rear is a mess, further complicated by axle fitment and compatible diff ratios. If you want to do this the easy and complete way, you get a complete 05-07 GD STi drivetrain, suspension and subframes. Then bolt it up.

I know people say you can cut corners. But if a frugal company like Subaru is willing to throw down for new parts (like longer axles) they know something.

It's like Subaru started producing the GD before they really figured out what they wanted to do with it. Very different from the BC/GC cars where Subaru knew what they wanted from the start and progressively eliminated weaknesses. Revised components vs redesigned systems.

I love this car but not enough to drop $8-10K on it when R32 GTRs are now available. I'm going to go with stock width (GC) aluminum arms + anti-lift kit + dampers that will clear the rear coils.

Case closed.

[Legacy777]

Thanks for the follow up and info.

[James614]

I didn't get the same impression for the rear you did. Sounds to me like 05-07 STI lateral links, and 05-07 ST struts with 90/91 Legacy top hats would net you the desired result. Or GC struts for more camber. Swapping the rear sub frame only seems like it would make sense if upgrading to the GD differential.

As far as axles go, the length difference is small (less than an inch per side IIRC), someone correct me if I'm wrong but I doubt it will affect the CVs much since they have a decent amount of "plunge" in the joints.

[Ghost]

The GD STI subframe gives the suspension a different roll center. I read that the revised roll center is designed to work with the wider track in the rear. As the GD WRX Sedans have the GC narrower track and the 'normal' crossmember.

Really good suspension is all about synchronicity. If they were willing to go through the effort of moving the roll center, I regard it as necessary to the system. So do things the right way, in my book, you need the STI subframe.

[James614]

Okay. I didn't see the part about different geometry of the subframe (just that it mounts via solid vs rubber and has different lateral links). But if it does have a different roll center then I see your point, that's not a small detail if you're trying to do everything the right way.