A study on turbo crossmembers and steering racks. . .

So I'm dicking around with my Baja turbo and decided I'd see what it would take to use the steering rack, etc. out of a Saab 9-2x Aero I have laying around, which allegedly is the same rack the STi's got. (source)

 

I also had a 2008 LGT crossmember out and on the ground, so I figured I'd do some comparisons. This is essentially a cross section of two different platforms and spanning two generations in the Legacy side.

 

From top to bottom:

 

2008 Legacy GT

2005 Saab 9-2x (same as Impreza)

2005 Baja Turbo

 

 

Some initial observations:

 

Both the Baja and Impreza crossmembers are notched on both sides for uppipes. . . so hypothetically you could run twin turbos. Doubtful you would ever attempt to do that as threading it all around the steering input shaft would suck big time. . . but I found it noteworthy. The holes for the steering input shaft and power steering plumbing are more or less the same shape, so I suspect these are the same crossmembers the twin-turbo JDM models use. I would be surprised if a RHD steering rack wouldn't bolt up to one of these crossmembers.

 

The 4th gen Legacy crossmember is only notched on the passenger's side.

 

The Baja crossmember is very similar to it's non-turbo 3rd gen Legacy version in that it has no additional bracing, unlike the 08 LGT and STi versions, which at least have some gusseting to tie the front and back flanges together a little better than the plain-jane version. The 08 LGT crossmember has the best bracing of the three, but I don't plan on using it as it has no chassis brace mounting points. . .and also there's some differences in how the power steering plumbing works (more on that later).

 

 

The 9-2x/STi crossmember has attachment points for a chassis brace. All 9-2x's that I've seen to date have this brace (even the non-turbo ones), so they're excellent donors for otherwise hard-to-find and expensive STi version crossmembers. The chassis brace does work very well to stiffen up the mounting point for the control arms, which pretty much just hang in air on the unbraced version Subaru uses on nearly everything else. I don't know if even the non-turbo 9-2x has a notched crossmember. . but I have a couple at home I can look at. . .just haven't done so. I'll update this post when I know.

 

I plan on either using the 9-2x/STi chassis brace or making my own. . . although that will mean fabbing up some mounting points for it on the rest of the body (lower radiator support, frame horn ahead of strut tower, and floor pan behind LCA).

 

C2C dimensions for the mounting points for the crossmember to the body are the same on all three, so you can bolt any of these into any of the three platforms. I haven't measured the LCA mounting points, but I suspect they're the same as well.

 

Overall width from one tie rod end to the other is similar. The two Legacy platforms are roughly 57", the Impreza is 56". You could easily make that up with tie rod adjustment, but it's possible the Impreza uses shorter inner tie rods.

 

Impreza:

 

 

Legacy/Baja:

 

 

 

The steering rack u-joints are a little bit different between the three.

 

 

All 3 use the same spline pattern and diameter on the end that attaches to the steering column, but the lengths are a little different, and the Impreza/4th gen Legacy share a spline pattern on the steering rack end. Impreza is the shortest, 08 LGT is a little bit longer, and the 05 Baja is the longest of the 3. It's almost an inch longer than the Impreza version, but only about 1/4" longer than the 08 LGT.

 

Baja uses a coarse spline pattern, same as other 3rd gen Legacy/2nd gen Outback steering racks I've seen. Wouldn't swear to it but I think 2nd gen legacy/first gen Forester shares this spline pattern as I know I've swapped those two steering racks in the past.

 

 

9-2x and 08 LGT share the same fine spline pattern on the steering rack and are within 1/4" of the same overall height. I *think* I can get away with using the 08 LGT u-joint in my Baja so I can use the STi steering rack, but I'll update once I mount the crossmember. If that doesn't work (because it's too short), I'll wind up chopping up a couple of these and making a hybrid joint.

 

 

No pics yet, but the Impreza and Baja racks share power steering plumbing connections. 08 Legacy crossmember I have came from a car that was hit hard enough to break both motor mounts and push the engine/trans back into the firewall, so it's possible the hoses on my steering rack were bent in the crash, but they're definitely in a different position from the Baja/Impreza connections.

 

More to come!

good info

Try to use a u-joint from a 2005 and up Outback as it should be the proper spline pattern and length you need. I've been toying with the same idea on my '04 sedan to swap in a STi rack.

The 08 LGT joint actually fit just fine. . . did the work, haven't updated the thread.

 

 

Only other issue was fairly minor: LCA bushings are shorter on the Legacy platform. Easily compensated for with washers, and bonus is if you're willing to slot the mounting holes for the transverse bushings (not an option on a 4th gen tho), you could adjust caster this way.

 

 

I installed mine in the full-forward position which was where they ended up when the transverse bushings were snugged up.

 

Better solution would probably be to use Impreza LCA's but I didn't have a pair of them.

 

For your 04, you should be able to use the Impreza steering joint.

The STi uses a 61mm long bushing and everything else uses a 55mm bushing.

I guess it's safe to include Saab 9-2x in the "not everything else" category then too

 

I'm thinking the 05-09 Legacy steering joint is the one to go with to use this crossmember in a 3rd gen Legacy/2nd gen Outback platform. I haven't seen a 3rd gen Outback joint up close and personal but if the difference in length is similar to previous generation Legacy/Outback joints, it'll be waay too long.

 

I ran across a steering joint I grabbed from a 2000 Legacy wagon when I was toying with the idea of removing the subframe spacers on my 00 OBW and compared it to the Baja joint. . . it's a full 2" shorter.

 

So here's a question: did all STi's get aluminum LCA's? If so, I assume they all have 61mm bushings. . . and aren't much good as swap fodder unless you're running the STi/9-2x crossmember.

02+ impreza sedans use the longer bushing

<02 impreza and 02-07 impreza wagon uses the narrower bushing.

<04 legacy should also use the narrower bushing (cannot confirm) and i guess 05+ legacy uses the wider bushing based on the photo of the 08 LGT crossmember

 

if you have this crossmember with the wider bushing gap, you could use 02+ Impreza sedaon arms (or STi aluminum ones). cannot use jdm <02 Impreza or <04 B4 aluminum arms without spacing them (same problem

 

 

having said all that, thank you (seriously) for posting this comparison. it is very helpful!

Sorry for the necrothread, but I am having an issue with a swap and think the universal joint may be the issue.

 

I swapped a 04 B4 RSK complete sub frame with rack, u joint, and column into a 99 LEGACY WAGON.

I am experiencing very stiff steering, it feels very similar to not having power steering at all, in that it is very darty, sluggish to change direction, is zero return to center. I have had an alignment and was told they thought it was a binding of the struts. I have since replace them with coilovers with camber plates.

No Leaks

No Noise from Pump.

Swapped pumps

Flushed fluid twice.

 

I am beginning to think that the joint is bad , or that the geometry between the rack and column are misaligned and is causing the binding.

 

Ideas?

I've had bad joints do that before. They typically feel noticeably stiff once you get them out and in your hand.

 

Not terribly difficult to change one. Most fun part is trying to keep the wheel and rack in more or less the same clock position during reinstall. Not the end of the world if you get them out, it just means you may have to reclock the steering wheel to retain toe settings.