Super-fast ratio Corvette power steering rack in '88 Fiero

[Series8217]

The passenger side mount is stock '88 Fiero.

It's possible for my driver's side mount to be off. Maybe there are some reference points I can measure from to see if the rack is still parallel to the crossmember.

[The Dark Side of Will]

FYI...

I ran across these a while back, but forgot where they were listed.
I'd been thinking for a long time about how to get rid of those silly rubber steering rack mounts.

http://www.flamingriver.com/index.php/p ... 0013/s0012

BMW is shameless about hard mounting steering racks and suspension pivots...

[Series8217]

Cool. It would be easy to hard-mount a stock '88 rack (and the passenger side of the 'vette) with something like that.

On the Corvette rack, the driver's side mount is a cylindrical bushing perpendicular to the rack. Fabricating a solid insert would be trivial with a lathe. It just looks like a suspension bushing.

[The Dark Side of Will]

Do a bump steer measurement...
Yes, it's a PITA.
However, just like degreeing cams, you don't really know what you have until you take the measurement.

[Series8217]

Oh yeah, another thing I found with the ridiculously fast steering is that I can actually catch the back end stepping out before it turns into a spin. It's not the fastest way through a corner, but on more than one of my autocross runs I saved it when there's no way I could have with the old slow stock steering.

[The Dark Side of Will]

*THAT* is the only reason to go to power steering, in my opinion... To have reasonable effort when making the steering fast enough to catch a spin.

[Series8217]

I've been looking into ways to increase the steering effort and get some feeling back in my steering.

I just got off the phone with Jeff at Turn One Steering. This guy knows his stuff. I learned a lot in just a brief phone call.

1) The torsion bar presses into the pinion, so the valve assembly includes the spool valve. This means that an assembled spool valve is tied to a rack ratio, since the pinion can't be changed out.

2) Turn One might be able to rework a spool valve to have a stiffer torsion bar, but it's not easy. Possible, but very difficult. They do have the means to do it, but I should look into other possibilities first.

3) Turn One has some parts for the slower-ratio Corvette racks. My rack is two turns lock to lock, but Jeff explained that the number of turns is not a good way to check the rack ratio, because of external and internal travel limiters. If my rack is a fast-ratio rack, then the Turn One does have different spool valves that will fit.

4) The rack rebuilder (I have a rebuilt rack) may have made a mistake during the rebuild, that increased the assist of the spool valve. By checking the operating pressure of the rack we can see if this is what's happening.

I now have some action items:
1) Verify the steering rack ratio by turning the pinion 360 degrees and measuring the linear motion of the rack.
2) Measure the power steering pressure on the high side during a static steering maneuver to see if the spool valve is operating properly.

Also if my rack is indeed the fast-ratio rack, Jeff doesn't think it's from a '94 (which is what I thought I got). Definitely got some investigatin' to do!

[The Dark Side of Will]

There's some magic which can be worked via changes to design parameters of steering gear, but to most shops they're black boxes and to most rebuilders magic recipes.

I had a customer who ordered a rebuilt 282 from a big supplier and received a gearbox with the right bellhousing, VSS and clutch mechanism to go into his car, but the international market Q4 minivan gearing...

I was wondering about trying an electric assist at the pinion with about a 1.5:1 steering quickener in place the steering shaft, if it can be made to fit. With optimized offset and steering geometry, that should work reasonably well.