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Rack & Pinion into C3

kiwi vet

Well-known member
Joined
Jul 14, 2005
Messages
247
Location
New Zealand
Corvette
1981 Black/Camel T Top "RAC3R"
Hey All

I have the opprotunity to purchase a 1985 corvette Rack & Pinion for a very reasonable sum = $ 100. It is in perfect condition, infact NOS.
All the info I can find here and on Vette.faq uses the Steroids System, which although it gets excellent reviews and is well documented for installation procedures - it is approx $3000 (NZ) landed here plus install.
As I dont have the rack in hand I cant measure or compare to the car.

Question - Can this 1985 Vette steering rack be fitted into the L81 C3?

Any info appreciated.
:beer Grant
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
Unfortunately NO!

Steeroids is a rear steering center take off rack and pinion, it allows you to place it about where the stock center link is and the center take off means it has a bracket in the center that tie rods bolt to.

The C4 corvette rack is a FRONT STEER END TAKE OFF rack and pinion, meaning it's placed IN FRONT of the steering axis, unlike the steeroids which like the stock box is rear steer. This means that the rack operates the other way around, if you were to place it behind the steering axis turning the steering wheel left would make the car steer to the right . This means the rack HAS to be placed in front of the steering axis. This is a major problem with the available room. Another even bigger problem is rack width. With a center take off rack you can modify the center rbacket for proper geometry (bumpsteer geometry that is), with an end take off rack you are stuck with the rack width, that is the tie rod pivot to pivot length. These have to align properly with the suspension and the placement is critical.

Because our C3s have a very narrow placement of the lower control arm cross shafts we can't run a wide rack. From cross shaft to cross shaft it's about 16" . If you place the rack higher you'll gain more room but there's a radiator there and the steering arm will become a clumsy piece of equipment. Hanging the rack lower means it has to be narrower than 16" and there's nothing on the market for that.
Here's the problem, the C4 rack is much too wide, it'll never fit properly and even if you cram it in there you'll have horrible bumpsteer or you'll have to stiffen up the suspension so much that the deflection from full bump to full droop is minimal and so is the angular effect of a misaligned steering setup.

The closest way is to use a 16ish inch rack and pinion from appleton, sweet, woodward, coleman or similar. This will allow you, with a lot of fabrication (and also, keep in mind the spindles and steering arms have to be flipped an adapters for proper ackerman angles have to be fabricated) to run a front steering end take off rack, the best kind of R&P you can get for a double a arm IFS (center take off is more sutied to mcpherson struts).
There's some drawbacks to rear steering, has to do with bushing deflection and steering input leading to oversteer rather than understeer but that's a whole different story :)

BTW, I have a front steering end take off setup....took some work but it's done:





ackerman adapters not yet installed






and it even works:
http://members.home.nl/y.jongman/MOV00340.MPG
 

kiwi vet

Well-known member
Joined
Jul 14, 2005
Messages
247
Location
New Zealand
Corvette
1981 Black/Camel T Top "RAC3R"
As Always

Thanks Again TT

As always, your information was very precise and informative :BOW

Maybe if I install it backwards/upside down I could make it RHD ;LOL ;LOL ;LOL

:beer Grant
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
you could buy a 16.75 appleton rack :)
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
Yup, it's a 99-02 jeep box with internal assist, indeed you delete the valve and assit ram. Either you use a manual center link or immobilize the stock steering valve (and eliminate the damn slop that's in that thing and you can't get rid of it when retaining it)

It's bolt in, the jeep box is a modern box, much larger. Corvettesteering remachines the pitman shaft since the Jeep box uses a larger shaft and pitman arm, their kit allows you to use the stock pitman arm. A very clever kit indeed. You retain the stock center link, so also the stock steering geometry.

It's the same system as what Norvalwilhelm is using but he puzzled his together himself, modified the stock pitman arm (rossbreed between jeep and corvette) and he modified the frame for a stiffer and cleaner install (not using the adapter brackets and the extra drilled holes in the mounting ears)

Maybe he'll chime in here.
 

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
I've been thinking seriously about using the jeep box. I hope we can get some feedback from somebody that has it. Maybe you should start a new thread...

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.
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norvalwilhelm

Well-known member
Joined
Apr 20, 2004
Messages
396
Location
Waterloo, ontario
Corvette
75 blown bigblock
I've been thinking seriously about using the jeep box. I hope we can get some feedback from somebody that has it. Maybe you should start a new thread...

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I had the option of going either way, the jeep box or steroids and after carefully looking into both two very knowledgable guys, one being Twin turbo advised me to go the jeep route.
For those paying for a system the jeep box route is 1/2 the price of steroids and I honestly believe it is better system. It makes for a very neet installation.
The steroids input shaft with dual universals and prone to binding really botherered me. It hangs extremely low under the pan and the high pressure lines can be a pain to hook up. Also the $1249 price tag sucks.
I went with the stock box and like Marck said fabricated my own pitman arm but the kits use the stock arm.
I also cut the frame and inserted a 3/8th plate with the proper holes drilled and taped into the frame but the kits use an adapter and bolt in the stock holes.
Gone is the control valve , slave cylinder and hoses.
You do NOT need a new center link. The kit does away with the control part of the valve and immobilizes the ball stud.
It makes for a very responsive system, very clean and occupies about the same room as a stock box.
It is a very modern box with a very precise control valve right at the input.
You do not use a rag joint any longer but a nice universal joint with no slope.
I have also installed the kit and it has everything you need for a bolt in installation. Tom while grump to talk to asking for advice puts out a really good kit, complete and if you need customer service because of a problem you encountered he will take care of you.
I wouldn't touch a steroid personally.
 

kiwi vet

Well-known member
Joined
Jul 14, 2005
Messages
247
Location
New Zealand
Corvette
1981 Black/Camel T Top "RAC3R"
Thanks Guys

Sorry about neglecting my own post, been away in Aussie working for the last week or so.

Thanks for the feed back, sounds like this will be the way to go and I could have it here landed for around $1200 kiwi's, which makes it more achievable.

:beer Grant
 

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