Gordonm

In one of the Vette magazines there is a 63 Split Window that has a power steering box out of a regular GM car. Looks like a power assisted box that is in all types of GM cars. The owner said it was a great upgrade to the Vette steering. i was wondering what mods are to be made to the linkage and if this is worth the effort. I figure a tight box out of a WS6 Trans Am or Z28 would work well. Anyone done this or have info on this.

mrvette

I had looked into that some years ago, well before I started this latest Rack/Pinion setup....when I first bought the car....and it seems to be not enough change to be worth it....you can tighten up the steering a bit, but on a turns ratio, lock to lock you will find the later camaro box for example has limit bushings internal to the box, that will effectively narrow the range of throw available to the drag link, so the steering radius is then much larger, even though the 'turns lock to lock' are less....
IMHO, the rack/pinion is a far superior conversion....MUCH more worthy of the time/effort.....

GENE

Gordonm

OK Makes sense to me. I like the rack and pinion idea also.

71roadster

I have been looking for the same type of upgrade. I saw something I thought might work at a goodguys show and after looking around I found this...
http://forums.corvetteforum.com/zerothread?id=190216

They sent me this in an email...

"Power box:
You need to shorten steering shaft (Need to push it up in)
power steering has valving in the upper part..
Yes it is high point centering just like all saginaw boxes
you would use manual drag link..
Pitman arm would come from us !!
Guys in Arizona are use these in 66 & later corvette for raceing
and I have one in a 66 Corvette of my own..
If you are interested you should call me..
CV Steering Tom Reina 864-287-9990 "

The bit about internal stops is soomething to consider, but I believe this box comes out of a newer jeep gran cherokee, which I think has a fairly tight turning ratio. And since the ratio is dependent on the length of the pitman arm, it would be worth a phone call to these people to see how the final turning radius works out.

Chris

Jim Shea

I was aware of the CV Steering websight a while back.

I eMailed those guys at CV Steering the end of November with some specific questions on how they could fit the 1999-2002 Jeep Grand Cherokee power gear in a C3 Corvette. Before I retired, I had access to the engineering drawings for the original C3 manual gear as well as the Delphi Jeep Grand Cherokee gear. So I had some questions on the installation. Unfortunately, they never answered me.

The problem is that the Jeep gear is a four bolt mount gear. The C3 gear is a three bolt mount. If you try and lay the two gears on top of each other so that the input input shaft centerlines are the same, there are two of the mounting bolt holes that are very close to one to the other which makes them interfere. From their websight they appear to be using a some type of adapter plate. It would seem that the adapter plate would throw the gear inboard and screw up the linkage geometry.

These are my observations.

tworottiedogs

I did talk to the guy in S. Carolina. Really nice guy and he was very honest in saying that he is not ready to push the conversion on the Corvette world yet. He has it in his Vette. There is an adapter plate and he was also trying to work out some angle problems with the steering shaft. I plan on going that route once he has the bugs worked out.

ddecart

Jim,

I've seen this topic enough lately that i finally pulled out those drawings of the jeep and Vette gear. (Now that I found them cleaning the basement this past weekend) Hmmmm.....

The input side of the Jeep gear is still a good bit longer than the Vete gear by about an inch & 1/2 or so. So the colum would need to be shortened a little to allow mating the two together.

The relative orientation of the pitman shaft to worm shaft is pretty close. Off by no more than 3-4mm. Hardly enough to shake a stick at given the tolerances on the Vette back then.

The mounting surface is the big question mark. The Vette, as you recall Jim, has a mouting surface that's 3 degrees off the vehicle's x-axis while the Jeep's is parallel and the mouting holes are clearly different, 3 vs 4.

I'm trying to recall our past conversations. Didn't someone make some gears on a trial basis that were integral gear housings with the 3 degree offset? Do you recall which gear it was (600 or 700)? That info is barely hanging on in my memory :)

Too bad those guys at CV didn't get back to you on that install that we talked about with the Jeep gear. That was an interesting setup.

The Jeep also has a little faster ratio. 12.75:1 vs 16:1 (steering box ratio) if I did my calculations correctly.

Gordon: To answer your question, YES, it can be done (of course). We don't know exactly what it takes....yet :D

Dave

Jim Shea

Back in 1967 Saginaw Steering Gear Division (now Delphi Saginaw Steering) actually made some castings for their 700 gear to fit the Corvette (i.e. the 3 degree offset, three cast lugs on the pitman shaft tube located for the Corvette frame mounts). We built one or two for Chevrolet engineering and another one just happened to make its way into a big block 1968 Convertible that belonged to one of the Saginaw engineers. Even with the special gear casting, the frame on the '68 had to be "massaged":smash: a bit to fit the gear in the car. That car (with that gear) is still in the Saginaw area!

Unfortunately, that one car and that special gear is all that is left in the world of that project (unless the Chevrolet engineering cars somehow got out to the general public). But typically after the frame is modified for an engineering project it is cheaper to just crush the car than to rebuild it with a new frame.

The Jeep Grand Cherokee gear is the latest type of recirculating ball gear that Delphi Saginaw manufactures. It is lighter than the old 700 gear and has a more precision valve. The Jeep gear is the closest design that has a chance of fitting the Corvette frame.

If anyone wants the overlays of the two bolt patterns, I can probably scan them and send them by eMail.

JIML82@aol.com

ddecart

Ok Jim. That's along the lines of what I had recalled.

This whole thing has me thinking a bit now. If I could put a 3 degree slope on the jeep mounting surface, drill a couple new holes in the frame, shorten the steering column accordingly, then I should be able to put the Jeep gear in with relatively little muss & fuss. Can you think of a reason why NOT to put holes in the frame?

Didn't you once ask someone at Saginaw about shortening the steering column by compressing it and they surprisingly said that was an 'acceptable' thing to do?

I'll have to give this more thought and run it by some of the other guys at work. Any idea what the valve and t-bar are in the Jeep gear? Or should I play engineer and read the print? :D

Dave

Jim Shea

Dave,
Shortening the steering shaft by compressing the lower shaft is acceptable.

But the big thing that I am not sure of is this. I know that some frames have cylinderical spacers inside that prevent the rails from crushing from the compression of the gear mounting bolts. I don't know if all frames have them or if the C3 frame has them. Unless the C3 frame material is so thick that is doesn't need spacers, I don't know how you can go and drill new clearance holes for the Jeep gear mounts without somehow going inside and adding some spacers. Also two of the bolt holes are so close that when you try to relocate the mounting hole to fit the Jeep gear, I would think that you would be drilling right through the side of one of the spacers. It would be interesting to find out what the C2 boys did in mounting the old 700 gears in their Vettes.

Jim

DaveL82

Sounds like you guys are onto something with the Jeep steering box!

However, I'm thinking about going with the company called Steeroids(spelling?) in houston. They just released a complete rack and pinion kit for the C3 (everything less pump, because old PS pump is used).

I think the kit is $1100 which at first seems high, but when you consider the fact that it is bolt in and replaces everything else that leaks or adds to steering play, this seems a good deal. It's supposed to eliminate bump steer also.

Dave

ddecart

Jim,
Ahhhh....never considered anything inside the frame rail to strengthen the frame from collapsing. I'll have to take a look to see what i can see under mine. Sounds like a possibility though if stiffeners aren't there.

Dave,
IMHO, that steeroids system needs a little work, especially with the outer tie rod connection to the steering arm. In the pics that burners posted, there was an extension on the end of the tie rod to raise the end above (below?) the steer arm. This is not a good situation and I woudln't put that on my car. As stiff as you want to say that bolt/extension is, it's going to flex and there are going to be some pretty high stresses on it.

Dave

mrvette

Dave, Jim Shea and I have exchanged emails off line about that steeroids design, and from what we see in the pix.....we both have similar reservations, and they extend to about 2 main points, that plate on the inner tie rod ends adapting to the rack....too much twist loading on the rack center piece....I"d call it a 'travellor' or 'car'.....
and I"d still preferr the stock type tie rod ends over that Heim joint arrangement, much less the extension on the knuckles....

GENE

DaveL82

I'm also concerned about the rod end spacers on the steering arm. May not be an issue for normal driving, but if the wheel went off a curb and hit a pot hole I would worry about it breaking and losing control.

71roadster

My guess is that the adapter plate that corvette steering is using incorporates the 3 degree angle and uses the stock bolt holes for the reasons Jim mentions. If you wanted to drill your own holes in the frame, I think the way to go would be to some how get the spacers that Jim refers to out of the frame (maybe cut out that small section of frame on the outer side), and weld in a new plate with the correct holes and spacers. I recall that the GM manual on racing vettes recommends welding up all of the unused holes in the frame to minize flex, so I wouldn't want a bunch of unused holes in that high stress area. If you come up with a way to use the box without an adapter plate and use an off the shelf pitman arm I would be very interested in that project.

And since corvettesteering is saying that it is necessary to use their pitman arm, I am thinking that their custom arm makes up for the offset introduced by their adapter plate. I am real interested in their setup but would have to see it before I purchased...unless they offered to refund if I didn't like it after I tried it, but that is unlikely.

As for that rack and pinion setup from steeroids, I agree with you and Jim. It just looks a little to Bubba for me, but it may drive very nice, who knows. I like the replacement box idea much better.

ddecart

Yup. This is going to take a little more work to make things work right but I think we'll get there.

Does anyone have a part number for the frame assembly? I'm thinking I might be able to find frame drawings someplace and figure out what's inside that frame rail.

I showed that steeroids setup to some people at work and it was pretty good for some chuckles. Not necessarily laughing at the concept, but more of a "They did WHAT?" critiquing of the system. That's what you get when you pile a bunch of vehicle dynamics engineers in a cube with steering system pics :)

From here, I think that going to an integral gear should be a relatively simple process. As nice as rack and pinion would be, I think a well-designed and optimised system is a ways off.

Dave