I finished my Tremec TKO installation this weekend and went back to working on my steering box. A few weeks ago I did a complete rebuild with new bearings and seals. At the time I measured the bushing clearances in the pitman arm shaft and found them to be about .010. They looked fine so I left it alone. I also measured the adjustment screw clearance and found it .006 so i tightened it up to .002 by adding a thicker washer. I also made a new dropped pitman arm to move my inner tierod down 1.250 inches to try and improve my bump steer. While the box was off I beefed up the frame where the box mounts with 1/8 plate as per the GM manual on racing a 75 corvette. The frame really flexes in this area when the wheel is turned. After reinstalling the box I grabbed the pitman arm and pulled it back and forth and I could see the pitman shaft wiggling in the box. I will remove the box and machine new bushings to tighten the clearance up to .001. These are 2 bushing about 1 inch long. One in the main body of the box and one in the removable cap.
I also looked at my rag joint that was replace last year and I don't like it. I was thinking of maching one from nylon or teflon. Do you think this would work? Would the nylon or teflon be too stiff? Do you need give in this joint for alignment purposes between the box and steering shaft?
Any comments would be appreciated.

 

Norval
I've replaced the rag joint in my 74 and it's OK but I still think it's a wear prone part that could be upgraded. I'm going to look into replacing it this winter with a universal joint from Borgeson ( I think that's the right spelling). They are very big in the street rod scene and their product looks very trick. You might want to check them out.

Yeah, I was right on the spelling. Check them out here
http://www.borgeson.com

Looks like part number 736 on page 10 of their PDF catalog should do the trick. If you go that way let me know how it works out. Hope this helps.


[Modified by vettfixr, 9:15 AM 10/22/2001]


[Modified by vettfixr, 9:21 AM 10/22/2001]

 

Norval, I sure would like to see the manual on racing a 75 Corvette. Is it in print anywhere? If not, can you post it to the CF archives?
thanks,Will

 

vettfixr. I contacted Borgeson to get a price on the aluminum and steel universal joint to replace the rag joint.
Thanks


flynhi. 10 years ago I got a service manual from GM with a large section on how to set up the 75 corvette for racing. It gave the modifications that should be preformed on the frame. steering, brakes, rollcage etc. etc.
I wouldn't have a clue where you would buy it today. A dealer gave it to me since it was of no use to him.
Thanks for inquirey.

 

Norvalwilhelm,
I assume that you also lowered you idler arm attachment to the relay rod by that same 1.25 inches.

Although the universal joint will have a much higher stiffness than the flexible coupling there could be one pitfall. You do have some body to frame motion while the car is being driven. Also there could actually be some settling of the body and a slight misalignment of the body to gear with time. The flexible coupling can "breath" in and out as well as up and down to allow for a little of that motion. The universal joint will not be forgiving in any of those modes. It could cause an overstress condition with either the lower column bearing or the gear input bearing.

The original equipment flexible coupling disc has seven laminations of cotton and neoprene rubber and is actually quite stiff. Some of the aftermarket coupling rebuild kits only come with a coupling disc made with four laminations. These discs will be considerably "softer" than the seven ply parts. If you buy 7818568 coupling from a GM dealer it will be the correct seven ply disc. I don't know if the complete flexible coupling assemblies from Corvette suppliers are the softer four ply or the correct seven ply discs.

 

Thank you Jim. I made a new rag joint out of teflon but I am concerned with it being too stiff. I bought a cheap aftermarket one last year and it feels so flimsy. I haven't received word on the universal yet but I am concerned with the give. I did lower the idler arm the same amount. I have not yet removed the rebuilt box to replace the bushings but that is only time consumming not a big deal. Since I have alot of time between now and spring I will not cut any corners in trying to make the best, tightest steering I can. I will also experiment with the bump steer to see if lowering the inner tie rod ends makes a difference.
I will probably order a GM rag joint.
Thanks for the part number.

 

Jim I just called the dealer for the rag joint with your part number and it is $112 CDN for the joint. They don't sell the rubber by itself but want you to buy new flanges. Too much for just a rubber.
Thanks