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My 1972 base 350ci corvette with power steering has about 1/8'' of play each direction in the steering shaft/wheel. It does not appear to be the rag joint because both sides of the shaft move equally on each side of the rag joint. It looks like I'm going to need a refreshed steering box. My question is: Do all Corvettes, both manual steering and power steering use the same steering box? I would like to keep the car stock. Who makes a great replacement? Are the new Lares units from Rock Auto any good? Lares also offers rebuilt units with a core charge. Are these steering boxes numbered to the car or date coded in any way or can they just be swapped out for a similar unit without regard to originality? Thanks in advance for the help.
Last edited by keithg78; Mar 15, 2020 at 08:51 AM.
Yes, manual and power steering cars use the same box. You could install a Borgenson box, but it will not be stock and you will have to cut down your steering column. I would contact Gary at GTR1999 on this forum. He is the go to person and knows his stuff with respect to trailing arms and steering boxes. Have you tried to adjust the box? Search the C-2 and C-3 forums for adjustment specs. Jerry
Your 72 has a flat spot on the upper shaft going to the rag joint. With that flat pointing straight up, loosen the lock nut on top of the box, gently tighten the screw in the center of the lock nut, once you feel resistance, stop, and tighten the lock nut. Gary demonstrated this technique at one of his presentations.
There could be a couple things. Here's what I would recommend:
1) Clamp a vise grip pliers to the steering box shaft (below the rag joint). Tie the vise grips with some light rope, or whatever, against the frame or exhaust pipe. The steering wheel should be on-center and the vise grips non-movable. Then gently wiggle the steering wheel. If you feel the play it's BEFORE the box. It could still be the rag joint, or the upper shaft. Could also be a loose lower column bearing/bushing. The rag joint is ..decades old and the rubber gets hard and brittle too assuming it's original. Try that and see what you find.
2) The wear could be in the steering box, or the power steering valve, or even in any of the steering links. There's a very good chance that your steering box could benefit from just a simple bench recalibration. Essentially remove the steering box, put in a vise, loosen the adjustments (check the output bushing for play), then retighten the pre-load ..then the top screw. The top bearing on some of these boxes often got rusty (it's a small bearing) and the lower bushings can wear slightly too. But a simple bench re-cal could really tighten things.
There will be significant 'lost motion" (play) in a C3 wth power steering....until you fire the engine. The C3 P/S system requires P/S fluid pressure to eliminate that "slop".
So, fire the engine and redo your testing. If the "play" is still in the steering system, you have a hardware problem or you need adjustment on the steering box.
To the OP's question, there is a difference between 1968 steering boxes and later boxes. The C2s and 1968 C3s used a 36 spline yoke. 69-82 used a 30 spline yoke with a flat. There is no difference in the boxes between manual and power steering.
@GTR1999 rebuilt my steering box using a 36 spline yoke. I sent him a core from a 1980 Corvette, but not my original. It is production date coded, but not serialized. I converted to manual steering with the rebuilt box. It's great! If you want to maintain absolute originality, sending @GTR1999 your steering box for a rebuild may be your best bet, assuming that your 30 spline hardware is rebuildable (mine wasn't).
To @7T1vette's point, if you can get the car on ramps, safely, and observe the motion of the steering components while the engine is running, it will give you a better idea of what is going on. There is slop in the power steering valve if the power steering fluid is not pressurized. There is an adjustment you can do to tighten up the box, but it is best done with the box on the bench.
Last edited by Bikespace; Mar 15, 2020 at 06:57 PM.
If you want to retain the OEM box, GTR 1999, Gary Ramadei, who has custom blueprinted/rebuilt not only my OEM box but many others on the forum, will make your box better than new with zero play.
If you want non originality, Borgeson...............
You can rebuild your OEM box, it isn't hard. You'll need to get or borrow one specialized tool, a 0-30 in beam type torque wrench for a final adjustment, but other than that just common tools and a rebuild kit. The process is straight-forward. There's a few good step-by-steps on line.
Rebuilding the box yourself is not hard, as stated above,^^^^^^^^^^^^^^
BUT the specialized tools, hand adjustments, and in the GTR 1999 rebuilds, Specialized custom parts. he adds during his rebuilds, will mean the difference between a standard used box that was "rebuilt" and a blueprinted rebuilt OEM box that has zero play which even the new recirculating C3 ball boxes had direct from the factory. The crucial difference between you doing a base rebuild and a blueprinted rebuild is the hand adjustments during the process and the custom shaft bushings that eliminate all play. You will not be able to achieve zero play doing a standard rebuild.
A brand new perfectly adjusted OEM steering box (which they were not adjusted correctly from the factory) will have a fair amount of steering play, due to the inherent design of the box style, recirculating ball.....I had a friend with a brand New BMW 540 in the early 2000's which was one the last cars still using recirculating ball steering at that time and I was shocked at the amount of play in the steering box, new from the factory. My advice is for a zero play factory Factory steering box, utilize GTR1999, worth every cent.....
Last edited by jb78L-82; Mar 16, 2020 at 09:41 AM.
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My advice is for a zero play factory Factory steering box, utilize GTR1999, worth every cent.....
I agree completely. I also agree that the Borgeson box upgrade is a game changer that can make the car feel like a modern coupe. I didn't want to choose, so I have one of each!
Gary is the man. He has done my steering box, rear end, and T-arms. Gary parallel grinds shins to the exact size needed rather than just stacking them to get close. That attention to detail is what makes it worth it.
I just replaced a bunch of steering components and having new tie rods ends and idler arms also tightened up my system.
Thanks for all of the recommendations. I inspected it closely and the play appears to be in the steering box and not in the rag joint (rag joint was replaced at some point in time). There is definitely 1/8'' play in the input shaft of the box (not the rag joint) and the pitman arm does not move at all on the bottom. Also when driving the car I can slightly turn the steering wheel each way without any movement in the tires. I tried adjusting the screw about an 1/4 of a turn until I felt resistance on top of the steering box and it helped a little but not enough. Plus there are only 2-3 threads showing and I read that's about the end of it's adjustment limit for wear. The car has 90,000 miles on it so I'm sure it's time to have it rebuilt/reconditioned. All of the other components in the steering system are newer (ram mount/cylinder, ball joints, tie rods, steering valve, power steering pump and hoses, etc.).
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
theres not many parts in a steering box. Chances are it just needs a good cleaning.
You can see the gears are tapered. If you screw the bolt down in you can see it will take up the slack in the gears.
Thanks for both links^^^^^^...READ the second link and Gary's step by step rebuild procedure and you will understand that these boxes are NOT just a couple of parts that can be rebuilt easily. Again, the proper rebuild requires a couple of specialized tools PLUS the proper hand adjustments during the assembly process AND a few custom NON FACTORY parts to make these boxes superb with ZERO play.
A basic disassembly and reassembly will NOT net a no play steering box....just to be clear....
Thanks for both links^^^^^^...READ the second link and Gary's step by step rebuild procedure and you will understand that these boxes are NOT just a couple of parts that can be rebuilt easily. Again, the proper rebuild requires a couple of specialized tools PLUS the proper hand adjustments during the assembly process AND a few custom NON FACTORY parts to make these boxes superb with ZERO play.
A basic disassembly and reassembly will NOT net a no play steering box....just to be clear....
Agreed. And if you attempt to adjust the lash without the box being on EXACTLY high center, you risk inducing wear in the gears and making things worse. Gary is the man and I highly suggest reaching out to him.
Keith, before making any adjustments to the steering box, always be sure to verify the condition of the rag-joint...
and the idler arm are 100%
Theses are two of the major sources of play in the steering linkages on the C2 & C3 Corvette and also two of the easiest to R&R. Since you've verified the integrity of the rag joint, be sure to check the idler arm before going any further.
Play in steering box
