Steering Wheel is a half turn off after disc brake conversion
 

So I have a 1968 C10. I swapped in the power steering box from an 86 C10 a couple years ago. I just recently swapped in an entire front crossmember, with all of the steering components all from a mid 80's suburban.
The pitman arm was bad so I bought a new one from a mid 80's C10 with power steering.

I looked to set the toe in close so I could run down an get it aligned. Interestingly, the toe in is dead on, but the steering wheel is one half turn off. To go straight I have to have the steering wheel turned to the right a half turn, so, I only have a 1 and 1/4 turns to the right before i hit off the stop (pretty terrible turning radius) and can turn 2 1/4 turns to the left.
At first I did not think this was a big deal. I would just adjust the tie rods over to bring it back in, but when I went to the alignment shop, they pointed out that the tie rod ends were pretty even. He kept trying to tell me my steering box was bad and that I needed to replace it for him to do an alignment, but that box has worked great with the original 68 front end for the last couple years.

The frame is the exact same width, so I cant see why this would be the case. I did have the thought the Pitman arm could be wrong (splines clocked incorrectly) so I went to the parts house and looked to get another one. The one the parts guy pulled out was splined exactly the same. Of course it was the same brand and could possibly have the same defect.

Was just wondering if anyone else had run into this. Is there something that could possibly be missing?

Re: Steering Wheel is a half turn off after disc brake conversion
 

Your steering wheel is splined to the steering shaft. I would imagine if you got your wheels straight, took the steering wheel off and put it back on straight it should fix the issue?

Re: Steering Wheel is a half turn off after disc brake conversion
 

That was my original thought - just re-clock the steering wheel. But he says he only has 1 1/4 turns to the right and 2 1/4 to the left, so something else is going on...

Is there a possibility the steering is hitting something other than the steering stop?

Re: Steering Wheel is a half turn off after disc brake conversion
 

That won't fix the difference in the left and right turning radiuses..

The root cause of the OP's problem is the mixture of miss-matched parts, and/or possibly wrong parts.. Try adjusting the tie rod lengths to center the steering wheel.. A small amount of length difference shouldn't matter..

Re: Steering Wheel is a half turn off after disc brake conversion
 

Is it possible that the steering box was damaged when you got it? Steering boxes have a sector shaft that is designed to take some of the energy from a crash so it will twist. That way the steering wheel does not violently jerk and brake your hands. If the doner vehicle had suspension damage the box may also. The fact that you have limited number of turns in one direction is why I ask.

Re: Steering Wheel is a half turn off after disc brake conversion
 

The pittman arm is probably installed incorrectly. To the OP- disconnect the pittman arm from the steering gear box (that is really fun), turn the steering wheel lock to lock, recenter it to half the number of turns, set the wheels facing straight ahead and then reinstall the pittman arm on the box. Go ahead, ask me how I know. An easy check before doing all this is to drive it down the road and notice that it just doesn't hold the road. That comes from not having the steering box sector gear on the high spot due to incorrect pittman installation. Once you get that straightened out, get the front end aligned properly. THEN turn the wheel as needed. It is critical that you tell the guy aligning your truck after this that the steering wheel probably doesn't match up with the steering geometry after all the front end work. Otherwise, they will just center the steering wheel and adjust the tie rods, which may still end up having the pittman arm off by one tooth, which will still give the "hunting" problem, going down the road. It is important to note that this is extremely rare, and most shops will not know of it, since most people never tear into a vehicle like was done here. HTH.

Re: Steering Wheel is a half turn off after disc brake conversion
 

I replaced the pitman arm on my 97 Suburban a couple years ago. The pitman arm is keyed, so it can only go on 1 way. Once I was done, the steering wheel was at least 45* off. Apparently, that brand pitman arm is 1 tooth off.

Re: Steering Wheel is a half turn off after disc brake conversion
 

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My '67 Panel Truck has the same problem after a complete cross member swap. I haven't looked into it yet. It will also wipe the wheel weights off of the rim on the inside because it turns so sharp to the left. (this probably depends on what wheels you have)

LockDoc

Re: Steering Wheel is a half turn off after disc brake conversion
 

Were they keyed in '68? I don't know, but now you mention it, it should be, I would think. If the Pittman arm is off a tooth, the tie rods should be adjusted to keep the steering wheel centered instead of pulling and turning the steering wheel, since that is (hopefully) where the high part of the sector gear is/was.

Re: Steering Wheel is a half turn off after disc brake conversion
 

+1.

Re: Steering Wheel is a half turn off after disc brake conversion
 

yea, the pit-man arm is keyed. Has 4 flat spots at 90 degree increments around the shaft. I had a thought for a minute that I had installed it 90 degrees off, but looking at it, it is only about 5 degrees off or so. I have all the tools to pull it easily, so that isn't an issue. I should have mentioned that. That is why I tried to take the pitman arm back. I figured the one I got was made wrong, since that is the only new part, and the rest is all off of mid 80's C10/suburban.

I could just check another brand pitman arm. That was the only brand they had at the part store and both parts were identical.

The alignment shop stated they thought it was the sector shaft, but I have been using the box for two years now and it was fine before I swapped on the new crossmember.

Is there something i could have installed wrong on the idler arm that would have it off?

Re: Steering Wheel is a half turn off after disc brake conversion
 

Curious, what brand is your pitman arm? Can you compare it to your old one or the one originally from the 80s c10?

Re: Steering Wheel is a half turn off after disc brake conversion
 

NOT saying this is your problem, but when I had to replace the pitman arm on my old chevy truck I went to Autozone and got the cheapest one. Same problem you are having.
It had been made in china and the keyed splines were a mirror image of the original pitman arm. I took it back and got a higher priced one and it fixed the problem.

Good luck, Rg

Re: Steering Wheel is a half turn off after disc brake conversion
 

Take your pitman arm off center your steering wheel and reinstall the pitman arm.

Re: Steering Wheel is a half turn off after disc brake conversion
 

Grab a torch, heat the pitman arm until it’s glowing red and bend it until all your wheels are straight. Just kidding, DON’T do this!

Re: Steering Wheel is a half turn off after disc brake conversion
 

If it has been a while since you had a wheel alignment, kill two birds with one stone.

Re: Steering Wheel is a half turn off after disc brake conversion
 

Pull the pitman arm off, center the steering box, reinstall the arm.

With the box centered and the center link installed, the pitman and idler should be parallel right/left and up/down. If not, you have something installed wrong or a bent center link or frame.

Re: Steering Wheel is a half turn off after disc brake conversion
 

With 4 key points, and a difference of 1 turn between right and left lock, I'd say that the Pittman arm is off half a turn of the steering output shaft...unless the key splines are asymmetric. If you can get it off easily, try what I said before. I could be wrong though, if the keys are asymmetric. Easy to check!

Re: Steering Wheel is a half turn off after disc brake conversion
 

Yeah, I have already tried pulling it and reinstalling. like I said in the earlier post, it is about 5 degrees off. Not far enough to go on the next set of splines, but too far off to align the truck. I would run out of threads on one side with the tie rods.
I did get it from autozone. I went to Napa today though and the splines are exactly the same. I may try one more since I have heard this does happen. I wish I still had the old one. Sold the whole thing as a unit. Was wanting to compare that and the center link. Anyone know if the manual steering center link is same length as the power steering one?

Re: Steering Wheel is a half turn off after disc brake conversion
 

I think the center link is the same, but it’s worth checking the part numbers to see if the idler arm is different.
Have you centered the steering box yet? Do this with the pitman arm off. And don’t worry if the wheel isn’t centered, you can r&r it to remedy that.

1.Center the box with the pitman arm off.
2.Check that the steering wheel is level. If it’s not, pull it off and level it.
3.Put the pitman arm back on
4.Now check for parallel on pitman and idler
I’ve been thru this before, it will diagnose what isn’t correct.

Seems like 5 degrees shouldn’t equal the lock to lock difference that you are seeing.

Re: Steering Wheel is a half turn off after disc brake conversion
 

Ok, I centered the steering box. The steering wheel is straight. The pit man arm will not go back on unless I turn the steering wheel a half turn (about two splines on the pitman arm) I took a picture with the steering box centered and the pitman arm on. The wheels are turned lightly to the left.
the pitman arm looks parallel with the frame but the idler arm is turned slightly in. About half the ball joint is under the frame. I have a pic of this as well. also took a pic of the idler bolted to the frame.

not sure how the pitman arm could be parallel with the frame and the idler arm not be. The frame width is the same in the 85 and the 68.

It doesn't take much off on the angles to add up to a lot.

Re: Steering Wheel is a half turn off after disc brake conversion
 

Yep, just pull the wheel and put it back on straight. Might wait until after the alignment to do it. He said the difference was because he already had the steering turned 1/2 turn to straighten the "steering" wheel, not the front wheels.

Re: Steering Wheel is a half turn off after disc brake conversion
 

no, moving the steering wheel wont help. The steering box is not centered then. The picture is with the steering wheel straight. The front wheels are turned to the left. Moving the steering wheel I would have a half of a turn less on the right and an extra half turn going left.

Re: Steering Wheel is a half turn off after disc brake conversion
 

Just a thought , have you measured the tie rod assemblies ? measure zerk fitting to zerk fitting on both sides , They should be equal or close . :chevy:

Re: Steering Wheel is a half turn off after disc brake conversion
 

By centering the gearbox do you mean you count the turns on the steering wheel each way and then come back to center?