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I知 putting in new power steering components in my 1978 Corvette including the valve, cylinder, pitman arm, steering box and coupler. I have everything mounted now except for the pitman arm. The new steering box came with a yellow line on it to mark the center and with the pitman arm off, when the steering wheel is centered it gets 1 3/4 a turn each way. The issue is the pitman arm is about an inch or two off the stud on the valve even though I have my wheels straight and box straight. I can not for the life of me figure out what I知 doing wrong. Another red flag is that the pitman arm hits the cylinder to frame bracket so I only get about 1 1/4 turns that direction instead of hitting the normal lock. Any ideas what I知 doing wrong? The pitman arm has flat splines at 90 degree angles so I don稚 know how I壇 be that far off there. I attached a photo below
First question is with the yellow stripe, is it on true center or high lash? In theory they should be the same but rarely are from day 1. Is this your original box or a replacement? If original were the gears replaced, if another box are they original gears? Hint if you paid under $300 for the box it does not have new gears in it.
The arm should not contact anything and yes there is only one correct position the arm can be on the box, there are 4 possible but they would be out 90-180-270* no way it would come close.
Box travel lock to lock is about 4 turns but in the car, referenced from center about 1.5 turns.
If you have access to a 0-30 in/lb dial torque wrench I can tell you how to check the box, no sense using it if it's not correct.
PS I can see your picture on this PC so can't say if there is anything there wrong.
Hi Cb, this is a pic of the setup on my '70 Seems the angle of your valve is off? Do you have the original components to compare? Have you read this? PS and non PS Pitman arms.
First question is with the yellow stripe, is it on true center or high lash? In theory they should be the same but rarely are from day 1. Is this your original box or a replacement? If original were the gears replaced, if another box are they original gears? Hint if you paid under $300 for the box it does not have new gears in it.
The arm should not contact anything and yes there is only one correct position the arm can be on the box, there are 4 possible but they would be out 90-180-270* no way it would come close.
Box travel lock to lock is about 4 turns but in the car, referenced from center about 1.5 turns.
If you have access to a 0-30 in/lb dial torque wrench I can tell you how to check the box, no sense using it if it's not correct.
PS I can see your picture on this PC so can't say if there is anything there wrong.
My guess is the box or the pitman arm is wrong. What do you mean by high lash? I have it centered so that the yellow line is lined up on the pitman arm end which results in the steering wheel being centered with about 1 and 3/4 a turn each way. The steering box is a rebuilt one from a online corvette specialty shop so certainly not the most expensive one out there.
Hi Cb, this is a pic of the setup on my '70 Seems the angle of your valve is off? Do you have the original components to compare? Have you read this? PS and non PS Pitman arms.
'70 vette ps steering valve.
The parts look almost identical to the originals as far as I can tell. I don稚 have the valve tightened so it can rotate freely at the moment
I assume the box is connected to the steering shaft. or If not by hand turn the box full left without the pitman arm attached. Now turn the box full right - accurately count the turns and part of a turn. Now turn the box 1/2 the count you got to the left.
This is the center of the box. See if the arm fits / aligns. If not the arm is off or the box is bad.
You may have to re-align the steering wheel by loosing the rag joint.
I assume the box is connected to the steering shaft. or If not by hand turn the box full left without the pitman arm attached. Now turn the box full right - accurately count the turns and part of a turn. Now turn the box 1/2 the count you got to the left.
This is the center of the box. See if the arm fits / aligns. If not the arm is off or the box is bad.
You may have to re-align the steering wheel by loosing the rag joint.
I imagine it痴 a bad box or arm then. I did this earlier with the arm off but steering wheel attached. I値l have to call up the store and see what they say.
To me, it looks like the steering valve needs to be rotated on the center link, to both match the angle and length of the arm. If the box is correct, the arm is correct (and manual and PS are both the same length, just with a different curve), that's all that is left to line up.
My guess is the box or the pitman arm is wrong. What do you mean by high lash? I have it centered so that the yellow line is lined up on the pitman arm end which results in the steering wheel being centered with about 1 and 3/4 a turn each way. The steering box is a rebuilt one from a online corvette specialty shop so certainly not the most expensive one out there.
ok, High lash is really the point to reference from, it is he highest point of drag through the gear mesh. The true center is the difference between travel pt to pt. They should be the same so that with the box on center the highest drag is also on center. They rarely were from day one and many who slap these boxes together have no clue on how to set them up, take my word on this point. So my question was if the yellow line is true center- which it mostly is or possibly someone out there understood high center when rebuilding that box and marked it- I really doubt it but you never know. You can check it simply by splitting the difference for the true center, a dial TW is needed to check the high lash and the box has to be out of the car. I mention all this to try and save you a lot of stress because if the box is not correct and you install it you may find the steering isn't as tight as you expect. Then you get mad, call whomever sold it to you, they tell you that is how they were 40 years ago, you get madder, pull the box, spend more time and money installing an aftermarket setup and scrap your stock one. I know it might sound extreme but it happens all the time. Now if you can check it and know it is right then you can move on. With the box on center the arm should point forward, there is a chisel mark on the arm on the splined end, that should be a 12 o'clock and the arm should line up with the control valve stud. If the box rebuilder assembled the sector off a tooth, possibly but obvious, then the center is off. There is a supplier out there that has been building and selling junk for years, one trick they use is to flip the worm nut upside down to try and save worn out gears. This is not correct, there is no adjustment in the gear lash, the feel is terrible, and it is plain dangerous yet they market them and have for years to resellers who don't know a thing about them, and they end up in a car. I don't know if that is what you have but I would be happy to go over it with you so you can tell. Just email me your ph# and I will go over it with you. You should not have to do this but that is how things are done today.
The control valve, as I am sure you know, has a pinch bolt and there is a D-Flat on the centerlink. It can only be installed one way but there is a dimension in the AIM since you can set the total length and that will affect arm location.
A ps arm is a #383 arm, the last 3 digits cast into it. The offsets are different between the manual, #451 arm, and the PS arm. Those are very good pictures above.
This is not a hard process but can be very frustrating if one part is not correct. Now if you want to talk about frustrating part fitment we can talk about differential parts!
Hope this helps you better understand the system. Also check full travel lock to lock once you are done because some of the hoses on the market are slightly shorter then original and get very close to the stress/break point.
To me, it looks like the steering valve needs to be rotated on the center link, to both match the angle and length of the arm. If the box is correct, the arm is correct (and manual and PS are both the same length, just with a different curve), that's all that is left to line up.
The valve can be rotated, it痴 not so much the angle that I知 worried about as that is set off a pinch bolt. I can rotate the valve to match the angle fine. The issue is the pitman arm is about an inch out from that which would require backing the valve off threads which isn稚 a correct fix.
ok, High lash is really the point to reference from, it is he highest point of drag through the gear mesh. The true center is the difference between travel pt to pt. They should be the same so that with the box on center the highest drag is also on center. They rarely were from day one and many who slap these boxes together have no clue on how to set them up, take my word on this point. So my question was if the yellow line is true center- which it mostly is or possibly someone out there understood high center when rebuilding that box and marked it- I really doubt it but you never know. You can check it simply by splitting the difference for the true center, a dial TW is needed to check the high lash and the box has to be out of the car. I mention all this to try and save you a lot of stress because if the box is not correct and you install it you may find the steering isn't as tight as you expect. Then you get mad, call whomever sold it to you, they tell you that is how they were 40 years ago, you get madder, pull the box, spend more time and money installing an aftermarket setup and scrap your stock one. I know it might sound extreme but it happens all the time. Now if you can check it and know it is right then you can move on. With the box on center the arm should point forward, there is a chisel mark on the arm on the splined end, that should be a 12 o'clock and the arm should line up with the control valve stud. If the box rebuilder assembled the sector off a tooth, possibly but obvious, then the center is off. There is a supplier out there that has been building and selling junk for years, one trick they use is to flip the worm nut upside down to try and save worn out gears. This is not correct, there is no adjustment in the gear lash, the feel is terrible, and it is plain dangerous yet they market them and have for years to resellers who don't know a thing about them, and they end up in a car. I don't know if that is what you have but I would be happy to go over it with you so you can tell. Just email me your ph# and I will go over it with you. You should not have to do this but that is how things are done today.
The control valve, as I am sure you know, has a pinch bolt and there is a D-Flat on the centerlink. It can only be installed one way but there is a dimension in the AIM since you can set the total length and that will affect arm location.
A ps arm is a #383 arm, the last 3 digits cast into it. The offsets are different between the manual, #451 arm, and the PS arm. Those are very good pictures above.
This is not a hard process but can be very frustrating if one part is not correct. Now if you want to talk about frustrating part fitment we can talk about differential parts!
Hope this helps you better understand the system. Also check full travel lock to lock once you are done because some of the hoses on the market are slightly shorter then original and get very close to the stress/break point.
So you池e saying even though I have it such a half of a full set of rotations makes the steering wheel centered it is possible the splines on the bottom for the pitman arm are not correct? At this point I知 pretty sure it痴 my box as the arm should not be hitting the cylinders bracket. At this point I might call the distributor Monday Andrew see what they have to say before I take the box back out and begin diagnosing it.
I just found this thread via a google search since I experienced the same problem. The issue is the new steering box you purchased. I purchased a brand new steering box back in 2002 from Chevrolet. It is not the true "Road S" marked box, as GM farmed out these steering gears to overseas manufacturers. Long story short, the sector shaft is not machined properly. The 4 indexed splines are not located at the proper position, which completely throws off the centering of the steering, causing the pitman arm to hit the bracket.
04-18-2019, 10:36 PM
1978 Pitman Arm and PS Valve alignment
