Steering issue - 70 GMC 3500

[CCCC]

Bought the truck with about 150k miles on the chassis/susp. On the 500+ mile highway run home the steering performance was solid with very little "play" or "wander". But, now on rougher roads, with ruts, etc., the steering wheel tosses back and forth in rutted/rough places.

Inspection shows no troublesome wear/play. So:

1. Might this be a common issue with one ton trucks of this vintage and can it be corrected with a pneumatic "damper" (shock absorber?) on the steering cross link. A 69 K20 here with big tires had such a damper already installed when I bought it and it gives no such "tossing" effects.

2. Might this particular issue be centered in the steering gear box and can anyone tell me the best way to check for undue wear/play in that component?

3. Other thoughts?

A similar inquiry got no replies on the "Suspension" forum. All helpful info will be appreciated.

[PanelDeland]

Rock the wheel while watching for play between the input shaft and the pitman arm.This will show wear in the gearbox.I would guess the wheel is being pulled by the ruts.If so a steering Damper might help.

[CCCC]

PanelDeland - thanks - I tried to do that check by myself as well as possble when I first got it home, but really need a buddy to turn the wheel while I am under there looking. Will get my wife out there with me tomorrow and take a more precise look.

If the damper unit is the answer, do you know where I can find one that will properly fit the C30/3500 steering gear setup? I see them advertised for C20/K20 , but don't know if such a unit will work on a C30 - different front end setup. Anyone?

[special-K]

A dampener will help a healthy steering system and whatever fits a C1500 or C2500 will fit your C3500. Check for that play,though. Working down from the steering wheel,it could be the rag joint,steering gear,or the pitman arm. I've seen the pitman arm wear where they mount to the steering gear.

[CCCC]

Well guys, a more thorough look at the steering setup (engine not running - no PS) reveals no play or wobble at either end of the Pitman arm or at any of the other joints out to the wheels. However, there may be some slop in the poer steering gear and I could use some indight.

There is no rag joint - the shaft from the steering wheel to the PS gear box looks to have some sort of a connector or joint about half way to the box. All of that has zero slack or play. But, that shaft going into the box rotates about 60 or 70 degrees before the output shaft/pitman arm moves. I do not know whether or not that is excessive. Do you have insight on that issue??

That input/output slack facter might change if the engine was running and PS activated, and I will try that next if need be.

A seemingly unrelated thing I noticed is that when the wheels actually begin to turn (on gravel, engine not running), it looks as though the very front ends of the frame (in front of the cross member, near the bumper - are those called "horns"?) seem to shift or bend a tiny bit left or right in response to the force exerted on the frame by the steering system. Would this slight movement at the frame ends benormal under such conditions? I can create this same action with other C30s to see if these movement factors are common.

All insights and advice appreciated.

[special-K]

The slop in the steering box sounds excessive. See what it does while running. I never noticed the frame flexing before. Maybe it's normal,but it sure doesn't seem normal. I'd think that would allow some loose steering feel. Does the frame look unmolested? All crossmembers present? Everything factory riveted?

[PanelDeland]

I agree with Tim.That seems like a lot of play.The wheel has to turn that 60-70 degrees before it takes up the slack.That slack gives the tires a chance to follow a rut or something before you can get the slack out to control it.
I would think the flex in the frame horns isn't normal but (unless yu know better or something is wrong),may be an optical illusion.

[GMCJOE]

I agree, I would do a adjustment on the steering gear box to tighten the play up on that.

[CCCC]

Ok guys - thanks for the replies. I will try to tighten it up with the adjuster - take some play out of the worm gear setup - and see what that yields. The free travel at the factory steering wheel (before pit arm movement) with truck not running is about 5 or 6 inches on outside rim.

Interersting with the frame horn movement - it is VERY slight with no PS and the tires on gravel, which gives more resistance than concrete or asphalt. May diminish or disappear on solid pavement and with truck in motion. All front frame aspects are as original, not damaged, tight rivets and even one added light cross member for front spare tire mount.

More later after I try the adjustment. Thanks again

[CCCC]

After further checking on several of the C30/C20 trucks here, there is about the same amount of free travel at the steering wheel (before any wheel/tire movement) on all of them - that mush may be :normal. If I have too much play on this GMC 3500, I must have it on all six - and that is unlikely.

Beyond the steering wheel travel, I can't find a single loose/play aspect in that GMC steering train.

After reading all the posts I can find here about removing any actual slack in the steering box gear setup - with their notes on warnings and eventualities - and given that two of these other trucks have steering system dampers, I am going to try a damper before I seek to adjust possible slack out of the steering box gear setup.

I will re-post here when i get to the bottom of this one. Thanks again.

[special-K]

I guess you checked your 12-6 & 9-3 o'clock wheel bearing/ball-joint/tie-rod play.

[CCCC]

Yes. Thanks.