The Stovebolt Site Forums The Shop Area Driveline Veers to right- bad steering geometry? Something else?

The last bug I need to work out on my 52 GMC 1/2 ton relates to steering. Some pertinent facts:
1. This truck had been in at least one accident in the past that damaged the frame in the vicinity of the second crossmember. I had to shim one rear motor mount.
2. I replaced the worn-out steering knuckle and steering arm with lightly-worn 3/4 ton parts from a parts truck. It all bolted together and seemed like a good idea at the time.
3. I added a 9th leaf to the front springs to try to compensate for using a heavier 270 engine. The vehicle rides about 2" higher than my other 1/2 ton trucks.
4. The steering gear is about used up and has no more adjustment left in it.
5. The axle is straight with no obvious twist and has equal shims under the springs on both sides.
6.The pitman arm is not seated as fully on the steering gear as my other trucks. No obvious damage to the serrations. Same pitman arm as other trucks.
7. King pins seem good.
8. All the other non-alignment factors in the shop manual don't seem to apply.

This truck was put together with primarily the best USED parts that I could obtain from several different vehicles. I realize that given this extensive list of potential problems, it would be difficult to remotely diagnose this particular truck from afar. The tendency of the truck to veer to the right is irritating but slight.

My most immediate questions on where to start include:
1. Is there any inherent problem with 1951 3/4 ton steering arm and knuckle ruining the steering geometry on a 1952 1/2 ton?
2. Is there an inherent problem with heavier 9-leaf springs and steering?
3. What's up with the pitman arm not seating fully?

I can retrofit this truck with proper 1/2 ton steering parts and a better used steering gear. But before I go and purchase these parts, am I on the right track?

Thanks, Dave

The first thing anyone who is diagnosing a steering problem needs to do is have the wheel alignment checked by a shop able to provide some hard numbers on caster, camber, and toe. Until that happens, any advice anyone gives you is pure speculation.

A vehicle will pull toward the side with the most positive camber, and/or to the side with the least positive caster. For instance:

Camber: Right side +3 Left side +2- - - - -the vehicle will pull toward the right.

Caster: Right side +3, Left side +2- - - -vehicle will pull left.

In areas with a normal amount of road crown for rain drainage, it's customary to run equal camber on both sides, and 1/2 degree less caster on the driver's side to make the vehicle track straight and compensate for road crown.

Toe adjustment on a vehicle with the tie rods behind the spindles is usually slightly toed-in. Some vehicles with the tie rods ahead of the spindles such as early-1950's Fords get a little toe-out. Both designs tend to move toward a zero toe measurement when in motion.
Jerry

Alignment shops that still work on the old stuff are getting hard to find around here but it makes sense as the place to start.

Just checking the existing angles can be done by the average nose-picker trainee on a $20K laser alignment machine, between laps around the floor with a push broom. Making any adjustments other than maybe toe- - - -that's a different kettle of fish!
Jerry

I didn't look through the parts books for the following details. If the part number for those parts differs from your half ton then yes, they could cause a problem. You may have a situation where the steering box is not centered because of the steering arm. That will cause a problem. As far as the Pitman arm is concerned, it doesn't seat all the way in but sort of jams on the splines part way. It is very secure that way. You can take a carpenter square and get an idea whether the caster on the front wheels is the same on both sides. The steering should be centered forward to check it.

How do you check caster with a square?
Jerry

The bent frame issue is a red flag for me. That will thwart most of your processes of elimination of potential other problems caused by the changes from stock which you have made.
I would suggest that you have the frame straightened, regardless of your frugal budget. I am also the frugal type, but sometimes you have to dole out some cash.
Carl

Have the front end shop do a "thrust line" alignment check. It might surprise you to find out just where the rear end is trying to push the truck.
Jerry

I meant to say camber, not caster. With a level floor I use the square to compare the camber of both wheels.

I agree that the bent frame is the big-dollar elephant in the room. I didn't drive this truck much before re-doing it but I don't remember an alignment problem. There are different parts numbers for 1/2 and 3/4 ton trucks. I did use a square to at least eyeball the relative position of the flats on the axle where the springs bolt on. They appeared real close which is why I said that the axle doesn't appear to be twisted. And the word "frugal" does sound so much better than "cheap":)

I've guesstimated caster on a few race cars in the pits after a crash repair by dropping a plum bob from the top ball joint and looking at the distance to the lower joint, and my favorite camber checking tool was a 2 foot carpenter's level. Lots of sneaky ways to get one back on the track in a hurry!
Jerry

OK, I've decided what I'm going to do. I've got an appointment tomorrow at a frame/alignment shop that works on old vehicles. I'll spend what it takes to straighten the frame and align the front wheels using the old equipment. I've been concerned about frame damage also, hence #1 on my fact list. Back when this project was at the "chassis only" stage, I didn't have a way to transport it anywhere, but that would have been the ideal time to do this. Now it's licensed, insured, and able to move under its own power. I also know what needs more TLC from having driven it awhile. In another month, driving season will be over and I'll have all winter to redo steering gear, steering arms, and re-shim body sheet metal on a straighter chassis. Thanks, everybody, for your help. Sometimes, I need the perspective of others to nudge me into doing the right thing. Dave

I did not use the work "frugal" for your benefit, but for my own, as I am cheap and very sensitive.
Carl

I'm cheap too, Carl, and was presented today with the downside of cheapness. The professional shop today diagnosed a bent front axle, "shot" king pins, and steering gear that is so loose that the repairman considered the vehicle unable to be driven. I knew that the steering gear was loose, but not dangerously so. I knew that the king pins had a little movement, but not "shot". I knew that the vehicle veers to the right, but not that the axle is bent. I've become so accustomed to USED parts, that I barely know what NEW looks like! I wonder what the frame/alignment shop would think of my other trucks that I consider perfectly OK and safe.

So, I've come this far and have scheduled the repairs. Well in excess of $1K. The thought process kicks in: "I know where I can get an entire USED axle for $100 and another USED steering gear for $50 and put them in myself and save BIG BUCKS!" But I clearly lack the perspective to tell whether they are safe. Maybe paying-up for a professional job will expand my horizons in this area. Maybe not.
Dave

Since I don't know what your mechanical aptitude is, I can't advise you to do-it-yourself. But in terms of degree of difficulty, your items are not too difficult to fix or change, as long as you have the Chevrolet Factory Repair Manual, and can read.
Carl

Something else that has to be considered beyond being able to install the parts, and that's knowing what the tolerances are for a given part, and how to properly measure it. Being within tolerances on the suspension and brakes is extremely critical for safe operation. Many times, those tolerances are very tight, measured in thousandths of an inch.

This is not a comment on this truck but correct me if I am wrong here. If you can demonstrate any wear on the kingpin and bushings, it should be replaced.

Usually, if no spec is given, the any perceptible play is considered out of spec. This is the case pretty much 100% of the time with tie rods, and as mentioned, any time there is no spec given.
In the case of the king pins, I could not find a spec other than .002" clearance between the kingpin and the bushing. Any excessive play will throw off the alignment accuracy.

I can remember a customer back in the late 1950's who was outraged that Dad's partner wouldn't try to do a wheel alignment on a car with the idler arm held onto its bracket with clothes hanger wire! He was sure they were trying to pad the bill with unnecessary parts!
Jerry

I agree with the direction that Bill and Jerry are headed regarding tolerances and the need for professional services. I can change used parts all day long. I can install an engine, tranny, or rear end but don't think that I could rebuild them with hand tools and a shop manual. More often than not, I've gotten away with installing used parts. Often, used parts are all that are available. But I admit to being a little un-nerved that a steering problem that I thought was "irritating but slight" was viewed as a major safety problem and undrivable by a professional. I'm questioning whether my inclination to always save money with used, DIY approaches rather than purchasing new parts and professionally done services is always the right way to go. Especially regarding safety.

Steering box can be rebuilt. Skills required are not beyond you. King pins can be replaced, again skills are not beyond you. A bent axle...OK that is beyond most of us. Repair/replace tie rod ends, that you can do. Bent frame? OK that is beyond my skill level. So what to do? Fix the frame(Pro help for that). Find another axle or find a shop to straighten it. Get things as good as you can. Fix one thing at a time. First test drive with my truck(52 1/2 ton) revealed funny steering and constant attention. It was toed out about 1/4 inch. Not good. But, silly me the numbers were in the book if I had bothered to look. Adjusted the toe in and the truck steers fine. True and easy when it is rolling. I also found that the spring bushings can play a big part in the stability so check them as well. Do those things you can. Get help with those things you don't have the skills or tools to do. Good luck. I have had good luck with a pro shop checking "used" parts before install. Think axle. Verification of a used part is part of the process. Who said learning is free? Let us know how it goes.

I repaired the tie rod ends and spring bushings on this truck. I've done king pins before on my 1950 truck. Yeah, I could probably rebuild the steering box. This shop will straighten the axle. I did the toe-in myself within 1/8".

The toughest part of this steering journey so far has been in overcoming the inertia to call in a specialist. I take some pride in doing my own work and I like to save money. The sheer convenience of just writing a check and letting someone call me when it's done seems appealing this time. I'm interested to see if a pro steering alignment is a lot, a little, or no better than the DIY steering on my other trucks. I never thought that they were particularly unsafe before.

By the way, this shop expressed no concern with the frame, spring modifications, or 3/4-ton steering parts as they affect alignment. And the rear axle tracks true within 1/2 degree.

Thanks, Steve and all, for the encouragement. Dave