M37 steering and wander

[jmacqueen]

So after a long break due to life getting in the way, I have my M37 back together and on the road..

I have a couple of issues though.

I put a saginaw PS box and pump on for steering, and the boost is way too much. I'll be going into the pressure/flow valve and lowering the output pressure to hopefully get it to have a bit more feel and force needed.

The truck seems to want to wander though, worse as I go faster, and with too much power assist and huge wheel making small corrections into big ones it's a bit of a PITA. So hopefully lower power assist will help with that.

Front end alignment is next to look at though. How do you guys set toe in at home, or does everyone find a shop to check it. How about caster? anyone had to change it?

[Charles Talbert]

Cart before the horse??

Caster and camber are fixed and non-adjustable. If you have not gone through the steering knuckles and rebuilt back to new specs, now is the time. This will set caster and camber correctly. Toe in should be as near 1/8" as you can get it. If you have not gone through all the steering components searching for loose motion throughout the system, idler arm pin/bushing, drag link ball joints, tie rod ends, now is the time. Correct anything you find, especially end play at the idler arm pin. That will cause wander like crazy. There are no repair parts for end play elimination, you will have to weld and machine to fix this issue and it is an issue on almost every truck. Installing power steering without doing all of this prior will never produce a favorable end result. I'd strongly suggest looking into all of the above before going into the box valving; it won't be the best it can be until you do regardless of hydraulic sensitivity.

[jmacqueen]

Caster and camber are fixed and non-adjustable. If you have not gone through the steering knuckles and rebuilt back to new specs, now is the time. This will set caster and camber correctly. Toe in should be as near 1/8" as you can get it. If you have not gone through all the steering components searching for loose motion throughout the system, idler arm pin/bushing, drag link ball joints, tie rod ends, now is the time. Correct anything you find, especially end play at the idler arm pin. That will cause wander like crazy. There are no repair parts for end play elimination, you will have to weld and machine to fix this issue and it is an issue on almost every truck. Installing power steering without doing all of this prior will never produce a favorable end result. I'd strongly suggest looking into all of the above before going into the box valving; it won't be the best it can be until you do regardless of hydraulic sensitivity.

I rebuilt the steering knuckles, replaced all bushings and seals, bearings, used a bearing on the top of the knuckle instead of the brass cone bushing and shimmed to spec. I also replaced all leaf spring pins and bushings, replaced the idler arm pin and bushing and rebuilt all 4 of the drag link ball joints and replaced both tie rod ends so everything is as tight as it can be.

I'll take another look at the end play on the idler arm pin though. Maybe I should recheck the drag link ball joints as well just to be sure.

Rear spring pins and bushings have also all been replaced, as well as new shocks all around.

I'm also still on pretty old NDT tires which could be an issue I guess.

I can turn the steering wheel lock to lock easily with my little finger just sitting at idle. My thoughts were to drop the pump pressure a couple hundred pounds at a time by using a couple of washers to lower the relief spring pressure internally in the pump like the mustang folks do for reducing pressure when they use a saginaw pump with a mustang II rack and pinion or a later model camaro uses as they run lower pressure than most. I'd like at least a little bit of force required and little bit of feel to the steering, as is there is really no feel to it at all.

One of these kits.. http://www.summitracing.com/parts/BRG-899001/

It's either that or a smaller steering wheel.. ;)

I was under the impression you could change caster with a slim wedge between the axle housing pads and the leaf springs. Don't remember where I read it or got that idea.

Does anyone here check their own toe in? if so what tool/method. Shops around here are likely going to look like a deer in the headlights if I pull into a place around here with it. I had all kinds of issues trying to get someone to just break a bead for me on the combat wheels. I'm thinking it's a mix of toe in and too much power assist with maybe a bit of old tire exacerbating things.

[Gordon Maney]

Yes, you can change caster with tapered ships, as you describe. Camber is not adjustable.

If you ever saw how simple the early, commercially produced toe-in measuring bars were you would understand you can do that yourself.

Imagine with me for a moment....

Jack up the front end, then center the steering gear. Turn the gear lock to lock, counting the turns, then count back to the center.

Get a scratch awl or other sharp tool. Rig a prop so you can hold the tip of it near the tire tread, at the center of the tread. Turn the wheel and keep the point of the tool steady as it scores the dirt on the tread [or chalk the tread and score the chalk]. Continue until you have scored all the way around. Do this on both front wheels.

Now look at one of the front wheels from the side. See the points of the tire that are at 9 and 3 o'clock. That is where you want to measure. The problem is you can't stretch a tape measure from left to right at that elevation.

You have to make up some sort of base with a pointer — like a stiff piece of gas welding filler rod — up to that height. Measure between the two wires, once at the front and once at the back. Fool around with this and see how careful you can be and how confident you can be.

If it ends up you are not entirely confident, you can at least use this method to make an initial adjustment allowing you to drive it to an alignment shop.

[Charles Talbert]

The point I was trying to push home in an earlier post is that unless your front axle has issues, caster and camber should within design specs without shimming once knuckles are built to spec., usually they are after putting back to new condition. If you think it isn't then it needs to be checked on a front end machine to verify. Like Gordon has said, you will have to do the toe in yourself most likely unless you have a specialty shop capable of and willing to do it for you. That you will have to check out in your area, impossible for us to know that info. The fact that you are running worn NDT tires will effect handling characteristics drastically. Most of our customers love the way their truck handles after a rebuild with power steering. In the eyes of the majority, it isn't the fact that it doesn't feel like mom's late model mini van steering. I've never had a customer yet that was not in love with it after they had driven just a few miles.

If you are the exception, then all I can say is you will have to play with it until you get it to meet your specs.

The wandering you spoke about will not correct itself, the most common cause for that is end play of the idler arm. The arm and bracket wears as a combination, replacing pin and bushing does nothing at all for end play. Only a slight amount will make it wander. Only way to fix it is disassemble, build up the worn area and machine back to a tight fit, so "0" end play is possible. We do it on every build, makes all the difference in the world with power steering.

[DrPepper]

Just a thought...

I believe the Saginaw steering box has a center spot where there is no play. If you have the box set to the center of the pitman swing and it is off of the center point it will be loose. The box has to be centered, then see what you can do with the steering wheel.

I am going to be getting into this with my 57 TWPW this year I hope. Like to see some pix of the project.

DrPepper

[Charles Talbert]

I believe the Saginaw steering box has a center spot where there is no play. If you have the box set to the center of the pitman swing and it is off of the center point it will be loose. The box has to be centered, then see what you can do with the steering wheel.

I am going to be getting into this with my 57 TWPW this year I hope. Like to see some pix of the project.

DrPepper

This is true, this is why we build our own box brackets custom to every truck; so we can adjust system geometry to where everything comes together at the correct timing.

[jmacqueen]

Yes the saginaw box meshes the gears tighter in the center of it's rotation than it does off center, basically for less wandering when pointed straight down the road. I do have the box centered, I centered the output shaft of the box and the steering the best I could when mating the two and fabbing the box bracket. I should probably check the box adjustment, it's a rebuilt box and should be adjusted properly but I guess there is no guarantee of that.

Charles, why couldn't you use a thin steel thrust washer to shim up the end play between the arm and the bracket? Would seem easier than welding/machining.

So I need to recheck the box adjustment, recheck that end play in the idler arm, recheck the drag links, make sure toe in is 1/8" at the outside circumference of the tires.. And get some new tires.. I checked toe in myself just to get it driveable, but I did it at the inside bead of the wheels, not out at the outside of the tires and I didn't build a rig to measure it that accurately.

[Gordon Maney]

Regarding the measurement of toe-in, do not measure off a rim flange or physical feature of any sort. The reason is that approach can include error from bent wheels, split rings, or tire manufacturing inaccuracies.

Always score a line in the tire tread while spinning the wheel. That defines your accurate line based on the axis of rotation. A wheel flange does not do that when the wheel is bent.

You can chalk the tire first, making it easy to see a score line.

[Charles Talbert]

Yes the saginaw box meshes the gears tighter in the center of it's rotation than it does off center, basically for less wandering when pointed straight down the road. I do have the box centered, I centered the output shaft of the box and the steering the best I could when mating the two and fabbing the box bracket. I should probably check the box adjustment, it's a rebuilt box and should be adjusted properly but I guess there is no guarantee of that.

Charles, why couldn't you use a thin steel thrust washer to shim up the end play between the arm and the bracket? Would seem easier than welding/machining.

So I need to recheck the box adjustment, recheck that end play in the idler arm, recheck the drag links, make sure toe in is 1/8" at the outside circumference of the tires.. And get some new tires.. I checked toe in myself just to get it driveable, but I did it at the inside bead of the wheels, not out at the outside of the tires and I didn't build a rig to measure it that accurately.

I have tried shimming to correct end play, no dice as it's impossible to get enough shim in there to correct the issue. The wear pattern is not flat, that makes it impossible to get it all out by shimming. Building up and machining works every time. You can get it right and it stays right if you take the time to do it.

I like measuring toe-in from center to center of the tires, best result that way. You will have to have good tires installed to get it just right however.

[jmacqueen]

I have tried shimming to correct end play, no dice as it's impossible to get enough shim in there to correct the issue. The wear pattern is not flat, that makes it impossible to get it all out by shimming. Building up and machining works every time. You can get it right and it stays right if you take the time to do it.

I like measuring toe-in from center to center of the tires, best result that way. You will have to have good tires installed to get it just right however.

Rgr that, I don't think there is much if any end play, but it's been long enough since I did the new pin and bushing I don't remember for sure.

Heck this could all be 100% old tires.

I have been putting off getting new tires until last basically trying to decide what tires to get. I don't mind NDT's but something with a little more street friendly tread would be nice, but I want the same or larger diameter as the NDT tires. It's going to be a job though, going to have to recondition the combat wheels inside as well when I do it.

I think I'll likely just wait and get new tires before going farther with the toe in adjustment, really can't trust these old ones much farther than I can throw them anyway, they are well past there use by date.

[DrPepper]

Marking the center of tread can be an aggrivation....

so jack up the axle and wrap the tire tread in 2" masking tape. Use a 2x4 (or whatever is wide enough) rigged across the tires and a couple of c-clamps to steady a good Sharpie marker to make the line. Lock the steering wheel or tie rod in place and have someone rotate the wheel. Mark the smooth surface of the masking tape. Now you can see and measure the toe. Not perfect but will easily give a good +/- 1/8" measure. Also will give a visual of the tire run out.

DrPepper

[jmacqueen]

Just to follow up, I did jack up the front, marked the tires and did the best I could for now on the toe in. It was toed out a decent amount.

Quite a bit of tire run out, especially on one side. I had to go two turns out on one tie rod to get the toe out gone, it drives a lot better now.

I also dropped the PS pump pressure down to about 800 psi according to the kit I bought. The steering has decent feel to it now, I like it. Might could even use one more shim in the relief valve on the pump.

I don't think I can do much better with the alignment until I get some new tires on it.

Now I have some kind of quite loud whistling/squeaking type sound from the front left when I get up to about 50mph I have to figure out. It's either wind or part of the running gear. It keeps making the sound if I push in the clutch and coast, and the lockout hubs up front are disengaged, I'll have to get someone else to drive so I can put my head out the passenger window and try to localize it.

[Matthew Ziegler]

hubs

I had a similar noise, turns out the new selectro hubs I bought have to be greased, they were shipped dry.

[jmacqueen]

I had a similar noise, turns out the new selectro hubs I bought have to be greased, they were shipped dry.

Hmm, That could be it. I have Selectro hubs as well though they look pretty old. They were on it when I bought the truck though. I had them off but didn't look at them, could be the passenger side hub. I'll try greasing them and see what happens. Or I guess I could just engage them and see if the noise stops first.