Power steering pump and alignment issues

[david85]

Got back from a longer trip and the truck did "OK", but still had a dead zone pointing strait ahead sometimes (road vibrations helped reduce the effect). I'm wondering if it could be the ball joints of the tie rods wearing in such a way that they snag in the strait ahead position.

3.1 degrees of caster seems to be slightly on the low side, but should still be enough for return to center, right?

 

[hahn_rossman]

3.1 is definitely in the zone. Did you measure both sides? I like your technique for trying to determine caster angles! What I have usually seen is using levels to measure camber, and I think the 20 degree turn angle is just to have a standard for the machines. I'm sure that further is better, as its easier to measure larger differences. Have you been able to tell what offset bushings are already in the upper balljoints?

 

[david85]

It has kingpins so there are no upper or lower ball joints and no they are not offset. From what I can tell, the radius arm bushings are not offset either.

No I didn't check the other side. I wanted to get some feedback to make sure I was on the right track with my method. Yes, going close to 40 degrees of steering swing was in the hope of getting as large measurements as possible to absorb as much of the measuring error as possible.

3.1 seems to be in the range, but 4 is supposed to be ideal with max being 6!. Considering the truck seems to track better with weight in it, I'm thinking increasing the caster all the way to 4 degrees might help. Right now it will try to return all the way to center, but can't quite pull it off making lane tracking tiresome at times. The tires have to be shaking just right for it to come all the way back to center.

 

[Hybrid455]

It seems I'm surrounded by overqualified people.
Yes, I understand that swapping parts out can be dangerous when you are dealing with 6000lbs of steel rolling along at 70 MPH.

Ok guys, tell me what you think of my method here (all happening on a smooth shop floor).

I installed a large camera tripod on the rim of the truck by strapping it to the rim.

Then I jacked that wheel up, and calibrated the center of the tripod by rolling the tire by hand and making adjustments against a steel square against the foor of the shop. I got the wobble down to about 1/16". I hope that was enough to get a good enough center.

Now that the tripod was calibrated, I lowered the wheel off the jack and rolled the truck back about 4 feet then forward again, to make sure the weight of the truck was settled well.

First measurement was taken with the steering wheel turned 2 turns to the right (from center). Marked the location of the tripod point on the floor, and measured the height off the floor(13 - 11/16").

Second measurement taken with the wheel turned 2 turns to the left (from center). Marked the location of the tripod and measured the height off the floor(15 - 9/16"). At this point I can measure the distance between 1 and 2 (34 - 7/8").

Third measurement to the floor taken with the wheels pointed strait ahead.

Fourth measurement taken after rolling the truck back and fourth ~4 feet to verify that the suspension is in the neutral position. difference between 3 and 4 was within the error of the tripod capibration (less than 1/16").

I plotted all the points in AutoCAD and dimentioned the slope................

3.0775 degrees.

So what to you think? is this method good enough to consider the result accurate? Or should I retest with only the 20 degrees of steering movement from the strait ahead position?

I'm impressed! Genius at work! Most of the new machines only use a 10 degree turn. The older stuff used 20 degrees. I'm of the opnion that you are well within the ball park of accuracy. If it was me I'd crank it up to 4.5 on the right side and 4.0 on the left. I think the offset bushings advertise 2 degrees so you should be able to get that. Drive it and see what you have!

 

[david85]

I ordered the offset bushings and got one side installed today. Hope to do the otherside tomorrow before a long highway drive. After this, its over, theres nothing left I can to with it.

I'll let you guys know how it turns out.

 

[itn]

any update?

 

[david85]

It did make a slight improvement and it might just be good enough now. Pulls a little to one side thanks to some other issues, but the truck responds well to imput at higher speeds now and is quite easy to handle in the critical 65-75 speed range.

I also have to recheck the alignment of the front end but haven't had the time yet.

The kit claims that total adjustment range is only 1 degree, so based on that, I only added another 0.5 degrees to get it to a theoretical 3.577 instead of 3.077. Its still not quite 4 degrees but I'll use it as is for a while and see what happens after I fix the rear springs and tire balance issue. The old bushings were also getting a little raggy.

The rag joint on the steering shaft has also seen better days and I might consider upgrading it some day to an all metal shaft that some guys here mention. There is still some slop in the steering that I would rather not have.

Only other way I can think of to get more caster angle is to bend the radius arms or lower the radius arm brackets. Not in the cards...

 

[starmilt]

David I have run into several two wheel drive F250s of this era that the crossmember rivets let it move just a hair causing symptoms like yours. The 70s models were welded but the 80's are riveted for what reason I don't know, just something to check.

 

[f-two-fiddy]

I'm still of the opinion that a new Red Head Steering Box is what You need.

 

[david85]

UPDATE!!!!!!!!!!!!!!!!!!!!!!

The truck now tracks as good as my rack & pinion steer saturn!

So far I think I can track down the problem to two factors:

1) I may have used an incorrect grease that was intended for HD commercial application (thick chunky and and not very greasy) but its hard to say due to....

2) I found play in one of the knuckles. Not a lot but enough to notice, at first I thought maybe it was the bushings being honed too slack. It turns out the lock pins that are supplied with the king pin kit I bought were made of a really soft steel compared to the OEM wedges. This allowed the kingpin to eat into the locking pin and that in turn allowed the kingpin to rock a little inside the I beam bore. Trying to tighten the nut on this wedge made no difference and I could feel it starting to stretch the stud.

Since I still had an original lock wedge lying around, I removed the aftermarket one and replaced it with the old one. I gradually tightened it and this removed the play completely on that knuckle. Interesting....................

This already had a slight improvement in the lightness of the steering but later I switched to a different grease and over the next 3 servicings, the return to center steadily improved.

Now its so light I can drive the truck anywhere from 50-80 MPH with one fingertip on the steering wheel. The steering wheel itself is strait ahead like an arrow. I've also tightened up the steering box and the slop has been reduced even more. On the freeway there is an ever so slight pull to the left but that is usually negated by the road camber.

I'm also now running some LSD compatible 80/90 gear oil in the powersteering but I don't know that is making much difference.

Best I can figure is with the king pin on a slight angle, caused it to pinch the thrust bearing that carries the weight in the knuckle, thus producing that extra friction I was feeling in the steering. Now that the king pin is at a correct 90 degree relation to the load bushing, the bushing had a chance to wear in properly with load spread around its surface instead of focussed at one side like was happening before.

At least, thats my theory....In case anyone else is still fighing with this same problem, it seems the king pins and bushings are of good quality, but in my case the locking wedges were not and likely caused much of my grief.

In any case, I couldn't be happier with how the truck handles now and I am still feeling improvements as of this week. I'm even thinking to start experimenting with different types of grease to see if that could be playing a role. If anyone has some suggestions on that I would be glad to hear them - lubricants are not something I have a lot of backround in. One type of bio-grease I saw in the isle the other day claimed to have superior corrosion resistance and better lubrication than dino grease (intended for boat trailer bearings, so I figured it could be good to prevent rust on the pins - haven't tried it though).

 

[towcat]

I'm coming into this thread a little late, but has anybody suggested checking the intermediate shaft between the steering column and the steering box? also, the rubber coupler biscuit at the end of the steering box should be looked at too.

 

[david85]

Its possible and I heard of a better all steel steering shaft that some guys here swear by. From what I can tell though, the problem was always one of too much friction in the steering linkage and I think I've been able to kill a good 90% of it. I might like to get that improved steering shaft eventually though.