brainfade

Anybody have the factory specs for alignment on a '91.5 W250? I'm interested mostly in castor, toe and thrust angle. The computer on the machine at work only goes back to '94. Thanks.

wannadiesel

Camber: 0, -1 to +1 OK
Caster: +2, +1/2 to 3 1/2 OK
King pin inclination: 8.5 degrees
Toe in @ hub height: 0.20 deg., -0.05 to +0.45 OK

ChrisLib

At least your truck fits on the rack, we have an "import" sized lift for our alignment rack and unfortunately my truck is about 24 inches too long...GRRRR! Does yours pull to the right?

Boatnik

No, mine doesn't pull just to the right. It kinda pulls right or left when ever it gets a mind of it's own. Today it did a slow speed death wobble of sorts. I got it home while it was still misbehaven and jacked the front off the ground. It is most probably the power steering pump but I do not understand the mechanism.

brainfade

Thanks, Oh mighty Wanna. I was starting to feel like the last kid picked for dodgeball.

ChrisLib, I'm really lucky that the place I work has about one of everything. We're also open 24/7, so if what I want to use isn't broken or missing parts I can usually do just about anything. I don't have a pull, more just a wander. I've been messing with the springs, trying to get a reasonable ride quality without sacrificing payload, and after a bunch of experiments, I'm getting close. Custom springs, fabricated wedge blocks, Timbrens. I've got the ride pretty good, just have to get the driveline angles correct and then make it go straight. Since everything in the front end is tight, I'm guessing the wander is due to incorrect caster, or possibly thrust angle as there is a on/off throttle direction change. But after searching the forum for specs with no result (thanks again Wanna) and seeing a lot of talk about broken steering mounts, I'll be looking into that as well.

Boatnik, if I figure out where my wander comes from I'll post it up.

TLRMAN

That could also be a warn out pinion arm or tye rod end. Check them out.. Do you have any slop in the steering wheel?

Alec

What are you using the wedge blocks for -- it seems to me that you haven't adjusted your caster yet, and they would just mess up the pinion angle in the rear . . . Just curious.

On a related topic, when I got my truck, both front tires were worn out on the passenger's side edge -- that is both tires were cone shaped, left worn on inside, right worn on outside. So bad that it made the truck pull to the right. Rotating the tires improved the pulling, but didn't quite get rid of it. I rebuilt the king-pins, put on new tie rod ends, etc., still better on the pulling, but not gone. Now it looks as though my driver's side front tire is wearing on the inside again, and I think the pull is getting a little worse. What do you think the culprit is? Or maybe just accept the truck doesn't have enough cross-camber, and rotate the tires more?

Thnaks,

Alec

brainfade

Hey Alec,
The wedges serve two purposes - brings the pinion angle down on the rear axle (for some reason the new springs left me with the pinion about 8 degrees up) and gives the Timbrens a place to land. I made the wedges out of the old 3 inch blocks that I took out when the new springs went in. Machined about 2 in. off the total hight and added the angle correction. The 'shelf' that extends out from under the spring towards the inside is square and flat, hence the 'landing pad'. That fixed the rears, but I'm still fooling with the front.

On your wear issue, the only thing I can think of is if your thrust angle is way, way off, causing the front tires to be turned to the left even going straight down the road. If that was the case, it might cause the fronts to scrub all the time. I'd think it would have to be far enough off to make the truck dog track. Maybe have someone drive the truck and follow behind? If you take it a shop, be sure they do a four wheel alignment. That's the only way to get a thrust angle as far as I know.

Alec

Thanks brainfade -- I guess I need to try measuring the thrust angle again, and maybe even break down and pay somebody to measure it on their rack.

I guess they expected you to put a CV joint on the front of the rear drive shaft . Sounds like your modified blocks take care of the problem, though.