Chasing Caster

[hunter1]

$736.81 to be exact. I just had mine done at Mitchell Differential in Mass. I pulled the dana 44 and brought it to them basically bare with the exception of the gear set. They pulled the gears replaced the inner seals and the pinion seal and did the cut and turn. I went and picked it up and brought it home. I think James is spot on with his estimate of $3k to drive it in and drive it out.

Did you have your caster angle determined and a new location to turn to marked on your tubes before having them do the work? While you still had the axle installed and at ride height? Just curious.

 

[Otis Campbell]

Are you looking for a auto repair shop to do it, or a fabrication shop to do it? Looks like you've got a lot of big fab shops in your area. I'd think that you're going to need a smaller shop to take on that project.

Fab/machine shop.

 

[ntsqd]

Ask the big places that turn you down if they have any suggestions for who might be able & willing to do the job. They're going to know who those shops are because some of them likely sub-let parts of their bigger jobs to smaller shops.

 

[TheLimeRanger]

Did you have your caster angle determined and a new location to turn to marked on your tubes before having them do the work? While you still had the axle installed and at ride height? Just curious.

i knew what it was before i pulled it with the lift i had on it and the bushings i put in it. With James's guidance in spite of my own stupidity, we got it sorted out.

 

[Otis Campbell]

So, I pulled the 44 - - doing the cut and turn. I've got a buddy who is a M.E. and a certified welder who is going to do the final welds after I tack the knuckles where they need to be. In the picture, I've got the pinion pointing 2 degrees below the driveshaft angle and am showing 6 degrees of negative caster. Am I correct that using 0 degree C bushings (or the equivalent by flipping fronts over) I will need to turn 12 degrees in order to net 6 positive? Seems like a lot compared to the 5-9 I see folks say is "normal."

 

[Broncobowsher]

The only thing that may have been overlooked, and i did it when fixing rear pinion angle, as you angle the pinion up the driveshaft angle also goes up. The angle at the CV is less.

Made up numbers, but for the mental example. If you roll the axle 5°, the driveshaft is now higher and 2° less, and you now have 7° of pinion change.

 

[Otis Campbell]

The only thing that may have been overlooked, and i did it when fixing rear pinion angle, as you angle the pinion up the driveshaft angle also goes up. The angle at the CV is less.

Made up numbers, but for the mental example. If you roll the axle 5°, the driveshaft is now higher and 2° less, and you now have 7° of pinion change.

This makes sense. Thanks. I'm thinking I should reinstall the diff with the C bushings flipped/zeroed out, and remeasure the driveshaft angle? Then do calculations based on that new angle?

 

[ntsqd]

I'd think it easier to do whatever it takes with C bushings to get the drive-shaft optimized at normal ride height first. Measure the angle on the diff cover gasket surface and reproduce it out of the truck. Then cut the C's loose and set the Caster.
Not having done it myself, that's just my thought on how I'd approach the project.

 

[widowmaker77]

So when I did mine, I may have done a little too much but I took a spare 44 housing and cut all the wedges and the inner c’s off. Then I put the axle on jack stands under the bronco and hooked the driveshaft up and adjusted it close to where I felt like it would need to be. Then I put 2* bushings and the axle wedges in the radius arms and loosely bolted them up. I had taken ride height measure before I tore it apart. So I lifted the front of the bronco to the measurements I took then rotated the axle housing to get the driveshaft /pinion angle right and then torqued the radius arm down. I Put the springs back in and let the weight of the bronco sit on the axle. My jack stand were adjusted so the axle to ground clearance was the same as my 35’s give me and I made sure my rear axle ground the axle measurements were matching my front . So after everything was at ride height and the full weight of the bronco was on the axle then I set the angle of the inner c’s double then triple checked everything was the same and tacked all four of my wedges and both inner c’s. Pulled everything back out and welded it up solid. Cutting the wedges off was probably overkill but it’s what I did.

The axle I had been running under the bronco had 7• c bushings with stock radius arms and with 3.5” of lift I had positive 1.5* castor.

 

[jamesroney]

This makes sense. Thanks. I'm thinking I should reinstall the diff with the C bushings flipped/zeroed out, and remeasure the driveshaft angle? Then do calculations based on that new angle?

OK. Go back and read post #8. I gave you those details because they are important.
1. Yes, go reinstall the diff with the c-bushings that you are going to run.
2. SET the GAP between frame and axle on BOTH front and rear. This is not optional. It is not a recommendation. It is a requirement. So do it.
3. Ignore any advice that says to put 2 degrees between the driveshaft and front pinion. That is only for rear leaf spring applications. 1 degree is plenty, and if it HAD to be done, it should be 1 degree UP in the front. (front pinions pull down under forward load)
4. @Broncobowsher is spot on. Your target "driveshaft angle" is not the correct or desired number. It will absolutely move when you roll the pinion.
4a. This about the time you learn that all Bronco Dana 44's are exactly the same. (at 0 degree wedge, you get 8 degrees pinion, and 4 degrees caster. Every one, Every time.) I used to believe that they are all different. Then I started measuring...

5. once you figure out what the total angle is supposed to be, send me a PM and remind me to give you two more tricks that make it easier.

 

[jamesroney]

I'd think it easier to do whatever it takes with C bushings to get the drive-shaft optimized at normal ride height first. Measure the angle on the diff cover gasket surface and reproduce it out of the truck. Then cut the C's loose and set the Caster.
Not having done it myself, that's just my thought on how I'd approach the project.

This is going to be a little geeky. Don't read this if you are not tech saavy. (I'm using engineering language, and not mechanic language...)

You wouldn't actually do it this way. It is mostly correct conceptually...but you don't do it that way.

Because the OP has stated that he is not intending to move the wedges. If you do not have that degree of freedom...the driveshaft to pinion angle is constrained. If you are fully unconstrained...you can calculate (or empirically derive) the optimized pinion angle, then set the caster, then locate the wedges. BUT the wedges are not allowed to be a variable in the calculation. The wedge to pinion angle is fixed. So regardless of theoretical optimized pinion angle, you don't want to set the caster to an angle that your wedges don't correspond to.

Cutting off the wedges is a lot of work for zero benefit. Especially at 2.5 inches of lift. I postulate that if you liberate the wedges, establish the optimal pinion angle, and install the wedges with 0 degree bushings...they would go back to within a degree of where you cut them off. So don't. In practice, I establish the ride height. Then I "select" the C bushings that get me closest to desired pinion angle. Once I establish the "best fit" pinion angle...I use that to create caster. ( 2 degrees is trivial at the pinion...but critical at the knuckle.)

If you are narrowing a full width, then the wedges are already divorced from the tubes. In that scenario, you have full control of the wedge to pinion relationship. So you are not constrained to the 0, 2, 4, 7 degree C bushing increments... as @widowmaker77 confirmed. But what he didn't mention is exactly how much he moved his wedges.

I hope that make sense...
James.

 

[ntsqd]

I worded it poorly. With no intent to move the wedges what I posted is exactly how I'd do it. Find the set of C-Bushings that optimized the drive-shaft alignment and then measure the angle of the gasket surface while at ride height.

Then duplicate that angle out of the truck where it's easier to work on moving the C's to the desired Caster setting.

 

[Otis Campbell]

I'm happy to report that after performing the cut and turn the test drive was an overwhelming success. Tracks straight. Got it up to 70 mph on the test drive and had been afraid after 45 previously. Thanks to all for the help, advise and encouragement!

 

[DirtDonk]

Great to hear! So chase was worth the catch.

 

[DirtDonk]

And vice versa!