dropped axle, split bones install questions.

[37pickupproject]

I have a superbell 4 in drop axle, pete and jakes split wishbone kit, and a posies reversed eye front spring I plan on installing tonight. The split wishbone mount mounts in front of the original location using 2 of the original rivet holes for the trans mount as a guide for install. I have installed the mount, welded the threaded ends into wishbone and mounted the bones at the rear.

I have a few probably dumb questions about the rest of the install. How do I know what length to adjust the bones before installing the perch bolts into the axle? Do I just adjust the bones until the perch bolts line up with the axle?

How do I know if the front spring is aligned correctly before tightening the u bolts? It seems to have a lot of play front to back which would move the eye of the springs front to back.

Also what about alignment? Is the axle pre bent for camber and caster? Is there a front or back to the axle or can it be installed either way?

Hopefully I have explained myself enough for someone to understand. Thanks for your help.

[JSeery]

For starters think you are going about it backwards. I would mount the wishbones on the axle first, then the spring, then install the spring/axle onto the frame and then attach the tie rod ends at the back. You have to check the angle of the axle kingpins and adjust the castor after it is installed. The castor is adjusted by turning the tie rod ends in and out and re-installing them. You can not make much adjustment this way, so if it is off you will have to use some other methods to get the correct castor, but you won't know until it is all installed with the proper weight on the axle. The spring should have a square bolt head at the top that goes into the square opening in the crossmember. If the camber alignment is off the correction is to bend the axle, the caster can be adjusted if required and toe is set with the tie rod adjustments. There is not a front or back to the axle.

[Ralph Moore]

Camber is set, caster you can check with an angle gauge. I have a needle style, but digital is a bit more accurate. Best way to check is to have a tool, I had one made, that fits in the kingpin hole snugly and then has a flat on the kingpin centerline axis. Your angle Finder goes on the flat and you get an accurate measurement of caster. Of course the car must be at ride height to check this. I think I set mine at 6 1/2 degrees. You can also measure from a set point on the chassis, say trans mount holes, to king pin center on each side to ensure your axle is straight and in alignment with the rear axle.

[alchemy]

You cannot bend a Superbell axle. They are cast and it will break. The correct way to adjust caster is in the wishbones. If you need more caster you will have to make a slice in the wishbone right where the forged front yoke welds to the tube. Usually cut from the top down, but leave the bottom edge connected so it isn't flapping around. If you are lucky the thickness of your cutoff wheel will be enough for the caster to be adjusted where it needs to be. Bend the slice closed up tight and weld thoroughly. Now, what that degree needs to be set at is a whole nother story.

[JSeery]

Originally Posted by alchemy

You cannot bend a Superbell axle. They are cast and it will break. The correct way to adjust caster is in the wishbones. If you need more caster you will have to make a slice in the wishbone right where the forged front yoke welds to the tube. Usually cut from the top down, but leave the bottom edge connected so it isn't flapping around. If you are lucky the thickness of your cutoff wheel will be enough for the caster to be adjusted where it needs to be. Bend the slice closed up tight and weld thoroughly. Now, what that degree needs to be set at is a whole nother story.

Yep, I agree with alchemy on the pie splices. I was just going to wait to see what you ended up with before getting into that part of it. If it is a cast axle you will not be bending it, anyway not intentionally! And castor degrees are like oil, everyone has a different idea what is best. I would shoot for around 4° as a starting point and then we can debate what is idea.

[V8COOPMAN]

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AND........as you have now split the wishbone, the rear ends of the bones are moved outward, which moves the front, spring hanger portion of each bone closer together as it rotates about the perch pins. Not only does this effect spring length, but the shackle hanger eyes will not be situated at 90 degrees to the axle any more, and will each need to be bent back to a 90 degree reference so as to preclude shackle mis-alignment and possible binding. DD

[Krylon32]

The caster is set by the wishbone splitting kit mounting points. Adjusting the ends in and out will only move the axle back and forth and not affect the caster significantly. I have done many of these conversions using the P&J/Posie stuff and have not had to cut the bones for caster adjustment yet. I have done this in conjunction with a CE rear spring setup. I usually end of with 3-4 degrees of rake on the chassis using 235/15s on the rear and 165/15s on the front. This has resulted in 5-7 degrees caster which in conjunction with 1/8 toe in results in a good driving car.

[37pickupproject]

Thank you everyone for the replies. I have a better understanding of how this front end design works and how it's adjusted now. The only reason I installed the wishbones at the rear first was because I knew I had to heat and bend the eye of the wishbone. I just wanted to know everything was in correctly before bending the eyes to match up with the spring eyes.

The posies spring I have does not have a square bolt on top to meet up with square in the crossmember. It is round and has some play within the crossmember.

[V8COOPMAN]

Originally Posted by 37pickupproject

It is round and has some play within the crossmember.

Close enough! DD

[37pickupproject]

I will have to find a point to measure to the spring eyes on each side then just tighten it down I suppose. After that it should be close enough to heat and bend the bones. Then install the spring and onto the spindles !

[37 truck]

I think that the wheel base measurement is what you are after here. 112" with the same measurement on each side. Both axles being square relative to the frame.

[Andy]

You should bend the tube part of the wishbone and not just turn the spring mount. You will shorten the spring distance by just bending the ends.

[alchemy]

Andy, he'd probably only shorten the eye-to-eye distance by 1/8 inch or so. Not enough to worry about there.

[JSeery]

The type of split wishbone setup being used moves the position of the wishbones a very small amount from there original position. It is a bracket that bolts to the center X-member. If you were moving them to the outside of the frame rails it would be a totally different geometry. Something similar to this. If you consider the width of the original wishbone ball forging piece, the radius rods are moved very little.

[flathead47]

37 , you stated a superbell dropped axle , but did not say tube or I beam. If it is a tube they recommend a 4 bar setup as the split wishbones on a tube can cause the tube axle to twist & put stress on the weld. The I beam axle can handle the twisting action during suspension travel.

[Ralph Moore]

I moved mine out to the frame rails, and as JSeery says, it creates a whole lot of other issues like tire clearance, turning radius, etc.
if I ever tear it back down I'll probably move them back in.