Shimming for Caster Correction

[srgould41]

The PO on my '71 FJ40 had a mild shackle lift installed. The shop sold him some 4 degree shims to correct the caster, but he elected not to pay them to install the shims. I decided to install the shims to help with the wandering on the highway. The shim completely captures the spring pack pin so that the axle's spring perch doesn't engage the pin at all.

How have others resolved this situation? I did a bit of searching, but didn't see this issue addressed. I was thinking of welding the shim to the axle perch, but not sure if that is wise.

Thanks for your advice.

Steve

 

[John Smith]

I would buy longer center pins or use grade 8 bolts before I would weld them to the spring perch.

 

[dgangle]

Couple ideas for you.

1. Use a 3/8" bolt, double-nutted. The nuts won't fit into the hole on the underside of the spring perch so you will need to round the heads of the two nuts with a file or angle grinder and/or drill the hole in the spring perch larger.

2. I think MAF sells spring centering bolts with a taller head if you prefer to buy something instead.

3. Buy different shims that don't recess the head of the spring centering bolt. Available at your local well-stocked spring company.

4. If your shims are steel, you could possibly weld up the hole and re-drill to the diameter of the shank of the spring centering bolt.

5. Again, if your shims are steel, weld them to the spring perch then this is not an issue.

 

[mixerman]

I just put 6 degree shims in my 40 and had the same problem . Ran a nut to the the head and ground it round to match the center bolt head .worked great.

 

[srgould41]

Last night I did as you guys were talking about. I had some bolts in my stock that I ran from the bottom up and double nutted with self-locking nuts. Perfect height and just fit the hole in the axle perch.

 

[dgangle]

Glad this worked for you. It's a real home-grown how-to.

Inexpensive, quick, easy and does the trick....