Real time CASTER HELP >>>> Fj60 (1 Viewer)

[In2cruisers]

Hello mudders..
Ran into a new 60 owner at Home Depot the other day.... he had just purchased it and the PO had just done some suspension work New OME front and back.. and looks like 1 inch longer front shackles to level?? he asked me to drive it.. and it drives like your on ice skates..... had him come by the house the next day to measure caster and its 0 ... he asked if I could help him.. hes a beginner wrencher... I told him to buy some shims and we"ll play this weekend.....
Now....... its been sometime since I have done this.... some rigs seem to need this... some not so much..... So to avoid looking like to much of a old dumb ass.. from 0 Ill want to rotate the axle clockwise from the drivers side hub..... correct ?? which would put the fat end of the shim forward ??? Like I said.......................................been a while......now Im second guessing myself..... HELP ????

 

[cruisermatt]

That is correct! I like to use the forks on a chopper motorcycle vs a mountain bike as a example... Think about which one is better at high-speed tracking. The fork angle is the caster on a motorcycle, just like the upper and lower trunnion/knuckle bearings on your axle.
We usually install 4-degree shims on almost every truck here, in fact we were installing so many we ended up manufactuing our own brand of shims.

CruiserMatt's 4-Degree Caster Shim Set for Land Cruisers

Installing a lift kit on your leaf-spring Land Cruiser? Then you need these to correct your caster angle after! Most universal shims on the market are made for Jeeps and don't fit properly, or are aluminum and can split under heavy use! Ours are made of steel, right here in the USA. NOTE...

cruisermatts.com

 

[gnob]

to add caster, you're putting the thick end to the rear.

 

[Devils Paw 80]

Yeah, to add caster I thought it was thick part to the rear.

 

[cruisermatt]

to add caster, you're putting the thick end to the rear.

Yeah, to add caster I thought it was thick part to the rear.

It would be dependent on Spring-under vs Spring-over configuration, but on a Spring-under axle (which is most likely what the OP is referencing) that would be decreasing the caster angle, not increasing it.

 

[In2cruisers]

Yeah, to add caster I thought it was thick part to the rear.

Ya.... thats what I ment..... see I can even confuse myself.....

 

[Hokie LX]

Thick part towards the front to add caster on a SUA axle like Matt said.

 

[crikeymike]

Maybe it's over-lifted in the front? Could pull the longer shackles and put on regular ones to lower it down and regain some caster without extra work. Also, if he has heavier springs than needed, those would be adding extra lift as well. Could possibly pull a leaf from them as well.

 

[DrRock]

Just to add a data point here regarding handling. I recently installed caster shims on my 60 and what a difference. My truck has OME springs and Dobinsom MRR dampers and the caster shims made it track much better. Don’t skimp on these items and get the steel ones from @cruisermatt

 

[too tall]

It would be dependent on Spring-under vs Spring-over configuration, but on a Spring-under axle (which is most likely what the OP is referencing) that would be decreasing the caster angle, not increasing it.

Postive caster is lower king pin or trunion forward of the upper king pin or trunion. Regardless of spring over or spring under, to increase caster the fat part of the wedge goes to the rear of the vehicle. I'm not sure why you think would change that based on the spring configuration.

 

[cruisermatt]

Postive caster is lower king pin or trunion forward of the upper king pin or trunion. Regardless of spring over or spring under, to increase caster the fat part of the wedge goes to the rear of the vehicle. I'm not sure why you think would change that based on the spring configuration.

Here is a simple diagram showing why the direction would be opposite to accomplish the same thing based on based on spring under vs spring over. So, you are correct for a spring-over. Not for a spring-under which is how the vast majority of Land cruisers are

In this diagram, the caster of the axle is being reduced in both configurations. (the opposite of what is needed when installing a lift kit on a Land Cruiser)

 

[In2cruisers]

ok..... the wrenching didnt happen this weekend..... but re-slated for Wednesday.....After reading the postings...

The 60 is spring under.... OME heavy s...front and rear .1" longer front shackles...... he purchased 5 degree shims.... and I have a couple big head spring bolts..so we are ready for Wednesday the owner is very excited about his purchase....but can tell hes not a hands on type of guy....yet

Soooo for myself and for the record.... Shims = Big end rear

Thanks Cruisers

 

[cruisermatt]

Soooo for myself and for the record.... Shims = Big end rear

No. Incorrect. Think about which direction you want the axle to rotate.

 

[BurntToast]

Fat end goes forward

 

[In2cruisers]

Ahhhhhh......... this is hurting my brain

Thanks guys

 

[AussieHJCruza]

Postive caster is lower king pin or trunion forward of the upper king pin or trunion. Regardless of spring over or spring under, to increase caster the fat part of the wedge goes to the rear of the vehicle. I'm not sure why you think would change that based on the spring configuration.

Think about what you're saying...lower trunion forward of upper trunion.

So to do this, you want to rotate the top of the axle to the rear of the truck.

To do this, thick part of the caster wedge must go at the front.

 

[too tall]

Ok vice versa but spring over vs spring under makes no difference. Pardon my mix up. I don't ever use those shims you guys talk about. I cut the welds off the balls and rotate them to the correct caster number.

 

[DrRock]

Ok vice versa but spring over vs spring under makes no difference. Pardon my mix up. I don't ever use those shims you guys talk about. I cut the welds off the balls and rotate them to the correct caster number.

Then to be crystal clear here:
1. If one is using shims to increase caster, then orientation of shims change ( thick end facing front or rear of vehicle) based on spring under or spring over configuration. This is straightforward geometry solution based on datum structure. See Matt’s illustration for clarification.
2. Question: What balls are you referring to? If it’s the end of the axle, this seems like an over complicated way of solving a simple problem but maybe I’m missing something here.

Cheers, James

 

[Mark W]

You have an SUA configuration on the rig you are working on. You want more caster. Fat end forward. No question, no debate. Fat end forward to roll the axle (and the "king pin" angle) backwards.

Fat end forward.
Fat end forward.
Fat end forward.

That is to say...
Fat end forward.




Mark...

 

[Augustiron]

As stated, shims go fat and forward for a spring under axle.

Also, you can do this without removing the spring pack from the vehicle to save yourself a lot of time.

Remove ubolts on one side of the vehicle,
jack up the axle on that side so it's not sitting on the springs.
Put clamps on the spring pack to the front and to the rear of the axle location to hold all the leaf springs in place.
Remove the spring pin,
install the shim (fat forward!) .
Reverse to reassemble.

Make sure the center pin lines up in the spring perch. Sometimes you need a strap to pull The axle forward or back, or a crowbar to help line it up.