caster specs (1 Viewer)

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Apr 19, 2019
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Vancouver wa
New guy here. I have a 90 4 runner that has had a SAS using Land Cruiser running gear. I am not sure of the year of donor axles but the front axle was coil sprung and square tube and the rear diff offset not centered. Trying to determine the Caster specs that the front axle should be set at. Using a magnetic bubble level tool set on 0 degree when wheels are straight I am getting a reading of just over 1 1/4 degree when wheels are turned to the 20 degree position, basically full turn to steer stop. I am wonder if I need more tilt. the pinion flange is measuring at 85.2 degrees with an electronic degree tool. Any input would be appreciated.

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I'm guessing that axle was off an 80 series. In which case spec for caster is 3 degrees +- 1 degree.
 
at 0 degrees caster your going to get a lot of wandering du to lack of caster, depending on what year the axle came out of caster spec is 1.4 +-1 or as mentioned above 3+-1. safe bet is just shoot for 3 and make whatever you come out with work
 
Spec for an 80 series is 2-4 degrees, but I would definitely aim for 4 in your shoes. The more caster the better the road manners... to a point.

Pics of this beast!
 
About the only way to adjust the caster is a cut and turn or off set knuckle bearings. Sounds like they welded the spring purchase on wrong. Or you could change them.
 
If it's leaf sprung how about caster wedges?
 
If it's leaf sprung how about caster wedges?
personally I would never run wedges in the front. I'm thinking those wedges are for driveshaft angle in the rear only
 
could look at the delta vs radius arms, their longer than stock to correct caster. or go with castor correction plates as another option
 
read the whole post he's on leaf springs
 
personally I would never run wedges in the front. I'm thinking those wedges are for driveshaft angle in the rear only
I had no problem with them in a HJ47, 4" SUA. As long as the centre bolt of the spring is long enough I think it would be fine
 
The steering puts too much force on the front spring mount. I'm sure it was fine but no reputable shop will do it. Blocks & wedges have no place on a front axle JMHO
 
I ran caster wedges in my fj60 in the front with no I'll effectss, fwiw
 
I put wedges in semi's front suspension all the time. That's the only way to adjust the steering. Other than having the axle bent but not many places are willing to do that anymore.
 
The steering puts too much force on the front spring mount. I'm sure it was fine but no reputable shop will do it. Blocks & wedges have no place on a front axle JMHO


Totally agree.

Cut & turn it if you want it right.

Cheers
 
Ok great to hear your ideas. Does anyone have a 80 series that is stock that could get a reading either on the pinion flange or even on top of the axle in the center? Either of those measurements would be helpful in determining where I am caster wise compared to a stock rig. I understand all the arguments of cut and turn being the right right way to do a lift. I am just concerned at the present time to determine where my caster is. The tool I was using is actually a camber gauge and is different than the caster/camber gauges I have seen on YouTube. I have a digital degree tool so if I had the info off of an in altered rig I could see where i sit. Cutting the spring pads off and redoing them is a consideration but I would still need to know where I am . This axle is not spring mount friendly since it is square and not even the same size square on the drivers side. Thanks!!!
 
Yes you will have to customize the perches.

Go to the Home Depot. Buy a scribing tool. It will aid you greatly on the custom perches.

Honestly it does not matter what you are at compared to a stock 80. Coil spring vs leaf sprung doesn’t even matter. Your application is custom.

Put your truck on a surface you know is level. Load it up with whatever you carry when you use the truck. You really shouldn’t do this yet if you plan to add front bumper, winch and more weight later. You need it how it will be end game weight wise to do this right and do it once. It also needs to be at ride height on the jack stands when you do this.

While you are at Hone Depot buy a 3ft digital level too.

Put your truck up on jack stands, make sure it stays level. Take off front wheels. Make sure steering is pointed forward and is straight. Pull your front driveline. Put your angle finder on the tcase front output flange. Take a reading and write it down. Make sure your reading is at a 90* angle.

Get yourself a couple 20” long straight edges. Put your 3ft level on top of the knuckle. It is actually best to do this without the cap bolts in, I do it with a bare housing and take my ready from the center of the trunnion bearing cup on the knuckle ball. Use the straight edges, clamp them to the frame rail or whatever and use a tape measure to make sure the level is parallel with the frame rail. Take your reading and write it down. Do it for both sides.

Now what you got to do is cut your perches off your housing and start fabbing your new ones. I usually buy the Ruff Stuff FJ60 SoA Kit for this and modify it to suit the build I am doing. Set your pinion the same as it is on the tcase. Tack weld the perches, or don’t I usually don’t but that is a safety thing and your call. Bolt up your leaves. Put weight on it. Your pinion has changed, take note of adjustments needed. Tear it down and make adjustments to perches to get the pinion where you want it. Once happy with the pinion you can burn on your perches. You must have weight on it for your pinion before you burn on the perches.

Now cut the knuckle ball with a thin cut off wheel on a 4” grinder. Cut behind the factory weld but right next to it. Only cut as deep as the axle tube, do not cut deeper! Put a little mark with your grinder wheel on the tube and knuckle ball so you know where it was before you moved it. Put a big pipe in it through the trunnion bearing holes. I use soft metal for this, a big chunk of aluminum solid stock is ideal. Beat that pipe or rod with a small sledge to rotate the knuckle ball. You want to set it at 3.5-4.5*. More caster for bigger tires. I always give it a bit more on the RHS for the crown in the road, like .3-.5*.

Once you are happy open up your cut with a grinding disc making it a fuller all the way around. Burn out any oil in your area to be welded with a torch. Burn it in and make sure it is the best weld possible.

That’s it. You do that and it will drive absolutely amazing. You will have zero pinion issues as well and no need for a DC shaft. 80mph down the hwy with one finger on the wheel and it will track perfectly straight and true.

*Disclaimer: you are 100% on your own here, liability is all on you, I am only offering advice.

:)

Cheers
 
Last edited:
Leaf springs make it easy, try different caster shims until you find the happy spot, where it drives how you like. Then get some steel shims and weld them to the perch. Have done this a bunch of times with zero issue. As long as it is done correctly, pin hole size is right etc, don't see how a welded shim is different than a welded perch, if you cant weld one, likely shouldn't be welding either?
 
Yes you will have to customize the perches.

Go to the Home Depot. Buy a scribing tool. It will aid you greatly on the custom perches.

Honestly it does not matter what you are at compared to a stock 80. Coil spring vs leaf sprung doesn’t even matter. Your application is custom.

Put your truck on a surface you know is level. Load it up with whatever you carry when you use the truck. You really shouldn’t do this yet if you plan to add front bumper, winch and more weight later. You need it how it will be end game weight wise to do this right and do it once. It also needs to be at ride height on the jack stands when you do this.

While you are at Hone Depot buy a 3ft digital level too.

Put your truck up on jack stands, make sure it stays level. Take off front wheels. Make sure steering is pointed forward and is straight. Pull your front driveline. Put your angle finder on the tcase front output flange. Take a reading and write it down. Make sure your reading is at a 90* angle.

Get yourself a couple 20” long straight edges. Put your 3ft level on top of the knuckle. It is actually best to do this without the cap bolts in, I do it with a bare housing and take my ready from the center of the trunnion bearing cup on the knuckle ball. Use the straight edges, clamp them to the frame rail or whatever and use a tape measure to make sure the level is parallel with the frame rail. Take your reading and write it down. Do it for both sides.

Now what you got to do is cut your perches off your housing and start fabbing your new ones. I usually buy the Ruff Stuff FJ60 SoA Kit for this and modify it to suit the build I am doing. Set your pinion the same as it is on the tcase. Tack weld the perches, or don’t I usually don’t but that is a safety thing and your call. Bolt up your leaves. Put weight on it. Your pinion has changed, take note of adjustments needed. Tear it down and make adjustments to perches to get the pinion where you want it. Once happy with the pinion you can burn on your perches. You must have weight on it for your pinion before you burn on the perches.

Now cut the knuckle ball with a thin cut off wheel on a 4” grinder. Cut behind the factory weld but right next to it. Only cut as deep as the axle tube, do not cut deeper! Put a little mark with your grinder wheel on the tube and knuckle ball so you know where it was before you moved it. Put a big pipe in it through the trunnion bearing holes. I use soft metal for this, a big chunk of aluminum solid stock is ideal. Beat that pipe or rod with a small sledge to rotate the knuckle ball. You want to set it at 3.5-4.5*. More caster for bigger tires. I always give it a bit more on the RHS for the crown in the road, like .3-.5*.

Once you are happy open up your cut with a grinding disc making it a fuller all the way around. Burn out any oil in your area to be welded with a torch. Burn it in and make sure it is the best weld possible.

That’s it. You do that and it will drive absolutely amazing. You will have zero pinion issues as well and no need for a DC shaft. 80mph down the hwy with one finger on the wheel and it will track perfectly straight and true.

*Disclaimer: you are 100% on your own here, liability is all on you, I am only offering advice.

:)

Cheers
This is the best way to fix this.
 

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