caster angle

[mikemrq]

84 CJ7, 360 auto. Installed Rough Country 4" Suspension lift with a 1" lift shackle. After the install I took it for a ride and noticed that the steering was very light and wandering a little on the highway. I took it for an alignment and the mechanic said that my caster angle should be 8 degrees and was way off. He recommended that I install a shackle reverse to gain some caster angle and a better ride. After installing the shackle reverse my caster angle went to 5.5 degrees. My mechanic said that he doesn't believe in using shims. I still have light steering and some wandering on the highway. I guess that I need 2 degree shims to get caster at 7.5 degrees which would only be 1/2 degree from what my mechanic said of it should be 8 degrees. Are shims that dangerous? A 2 degree shim wouldn't be very thick to worry about. Any ideas? I just want my jeep to drive straight.

 

[Torxhead]

Any chance of installing a longer spring shackle? if not maybe those shims might have to do. If you had not installed the shackle reverse, I would have suggested reinstalling the oem ones.

 

[mikemrq]

Where would the Longer spring shackle go? How thick would the 2 degree shim be?

 

[Torxhead]

Looking at the pics of your rig they seem to be prior to the shackle reverse, so i'm not sure what they look like now. If you do install those shims it will affect your front pinion angle by the same amount. It would be a quick fix though and easily removed when a better solution comes up.

 

[mikemrq]

I'm looking for thr correct fix before I measure and order a longer driveshaft for the front. I have a cv shaft on order for the rear.

 

[Old Dog]

I'm not a fan of shims in the front axle, there's alot of sideway force there when you turn. And as torxhead said it will affect you front pinion angle in a neg. way.
Unfortunatey the only other fix is to cut the C's off and reweld them on at the right caster angle. This is the right way to do it to start with if you have problems.

For what it's worth I have a 4" lift with stock lenght shackles and have no caster problem. Im not sure the SRS was the right answer to begain with.

 

[Tinman22]

Bolt on as well as weld on degree shims are available up too 8 degrees I think . Not as good as reclocking the cs but it's easy. Also napa shows adjustable ball joints for a Dana 30 up 2 degrees.

 

[PaRenegade]

The correct caster for a CJ7 is at 6 degrees+, not 8 (as per the 82'FSM). Even the FSJ models are at 4 degrees. And a half degree off is no big deal. Even at 2 degrees out it won't effect it radically.
As for shims, even the FSM recommends shims to correct the caster.

Could be the wrong preload on the ball joints also, too tight. Or if it gets pretty hostile (jerking) on it's left and right wandering check for worn / dried axle u-joints. I'd get a second opinion. The alignment guy seems a bit inept.

 

[BIGTRUCKNUT]

I think that you are over thinking the caster/pinion angle issue - if your caster angle is within Jeep specs and you haven't dropped your transfercase, the front axle pinion angle should fall within specs. The only reasons why you'd have to change the pinion/caster angle relationship by cutting and rewelding the Cs is if you drastically dropped the transfercase (thereby changing the front output yoke angle upward) or you go to a CV joint driveshaft in the front which would require you to point the front pinion up at the transfercase to run vibration free.

I've never had a problem with front caster angle with lift springs as long as I removed the angled shims that sometimes come installed on the lift springs from the manufacturer. They often do that in an attempt to reduce driveshaft u-joint binding or compensate for a driveshaft that is now too short as a result of the lift. Longer "lift" shackles in the front will also reduce your caster angle - "1 inch lift shackles" are actually 2 inches longer than stock.

As for the use of degree shims - they aren't lift blocks. There is no reason not to use them on the front axle if you need them to correct caster as long as there is enough engagement between the spring centering bolt and the spring pin hole in the axle spring pad. Better yet, I have used the type that go UNDER the spring centering bolt head and are tightened down as a part of the spring pack. That way they won't move and you have full engagement of the spring centering bolt in the spring pad hole.

Just my 30+ years of experience building Jeeps and trucks.

 

[billyballer]

84 CJ7, 360 auto. Installed Rough Country 4" Suspension lift with a 1" lift shackle. After the install I took it for a ride and noticed that the steering was very light and wandering a little on the highway. I took it for an alignment and the mechanic said that my caster angle should be 8 degrees and was way off. He recommended that I install a shackle reverse to gain some caster angle and a better ride. After installing the shackle reverse my caster angle went to 5.5 degrees. My mechanic said that he doesn't believe in using shims. I still have light steering and some wandering on the highway. I guess that I need 2 degree shims to get caster at 7.5 degrees which would only be 1/2 degree from what my mechanic said of it should be 8 degrees. Are shims that dangerous? A 2 degree shim wouldn't be very thick to worry about. Any ideas? I just want my jeep to drive straight.

Did you ever figure out your handling issues?

 

[mstar]

The alignment specs.(caster degrees) that are being quoted are for factory
equipment.Larger tires and wheels and aftermarket springs and such are not factory equipment.So you may as well figure some adjustment is going to be required.Anytime you change a part from what the vehicle was born with you will affect another part. That's just the nature of modifying vehicles. mike

 

[bearsden]

I currently am going through the same thing...look in the technical threads forums for "td hofstetter's" trouble shooting and correcting your steering.I'm doing this this weekend.