Caster and wedges

[Hedgehog]

Funny how these things work out. My old 1975 CJ drum front axle ran just fine with all caster wedges removed. 75 mph, no problem, the steering was light, but easily doable. So what do I go and do. I pulled the 1975 drum axle off and transplanted in a 1978 disk axle. Thinking that the original ran acceptably with no wedges and with nothing changing (the same springs, the same shocks, the same steering gear box) wedges were left out.

The CJ drove terribly. So off to the alignment shop she went. The alignment mechanic said that everything was tight, I only had a little over 1* of caster angle. As expected the toe-in was off so he adjusted it. He said, drive it, it's a lot better, but it would be better with at least 4* more caster. I drove it home and found that the steering was better, but FAR from what it once was. So with his words ringing in my ears I stopped by Willys Works for some wedges and yes Lumpy some longer spring shackle bolts. After looking at his wedges and being the American I am, and remembering some posts here, I bought a set of 6* wedges. After all if 4* will work, 6* must be better.

Honestly, Rob and Willys Works is a bit dubious about the 6* wedges. He said that I should ask you guys this question.

What happens when you have too much caster angle or to much wedge?


Hmmmmmm, this should not be in the Drivetrain Forum it should be in the Steering Forum.

 

[Lumpy Grits]

IIRC-You want 6-7* caster with over-sized tires.
Pretty much what I'm run'n now, and have for decades.
Hope this is a steel 'wedge' and not one made of alum or zinc.
BTW: It's not a 'spring shackle bolt' It's the spring center bolt
LG

 

[Torxhead]

Hedge, as you stuff those wedges in there you are changing the front pinion angle also, which can create another problem. I agree with Rob and Lumpy on about six degrees. Adding those shims also really cuts down on the diff ground clearance. With your welding skills, you could move things around where you would not need those shims anyway.

 

[Woolyworm]

My 2C.....The back of the pinion yoke should be about plumb. When you add lift springs and or longer shackles it rotates the back of the pinion up requiring shims to rotate it back down but it should end up plumb again which gives the correct castor at the yokes bringing things back to the stock position.

The shims will lift the axle up off the springs a little bit.

If you don't rotate the axle too much the pinion shouldn't point down in the back and you shouldn't cause any loss in clearance at the pinion but it will cause a small amount of clearance loss from the frame and everything attached to it except the axle.

Cutting off the axle mounts and rotating them just gives you a theoretically stronger mounting point and reduces the amount of frame clearance loss.


Wooly

 

[Hedgehog]

So, it sounds like we are mostly in agreement, 6* (with the ~1*+ 6* it should be in the ~7* range) should do just fine. This weekend I'll do it and we shall see how everything works out. Honestly folks, Loosing a little under 1/2" ground clearance doesn't bother me at all. That is as long as the CJ can safely get down the road. That's the most important part for me. I will check the change in differential tail clearance though. All in all I think everything will be Okay. But you've given me something to think about.

If all seems well I'm not opposed to cutting and welding, sorta scares me to death. Not the welding or the cutting, but the getting it right the first time. I suppose it would be easy enough to cut the perch off one side using the other side to maintain the proper angle. then welding one side. Then going through the same procedure on the other side. That would likely work. Or or or well now I'm thinking on it. No matter what I'm going with the wedge shims first.

Lumpy ... ... It figures that you'd notice my wording mistake, I meant to write spring stack, not shackle. Getting old I think. Keep keeping me in line my friend, from time to time I need it.

 

[Lumpy Grits]

Lumpy ... ... It figures that you'd notice my wording mistake, I meant to write spring stack, not shackle. Getting old I think. Keep keeping me in line my friend, from time to time I need it.

We're in that same leaky boat.
---------
BTW: Whether you use shims, or re-locate the axle spring perches. The pinion will be in the same spot.
You might need new(longer)axle "U" bolts, with this shim install.
Hope the install goes easy.
LG

 

[Woolyworm]

I cut off my rear perches and replaced them - they were rounded over from the AMC 304 torque, but I used steel shims on the front. The fronts look like a solid block of steel welded to the axle-are they?


Wooly

 

[Woolyworm]

Before and after






Wooly

 

[rockinreel]

I just don't understand. I have been fighting the same steering issue. Changing lanes or road ruts are hazardous. A second steer or after steer to right the jeep is always necessary.

No shims, is like suicide. 2* not much better. 4* a lot better and my gf could drive it. ...took her to the shop for an engine swap, and they said my pinion angle was too far off, they wanted to adjust it. I let them. My pinion angle is right, but it drives like again.

The perplexing part is I "know" 6* shims would fix the steering, but you can't have the proper pinion angle with shims, so what does one do without dropping the TC? Why is a front pinion angle so important because the front drive shaft doesn't spin at highway speeds.

(4" SL, 1" BL)
thanks

 

[CJim7]

I just don't understand. I have been fighting the same steering issue. Changing lanes or road ruts are hazardous. A second steer or after steer to right the jeep is always necessary.

No shims, is like suicide. 2* not much better. 4* a lot better and my gf could drive it. ...took her to the shop for an engine swap, and they said my pinion angle was too far off, they wanted to adjust it. I let them. My pinion angle is right, but it drives like again.

The perplexing part is I "know" 6* shims would fix the steering, but you can't have the proper pinion angle with shims, so what does one do without dropping the TC? Why is a front pinion angle so important because the front drive shaft doesn't spin at highway speeds.

(4" SL, 1" BL)
thanks

If the pinion angle is off drastically, you can bind up the ujoints under torque....but even that is unlikely. The farther off the angle, the more vibration and heat is produced.
My personal opinion falls in line with your question: It is a low-speed driveline. In my case, the front shaft rarely turns faster than 4-low, 2nd gear.
the front driveline is also much longer than the rear. I think it takes a LOT to get the angle off enough to be a concern.

 

[Neuner]

The perplexing part is I "know" 6* shims would fix the steering, but you can't have the proper pinion angle with shims, so what does one do without dropping the TC? Why is a front pinion angle so important because the front drive shaft doesn't spin at highway speeds.

(4" SL, 1" BL)
thanks

I think CJim7 is right. On mine, one of the POs installed CV Joints and Shafts like these instead of using the TC drop kit from RE lift kit; Tom Wood's Custom Drive Shafts - BAMF CV JOINT

 

[Dolamite]

I had between 0* and 1* for caster before putting in 4* shims. Before the shims it was risky to go over 40 mph. After, I can drive 65-70 without an issue. I could almost let go of the wheel. I haven't noticed an issue with the front pinion angle, but my Transfer Case was dropped about an inch when I installed my lift.

 

[Lumpy Grits]

A double cardan u-joint helps with the angle deal.
http://www.pirate4x4.com/tech/billavista/PR-shaft/DCP_6524.JPG

LG

 

[hdgapeach]

I just don't understand. I have been fighting the same steering issue. Changing lanes or road ruts are hazardous. A second steer or after steer to right the jeep is always necessary.

No shims, is like suicide. 2* not much better. 4* a lot better and my gf could drive it. ...took her to the shop for an engine swap, and they said my pinion angle was too far off, they wanted to adjust it. I let them. My pinion angle is right, but it drives like again.

The perplexing part is I "know" 6* shims would fix the steering, but you can't have the proper pinion angle with shims, so what does one do without dropping the TC? Why is a front pinion angle so important because the front drive shaft doesn't spin at highway speeds.

(4" SL, 1" BL)
thanks

Pinion angle importance? To keep from bustin' u-joints and screwin' up a Transfer Case . Never intend to use 4WD - don't worry about the angle!

What kind of suspension modifications do you have on your ride that makes both desired angles (pinion and castor) unobtainable?

 

[rockinreel]

@hdgapeach, I've come to realize that my "unobtainable" pinion angle and desired castor is because I installed my shims backwards. (sadly I was sober) I've read on this forum about castor that you don't want a shopping cart ride, you want your castor to be more like a chopper. So I interpreted that as meaning the top of your axle should lean towards the rear. Thus, I created a steep pinion angle.

I guess if I put 6* shims in the correct way, I'll be on my way to better steering. Glad I don't make a living as a mechanic!

 

[Posi]

I installed my shims backwards. (sadly I was sober)

Don't feel bad, when I purchased my 42 MB a "professional" 4x4 shop installed the shims backwards as well. I have the receipt from Kong 4x4 offroad center in Phoenix, AZ that installed the lift and shims

Kong's install



After I corrected their mistake

 

[Lumpy Grits]

@hdgapeach, I've come to realize that my "unobtainable" pinion angle and desired castor is because I installed my shims backwards. (sadly I was sober) I've read on this forum about castor that you don't want a shopping cart ride, you want your castor to be more like a chopper. So I interpreted that as meaning the top of your axle should lean towards the rear. Thus, I created a steep pinion angle.

I guess if I put 6* shims in the correct way, I'll be on my way to better steering. Glad I don't make a living as a mechanic!

You are not the first or will you be last person, who has/will do this. It's part of learning.

LG

 

[tinman]

Does the rear matter as much as the front? I think both the front and back are installed wrong on mine.

 

[Lumpy Grits]

YES-Both are important, but for different reasons.
LG

 

[JR74CJ5]

You are not the first or will you be last person, who has/will do this. It's part of learning.

LG

Ditto... I installed my rear springs backwards thinking they were centered evenly... nope...

Had already had the rear driveshaft re-built too... couldn't figure out why my rear driveshaft was 2" off where it was before my OME springs...

Just gotta learn the hard way sometimes...