CASTOR Adjustment ? (was camber) (1 Viewer)

[nspctr1]

OK, If I wasn't confused before, I really am now. I have a 73 40 with a small shackle lift that was installed by the PO. I'm trying to tackle my steering issues and have replaced the TRE's, center arm, and have made adjustments in the steering box and several other things , all to no avail. So, broke down and read hundreds of posts on steering wandering and adjusting camber over the weekend and I still have questions. First, If I read correctly you can measure the degree of camber from either the knuckle studs or the flat top of the axle housing. Is this correct? I can check the angle on both and the knuckle studs are almost dead level and the axle housing is at a 15* angle approx. Is this angle the same on all of the ribs on the axle housing or just the top? This is being done using a really cheap angle finder that I use for cutting metal etc. Does this sound right? I am looking at installing shims to reduce the angle if I need to do that and trying to determine what degree shim and how to install them. The SOR manual says to install the fat end of the shim to the rear but that doesn't make sense to me either as you will be increasing the angle even further.
Also, I don't want to do a cut and turn unless I absolutely have to.

Thx.

 

[BELMONT148]

I think you mean caster. Camber can not be adjusted on a solid axle.

To check the caster, use the top of the steering arms not the diff.

Jeremy

 

[John Smith]

As said above you mean caster not camber. You want to install the caster shims with the thick end towards the front of the truck so you tilt the pinion towards the ground to increase your caster. This will correct the caster issue your extended shackles created and stop your truck from following any and every rut in the road and get rid of the super scary wandering steering feeling.

 

[Pin_Head]

Bad camber is usually a sign you have bent the axle housing and it can be corrected by replacing the housing or bendingit back. However this wouldn't have anything to do with wandering. Wandering is associated with caster problems, as noted above.

You don't want to tighten the steering box adjuster nut if the pitman shaft bushings are worn out. This can crack your box casting when you hit a bump. Replace the worn bushings first.

 

[dgangle]

one can determine their own caster pretty close measuring any of these 4 places using a cheap magnetic angle finder available from any home center for $10.

#2,3 & 4 all give caster angle from vertical. #1 is 45 degrees from horizontal.

 

[dgangle]

these two pics prove to any nay-sayers that the third member mounting surface and the caster angle are parallel on an uncut FJ40 front axle

 

[Mace]

Nice pics

 

[BELMONT148]

That's definately good info. But I don't ever trust that these rigs are stock anything unless I am the original owner. I stick to the direct method, however being an engineering student I respect your attention to details.

Jeremy

 

[dgangle]

Well I am a Mechanical Engineer so unless your FJ40 front axle has been cut & turned you will get the same or very similar results. Certainly there is some error to be introduced from the position of the angle finder, the flatness of the floor, variance in interpretting the gauge......

A C&T typically involves rotating the pinion up ~10 degrees and rotating the knuckles back ~14 degrees plus new or seriously modified spring perches. These are pretty drastic modifications and should be obvious to the eye to someone experienced with both the mod and a stock axle. Then the only way to accurately way to determine the caster by yourself would be to measure #3.

 

[nspctr1]

one can determine their own caster pretty close measuring any of these 4 places using a cheap magnetic angle finder available from any home center for $10.

#2,3 & 4 all give caster angle from vertical. #1 is 45 degrees from horizontal.

View attachment 339466

Thanks for correcting my error. So, with this drawing, thanks dgangle, I can check the angle at locations 1 and 4. Anyway, when I checked the angle at locale 1 I have approx. 30*. Not sure if how to determine the correct angle at location 1. If it's 30* and needs to be nearer to 45 what size shims are needed?

 

[dgangle]

30*? wow that confuses me. On an uncut axle it should read ~43-44* as that surface is 45* from horizontal so your's would be +15* caster (45-30=15).

I'm not sure why the difference. You may want to try remeasuring. ??

Measure the pinion flange from vertical and report back (#4). This should be ~1*

 

[nspctr1]

At location 1 I laid my angle finder on that flat area on the top of the housing. it reads 30* . if i place it at the pinion flange it reads about 15*

 

[dgangle]

assuming you took the measurements without any appreciable error, then you either have approx +15* caster or your knuckles have been turned previously someone else. I bet the latter.

 

[nspctr1]

Sorry I dont have a star so I cant post up anymore pics but if someone wants to host a couple I will shoot them and send them so everyone can see what we are looking at here. I however do not see any evidence of a cut and turn but hell, I'm half blind and deaf

 

[dgangle]

here's some pics of his axle with more to come

 

[dgangle]

Based upon the bugger welds on the knuckles (pis 2 & 3) and the angle of the pinion vs. the front driveshaft (pic 2), I'd say your axle has had a cut & turn. This is not necessarily a bad thing.


Measure the angle (from horizontal) of the wiper seal backing plates as drawn on the first pic and report back. This should give you an approximation of your caster. My previous pics/angles were on an unmolested axle.

 

[nspctr1]

OK, Thanks, so, if the cut and turn has been done correctly and if the caster angle is correct,allegedly, along with all of my steering components being rebuilt, why would I continue to have sloppy steering? I rebuilt the knuckles and replaced the bearings when I did my mini disc conversion and I probably don't have 25 miles on it since because it scares the crap out of me when it decides to go it's own way.

 

[Pin_Head]

assuming you took the measurements without any appreciable error, then you either have approx +15* caster or your knuckles have been turned previously someone else. I bet the latter.

Either that or he is parked on a 15 degree grade. Why not take it to an alignment shop and have them check the caster angle if you are having trouble doing it yourself?

I wouldn't assume it has been cut and turned as it is still SUA.

I would assume that it may have negative caster as it has extended shackles.

 

[dgangle]

SUA doesn't exclude it from a C&T. Look at mine. I agree though if one can't figure it out, take it to a shop and pay them $60 to tell you your specs. I'm only trying to guide the guy through some free exercises.

1.measure you caster. make sure it is +1 (stock), +3-4 even better. adjust if necessary with shims, c&t, etc
2. check for play in the 345 possible compo nets in a stock FJ40 steering/replace
3. make sure trunnion bearing preload is ~10 lbs measured with a fish scale without birfs, wipers/seals/grease/etc
4. verify/adjust proper wheel bearing preload
5. set toe-in at ~3/16
6. u-bolts tight, new/good spring bushings.....alll the regular stuff for good care.


just go at it methodically and realize this is not a 2009 sports car and have realistic expectations for something that was designed in the 1930's.

 

[dargreg]

Could be my eyes and correct me if im wrong,but by looking at pic 4 and the caliper have they cut and turned the wrong way? Its definatly been cut and turned by the looks of the heat marks also.