Measuring CASTER angle? (1 Viewer)

[Brian in Oregon]

Can the CASTER angle on an FJ40 be measured by the average owner with common tools?

(I accidently posted CAMBER angle last night. Shouldn't post when I'm tired.)

Also, will aluminum wedges hold up? I've heard they can crack. How common is this?

 

[Tankota]

Camber is why I didn't answer ya

Castor is measurable. Go get a nice angle finder at the hardware store. I think mine cost $7 so it is a cheapie and I shoulda gone big and bought the $14 one Only reason is it can get a bit difficult to see 1/2 degree increments.

If you have your knuckles off it then measure on top of the trunion bearing race. If the axle is altogether then you can easily find another spot to use...like the flat spot along the edges of where the steering arms bolt to the knuckles...or the spring perches(less confident with this one) or the pinion flange.

 

[Brian in Oregon]

If the axle is altogether then you can easily find another spot to use...like the flat spot along the edges of where the steering arms bolt to the knuckles... or the pinion flange.

That's EXACTLY what I needed. Thanks! I didn't know if these machined surfaces were indexed or slightly off for angle compared to zero caster.

 

[peesalot]

if it aint all tore up you can usually use the magnetic angle finder on the tops of the studs for the steer arm, usually it is damn close to what you get when you measure on the knuckle itself when factory studs are in there..

 

[4x4 Station Wagon]

I chose to just strike this thread back up rather than post a new one.

Does anyone know what a person can base their measurements off of? What I am asking is basicaly has anyone ever went into the alignment shop and while getting their castor checked threw the cheap magnetic guage up on the pinion or third member or ?? to be able to know what the relation is. Basically as we all know if your vehicle isnt 100% level then the number is going to change... But if we had X and Z then we could figure Y based off of the difference.

The only way I can think of pulling this off is going into the alignment shop and while it is on the rack at perfect level taking a reading on the top angled section of the third member.

I admit its late and I have spent all day swapping knuckles which I now agree is the messiest fj40 job out there so I may be off my rocker. I know the right way is to take it in and have it checked but it would be nice just to be able to check your castor assuming you had a stock uncut axle under your rig. I really hope I am making any sense right now!!

 

[Pin_Head]

My experience is that the flat machined surfaces of the knuckle should be +1 degree, the spring perch 0 and the pinion flange 90 degrees on a stock cruiser sitting on a flat, level surface. Be sure to subtract the ground surface angle if it isn't level. These measurents aren't really that accurate. I would guess that they are +/- 1 degree. This would often be good enough to tell that the caster is wrong, but not good enough to be sure the caster is correct.

 

[4x4 Station Wagon]

Perfect! That is close enough for now. I have been working on it all weekend so i can haul it into an alignment shop, get a reading, take it back home, and cut and turn. But I wanted to take a guess at it out of curiosity!

 

[dgangle]

has this been discussed before ??

assuming one can follow instructions and accurately read an angle finder, measuring your own caster can be done with decent accuracy quickly and easily with a $10 magnetic angle finder available at any home center.

To see the surfaces on your front axle were to do this, see post 16 of the thread in this link: http://tinyurl.com/yl2luc7

 

[handcannon]

dgangle

Great info and pic in your link. An additional question about this, is this angle measurement the same or different for an FJ60 front axle? Or, in other words, is the angle of the pinion flange/third member mounting surface relative to the spring perch the same on the 60 axle as the 40 axle?


Thanks
Don

 

[dgangle]

I have no idea but this could be verified by measuring. Never took these mesurements on a 60. And I never referenced any of these caster measurements to the spring perch either

 

[4x4 Station Wagon]

I have no idea but this could be verified by measuring. Never took these mesurements on a 60. And I never referenced any of these caster measurements to the spring perch either

I have a gutted 60 housing sitting in my shop as we speak. I also have a cheap magnetic style gauge. I will find out tonight.

To see the surfaces on your front axle were to do this, see post 16 of the thread in this link: eating front tires

Awesome!! So now I can use the 45 degrees plus or minus the 4 degrees for castor on the third member or the pinion angle to determine what level ground should have been...... Then I can base my approx. curent castor off of that to give me an informal idea on how far my cut and turn will be. The reason for this is to help determine if my high steer arms are going to clear after the cut and turn because they do not at this point but I have the pinion rotated up assuming I will be going with a cv style driveline.

EDIT - My whole concept for this stunk..... There is no measurement that A person can take to determine if their cruiser is on level ground unless you knew exactly what your current castor was at. Then you could do what I was thinking of...... On a concrete floor you can approx. check the floor but in my case I was on gravel and it is harder to check so I thought there was a magic reference point.

 

[handcannon]

I have no idea but this could be verified by measuring. Never took these mesurements on a 60. And I never referenced any of these caster measurements to the spring perch either

I am aware that you did not reference anything to the spring perches. My bad for not being clear with my question. I was hoping for a way to correlate the angle of the 40 to the 60 axle by way of the perch. My 40 has a bone stock front axle and handles great. My 60 axle is setting on sawhorses in the process of being built and I would like to know ahead of time what I need to do and plan appropriately. I am venturing into all new territory for me so I need to learn so I can make the correct decisions. I am hoping for plug-n-play when it is time to make the swap, no surprises.

I am a dry sponge so any words of wisdom will be appreciated. And 4X4 I am very much interested in your findings.

Don

 

[4x4 Station Wagon]

Well here goes.... It appears with a bit of grime and surface rust flakes etc. (small I picked at it the best I could) that the measurements were as follows.

This is of course a bare 60 housing not currently under a vehicle.

Top of trunnion 6 degrees
perch 4.5 or 4 degrees
and face of housing where third member bolts 90 degrees

As mentioned before these are all with a cheap style guage that makes it very difficult to tell 1/2 degrees. Plus I didnt have time to thorougly clean the spots but should only amount to .5 a degree at most and would be on the perches if anything. I posted 4 and 4.5 becuase if I shopped around on the perch I could get both.

the problem with my data now is that the third is out so we have to assume the face of the housing is identical degrees as the pinion as with the 40 in order to have that data also but it should be right?



From what I gathered the 60 apears to be considerably different from the 40. The housing face where the third member mates up is clearly different from the trunnion angle as dgangle noted with the 40

#2. Third member mounting surface. On an an 'uncut' axle this surface is the exact same as the caster measurement #3.

I didn't want to post if the the above measurements were positive or negative because I was not sure. I know this though they are either both positive or both negative and if you were to bring them to zero the pinion would rotate up towards the t-case so I am guessing they are negative.

 

[4x4 Station Wagon]

So i am sitting on gravel that is fairly flat inside my shop. My pinion and the top of my flat machined high steer arms are basically 12 degrees. So assuming my floor is close to level (close) then my castor would be -12 and I would need to cut and turn approx. 16 degrees. Now I just need to get fancy and determine how far in inches that would raise my highsteer arms at the tie rods. At a quick glance it should be enough to clear the leaf springs since I am just a bit shy.
It should be significant for I saw rokcod rotated his a 1/4" which should add up when measured on an arm that sticks out 4 or 5 inches

 

[4x4 Station Wagon]

I am the king of doing stuff twice! Now that I pull my head out I beleive I will just use these measurements to closely approximate my cut and turn which I am certain I can get with in a degree or two of my intended third member vs. castor angle and THEN I can haul it in and get the castor checked and I will simply remove my perches that are only tacked as of now and set them accordingly.... End result is that my Castor should be dead on and my pinion angle will be within a degree or two of where I intended but who cares if I go with a CV style driveline it shouldnt matter.

The good news is that I got practice putting it all back together for the final time!

The intent of this post is to possibly help a future searcher. If anyone believes the pinion angle is seriously that crutial with a CV style driveline please be sure to post in order to keep me from steering others wrong. My intent is to say that if you intend to cut and turn and are planning on setting the pinion at 88 and you end up at 87 or 89 it isnt going to matter that much.

 

[dgangle]

I am aware that you did not reference anything to the spring perches. My bad for not being clear with my question. I was hoping for a way to correlate the angle of the 40 to the 60 axle by way of the perch. My 40 has a bone stock front axle and handles great. My 60 axle is setting on sawhorses in the process of being built and I would like to know ahead of time what I need to do and plan appropriately. I am venturing into all new territory for me so I need to learn so I can make the correct decisions. I am hoping for plug-n-play when it is time to make the swap, no surprises.

I am a dry sponge so any words of wisdom will be appreciated. And 4X4 I am very much interested in your findings.

Don

The advice of 4X4 stationwagon may be right but it makes my head spin.

The best advice I can think to give you based upon how I went about this with my FJ40 front axle would be to mount the axle in the springs with ubolts with the weight of the truck on it using jackstands. Don't weld the spring perches yet and rotate the pinion up to within about ~2* of a 0* angle on the front DS U-joint (at the pinion) and turn the knuckles to get the desired caster angle (of +3-5* depending on who you ask). With a CV/double cardan front DS, as the springs flatten and compress with the compression of driving, this angle will approach 0* on the front U-joint and be perfectly aligned with no vibes while driving. Tack weld the spring perches and knuckles. Pull the axle and weld to taste. Re-install the axle and you should be golden.

If you are not planning to use a CV front DS, make the front axle DS mounting flange (at the pinion) angle = to the TC front DS flange =. This will eleviate any vibes in 4WD as the angles/rotarion of the front DS U-joints will cancel each other and hopefully result in a smooth ride in 4WD at speed.

With how I did it I can drive 80+MPH in 4WD/hubs locked and not even know it is in anything other than 2WD.

 

[4x4 Station Wagon]

We offer a Zero degree choice for FJ40's without the knuckle turn, 8 degree's for a stock FJ60 or an FJ40 with the turn, & 14 Degrees for an FJ60 with the turn.

I found this info and it is in regards to a fancy front passenger side perch. It helps show the difference between an FJ40 and FJ60 setup.

The advice of 4X4 stationwagon may be right but it makes my head spin.

How do I get that in my sig line??