80 Series Caster Advice

[mudgudgeon]

Is there an easy way to check the caster on the 80s?

Simply, there needs to be a flat spot on the housing to use as a reference point.

are the radius arm brackets a zero reference? What about the steering arm mounting area?

What about the pinion flange? It should be possible to say at 0 caster, the pinion angle is "x".

Does anyone know that?

I've got a set of arb bushings to install and would like to know where I start and where I end up.

Put an angle finding gauge across the bolts at the top of the knuckle.
This is the caster angle.

Rough sketch below. This might not be 100% accurateif there's variation in bolt heads, but will be close.

If you don't have one, you can use a digital angle finding ( inclinometer) app on your phone.

 

[landtank]

I’m not aware of any concrete way to determine caster other than putting it on a rack, but you would need to use a digital angle finder and zero out the device to compensate for any slope where the truck is parked.

But if it’s a stock truck that has recently been lifted it’s simple to measure the distance from the front hub to the underside of the fender/flare subtract 20.5 and then multiply x 1.74. That is basically the amount of correction in degrees that you need to get back to 3* of caster.

 

[sunrk]

Is there an easy way to check the caster on the 80s?

Simply, there needs to be a flat spot on the housing to use as a reference point.

are the radius arm brackets a zero reference? What about the steering arm mounting area?

What about the pinion flange? It should be possible to say at 0 caster, the pinion angle is "x".

Does anyone know that?

I've got a set of arb bushings to install and would like to know where I start and where I end up.

Go to a tyre place and get a full wheel alignment report done. There's not really any sort of 'marks' you can use for reference as no two vehicles are exactly the same because of variances in all the associated parts, the wheels/tyres, etc.

 

[AcroSteve]

Go to a tyre place and get a full wheel alignment report done. There's not really any sort of 'marks' you can use for reference as no two vehicles are exactly the same because of variances in all the associated parts, the wheels/tyres, etc.

Right, for most people. That's hard for me to do. I'm building from scratch and it's not close to being on the road.

But there's gotta be enough to get close.

The bolts for the top pin are probably a likely option. Provided the pin cap and bolt heads are the same thickness front/back. They are a little close together

Next option would be the radius arm brackets. There is more surface there to put a level on, but then manufacturing tolerances would affect the relationship to actual caster.

Next would be the pinion flange. Which should be the same as the diff mounting surface. Again, manufacturing tolerances...

 

[AcroSteve]

Just checked using the tops of the bolts and wanted to double check something.

Right front, for what it's worth. Sitting on old factory rubber bushings.

The level on my phone shows 2 degrees when the screen is towards the outside, and -2, almost 3 when it's facing the inside. I can raise the front of the phone to get it to zero.

So, I think I've got +2 caster as it sets. Because if I were to lower the radius arm end at the frame, it effectively raises the front of the axle, right?

the left side shows 4 degrees. But the cruiser isn't perfectly level.

If those caster numbers are positive, I'm quite surprised as I've got a 3" OME lift on. I figured it would be worse.


I've got a set if eimkeith radius arm brackets that he says are good for 3.45 degrees.

I also have a set of OME caster bushings that are good for 2 degrees.

 

[AcroSteve]

After watching some more video, and a conversation or two, I do believe I'm at negative 2 or 3 caster.

 

[landtank]

if the truck is together with the springs in place just do the math I posted earlier.

Edit: Well I got a laughing emoji so I'll explain.

the factory spec for caster is 2-4* and caster changes at a rate of 1.74* per inch of lift, or the 2* represents 1.15 inches of lift travel

so if you take the measurement and do the math and you are off by 1/8" of ideal, that error would equate to a caster error of .217 degrees.

given that all the solutions are fixed solutions, that error is accurate enough to determine what solutions will work or not work and give you a good idea of the resulting caster when done.

 

[AcroSteve]

if the truck is together with the springs in place just do the math I posted earlier.

Um...

What fender?

 

[landtank]

Um...

What fender?



View attachment 3435115

Why are you even concerned about caster? There’s no weight on the truck yet

 

[Delta VS]

do not attempt to correct caster until at ride height with 90-95% of vehicle load

 

[AcroSteve]

Why are you even concerned about caster? There’s no weight on the truck yet

Look closer.

 

[AcroSteve]

do not attempt to correct caster until at ride height with 90-95% of vehicle load

Right. I agree completely


2900 lbs on chassis
Chassis is within 3/8 of level.

 

[Delta VS]

Right. I agree completely


2900 lbs on chassis
Chassis is within 3/8 of level. View attachment 3436081

Still recommend waiting

 

[SNLC]

Put an angle finding gauge across the bolts at the top of the knuckle.
This is the caster angle.


View attachment 3431988

Rough sketch below. This might not be 100% accurateif there's variation in bolt heads, but will be close.
View attachment 3431989

If you don't have one, you can use a digital angle finding ( inclinometer) app on your phone.

Only gives you a very rough idea. Any left or right rotation of the angle finder vs being perfectly straight inline with the frame rail will cause inaccuracies.

I have found the best way is to use as long of a digital level as you can, mine is a 4ft or 5ft because longer conflicts with inner fender in front and body mount at the firewall. I put it on top of the knuckle ball when the assembly is torn down. Right on the trunnion cup in the top of the ball but with no bearing. Then I drop a straight edge off the frame rails f&r or use a plumb bob. Then I use a tape measure to make sure the level is square to the frame rail.

I have done this a bunch for many years now and always get them aligned after. I am often within .2* using this method.

Cheers

 

[SNLC]

After watching some more video, and a conversation or two, I do believe I'm at negative 2 or 3 caster.

When you get used to all this and have looked at many trucks you can litteraly see it when there is good caster, no caster or bad caster. It’s obvious if the top of the knuckle is tilted one way or another or relatively flat. At least for me it is. I can’t look at it and say oh you got 4.5* but I can look at it and say you have no caster or you need more caster.

Alignments are $75-150 depending on where you live. That is the quickest way to know exactly what you have.

Cheers

 

[Octanejunkie]

Interesting thread, I'm looking at caster correction, again - currently running Slee plates but my steering link hits the radius arms at droop - so I am considering other options for caster correction. My current setup feels good on the road; no vibration, no strange steering behavior, but I will be changing out the front axle in the future (going to locking axles) so I GET to make a caster decision, again, lol

I'm lifted around 3"(2850 springs with 30mm spacer) and am looking at frame drop options, which are not really discussed here specifically, but look like a reasonable option especially when combined with offset trunnion bearings if additional caster is required after the addition of a particular frame-side bracket. So those are an option, too. Realistically, I could just move my Slee plates over, but I have found a few frame mount bracket kits that are interesting:

Eimkeith RAM (radius arm mount)

This is a weld on kit that drops the frame-side radius arm mount 50MM and moves the front wheel 25mm forward to help clear larger tires (37"+) AND keeps both caster and anti-dive at factory specs. There are no options for fine-tuning.
$100~ purchase price, requires welding, etc. and is reversable (bring vehicle back to stock) when you cut them off.

Ironman 4x4 Radius Arm Drop Brackets

This is a bolt on kit that claims to drop the frame-side radius arm mount 80mm, and moves the front wheel 15mm forward, again to help clear larger tires. There are no options for fine-tuning.
This is a $300~ investment and is reversable via unbolt and remove.

Man A Fre Front Control Arm Drop Brackets

This is also a bolt on kit that drops the frame-side radius arm mount but DOES NOT move the arm forward. There are purchase options for mounts that drop the arms 2" through 6" in 1-inch increments. Link to 3" bracket provided.
This is a $250 investment and is reversable via unbolt and remove.

Not sure if there are other products out there but these are the 3 I found "readily available" in the US market.

Anyone have any specific experience with these caster correction options and can share any practical opinions other than "well you have to weld that one" or this one is 3x the price of that one...

FWIW, I have spoken to a few folks that run these and no one has griped about them snagging rocks, etc. so the old "frame hooks" comments seem to be limited to the most hardcore drivers.

 

[deltapine1]

I chased this issue but I am running 285/70 17s. I went through and replaced wheel bearings (front & rear), tie rod ends, king pins and added the 2 degree TJM bushings to the stock arms. Ultimately mine ended up being solved by a combination of the Rear Upper Lefthand Control Arm bushings being shot and the Rear Lower Lefthand Control Arm Bushing being worn and the installation of a Delta Vehicle Systems Rear Trac Bar or Panhard Rod Bracket to raise the panhard rod back to original geometry. Without this DVS bracket the rear end is tracking in slightly different path than the fron end. This creates some serious wandering on crowned paved roads. By the way I have my stock 80 front lower arms with 2 degree TJM bushings (less than 4k miles on the bushings) I may be about to list on classifieds. I added the DVS arms after I got their bracket and solved the issue. Guess I just like spending money on the thing.

 

[808keith]

I'm running OME J lift with the exception of the rear running Non-J springs to get rid of the stink bug look and on 35's. Running the Delta 3" radius arms and their rear panhard bracket (this really planted the rear). It drives very straight on the freeway and on these Texas back roads unless its really crowned.. It's not bad as it was before with the OME offset bushings in the stock radius arms... 1000x better. Only bushings up front I have not done yet is the front pan hard bar, I plan on getting an adjustable one.

 

[Octanejunkie]

I'm running OME J lift with the exception of the rear running Non-J springs to get rid of the stink bug look and on 35's. Running the Delta 3" radius arms and their rear panhard bracket (this really planted the rear). It drives very straight on the freeway and on these Texas back roads unless its really crowned.. It's not bad as it was before with the OME offset bushings in the stock radius arms... 1000x better. Only bushings up front I have not done yet is the front pan hard bar, I plan on getting an adjustable one.

You running Delta 3" arms WITH RAM or without?

 

[808keith]

You running Delta 3" arms WITH RAM or without?

not running any radius drops or mounts.