Superduty 60 passenger side drop

[Skinny]

I'd want a touch more caster of I was going through all this trouble.

I had 3-4 degrees and the truck handled like shit. Super twitchy and almost zero return to center. Added just a couple more and it drives night and day difference.

 

[Oddball]

What did you set the pinion to?

Zero

 

[Oddball]

I'd want a touch more caster of I was going through all this trouble.

I had 3-4 degrees and the truck handled like shit. Super twitchy and almost zero return to center. Added just a couple more and it drives night and day difference.

Yea I know, and I read the same. I wanted more cuz I can always turn the pinion up. But when i shrunk the Cs on I didnt realize the axle shifted a bit and wasnt at zero. So i lost a bit. My last truck had a bunch of wedge to turn the pinion up, to the point that returnability was slow. It shouldnt be that bad. Anyways, it is what it is, they are not moving now.

 

[Oddball]

I'm reading now about Kingpin inclination, says here these axles have 12.5°. That seems like a shit ton, not sure how it will factor in. But I think you can run less caster with more KPI.

 

[Skinny]

I'm not a 100% sure how KPI affects how much faster you need. I'm only familiar with using it as a diagnostic tool for pre-alignment inspections.

Either way I think you can get adjustable ball joints to squeak some more or less caster in wherever you land.

I'm just a big fan of having slightly more caster then necessary because I always end up needing a hair more pinion up adjustment for driveshaft angle🤦

 

[Oddball]

I'm not a 100% sure how KPI affects how much faster you need. I'm only familiar with using it as a diagnostic tool for pre-alignment inspections.

Either way I think you can get adjustable ball joints to squeak some more or less caster in wherever you land.

I'm just a big fan of having slightly more caster then necessary because I always end up needing a hair more pinion up adjustment for driveshaft angle🤦

Isnt that always the case? Anyways, ill probably run BKOR king joints, sooo there will be no adjustable ball joints.

 

[Skinny]

Its always the case 🤣

 

[Tydes]

Zero

with the pinon set at zero the caster is 11.8 degrees on a stock 05+ dana 60

 

[chaplinfj60]

so with this now on the pass side have you noticed any extra drama with the drive shaft now being closer to engine ? or is there all kinds of room?

 

[Bebop]

I'm reading now about Kingpin inclination, says here these axles have 12.5°. That seems like a shit ton, not sure how it will factor in. But I think you can run less caster with more KPI.

uhhhhh?
KPI has nothing to do with caster.

 

['84 Bronco II]

KPI has nothing to do with caster.

It does have to do with how much caster you want. More king pin inclination means you are going to want more caster. In an ideal world, you wouldn't want any king pin inclination, but in reality, you are going to need some to make the scrub steer manageable/eliminate it. In a crawler application, some scrub steer is good within reason if you have the steering power to deal with it.

 

[Bebop]

It does have to do with how much caster you want. More king pin inclination means you are going to want more caster.

Why

 

['84 Bronco II]

Why

Here's a pretty good write up: https://ismasupers.com/wp-content/uploads/2021/11/Tech-02-Suspension-Geometry-relations-4.pdf

Here are the relevant excerpts that explain it:

The steering axis inclination causes the spindle pin to point downward on the end as the wheel is steered. If the right front wheel on a car with caster = 0, static camber = 0 and SAI = 8 degrees were turned 90 degrees the tire would take on camber equal to the SAI or 8 degrees. The problem is, on the right front the 8 degrees is with the top tilted out or positive camber, exactly what you do not want on the outside tire in a turn. Obviously, the tire is not steered 90 degrees but no matter what amount the RF is steered to the inside it is losing the initial static negative camber due to the arc the outer spindle follows with SAI. So, SAI on the RF spindle decreases the amount of negative camber that the car has as the wheel is steered into the turn and throughout the turn. Interestingly, the left front tire which is also steering into the turn is gaining the positive camber it needs due to the SAI on the LF. SAI therefore adds to the camber on the left front and takes away from the camber needed on the right front when the tires are steered toward the inside of the track.

Previously we talked about how, on the RF tire, SAI tends to remove static camber when the tires are steered to the inside and tends to add to static camber of the left front tire in the same turn. The trick on the RF is to get the caster set so the positive effect of caster on camber offset the negative effect of SAI on camber. The real challenge is that camber change due to SAI is non-linear while camber change due to caster is linear. The camber change due to SAI starts out very slow and as you steer it produces a change in camber at an increasing rate. The camber change due to caster is linear which means every degree you steer it brings on an equal amount of camber change.

 

[Bebop]

I don't necessarily agree with this. At least not in an offroad rig.

Lots of people have had success with different / non-conventional geometries.

Dirt / Loose surfaces and 40"+ tires do weird things.

 

['84 Bronco II]

I don't necessarily agree with this. At least not in an offroad rig.

Lots of people have had success with different / non-conventional geometries.

Dirt / Loose surfaces and 40"+ tires do weird things.

You never want positive camber on an outside tire, especially with big sidewalls that want to roll under the wheel and high steering angles. Isdtbower has some good pictures and notes on steering geometry.

 

[Bebop]

You never want positive camber on an outside tire, especially with big sidewalls that want to roll under the wheel and high steering angles. Isdtbower has some good pictures and notes on steering geometry.

Have you looked at Tim Cameron’s winning machines ?

I’m being the devils advocate here but he’s a very famous guy that builds against this.

 

[Skinny]

Since it's not adjustable in this case and custom knuckles/Cs aren't being discussed what difference does any of this make?

Rabbit hole of irrelevance...

 

[Oddball]

with the pinon set at zero the caster is 11.8 degrees on a stock 05+ dana 60

I highly doubt that.

so with this now on the pass side have you noticed any extra drama with the drive shaft now being closer to engine ? or is there all kinds of room?

I havent mounted it yet. I hope i can run a small diameter tube. Worse case a two piece shaft. Ive pushed the diff as far right as possible. Ill cross that river when I get to it.

 

[Oddball]

with the pinon set at zero the caster is 11.8 degrees on a stock 05+ dana 60

I see what you're saying after reading the sd tech thread. They have a lot of pinion angle stock. Im actually going to run this axle 0-1° of pinion angle. Truck will be as low as possible. The front driveshaft will be pretty long as well. Also, I should add, this is going into a Toyota.

 

[chaplinfj60]

Guys usually just do the sleeve method.

Measure from the cross pin the same amount on both sides, cut, install a sleeve that fits the ID of the tube's, swap sides, bevel, check caster and weld.

so measure same distance on each side. like 6 inches basicly? also the first pic is random pic i found. it is not the axle in question. if possible i will pics this weekend of axle with diff cover off. and do a good pic.

roughly right in this area both sides? cut tube sleeve weld back together. would you have knuckles and axles in to verify also?

 

[gt1guy]

You never want positive camber on an outside tire, especially with big sidewalls that want to roll under the wheel and high steering angles. Isdtbower has some good pictures and notes on steering geometry.

Caster turns into camber when you turn the wheels. Negative on the outside tire, positive on the inside tire.

 

['84 Bronco II]

Caster turns into camber when you turn the wheels. Negative on the outside tire, positive on the inside tire.

I know, that is why I am saying you want more caster with more king pin inclination which adds positive camber to the outside tire.

 

[Skinny]

I would want to take a look at the relationship between the pinion, tcase output, length, etc.

All I know is my SD60 in my S10 with pretty low ride height could use a little more pinion up with where my caster is.

My tcase is pretty flat tucked in, front shaft is a decent length for what the truck is, and my CV is just about maxed out at full droop.

So all of this doesn't matter unless you are mocking it up and know for sure before burning it in. Because the SD60 having a lot of pinion angle up from the factory I wouldn't guess that by looking at my set up.

A lot of people also miss how far offset that big bitch is.

 

[Isdtbower]

F

I know, that is why I am saying you want more caster with more king pin inclination which adds positive camber to the outside tire.

I think that adds "negative camber" on outside wheel turning So the wheel/tire does not tuck under.

Fold a small piece of paper. Use the crease of the fold as the King pin. And see what happens on turning. I had to do that when I didn't understand, but wanted to understand what the fast desert guys were doing with IFS geometry. With IFS, you can play a whole bunch. Different driver styles can change those numbers. Significant is a driver who likes to rear steer into a turn. To Bebop's point. That could be by true rear steer OR Sliding the rear into the turn..and counter steering in the front. That is usually used when the driver KNOWS what is ahead and wants to carry more speed thru the turn. The offroader who may not know conditions will brake hard into a turn, turn with low challenge, and then gas it past the apex. Robby G likes to back in to turns...and why I would not buy a Speed SXS. Not my style...Risky. Short track is different as you DO know what the turn is like. Robby does well with pre-running...as do others. Just different styles, and risk. I think I see a lot of rear steering out of Cameron's rigs. Straight axles have less opportunity to play...but less opportunity to mess up also. It seems like we used to have SA camber wedge or toe plates. If I was racing, I would add 3* negative camber to help the fronts out of ruts when going straight. I always think about a motorcycle front tire, and what it takes to make them work for you..IN my case it was easier to add or shorten swing arms between desert and trees. Why you can't focus on just one number. But you can write down the options you DO have ...for consideration.

Always think about the tire to the ground....not to the chassis...but chassis is what we use as terminology. None of that takes into account how a driver likes to "drive." All those 100% traction books.....Have LOTS of dust on them. Dirt track is a start. Then you have to use your thinker. Video is a great way to SEE what the tire is doing. Then write up what you want the tire to do. That may be 6-7 bullet points. Then look to solve them. 5 link IFS/IRS and such will give the the ability to solve the most (except maybe strength, etc.) Then it goes down from there. Most of the time a 5 link just won't "fit." So you have to understand the other options that others have generated. and....We can FU anything....Testing, testing. And I don't know Sh__ about shocks. Just know what feels better when the tuner makes knowledgeable changes.

 

[Oddball]

Weeelll, I'm going to pull these Cs off and add a few more degrees. I think a large puller should do the trick.

so measure same distance on each side. like 6 inches basicly? also the first pic is random pic i found. it is not the axle in question. if possible i will pics this weekend of axle with diff cover off. and do a good pic.

roughly right in this area both sides? cut tube sleeve weld back together. would you have knuckles and axles in to verify also?

Keep in mind there is only 4 inches of tube inside the cast section.

 

[YotaAtieToo]

Weeelll, I'm going to pull these Cs off and add a few more degrees. I think a large puller should do the trick.

Keep in mind there is only 4 inches of tube inside the cast section.

Look up Mr Stubs build, he changed caster after the c's were pressed on

 

['84 Bronco II]

I think that adds "negative camber" on outside wheel turning So the wheel/tire does not tuck under.

King pin inclination definitely adds positive camber to the outside tire when turning. It is the whole impetus behind the new Can Am front suspension and the reason fancy German automakers frequently use virtual pivot points in their suspension designs.