Negative 2.8 Caster

[BGBronco]

After completing some recent upgrades, took the Bronco into a nearby service station for an alignment / readout. The printer wasn't working, but the caster was about a -2.8. Based on what I've read, this isn't optimal.

I don't need everything dialed in perfect but I would like to get the numbers (cost effectively) into the reasonable range. The guy that did the alignment was nice enough but was clear that messing around with the caster and what could be done was out of his area of expertise.

Appreciate the input. Thank you.

 

[Rustytruck]

I see your front axle C-bushings are already polyurethane do you know what degree the bushings are? If they are 2 or 4 degree you can go up to 7 degree bushings which will help some. That's the easiest and the cheapest thing to do.

 

[WILDHORSES]

How does it drive down the road?

Jim

 

[BGBronco]

It drives well enough in town. Need to get it going at 55 or so and see what happens. This definitely won't be going on a long Interstate drive so thats about where I need it dialed in.

How does it drive down the road?

Jim

 

[B RON CO]

Hi, negative caster is not optimal, it is terrible. Is there any way he could have meant positive and said negative by mistake? I would think that if you had negative caster the steering would need constant corrections, and get worse at higher speeds. What work have you done, and was the alignment done on a modern computer laser front end machine? Good luck

 

[Apogee]

Wow...negative caster! Fun stuff! Maybe the C-bushings are upside down, but regardless, you want 3-5 degrees of positive caster IMO.

 

[bmc69]

Wow...negative caster! Fun stuff! Maybe the C-bushings are upside down, but regardless, you want 3-5 degrees of positive caster IMO.

That ^. Absolutely. I typically go for 6 degrees if I'm going to be running larger tires.

 

[Justafordguy]

Sounds like the C bushing could be upside down. Get some 7 degree bushings and install them correctly.

 

[Broncobowsher]

Looks like old poly bushings and new springs.

How much lift did it have before?
How much with the new springs?

Short answer, put the 7° poly bushings in and check the results. The 7° bushings are as much of an easy fix as you can do. More is possible, but it takes a lot more work to get it.

 

[BGBronco]

He said and wrote negative. It had a larger lift before, at least 4" maybe more. The poly bushing are from the previous lift.

 

[WILDHORSES]

This is why I ask how does it drive. As it has been pointed out it should drive terrible with negative caster.

You can eyeball caster if you follow this method. You won't know what degree but you should be able to tell neg vs pos.

Bronco sitting on level ground not jacked up.
Hopefully you have enough room to stick your head over the top of the front tire and look straight down. Imagine a straight vertical line right at the center. You are looking down on that vertical line. Now imagine a line drawn through the upper and lower ball joints or king pins.

If those two imaginary lines are exactly the same you have 0 (zero) caster.
If the line at the top is forward of the vertical line that is positive (bad)
If the line at the top is to the rear of the vertical line that is negative (good)

Good caster for the sake of this discussion 4-9 degrees positive is noticeable when you look down from the top of the tires.

See pic, tilt your head 90 degrees to the left;D. it's a 76/77 D44 but the principle applies to all. I can see this D44 has positive caster.

How does it drive? If it goes down the hwy at 75 and you feel in control I don't care what the numbers are the caster must be good. Just saying, peace out.

Jim

 

[Rustytruck]

Its even easier to check with a magnetic protractor attached under the bottom ball joint.

 

[DirtDonk]

It had a larger lift before, at least 4" maybe more. The poly bushing are from the previous lift.

So what lift is in it now? And if it's still in the 3.5" range (which is looks like by the way) you should have a dropped pitman arm and a dropped trackbar bracket. Even more important before, with it's taller lift.
It should have them either way. Surprised it didn't have them before, because they're considered mandatory items for anything over 2.5" of lift.
You can clearly see the angle on the links is too steep.

All this leads to the surprised sounds coming from out here when you say it drives ok so far. Most people with those specs are here posting up questions on how to stay alive while driving their Broncos!

Good luck with yours. Glad it's driving well now, whether it's got good specs or not.
Maybe the dual steering stabilizers really are helping!

Paul

 

[BGBronco]

It has a new WH 2.5" lift. I agree it looks higher, not sure why but starting to look into that. Thank you.

So what lift is in it now? And if it's still in the 3.5" range (which is looks like by the way) you should have a dropped pitman arm and a dropped trackbar bracket. Even more important before, with it's taller lift.
It should have them either way. Surprised it didn't have them before, because they're considered mandatory items for anything over 2.5" of lift.
You can clearly see the angle on the links is too steep.

All this leads to the surprised sounds coming from out here when you say it drives ok so far. Most people with those specs are here posting up questions on how to stay alive while driving their Broncos!

Good luck with yours. Glad it's driving well now, whether it's got good specs or not.
Maybe the dual steering stabilizers really are helping!

Paul

 

[gddyap]

Just drive in reverse.

I agree with check the bushings.

 

[DirtDonk]

Measure between the top of the axle tube and the bottom of the frame rail. In the front you should see somewhere around 9.5" for a 2.5" lift.

But no matter what, if you find that it does not drive well at speed or, as you get more used to driving it around town, decide that it really doesn't feel that great at slow speeds either, you should get the pitman arm and bracket.
While most still insist that you don't need them for 2.5" of lift, many members here have found that to be not quite true with their Broncos. Once installed the manners changed.

I'm driving around with 2.5" and no drops as an experiment and it drives passably well. But not as well as my other Bronco with 3.5" of lift. It's not exactly unsafe, but it's not perfect either and I don't like it. And have the drops waiting to go on for that reason.
Hope my theory pans out and it gets rid of the little loosy-goosy feelings.

Paul

 

[BGBronco]

Paul - I was thinking about your comments and maybe it's not good but simply just passable like you said.

The reality is that I'm really just driving it on short trips around town at 40 MPH or so and I also don't have a good frame of reference for how it should drive.

I guess I just need to forget all the nightmare posts I've read about removing the pitman arm and just do it.

Thank you.

 

[DirtDonk]

...I guess I just need to forget all the nightmare posts I've read about removing the pitman arm and just do it.

No, what you need to do is get out and actually drive it to see if it needs anything. If it drives well, then don't do a thing.
Now, if it turns out to be not-so-good after all, then you can worry about adding the dropped pitman arm AND trackbar bracket.

And what nightmares have you heard? I don't remember any trouble other than finding a puller that's the right size for a truck pitman arm. Otherwise they usually come right off.
If it's writeups from people that don't use the right tools or procedures, then those don't count.;D
General thin wall jaw-pullers won't cut it. A too-small arm puller won't cut it. Trying to pry one off with just the normal garage tools won't cut it. A hammer won't cut it.
You need to start soaking it in penetrating oil yesterday, keep a couple of large hammers handy and just get the right tool.
See? Nightmares cured.

Paul

 

[BGBronco]

OK. Did an assessment and it's basically fine at 45 - 50 as a driver in town but at 50 or so on a 2 lane country road not where I want it to be. I really think I need to build to 70 stability at 70, knowing that I'll never be headed down the interstate.

Based on feedback, Drop Pitman, Adjustable drag link and 7 degree C bushings, anything else? What's the priority list?

Thank you.

 

[B RON CO]

Hi, as mentioned, I think caster is the biggest issue, but you need the alignment done again after all the work is done. I have a drop Trac bar bracket which is a well in item. As Paul said, the pitman arm will come right off with a pitman arm puller, no substitute. Good luck