New Guy has a Question About Caster

[Rande]

Hello out there! Name is Rande, I live in southeastern Minnesota (Winona). I am not building a Tbucket but I am using a Tbucket style frame. I hope you don't mind my asking a few qustions here.I have read many threads about caster via the search function. Have learned much. Thanks to all the guys that are willing to share and educate. but, even with the searches and reading, i find I need some advice.

I am using a suicide style front with spring over axle, perch under spring. Long harpins (Speedway "Curtis"). During the frame build, my brother got a little ahead himself and fully welded the, then, tacked on perch. We hadn't yet gotten the front caster set. Measured it today with a simple angle gauge. The round ones with the hanging pointer.
Measured at the top of the kingpin and the top plate at the perch. Same 2* at each location so the spring is inline with the kingpins.

So, I have 2* of caster. Not enough from my reading here. I undestand that I can set the caster by adjusting the clevis's on the batwings or lowering the rear of the hairpins or, I would guess, a combination of the two.

The info that I am concerened about and have not found during my search is: How far can I adjust the caster via the clevis and/or hairpin methods before I begin to twist the spring and deflect the rubber bushings in the springs too much? From my reading, I am aiming at 7*. That's a 5* change. This seems a bit much. My reading suggests these adjustments should be used for fine tuning and the perch should be the main dictator of caster. I'm thinking a 5* change is beyond fine adjustment.

The frame is, as yet, unpainted. I am thinking its best to cut the perch off and reweld at 7*. The frame is presently sitting on the axles and tires at near its ride height and angle. It will settle some when the steel truck cab and wood flatbed are mounted. I will approximate that weight tomorrow when I go back to the shop (60miles away) before we do anything.

Now, for more general info, here is a link to the HAMB where I have an old thread with pics of what I am building. http://www.jalopyjournal.com/forum/showthread.php?t=325728&highlight=strep

It presently looks like a ratrod but that is not what its going to be. It will be painted (with shiny paint!) and dressed up a bit. If it comes out looking ugly, that will be inadvertant, not a design goal. If you look it over, I'd apreciate any feedback as to any concerns about the frame and suspension construction.

I have read that it would be preferable to have the drag link and tie rod mounted above the steering arms, I'm going to look into that tomorrow.

Any help you can offer would be greatly apprciated. This is my first hotrod build.

 

[Youngster]

I like to set the perch at 5 degrees from level on a loaded chassis. You can adjust with your clevis' but 3 degrees might cause a situation where you wouldn't have enough threads left in contact. When you adjust you run the top ones in and the bottom one out. You won't twist the spring but you will put the shackle in a bind.

If your chassis was in my shop, I would remove the perch and re-do it. When I build a frame I tack the front perch to the cross member and the bat wings to the axle till I can add enough weight to simulate the chassis loaded then finial weld. The frame, front and rear suspensions are the foundation of your car. As such do what ever it takes to get them as close to spec as possible.

Just my $.02.

Ron

 

[RPM]

The perch need to be on an angle. The angle should be what ever amount of caster you want. That will keep everything from binding up. If need be you can shorten up those radius rods to make sure you have enough thread in them.

 

[Rande]

I figured that cutting the perch off and repositioning it would be the best solution. My brother is suggesting a wedge shaped shim to tilt the spring (and axle) while leaving the perch as is. I saw this done in one of the threads I read but since the frame is not yet completed or painted, I'm going to cut the perch free. Nice thing about metal, it can be cut and rewelded.

Now, how far is too far for adjusting the caster via the clevis's so I don't bind things up?

One more thing, I am planning for a panhard rod. I am using a shackle at each end of the spring and cross-steering. Seems a panhard rod is a good idea.

 

[one finger john]

The perch need to be on an angle. The angle should be what ever amount of caster you want. That will keep everything from binding up. If need be you can shorten up those radius rods to make sure you have enough thread in them.

Geeze, I think that's a little far back to mount the cab. But if that's the style you want to go with .... via con Dios. I would really like to see the finished product.

John

 

[Rande]

You don't like the slingshot look?

Here's what I have for a front end. We're working on the shock mounts and now the perch tomorrow. I'll be using hydro shocks.

 

[Rande]

Here is what the truck is looking like right now. Still ratrodish but it'll change.

I know this is not what you normally have here but you guys have the experience with these front ends. I have go where the expertise is. I hope you guys don't mind a bit of "off topic" discussion.

 

[one finger john]

Like the six.

 

[Rande]

2 too short...its an eight!

 

[Youngster]

Nice project. I sent you a PM.

Ron

 

[one finger john]

2 too short...its an eight!

Even better. There were different cu. in. Buicks, how big?

 

[Rande]

Even better. There were different cu. in. Buicks, how big?

Its a 1950 263. Found it in a garage where a fellow had been building a boat-tail speedster from scratch. He was unable to finish his project and I got the engine.

 

[Ted Brown]

I myself would leave the caster at 2 degrees for now, (when all is said and done, it may end up to be even more, even though it is really not needed) you can drive 180 MPH using 2 degrees Caster with no problems...
A suicide front end is one where the spring is behind the axle, the reason it was called that is because if you broke a spring, the frame would want to fall on the ground, this way it only falls to the axle... I like your build, the 6 banger looks real good with that pickup cab...

 

[old round fart]

With the spring over the axle you can get a different shackle mount that is adjustable and you won't need to change the perch at all.

http://www.speedwaymotors.com/Forged-Adjustable-Spring-Perches,2080.html

 

[putz]

I agree with Ted but if need be they have shims for rear wheel aignment that you could use between spring mount and spring. Suprising how thin of a shim it takes to change.

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These are available at orielys in a lot of different styles that kinda tell how much they change alignment.

 

[Rande]

Well, we made a 5* shim (the perch was already at 2*). Welded a thick rectangular chunk of steel to some tubing, clamped it in the bandsaw at 5* and let it cut. Worked fine. No possibility of it shifting. We then reset the hairpins and we're at 7*. We decided to do it this way so we can change the caster angle with the clevis adjustments or by changing the shim if need be.

It was reading old threads via the search function that gave us the idea.