spring perch bones and caster

[Jeff]

I am tying to set up my front end at this point. I set the frame with the perch at zero degrees. My wish bones are slightly negative at this point, so I will need to take at least 1 1/2 inch off the rear mounting bracket to get close to allow them to be level when rod is on the ground and weighted with the perch at zero degrees. It looks like the frame rake is about right. I will have to do some final checking on the rear though. I think I am trying for 3+ degrees of caster. Any pointers you all could pass along. I my have to get some different mounting brackets. So-Cal has a couple different heights. Right now I am 4 3/8 with speedways but can cut them down some without a problem. So-Cal has a 1 7/8 and a 7/8 i think. I still need to measure how much the wishbones are up in the front from level now. Not too much but they are. So I know how much I need to raise the rear to be level with the frame when weighted on the ground.

 

[2old2fast]

Jeff , I'm trying real hard to understand what you're asking..... that 'bones don't have to be level , from a functional standpoint ....or even w/the frame....front axle caster ....usually these cars use anywhere from 5*-10* neg caster..... it seems "to me" that you're looking at "parts" & not the whole picture.... slow down , take a breath , &try to focus on what you're trying to ask .......
dave

 

[Jeff]

Ok I am trying to figure where the bones need to be to get the caster that I need using what is built in to the bones? I got a figure of 5 to 7 off another site on the web. Was looking to get the split range around 6. Good to know I can use as much as 10 degrees though. Right now my bones are slightly pointed up at the axel and should raise another 1 to 1 1/2 inches when the frame is loaded and on the ground. I don't think I can get away with that and get the caster that is needed? I am wondering if I take the upward measurement difference from the just behind the forged axle mount and rear mounting position on the bones and add 1 1/2 inches, then cut that much off my rear mount if I will be close to right on caster. or should I set the perch at say 7 degrees and go from there and adjust frame rake? The frame was set up for a four inch drop axle I only have about 3 inches on mine and want to use a set of 14 inch tires and wheels that I have.

 

[old round fart]

With the frame at the rake angle you want the spring perch should be about 7 to 9 degrees higher in the front (the caster angle you want) so you are not twisting the spring pack to get your caster. At that point you look at where the wish bones rear anchor point is and make your rear brackets. You may need to pie slice the bones to make the angle look like you want then to look.

 

[RPM]

We take a pie cut section out of the bones to tilt the axle back about 7 degrees, then weld it back. Now what kind of a spring shackle set up do you have? Usually you have to tilt the perch back 7 degrees also.

 

[2old2fast]

Too many words.... angle of frame , a.k.a. rake needs to be decided 1st... then frame height... then frt. axle ... then setup you're frt axle w/ the bones attached...you want neg. caster [top of kingpin laid back]... then the rear mounting of the bones.. so the arc the frt axle swings at is complimentary to the spring mounted angle [usually 90*] the caster is set by "pie cutting" the bones & welding them up.... it helps if you have mock up tires & wheels or make some out of plywood disc's to mimic the ouside dia. of the tires...
this is really difficult to explain w/out being able to create drawings , maybe someone w/those capabilities will jump in......
dave
My only other suggestion is for you to read &study suspension so you'll understand why things are done the way they are....
some guys type way faster than me

 

[stroker]

I don't think you can set all of your alignment figures at the point of your build that you seem to be at. What you are doing to figure the caster, rake, etc. can only be preliminary at this point. The actual numbers will come about only after you get everything put together. Engine/transmission weight and position, total weight, and spring rates will all enter in. What you are doing now is a great start on the ultimate stance of your Bucket, and something that many builders don't consider. You seem to have a good handle on where you are going.

 

[Zandoz]

Too many words.... angle of frame , a.k.a. rake needs to be decided 1st... then frame height... then frt. axle ... then setup you're frt axle w/ the bones attached...you want neg. caster [top of kingpin laid back]... then the rear mounting of the bones.. so the arc the frt axle swings at is complimentary to the spring mounted angle [usually 90*] the caster is set by "pie cutting" the bones & welding them up.... it helps if you have mock up tires & wheels or make some out of plywood disc's to mimic the ouside dia. of the tires...
this is really difficult to explain w/out being able to create drawings , maybe someone w/those capabilities will jump in......
dave
My only other suggestion is for you to read &study suspension so you'll understand why things are done the way they are....
some guys type way faster than me

Am I wrong, or do adjustable perches like this

simplify the need for precise specific initial layout....and allow dialing in after all is together?

I'm going to be using them, and plan on positioning the bracketry to set the caster at approximately 5°, with the frame at the target rake...then fine tuning once everything is together with the bar adjusters (or in the OP's case, cutting the bones). Am I off base with this plan?

 

[choppinczech]

My Speedway bones have caster built in. So my perch is kicked up 7°, my spring and shackles hang off of the bones at 7°, and the bones themselves are level to the ground.



But you can see here where I had to play with the location of the rear mounts to get it right.

 

[choppedtop]

That is what I have on my front end, with the exception that the adjustable part mounts to the batwings instead of to the perch. Same thing, just different. They allow caster to be adjusted somewhat without having the spring mount set at the caster used. I am set at 7 degrees of caster. If you had hairpins, it would be simpler to set up than with the bones, but bones are cool.
Lee

 

[PotvinGuy]

But you can see here where I had to play with the location of the rear mounts to get it right.

Whose primo body is that?

 

[Jeff]

Many questions in my mind have been answered thanks to all and for the great photos and useful information. Right now my bones are hanging about like the ones in the Choppinczech, but free hung with no frame load and perch at 0* with speedway 4 3/8 inch mounts. I pretty much am at the frame rake I want. I am using Speedways bones with pivots behind the axle, so spring angle should be ok? or could I put say a 1/4 inch say 7* milled spacer on top of the spring? How much of my tie rod end should I leave out for adjustment. 1/2 inch?

 

[Jeff]

Choppin could I get some photos of your radiator install? I have a 32 grill shell I would like to use. My frame is not z'd but front is about the same. You have a great looking ride there.

 

[choppinczech]

I ended up having to make my hangers just 2° because my frame is wide.




My radiator shell is a wider version of the glass '32 shell I'd bought. I needed a shell to match the shape of the firewall and the size of the Northern universal radiator.



Shell plug.




Shell reproduced in glass and mounted.




The cross flow radiator has a channel built into it's top and bottom. I used those to mount it. I'll make my intake manifold the fill point.






Then made a fan shroud.

 

[EX JUNK]

Your glass work is outstanding as is everything else that you've done on your car. You are a true craftsman.

Jim

 

[choppinczech]

Thanks Jim, kudos from fellow builders is the most appreciated!

 

[Jeff]

Many thanks for the helpful photos. It's always good to be able to get a clearer picture of how it's done and figure out what can be adapted to your situation to make it work. Your work is breath taking to the eye. Should be a real show stopper when done.

 

[Dan Noecker]

Hey Choppinczech,
I am over in the Fresno area. Would you be open to me visiting you? I would sure like to see your project.
I appreciate your consideration,
Dan

 

[choppinczech]

Hey Choppinczech,
I am over in the Fresno area. Would you be open to me visiting you? I would sure like to see your project.
I appreciate your consideration,
Dan

PM me.