Hot Rods Do you have to pie cut wishbones on the king pin end???

If I find that the spring doesn't sit in the crossmember just right, I heat & bend the spring perches till it is.

 

ENess,
That is a doable solution, when you are using a stock type of cross member it becomes a problem, you would infact need to heat and twist the entire cross member without knocking your chassis out of wack.

Sometimes when you heat and bend a mount like say a suicide perch you weaken it to a point that it will keep bending itself with the stress of bouncing down the road.

Another solution is to shim the spring to get your proper angle. You would in that case use a shim that was cut like a wedge so that it moved one side of the spring more than the other.

 

Are you using cross steer or side steer? It is important that the total geometry is calculated to avoid bump steer. There have been several threads on the H.A.M.B. describing "death wobble" from a first person account. Most of the cases were the result of design faults. Front end geometry is the most critical factor that effects handling and safety. Whereever you go, you are following the front end.

 

A lot of really good points here, but let's go back to the beginning. Have you put a protractor on your king pins yet to see how much caster you have?

 

You can pie cut them as a last resort if your front crossmember is welded in good. With the 37-41 bones I also have seen guys flip them over so where the original spring hanger was would now be on the bottom.

 

From what I see it looks like there is negative caster in it...not a good thing. The next easiest thing I see to do is cut the rear bone mount and lower/move back and/or Look at shortening the bones. this seems the easiest re[air to me. The spring is unaligned because the axle is pushed too far forward.

 

you can see where I cut them before I welded them up...

 

Split bones are a compromise at best. You need to consider both end at the same time. The rear mounting point is just as important as the front. Pie cytting allows the correct angle to insure that the instant center is correct for the steering used. The caster is only a function of kingpin angle. Adjusting caster by moving the rear bone attachment point will probably cause a conflict in geometry and result in an ill handling car. Set your front axle, shim the spring to the caster angle and then fabricate the bones to fit the correct suspension geometry.

 

Son of a gun,... That don't look like a 1935 & up wishbone , it looks like a 1932 or 33/34 (same as on my buddies A Coupe on the previous page),....turned upside down and a notch taken out so you can run it upside down? Should have been flipped over and not cut.

Below is a picture of a 1932-33/34 wishbone setting the right way,.. with plenty of compensation for caster.


To Illustrate this point this might help,... (still feeling the effects of the Meds,...)


The top wishbone is a Model A,.. There was a very low mounting position for it from the factory,.. so you can see there is practically no compensation for caster.

Second from the top is 1932-1933/34 you can see there is caster built in,...

1935-40 and then 1941-48 Same deal.

 

They where model A big truck and I was just showing the picture of where to pie cut the end of a wishbone... and they work just fine......

 

I think that one of the things we are missing here is that cutting the bone and rewelding it is a step that you take to get it to lay correctly. You can use it to change the caster but the real function of cutting the bone is to get the rear mount where you want it to lay.

The bulk of your steering geometry should be built into the original build of the chassis then the bone will serve its original finction that is to locate the axle and keep it from leaving its location when you apply force to it.

 

Okay, there are so many replies going on here, so I'll try to simplify my question I'm talking about leaning the top my axle back towards the motor. As you can see in my pics the spring wants to unstack and the shackle wants to bind. The answer sounds like re weld in my cross member with a few degrees of negative caster or put a shim on top of my spring and then cut the wishbones accordingly????????

 

One of the best quotes ever!

 

Redo your cross member to get the spring at the angle you want. Then see if you have to pie cut your wishbones to match that angle.

You don't want the spring at one angle with a cut wishbone pulling the axle to another angle, you want everything to line up and be at the same angle.

Cut the bones so that you can get the rear of the bones in a position where it looks good on the car.

Pie cutting them is about trying to make it look right and not winding up with the bones mounted six inches from the bottom of the chassis.

 

you can buy a set of adjustable spring perches that will allow you to adjust the camber of the axle without binding the spring ..... then you don't have to cut out your crossmember.

 

I have to do a pie cut on the bones for a chassis build for my '30 coupe, is the perch end cast or forged? How about re-welding it together, was it factory butt welded or is the end slid into the tube?
Thanks guys

 

on the ones i've messed with they are slid in a couple inches...i cut mine in the tube not the casting. not sure about cast or forged...there is a flashing seam about 3/8" wide in the center but that can come from either

 

Shortening, camber adjust, repair of Ford wishbones!

Here is a link to a thread i did on adjusting the caster.

 

WOW!! Looks like an easy mod. I was thinking it would be an aggravation to do! Thanks for the input and will post pics when I do it.
Thanks again
Steve

 

Just want to add for any "beginner" welders;
Finding out it wasn't "It's safe if done properly" is a real bitch.

 

I cut the bones last night, pretty easy with a thin-blade right angle grinder on the weld. Needs an insert to re-weld safely though, took all of a half hour to do it.