wishbone suicide - attaching perches

[phils]

I am attaching spring perches to my 37-40 wishbones. See attached pic. I had to slightly oversize the holes to be able to move the perches around to get my alignment true.

Since I am 5" away from the axle, I am wondering if there is enough strength in the bones to support the perch (speedway) if I just welded it as it is now in this pic?

Or I was thinking...maybe I should:
A.) weld a thick walled tube inside the wishbone, then insert & weld the perch.
B.) cut some 1/8" thick plates on each side that are maybe 2" x 4 or 5" long to help support the perch first to the bones, then weld the perches to the bones?
.........or do you think A/B is not needed.

I've been searching through past posts and have seen some neat ways to attach. Thanks in advance for any better ideas/suggestions that you could share with me.
Phil

 

[Blue Eyed Devil]

Sleeve the wishbone and then weld. Also make sure your spring is pre-loaded when you set the distance on the perches or you will constantly bottom out...

 

[phils]

Preloading the spring

Thanks for your input!

another question....You're recommending that I 'preload the spring' prior to welding the perches in place...would the way to do that is to get the tubes welded in place, then set the car's weight on the spring, then adjust the perches in and out so the shackles are at their normal ride angle of 45 degrees?

Before you suggested that, I was thinking that if I had the perches on 'an even plane' with the leaf spring eyes with the 1-3/4 centerline distance (shackle) between them, when I went to put the weight of the car on it, it should settle in at 45 degrees?

 

[fuzz]

BLD..is correct but it is very hard to get the weight of the car on the spring, cuz usually the car isn't complete so the weight won't be right plus you have to support the ends of the spring ect..
I would do like you are thinking..put the spring, shackles and perches together so that the shackles are level with the perchs and spring eye..tack perches and put the cars weight on it, the shackles should then be at about 45 degrees downward toward the spring. If the shackle angle isn't right then you adjust the point where you mount the perch.
If your spring is too soft the shackles will swing past 45 degrees, too stiff and the shackles won't swing down to 45 degrees..hope I'm makin myself clear.

 

[phils]

Here's what I'm thinking

My machist buddy turned the perches down last night so we have the same thickness all away across the part. We'll then make a close tolerance fit tube for each perch and I'll set them up and weld the perch tube into the wishbones. Then I'll insert the perches into the tubes and put some washers on it and tighten down the bolt, attach the shackles, and then go ahead and put the weight of the car down onto the spring (the car is complete and has everything in it).
If I get a 45 degree on the shackle, and jump on it a little to make sure she has the right bounce, and clearance issues are a go.....I should be good to go, I think?

 

[phils]

FINALLY....I got to this point where I could tack weld the tubes in the wishbones, insert the spring perches, add some washers on the other side & nut AND put the car's weight down on the spring......Problem (I think), the shackles are sitting about 75 degrees and not 45 degrees like I was hoping for. Nothing is hitting or binding on the spring/shackles as it travels up & down.
If I only had another 3/16 - 1/4" on each side to move the spring perches OUT further, I would have had everything perfectly parallel when there is no weight on the car! I don't dare trim back any more on the perches in order to do this. The cars sits right at the height I want and the caster came in at 6 degrees (so I got those parts right). anyways.....now I am thinking I can either return this 31" spring and exchange it for a 30" spring and re-adjust the shackles inward to get the 'perfect' fit, so the shackles are closer to 45 degrees when the weight is on it.....or is this close enough, finish up the welds and run it?

(BTW - This is a pic of my wishbones after splitting them, extending them & drilling some holes. That, and having the axle bent back to spec & drilled......plus doing the buick brake trick is why it took me so long to get back to my spring portion of this project)

 

[Blue Eyed Devil]

I know it sucks now but go with the 30" spring. It will suck a whole lot less than bottoming out every time you hit a bump, which is what is going to happen if you leave it like that. There is just not enough travel in those shackles to be effective. You are really close and everything else looks good, so take the time and make it right. Double check your wheelbase before you burn it in too. The only other thing I can see maybe being a problem when you get the shackle right is the proximity of the axle to the frame. If it gets even close to hitting it would be good insurance to put a small C-notch in it for clearance. Looking good man...

 

[phils]

R'cd this private message and I thought this person brought up some intersting discussion points on the setup I am building. Here's his meassge:

When I started on my learning curve I wanted to do a set up sorta like you are doing . Most of the time this type set up-spring attached to the bones-is done in order to push the axle out ahead of the frame , it is the look I was after . My research led to the following:all bones are not the same , some are thicker and therefore stronger, none were designed to support the weight of a frame and an engine , they were designed to keep the axle in line , the force/stress exerted on them is front to back ,not up and down . Most examples of this type set up have been beefed up with metal added to strengthen the bones. Most guys split the bones and run them parallel to the frame ,the same as hair pins do. This makes the spring perch go on to the bones at an slmost 90 degree angle , reduceing the stress on that most critical point of the set up . In the picture it looks like you axle is under the frame in about the stock position so you did not need to use the bones to acheive a certain look . Not trying to rain on your parade here , it looks like hitting a pothole at say 60 MPH could cause that very thin joint where the bone meets the spring perch to snap' If that happened you would go end over end for sure . Why dont you PM Don -Dons Rods- and ask for pics of the way he did his . He has done it ,where as i have not- i just decided to pass on building something that looked like a potential serious accident causer .


Here's my thoughts:
I did read thru Don's posts/pics on how he did his front suspension and am borrowing his idea on the perches, themselves...although, I am attaching them slightly different than he did, as he built/welded in reinforced/attachment plates underneath the wishboness.
The bones appear pretty sturdy (1937-40). From what I have read about Ford stock bones and in my first posting, my concern was the mounting point of the spring perches being further back from the solid portion of the bones. I also thought about the angle I am entering into the bones because they are still located under the car. I wanted to utilize my 1947 axle and because the wishbone attaches further out then most, I could not run the bones almost parellel to the frmae and mount them into the outside or underneath the frames (could not turn the wheels). Thats why they are mounted in the almost stock location near the tranny mount. I believe they refer to this spring-behind-axle setup as a suicide frontend for reasons you stated. I also feel the holes drilled in it and 3/16" wall tubes welded in, helped make the bones a little stronger than stock? But, I too am wondering about other ways I can 'beef up' the attachment point. If the perches did fail, I think the frame would just drop on top of the axle as the axle (of course, I will attach some frame bumpers). The axle doesn't sit outside the front of the frame like I see some of the '28-34 type setups I see built and posted on this forum and others.

BUt I'm no expert and appreciate any and ALL input. That's one of the reasons I am hanging-out at this board, hoping some of the knowledgeable folks here can share there experience with me & anyone else contemplating building a similar setup.
The last thing I want to do is build an unsafe car.

Sorry for the long post....Sure would appreciate any other thoughts on this!

 

[IAM-LDS-2]

some thoughts on the subject at hand

some thoughts on the subject at hand

R'cd this private message and I thought this person brought up some intersting discussion points on the setup I am building. Here's his meassge:

When I started on my learning curve I wanted to do a set up sorta like you are doing . Most of the time this type set up-spring attached to the bones-is done in order to push the axle out ahead of the frame , it is the look I was after . My research led to the following:all bones are not the same , some are thicker and therefore stronger, none were designed to support the weight of a frame and an engine , they were designed to keep the axle in line , the force/stress exerted on them is front to back ,not up and down . Most examples of this type set up have been beefed up with metal added to strengthen the bones. Most guys split the bones and run them parallel to the frame ,the same as hair pins do. This makes the spring perch go on to the bones at an slmost 90 degree angle , reduceing the stress on that most critical point of the set up . In the picture it looks like you axle is under the frame in about the stock position so you did not need to use the bones to acheive a certain look . Not trying to rain on your parade here , it looks like hitting a pothole at say 60 MPH could cause that very thin joint where the bone meets the spring perch to snap' If that happened you would go end over end for sure . Why dont you PM Don -Dons Rods- and ask for pics of the way he did his . He has done it ,where as i have not- i just decided to pass on building something that looked like a potential serious accident causer .


Here's my thoughts:
I did read thru Don's posts/pics on how he did his front suspension and am borrowing his idea on the perches, themselves...although, I am attaching them slightly different than he did, as he built/welded in reinforced/attachment plates underneath the wishboness.

I would think the reinforced/attachment plates are the key to making the bones sturdy enough to work safely .


The bones appear pretty sturdy (1937-40)

That's like saying a weld is good bcause it appears to be so . Even an experienced "eye " can't tell by looking


I also thought about the angle I am entering into the bones because they are still located under the car

What did you think ? The angle looks a bit "shakey" ? I think you were right to question the angle
. I wanted to utilize my 1947 axle and because the wishbone attaches further out then most, I could not run the bones almost parellel to the frmae and mount them into the outside or underneath the frames (could not turn the wheels). Thats why they are mounted in the almost stock location near the tranny mount.


Taking this into account is there a reason you didn't mount the spring over the top of the axle -as in stock location "

I believe they refer to this spring-behind-axle setup as a suicide frontend for reasons you stated.

If the axle and spring are mounted ahead of the frame ,with no frame horns it would be considered a suicide set up .


I also feel the holes drilled in it and 3/16" wall tubes welded in, helped make the bones a little stronger than stock

This may or may not be the case . Loading them until they break is the only way to know for sure .


But, I too am wondering about other ways I can 'beef up' the attachment point. If the perches did fail, I think the frame would just drop on top of the axle

Yes the frame would "just " drop on top of the axle , but the broken perch and the spring would drop down - maybe on or into the pavement .


the fact that your discussing a perch failure - perches do not fail in their stock location - would make me leery of using this set up.

BUt I'm no expert and appreciate any and ALL input. That's one of the reasons I am hanging-out at this board, hoping some of the knowledgeable folks here can share there experience with me & anyone else contemplating building a similar setup.
The last thing I want to do is build an unsafe car.


Excellent thinking , any time a person re engineers something the auto makers spend lots of dollars and time developing they are entering uncharted waters...Sure would appreciate any other thoughts on this!