Spring mounted to split wishbone? Sound engineering?

I'm planning on running an un-dropped axle and split bones on my roadster. I wanna achieve lowiring by mounting it suicide style in front of the spring ala-spenser...

I know Shine did this as well as lots of other folks and it works fine but something about it bothers me a little from an enginering perspective. Part of it being that as the spring moves up and down it might tend to push or pull on the bones. I'm not sure this is a huge problem but I'd just like to here what some of you think about the setup.

I know a lot of you run it with no problems so you don't necessarily need to tell me about how happy you are with it.

I love the look but before I build a purpose-built frame I want to make sure I'm doing it right.

Also if it is a good setup, where's the best place to attach the spring? Also how long does the forged 'bung' at the front of the wishbone extend up into the tube?

 

the bung goes back about 3 inches on a 46 bone,i put a tube, with the taper to suit the perch pin machined inside, through the bone, this way you can let the suspension settle, then torque the perch pin at the angle the sring pack wants to sit at. is that easy to follow? heres a pic anyway. just had a thought.. you could press a bronze bush through the tube and allow the perch to move in th tube to allow for any twisting ,but i dont think there would be enough rotation to justify it. if it was two degrees over the full travel i would be suprised.
the truth is i still dont know if what i have built is sound engineering or not. give me a year on the road and ill have a better idea...

 

Id say you are wooried for nothing,Kilroy....
Worrying is sometimes a good thing tho -It makes us re think what we thought we knew.
I'd guess the thrust laterally is minimul and would rather concern my worry with the twisting of the leaf spring[in conjunction with the axles twist]....... however slight that might be.
my axle is ahead of the spring about 1-1/2"[spring mounted in the crossmember]

 

lowsquire-
I've been wondering about this setup for a while because I plan to run it on my truck almost exactly the way you did it.

I have specifically been wondering about letting the perch pivot inside the wishbone, but I think the front end geometry, specifically the caster (camber? I always mix the two up), would change too much as the spring cycles.

which perches did you use for your setup? And where did you get the tube with the taper?

thanks,
dan

 

Leaf springs can twist small amounts with no problems.

Consider a parallel leaf rear suspension.
When you jack up one side,the axle stays flat on the ground as the body lifts,
which causes both springs to twist.
Same thing when the body rolls going around a corner,or you hit a bump with one wheel.

When the spring is mounted behind the axle,the transverse leaf does not push out on the 'bones.
All the load is straight down.It could only push out against the bones if you didn't run any shackles.

 

I am a licensed hot rod engineer and I say mount that bitch up.

I mean....... If done correctly it will work fine. Puts a bit more stress on the wishbones, but I wouldn't be concerned with it unless you mount the perches waaaaaay back. If you want to sketch something up, I'll give you my engineering .02 on it.

 

I am using this same setup on my Touring. The shackle mount has just a hint of "pivot", not enough to even be considered. For strength, I used thickwall DOM bungs in the bones and drilled them so they catch the cast end of the bone AND the tubing. V'd the DOM and the hole and welded them up. THe cast part was a couple inches back into the tube, you can see the weld joint usually. Sorry, pics are at work.

For reference, mine looks like Lowsquires.

 

Don't get too hung up on the engineering theory......It's hot roddin!! Lots of rods been built just that way going way back!!
Good luck,
Jon

 

I am planning the same set up using 48 rear wishbones modified to fir the front econoline axle. My concern is if the wall thickness in the wishbones is sufficient. My thinking is I will need to reinforce the area where I fabricate the spring mount but I don't want some huge ugly overkill stuff on there to make it safe.

 

I didn't build it, but my car has been on the road for several years with this set up. the perch is welded on under the bone for an even lower stance. and pivots in the mount.

 

2

 

When using this type of spring mount would there be any extra pressure put on the rod end and/or mount that would be enough to worry about? Just wondering.
Max

 

I aint no genius, but I wouldn't think so. People have been doing this for years without any problems. build it extra stong to be sure. I plan on redoing the front of mine insead of using a bracket and perch i plan to build the whole thing out of square tubing. Like in the May 04 issue of street rodder "Low Salt Dish". a real bitchin way to do it. I love the way the frontend of that car is setup. sorry about the crappy pic. I aint got a scanner, so its a pic of my mag.

 

this hasn't seen any road testing yet, but it should work ok

 

I was wondering if that set up from 60's style was going to make it on here. It looks very nice in person and should be more than strong enough.
Eric

 

Kilroy, If you ever need help with any of that stuff (tools&equipment) you can come by the shop anytime.
Jimmy White

 

if i remember correctly Levis Classic's setup is quite similar to the one 60s Style just posted. looks PLENTY strong to me.

 

to answer your questions, they are orig ford perches i believe, had the thread extended further up the shaft by a machine shop and cut them off. the tubes were made by them too. i cut the holes with a friends roto broach in a drill press. to get the angle correct i assembled the whole front end on the car,as the holes were 4mm oversize, and tacked them inplace, the blew it apart and welded them up. im sure thay are strong enough, although if that worries you go with 60's styles' brackets, they are bombproof!
teh only concern with my set up is if the spring breaks, the broken end of the spring would flick down and lock the steering cross shaft, theres always something thats gonna kill you, might as well be your hot rod.

 

here is my version

 

Thanks guys. I'm gonna do it!!

Not sure how yet though...

Mr. White...

Dude! Thanks a lot. I'll definately take you up on the offer. Very generous...

Thanks,
Phil

 

Bttt...

 

Yeah man, no problem I was thinking you might want to tig weld those bungs in. Just give me a call, I am also usually there on saturdays.
Jimmy White

 

heres mine on the last truck, as low as you can it. drilled through wishbone, and double welded.

 

[ QUOTE ]
this hasn't seen any road testing yet, but it should work ok

[/ QUOTE ]

60's Style,

That setup should work great. The stress is evenly distributed and the load is at the end of the member. Im thinking it's as good as Henry made it.

BTW I'll be stealing that idea when I get the opportunity.

 

kilroy, don't know if your still awake, but I can't call you and my cell is broken, I'll try calling you anout 8:00 when I leave and will be going right by your work, if not we can meet up later this week, sorry for the bad cell phone breakage timing

 

When you run a set up like this, and use a dropped axle, and deep drop steering arms that go below the bone, how much clearance should you have between the tie rod and the frame?

 

48 rear bones? I'd pass on that. Since you are using an Econoline axle why dont yoy fabricate some weld on batwings with integrated "spring behind" perches. You will need to fabricate hair pins or some other kind of radius rod strong enough to handle the torque of full braking. Those 48 rear bones are not up to that. In my humble opinion.

 

Just bumping this up, I'm starting my frame build this weekend and I need some advice on how much frame to tie rod clearance I'll need when running a set up like this.
Thanks!
Steve