Technical Setting up a transverse rear spring suspension

Blue One, Just curious, what are you running for a front suspension on this build?

 

I didn't have enough time to read all the posts yet, but I had to muddle my way through this when I set up the rear suspension on my bucket. I had trouble with it, too; it's still not done btw. Anyway, the spring rates for the springs Speedway sells are published on their site. And if it's any consolation, my "high arch" spring was made in the USA.

 

^Wonderful. I'm headed back to my catalogs, then. Many thanx, Gary

 

I hear what you are saying, I'm just being my sarcastic self. One final question then? Do you think Henry and the Ford boys did it by trial / error / fine tuning, or is there some engineering / math at work here that we all just haven't fingered out yet? Gary

 

Sooooooo
If I'm reading the chart correctly it means a big bunch of nothing since the model a spring hangers are at 49" . Where's the info on weight growth and distance once it's installed in the perches. That's what you need to know - Who ever developed that chart and bothered to print it missed the entire point of providing something useful. If you tried to apply that type of compression force into A spring rate decision you'll be confused.

 

Agreed - the table is marginally helpful, especially since it's not an exact reproduction of an A spring. If I remember correctly, the table was included with instructions to help you determine your spring perch width. For example, their "high arch" spring is 39.5" eye-eye with no weight. You then estimate your vehicle weight over the rear spring....since it's designed for a T bucket, those numbers are pretty small. I had no idea, so I guessed something like 500lbs, which stretches the 39.5" to 42"ish. Then you add in the distance of your shackles - 1.5" x 2 - to get where the spring perches on your rear axle go, so 45". That's what I did. Seems to have worked. Like everyone else has said, it's a guessing game, and you add/subtract leaves to tailor a 45* shackle angle with everything in the car, including you, fuel, battery, etc. And I know you know all these things, just spelling it out for others... What really sucked was trying to figure out pinion angle and ladder bar design along with guessing spring hanger width....

 

Here's the frame bare with the maverick rear , and no cross members.
8" total height kick up.
Then the rear with the quick change mounted.
(The tires and wheels are gone, they are being replaced by 500-16 and 700-16 Excelsiors)

 

One with the car All done - outside from the rear dead on.
The view that the guy behind you would have ?

 

With a transverse spring I would imagine you're gonna have to redo your exhaust tips.... You could probably keep your 4-link.... someone with more experience may say otherwise - listen to them not me. You'd also most likely have a notch in your bed for the crossmember, which cuts into your space, and you'd have to figure shocks, too. You could probably locate your shocks where your coilovers are, but it all depends on where your spring hangers need to be. I would leave it as is; it's a nice design and will be easier to accurately dial in.

 

Model A rear spring perches go at 49"

 

So their spring is much narrower. And it has fewer leaves/less load capacity. My axle housing is narrow enough that I don't know if I could have gotten away with a stock A spring width. Interesting.

 

Sorry, don't have one of those. This is the best I can do

 

By "narrower" do you mean -
The total length of the spring main leave from eye to eye measured along the curves is shorter?

Because eye to eye distance with out including the arch height means nothing.
And if the spring is shorter total length along the curves did the reduce the arch height or keep the height the same ? By keeping the arch height the same it would require shorter perch distance to maintain ride height, or did they reduce the arch height which would lower the ride height when installed in stock perch mounts at 49"

 

The biggest issue is that your shocks and transverse spring will want to be in the same place should you rename and reuse the coil over mounts to shock mounts.

Should you opt for the whole set up with friction shocks as pictured in the first post or move the shocks it should be pretty straight forward for a guy with your skills a bunch more wow back there to match the rest of the build.

 

This really is being over thought. It's not rocket science. I've built dozens of early Ford frames and many had Model-A rear springs. Basically you just reverse engineer Fords design and it'll work. A Model-A rear spring needs perches at least the distance apart which the Model-A has. It'll work nicely on 35-36 perches too. It'll even stretch to the 42-48 perch width although I do relieve the leaves a bit for them. You'll need to build or buy a very strong spring spreader to install it. Be careful it's very dangerous. If it's too hard later you can remove a leaf later. 7 leaves for a roadster. Make sure all longer leaves are present. Tighten the U-bolts very tight.

 

As far as the spring spreader I used my cheap hydraulic port a power, coarse this only works if you don't have revered eye's!

 

Front suspension is So Cal 4" dropped and drilled (drilled by me) forged front axle and transverse spring mounted suicide style to the sides of the bones, along with MT products Lincoln drum brakes.

 

I guess I just use the engineering Ford put into them. I always figured Ford had something right with spring rates. I take the measurements from a stocker, figure out what ride height I want and adjust from there by raising the cross member or lowering the perches and reversing the eyes if needed. 9 times out of 10 ride quality is good. Minor adjustments are easy by taking or adding a leaf or spacer.

 

Sound advice ! That's the approach I use too.

 

That's all there is to it! Really that it.

And it makes perfect sense to anyone who's done it before or at least have a stock unit to measure and modify from. With out that stocker in front of you it's hard. Most are trying to build something a little at a time as funds trickle in without everything they need to get started. Like starting out building a frame,,,,, Collecting stuff before hand without knowing what's the right stuff get provides you with shelves full of parts you're not going to use.

 

This one should be easy to make the modifications, since the car is a roller with the majority of the weight in place and the desired stance determined. Quite different than starting from scratch, with many variables.

 

You have a point, most the time I'm starting with more or less a complete chassis. You really don't have to have a stocker in front of you, I've been known to crawl under a car at a show (owners permission of course) with tape measure and note pad in hand. Here again with the internet today I'll bet you could get the measurements you need easy enough. If you asked on here what is the distance between the frame and axle as well as how far apart the perches are on a stock A you'd have an answer shortly, most the time that would be all you need.
The guys building with a collection of unknown or mismatched sourced parts from a swap would be a different ball game for sure, trial and error comes into play then.

 

Kool shit Marty as usual. Great craftsmanship.

Larry great craftsmanship too but you need to decide what you are building. A retro '50s or a '60s +. You keep changing. 9", banjo quick change. Disks, Drums. Coil overs, A spring. Your spinning your wheels. You'll never get this fucker on the road. But then maybe that's what it's all about.

Your friend Gary

 

What I'm trying to build Gary is not really to a specific target period.
I'm trying to build a fun and neat car to drive and have fun with.
Even with coil overs it will hit my target.
Sure my build has evolved over time but I have made changes to suit my tastes and budget.
I'm doing this entire thing pretty much by myself in my little 2 car garage and I will eventually get it done.
I'm going to stop making changes real soon as I do want to finish this thing
Larry

 

Sorry Larry sometimes I get in a mood. You'll end up with a kool kar whatever you do.

Gary

 

I get what you're saying. I don't have a complete A spring to compare it to, but I know when I borrowed some A leaves to add to the Speedway spring in hopes of some altitude, the leaves were not at all the same shape - similar but not. Anyway, I don't think you can compare Speedway's spring to an A spring... I can't see stretching the spring I have to 48" perches, even just the main leaf. Anyway, I won't derail this thread anymore. Carry on....

 

is that a stock A rear spring? I'm gonna run the same setup but will be moving my perches inward 1.5" each side, ill get a spring shop to shorten the spring the same on each side, and flip the eyes to the top

 

Glad to see this thread again... I'm either going to purchase a frame with the buggy spring rear already installed or just screw the whole deal and go to a 3 link / coil overs / watts link. I'm pretty sure I'd screw the leaf spring deal up on my own. Gary

 

I sort of like the coil over gig. I'd find some older units and rock that shit.

 

Great information
Thanks guys!