Spring over??? Spring behind???

[Jbird]

I got a bit of a wonderment here that I thought one of you old timey guys runnin their old timey dropped front axle suspensions could esplain for me. Is there an advantage in mounting the spring behind the axle vs over the axle. I wanna run a four link radius rod setup & I'm building my own axle beam. Any advice will be rewarded with praise. Jbird

[Grandadeo]

Oh sorry, I thought this was going to be about Daylight Savings Time.

Lee

[Bib_Overalls]

I'm not sure there is an advantage either way.  Spring over works best when you are using a stock 28-34 Ford crossmember. A traditional setup.

Spring behind is more closely associated with T-Buckets and other rods with fabricated frames.

You can get four bar batwings with provisions for a spring behind.  You say you are making your own axle.  Make sure your axle - batwing - spring configuration leaves room for the tie rod, panhard rod, and drag link.  A lot of components competing for the same space.

[Carnut]

I got a bit of a wonderment here that I thought one of you old timey guys runnin their old timey dropped front axle suspensions could esplain for me. Is there an advantage in mounting the spring behind the axle vs over the axle. I wanna run a four link radius rod setup & I'm building my own axle beam. Any advice will be rewarded with praise. Jbird

Spring behind axle results in lower spring mount with a standard or small dropped axle, if you don't mind the suicide configuration of behind mount.

Spring over axle obviously means spring mount will be higher and will need a larger amount of dropped axle to lower ride height.

[Dave]

T buckets use em a lot.. Just the way it is i guess. Id only consider it for height reasons but if you look  at a lot of t's with tube axles and hair pins with welded hair pin mounts on the axle you will get a better idea of why the t's run a lot of axles this way.. Money comes into play also. Its cheaper to do it with welded components on the axle .. If you ever get to look at the 32 4 dr that Jon Hall from michigan built and can look at the axle set up look very close.. Its actually got an axle with a rear mounted spring on a deuce chassis :!: .. some day im gonna do a chassis like that.. Its really cool and gets you down way low..
Dave    

[GPster]

I'll do something dumb (again)I'll suggest a little geometry into the situation. I would think there would be a difference in spring rate. The axel set-up is going to operate in a radius around the radius rod or four bar hangers on the frame. Probably the four bar length which is generally shorter than a wishbone will cancel some of the effect. If the axel moves up-and-down 3" then the spring on top of the axel will be deflecting 3". With the spring behind the axel a 3" axel movement will bring less spring deflection because it's in a shorter radius. The length of the wishbones or the shortness of the four bars or how far the spring is behind the axel are all going to give different results in spring rates. If you look at rear suspensions compare an early '50s Oldsmobile with long arms and coils behind  axel. Then look at late '60s Chevy trucks with long arms and the coils in front of the axel or '60s and newer coil rear suspensions with short arms and coils in front of the axel. I figure all are designed for an effect or the effect was placed and they had to design for it. Pieces may not just fall together and there may be some hidden trial-and-error to tune it but if you're going to build the axel you can probably sort it out. Bob Paulin could explain it better I'm sure because he would look at it even finer for tuning shocks. GPster

[enjenjo]

The further apart the springs are, the better the ride. Thats the reason Ford went to a spring ahead front, spring behind rear in 35.

[unklian]

Spring behind allows the rails to be lower,without a tall Bulldog perch.

[Jbird]

Thank you gentlemen, and you Team Smart members too..... Good boys,,,, good boys. Is that enough praise?

I'm going spring behind with a reinforced spring perch. I should be able to hide my mini steering rack under the spring.   Jbird