Suspension Travel

[redtailboa]

Hello , I've been working on a 38 ford pick up , chopped top ,custom frame ,4 link rear , 9 inch rear and 37 ford suicide front , i have the front all together now i will only have about one inch clearance from top of axle to bottom of frame . I'm looking to find out how much suspension travel or clearance is needed when everything is put together before i decide how to fix my problem , either switch too spring over axle , longer spring perches , clearance frame a little more . Thanks

 

[Toad]

Looks a little too close for comfort and that's before the load from the engine and trans!


Toad

 

[05snopro440]

You probably want at least 3" clearance. I'd say go more like 5". Keep in mind that the axle can tilt as well. The last thing you want is to contact the axle with the frame, you'll be replacing a lot of parts. Looks to me like the best bet would be to increase the height of your Z and move your spring mount down.

 

[Blue Eyed Devil]

Ooooh... No worky.

Honest advice? Keep your juice spindles and go to a spring over or spring behind axle setup. Those later setups just aren't meant to be used like that. Sorry to be the bearer of bad news, but that's a no go...

 

[Old Iron]

The area in front of the cross tubing needs to be cut off and the top and bottom of the frame blended into the tubing. That will give you clearance you need without doing anything else.

 

[redtailboa]

Thanks for the advice guys . I ended up extending the spring perch a little and cutting off the front of frame to clearance the axle , like Old Iron suggested . This is my first open wheel build and have learned alot from the site

 

[Blue Eyed Devil]

The other problem I am seeing here is the perch design. Where the spring mounts is just a flat piece of plate, and presents a major weak point. The way it is currently constructed will flex under normal driving conditions, and then it will break. Remember, the entire weight of the front half of the car is resting on that point. It needs some serious gusseting, especially if you have extended it even further.

 

[Old Iron]

Where the spring mounts is just a flat piece of plate, and presents a major weak point. The way it is currently constructed will flex under normal driving conditions, and then it will break.

I hadn't even paid attention to that part but, you are correct. It needs a vertical plate on each side welded on top of the perch plate

 

[forbigpicture]

More idea's for you redtail...

https://www.google.com/search?q=sui...dcQ9QEwAHoECAcQBA#imgrc=Avc_gyPX8B_vvM:&vet=1

 

[Dr Crankenstein]

Beef up that perch, for sure!

I also strongly suggest you reinforce your cut wishbones. Weld the pie cuts and weld a "fish plate" over the affected area, like this...

Do not square cut these plates. The pointed "diamond" ends serve to eliminate "stress risers", which you'll have with straight vertical cuts and welds...

.

 

[redtailboa]

i Used 3/8 plate to make the mount , do you think i still need to reinforce the top plate ? The wisbones where just cut to fit the axle in place , I usually just tack weld things first until i have everything fitting nice . Couple pics of what it looks like now

 

[Tripper]

i Used 3/8 plate to make the mount , do you think i still need to reinforce the top plate ?

Yes! I like to think of it this way... they don't call it a suicide front end for nothing. On something that important... l suggest gussets! I would put some cool looking plates on both sides of your top plate!

BoB

 

[Dr Crankenstein]

Your perch needs some "backbone" as Old Iron and Blue Eyed Devil said. From fbp's link, this design is far superior to a flat plate, no matter the thickness...

Again, do not compromise the integrity of your wishbones. Sleeve or fish plate as I described...


.

 

[Blue Eyed Devil]

do you think i still need to reinforce the top plate?

I don't think, I know.

The weight of a complete vehicle coupled with a working suspension will bend a flat piece of 3/8 plate like BUTTER.

Scale it down for an example - Take a flat strip of sheet metal in your hands. Bends pretty easy on the flat right? Now turn it up vertical and try to bend it - not so easy. That's with your hands and a thin piece of metal. The same concept applies with a heavy vehicle and a thick piece of metal.

Reinforce the perch.

 

[05snopro440]

The guys are 100% right. I marked up a photo to explain why they're saying what they are. The blue arrow is the force being placed on your steel plate, (in an upward direction), and the green lines are the distance between that force and the next support point. When a force is applied to a component away from the nearest support point, this creates a bending force shown by the red curved arrow (in engineering terms it's called a bending moment). If you held the plate with two fingers (one on either edge) and pushed up on the plate the same distance away, the plate would spin. Since the plate is fixed on one end in your case, you're putting a big bending force into that plate that increases and decreases as the suspension loads on it, which also results in cyclic stress and can result in fatigue especially in a poor design.

Make no mistake, this design needs attention before it can be considered safe, as you are at risk of not only bending the plate but can fatigue and crack it and you're testing fate as it is.

The gussets that OI showed should be added at a minimum.

 

[redtailboa]

Thanks everyone . My problem is trying to use the front end i bought . I intended on buying a nice front end and brake kit but 1500 US turns in 3000 Can by the time it gets to me . my first design was round perch ,but did not look right ,too stretched out . . So would adding the gussets on top be ok ,or should i redo everything like in the pic posted . The problem is having the spring out front and no travel for axle .

 

[05snopro440]

Thanks everyone . My problem is trying to use the front end i bought . I intended on buying a nice front end and brake kit but 1500 US turns in 3000 Can by the time it gets to me . my first design was round perch ,but did not look right ,too stretched out . . So would adding the gussets on top be ok ,or should i redo everything like in the pic posted . The problem is having the spring out front and no travel for axle .

I'm from Canada as well, after you factor in the exchange I'm not sure where the extra $1000 comes from, but I get it. The exchange right now and shipping is killer. Sometimes the cheapest thing you can do is spend money on better parts

Gusseting the bracket you have should alleviate most of our concerns with the design, but as was mentioned you need to plate where you've pie cut your wish bones as well.