suspension building question

[796spdbu]

Hey guys hope you can help me with a design problem.I know this is a little off camber for this site but, I have nowhere else to turn.Here goes,I'm building a frame from scratch for a 57' chevy truck(told you it was off camber).I have all ready built the rails to which i installed a MII front suspension.The question is this,the factory frame was 6" tall,I used 2x4x3/16 box tubing.So as you can see the frame is 2'' shorter than stock,then to make things even better the cab is about 2'' lower than the factory frame.Now i'm 4" beloow the new frame.Heres the problem,I want to install a 4-link.The truck will be a air ride system(this is why i'm here among talent,the truck site guys are all about laying frame not handling).As i figure it,the lower bars,in order to be parelle will be well below the frame.I would have to built some kind of bracket that would be 5''-6'' below the frame.The rear frame behind the rear cab mounts kicks up 1.5".Can a 4-link work properly if the lower bars run up hill.The bars will be 32.5".Should I make the uppers shorter?Will this work properly or am i dome from the start?the truck will be a daily driver,so the suspension has to work properly.I know that most of you on here are track guys,but who better to ask.I want to make sure it is over enginnered.I also know that a 57' truck is a brick and not race car by any means.All i want to do is make a chassis that is far better in design and hanlding than a 57' was ever intended to do.

[astroracer]

Read my response in this thread...
https://www.pro-touring.com/forum/showthread.php?t=15861
You state right up front that this truck will be a daily driver. Leaf springs are simple and they will do the job for a street driver. I hope you won't completely ignore them as an option. They are an excellant choice for a cheap, simple to build, good handling suspension.
Mark

[DonQuehotey]

You do not want your upper bars heading up hill towards the frame if your lowers are parallel with the ground. This will place your instant center somewhere behind the truck. You want the bars to come towards each other as they approach the frame. Now if you want to get technical about it, you can do a little reserch on "IC" instant center and figure out how it effects the geometry when it is moved. Jerry Bickell has a chassis book out which can give you a good start on four link geometry.

[796spdbu]

first astro racer,I agree that leave springs are low mantiance.Second,my delima is that if i go leave springs it seems as if there is about the same fabrication invovled.then if i want to haul a trailer then i have to add air springs any way so here i am with the delima again.I know round track parts suppliers have easy to mount spring hangers and shackles/sliders that would be awsome but if I have to fab up brackets to add air spring helpers why not go all the way with a four link.
Don i may have mislead you its the lower bars that are going to be running up hill.I have learned alot by reading and listening to people that post on here and not asking dumb questions knowing that they will be answered sooner or later.I got a handle on I.C. but I have oredered the chassis book you recomened.I have designed the frame to be as close to the origanal as i can (by ther way i did not have a stock frame to modify if any one is wondering,it was just a good body).The problem is that the frame is now shorter in height than the origanal frame demensions that I have found.The lower bars will need to be 5-6 inches lower than the rise in the frame be hind the cab(were the rear frame is 1.5 inches higher than the section under the cab to get the bed to line up with the cab).If i lower the mounts that low at ride hieght they will be almost as low as the bottom of the cab.That means no scrub line in the case of emergency.I'm not worried about punchering a air spring as much as i am worried about a flat tire.I know the bump stops i have desidned wil prevent the truck from digging into the ground if i cut an air spring.That problem is solved.i hope this will clear any confussion.Thanks