Suspension Geometry for tube chassis?

[Sirshredalot]

Ive got a few questions.

When working with a tube chassis, or really any chassis, in concern to the front suspension, What is the importance of everything being even or parallel?
Ive seen Cars before with one control arm slightly further back than the one on the opposite side and was wondering if this was because someone didnt measure right or if there is an advantage to this.

Also...Does anyone know any hard and fast ways to set up a ladder bar set up?...Just so I can get close?

Is there a benefit of mounting the bars higher or lower on the rear axle?
IS there traction to be gained be mounting the coil-overs in front or behind the axle?

God bless
-Shred

[cjbiagi]

Unless you are building a purpose built race car I would want everything pretty much even on both sides of the car. Some cars, like NASCAR will have different alignment settings because they are only turning left. If you are building a car that will be driven on the street keep things equal.

[NixVegaGT]

I was going to say the same thing. I've seen circle track and dirt track with some pretty crazy asymmetrical suspension geometry. I got a great book about building custom suspension geometry. It was pretty great. I'll see if I can find it and post what the title is. GOod stuff.

[chevyart]

hey shred most important thing about ladder bar setups that i know is to be sure that they are exactly parallel to each other, and initially setup and welded in parallell to the ground(level) the actual height that they are tucked under the car probably doesnt matter, and anyway there is never much room to mount then up high in chassis, go to the drags and look and they are always hugging the ground. there are usually 2 or 3 holes in front mounting bracket to slightly adjust the front heighth of bar to change how hard you want the tires to hit, but probably 95% of bars you look at are probably just about dead level. shocks and coilovers are usually allways mounted behind the axels. absorbs the weight transfer better being further back. ive heard of earlier pro stock guys experimenting with the coilovers and shocks in front of the axle, but i dont think this is a practical way for the average racer or street car..also be advised that ladder bars on a street car make that back end very very rigid and unflexable, probably be better off with a 4 link with poly bushings for the streety( if this is where your car is going to be most of the time. these are my beliefs and i could be wrong. anyone else care to add to this good luck Wes. hope this post helps. your posts always help me. just the other day i trimmed down my header flanges to make installation easier, as you had suggested to me a while ago thanks chevy art

[Sirshredalot]

Thanks for all the replies...Ive built quite a few engine combos, but this is my first time tackling major chassis stuff.

I feel bad asking this because its probably not for the monza...its for the 57 I bought. I'll post some pictures in the off topic forum once I get some taken. Its pretty cool though.
When I was welding up some mounts in the front I notices that the passenger side upper control arm is about 3/4-1" farther back than the drivers side. Ifigure it wont be that big of a deal...the rest of the chassis is pretty well done...but maybe the chassis was tweaked.

IM probably gonna go with a monza style rear suspension anyway since that is what I am the most familiar with...so lower control arms and Torque arm here I come...Ive already got the springs...I'll probably just rob the other stuff off the monza and fab the brackets.

IM going to gut the monza anyway.

You guys rock.

God bless
-Shred

[Astre-mutt]

Shred, the reason for the front control arms not being parallel, is to give a drag race car a little more roll in the lights. This lets the car get a little bit of a running start, with out red lighting.

[spyder_xlch]

Shred, the reason for the front control arms not being parallel, is to give a drag race car a little more roll in the lights. This lets the car get a little bit of a running start, with out red lighting.

Never heard that before and not sure how it would work. Wouldn't the tire that sits out further trip the light anyway?

[Astre-mutt]

Matt, the front tire brakes the beem, then doesn't show the car as leaving until the second tire passes through. Same principle as using larger diameter tires , but one step further. Not sure if there is a real advantage in times, but could help prevent a red light or two.

[spyder_xlch]

I've never drag raced (legally) so it may sound like a dumb question but, when you stag the tire breaks the beam, and then when you leave the line the beam is unbroken again and that's when the timer starts?

[Astre-mutt]

I've never drag raced (legally) so it may sound like a dumb question but, when you stag the tire breaks the beam, and then when you leave the line the beam is unbroken again and that's when the timer starts?

Time starts when the light turns green. Time from green light to when the tires leave beam, is your reaction time. (which is part of your elapsed time) Because most cars can't react in hundreds of a second, you actually start before the green light. (aka cutting a light) How much in advance you start to leave is based on how quickly your car reacts, and how much roll your car has. Roll is how far you can move forward, with out leaving the beam. You can get more roll by either having larger diameter tires, and or staggered suspension.

[Sirshredalot]

But how does that affect the performance of the chassis?
Does it dog leg?

I bought a full race chassis 57 chevy and its front control arms are like this...about an inch staggered.

I was wondering if this was a mistake but the rest of the chassis was so well done that I was hesitant to think so.

God bless
-Shred

[chevyart]

hey wes if you are really thinking ladder bar, then check out the competition engineering(Moroso) ladder link bar. they have that bottom link that lets you adjust the bar without taking the bar loose and then having that nasty time using a jack to, line up the ho;e again to put the bolt back in. you can call their tech guys for free and get educated, and they also have the custom shop that can make you up any special pieces that you may need. ive been bojiving with the guys out there for almost 20 years noiw and they are really helpful. years ago my friend out there named dan emerson made my spark plug wires up to my exact size request( iam so fussy). all their products are readilly available from summit. good luck with your projects chevy art

[spyder_xlch]

Thanks Scott for the explination. It would make sence to stagger the front tires then.
Wes, I doubt it would effect anything as long as you are going straight. As long as your alignment is set correctly. Circle track where you're only turning left it might help you turn too just like sprint cars with a larger outside tire on the rear. Road courses and street driving might not be the best but I'd give it a try. If it corners or handles funny on the street you could always get a chassis shop to move the control arms.

[Astre-mutt]

I would think street handling wouldn't be an issue. It mite turn a little better one way, or the other. Then again how much handling would you expect out of a drag chassis. You'll probably have narrow front tires, with tall rear tires plus ladder bar suspension. An inch, plus or minus in wheel base wouldn't make a big difference.

Shred, doesn't the chassis already have the rear ladder bars mounts welded on? If not then you should be able to find exact measurements for a 55-57 Chevy. If they haven't found the instant center buy now, then they never will. Below is a pic of an S&W racing rear ladder bar kit for the Tri-5's. It shows how they think it should look.

[Sirshredalot]

The frame rails are not the original ones. The rear frame rails are about 22 inches apart.

There are no mounts of any kind in the rear end for suspension or anything....just formed frame rails.

I am not sure if I want to go ladder bar or torque arm yet.

As soon as I get motivated to freeze by butt off and take some pictures I'll post them.

God bless
-Shred

1957 chevy 002.jpg

1957 chevy 002.jpg

1957 chevy 002.jpg