Front Suspension Design

[GMracer]

So I'm reworking my front suspension ideas in CAD currently. And what I've done so far is map out the points on my spindle, now these spindles are McGaughys 2" drop spindles for 99-06 silverados. I know I could just raise my suspension up, (like I did currently) which puts it at a stock stand point, but I'm curious if I could optimize this spindle to perform better and have better camber gain in the turns. Also since all the balljoints and tierod enter from the top I'm contemplating swapping the LCA and tierod to enter from the bottom. Which allows the LCA and steering rack to be mounted lower on the chassis, thus allow the engine to be lower.
I have the CAD file for my spindle, it's nothing crazy just a rough sketch with all my important points laid out from the front and side. As far as the caster angles I didn't lay it out with them, but stock is about 5*

the file is a dwg file. I'm interested in anyones thoughts and opinions.

Also the reason I'm sticking with this spindle (or my stock spindle, shorter in height) is because I want to run Wilwoods 16" rotors. I don't know of any other spindle that will allow me to do so. Besides the c10 I believe.

[ATOMonkey]

I can't open your file, but there are a couple of ways to enhance you handling by changing A-arm length and mounting points without changing the spindle.

Look into buying a book that describes instant centers and advanced suspension design.

[GMracer]

I'm well aware there is, I'm not asking how. Just looking to open the floor to see if anyone had some good advice, maybe something I'm not seeing that could help. My KPI is about 12* so I know that isn't helping me. Which if I build a spindle I could fix that issue.

[JRouche]

I kinda dont get what you are asking. My fault.

I see this that you wrote. " but I'm curious if I could optimize this spindle to perform better and have better camber gain in the turns."

Im not sure what you mean by optimizing your spindle. I couldnt open up the drawing either. I have MC, AC, SWs and DWG editor and all of them refused to open the file. So I cant see what you have drawn up. What did you use to create the drawing?

But Im sure you are aware that the control arms have a major impact on camber gain. So Id still like to see your drawing. Ill try again when I get upstairs off this laptop and on the desktop. It has some better software. JR

[ATOMonkey]

Well, IMO, it's easier to change A-arm length and mounting points than it is to cut and weld spindles.

That's just my opinion though.

Any changes you make on the spindle can be mirrored on the control arms.

[monteboy84]

You guys who can't open the file, you need to save the ZIP to your computer, and then extract it to access the DWG, before opening it in Autocad. I had no problem.

If I'm understanding your drawing correctly, it's a view straight on from the front of the control arm arrangement, with the 3 red lines representing the UCA, LCA, and tie rod? If this is correct, I'd shorten the C-C length of your tie rod, to lessen the bumpsteer. As it stands, you're going to see more bumpsteer than you want. Of course, I could be completely misunderstanding your diagram/drawing.

I LOVE your project BTW, very impressive....

[Twisted Minis]

Hello, I know you will laugh to see me posting here as well.

Anyways, I like to start with the spindle and move in from there. So if you don't want to build a new spindle, I would run with the one you have and work in from there. If you want to build a spindle that sets your scrub right in line with the center of the tire, great, now you have a new starting point and probably have to change everything. Most of what that scrub is going to do for you is to make your steering feel lighter, or more effortless. It's not the most important thing, but it is nice. We recently worked on a 69 Vette. The scrub on that car was about 1" inside the tire. The car handles okay, it's probably going to eat tires though, but the steering feels slightly heavy with power steering. I can't remember if you have power steering or not. If your scrub is about an inch of the center of your wheel, you will probably be happy. If you are intent on changing it though (I know the feeling, I started new spindles for one of my projects), I would probably start by modifying your existing spindle before building a new one. I'm modifying the hell out of an S10 spindle right now to put on a Mercedes, and essentially I just wanted it for the brakes I can put together.

[monteboy84]

You guys who can't open the file, you need to save the ZIP to your computer, and then extract it to access the DWG, before opening it in Autocad. I had no problem.

It's impossible to know if your spindle design is correct, without knowing your upper and lower control arm pickup points.

[GMracer]

Seth, currently my scrub is about .5" due to the offset of the wheel. But the KPI is 12* which is why I've thought about building new... however most likely I'm going to stick with what I got.

Monteboy, there are no pick up points right now... the chassis would be designed around that. I'm going to get what I can and then post up my final results for review.

[Twisted Minis]

Honestly you will probably be happy with .5" on your scrub. Are you building another frame? If you are looking for more camber gain, some people run a taller spindle or extended ball joint. You could build a modified spindle with a little more height to them (like the stock ones?) and add a little bit more KPI at the same time.

[GMracer]

I'm not sure, I really do want to build another frame. Call me crazy haha, but this time I designed it before I would build it and optimize strong points. Right now I feel like my backhalf won't be strong enough without a cage.

The spindle I have now is actually taller than stock, but maybe if I shorten my SAL it may help out. From what I've seen 12* of KPI is TOO much and should be somewhere between 5-10*

[Twisted Minis]

Do you own Tune To Win? If you are going to do another frame I would read that a few times. It will give you a good idea.

A stock S10 is about 5 degrees on the KPI, the spindles I am building right now are about 10 degrees. I never really heard that 12 would be a bad number, although I do get that at some point it can be too much and the tire will roll a lot in turns. But if you look at some pre runner stuff (I know different design forum) they sometimes are running as much as 20 degrees. They focus on making the scrub work to make the steering as effortless as it can be since they have wide tires, and then design the rest around the spindle. I would think you could do the same.

[GMracer]

Yea, that's true. And I do own Engineer to Win, Complete Car Suspension and Chassis Engineering. I go some good ideas, this chassis came out great... for my first one off but I know where I can improve and I want this truck to be perfect.

[Twisted Minis]

Get Tune To Win. It focuses more on the suspension design and build than his other book, and it is much better than Herb Adams book. I don't know about the Complete Car Suspension book though, haven't read it.

[GMracer]

I swear I ordered tune to win too, oh well. More the merrier