Short Arm Long Arm front independent suspension

[Prometheus]

Hello everyone. Long time reader first time poster.

I have found this site very informitive. But I have not found much information about what I am going to ask.

Background information:
I am planning a full custom build from the ground up. I want to design and build a Short arm long arm front suspension (unequal A-arm). I plan on making my own A-arms out of 1.5" OD .12 wall DOM Mild steel tubing. As far as the steering knuckle I plan on using one from a production vehicle. I am still in the research/planning phase of my build and am examining steering knuckles for a Ford Ranger, Chevy S10, Ford Escort, etc. (Light/compact vehicles).

Question #1: Has anyone ever used the steering knuckle from a production vehicle in a front SALA suspension, and if so what did you use? Other thoughts on this question is what kind of travel can I expect out of a production vehicles ball joints. I would have to do some research on this. I plan on using FOA 2.0 coilover shocks front and back. I would like 12-14" tire travel in the front. I am in the process of modeling my build in Inventor to make sure everything clears, and survives some FEA simulations.

Question #2: Since I am planning on using a production vehicles steering knuckle I will buy the hub, rotor, and calipers that fit the assembly. I will also buy the master brake cylinder (no booster) to apply the brakes. Has anyone used production vehicle disc brakes for their buggy build?

Question #3: I am planning on buying a 3x3 trailing arm kit from Appletreeauto. Does anyone know of any production vehicle 5 lug hubs to mount onto the swing arms that fit the splines of a 930 cv spindle?

Thanks in advance for any help.

[Mr. Unpopular]

My friends and I are planning something similar. We are doing a traditional A-arm setup (all long arms). What are the advantages of the SLA?

We are planning to use Chevy S10 spindles and ball joints for a few reasons:

1: We run S10 4wd hubs on the rear of the buggy with custom arms. We cut the S10 drive axle in half, weld it to an inner bus axle half. My friend uses Caddy rotors and calipers, but S10's would also work fine. No problems with stopping a 4 seat rail from 90mph with 32" tires on it and no front brakes.

2: Since we use S10 hubs in the rear (albeit splined 4wd versions) we want to use the same in the front, this way one spare hub will work at all 4 corners of the car (as long as you carry a splined hub as your spare).

3: We plan to use S10 ball joints and have measured 45 degrees total angle. The nice thing about S10 ball joints is they have a flat flange that bolts to the control arm. So we just need to build A-arms with a flat plate at the end to bolt the ball joints to. Another easy field fix.

I have drawn our basic design in CAD, and keeping front width less than 80", and having the arms almost meet in the middle of the frame, we get 26" of travel.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV

[DHale_510]

SLA front suspensions have advantages and disadvantages;

+ They are great for building in camber gain. This works well to keep the tire in full contact as the car leans over.
+ They can be made as light as the car requires, whatever that may be.
+ They are generally very adjustable for camber and caster.
+ They can be made to travel long distances.
_ They have lots of parts to maintain.
_ They have lots of adjustments to "readjust".
_ They have lots of parts to bend and break.
_ They have lots of parts to buy.
_ Long travel SLAs have weird camber "gain" at the extremes. Usually you need equal length arms for this, then bump steer issues are a problem.

The trick with picking a spindle [not just for SLA] is to determine what you want for Ackerman. This is the way the car responds when turning. Generally zero Ackerman is desirable unless you have a GOOD reason to do something else. This is where the imaginary lines from the tire patch/ball joint centers and through the steering joints converge at the center of the rear axle. Most production cars have longer wheelbases and their spindles mess up the Ackerman angles when adapted. Reverse mounting really screws things up. I won't tell how I "learned" this.....

Buggies are very light. VW trailing arms have nearly zero rear camber gain and nearly zero body roll, so have no need for SLA design. Camber is of little concern off road [except when you tuck under a swing axle!], but bump steer and durability are very important. That's why the antique VW system has worked so well for so long here. It's simple. strong and does what is most important. Cheaply.
Maybe equal length arms are good [see the really high buck cars and trucks now being built] IF they are strong enough and If center load steering is used. And IF you want/need/can afford 24" of front travel. Oh, and you need more than 3x3 rear arms to match that 24" of travel, and you likely want as much or more rear as front travel, or know why not.
Unfortunately these are not parts you can get from a 4wd truck, but if you can do it I'm ready to change my mind on everything above in a minute.

[Prometheus]

Thank you both for the replys.

Florida_Buggy, If you have some pics of what you have accomplished I would like to see them.

DHale_510, you are not the first person to raise the issue about the Ackerman. I will have to investigate this further. I don't know much about the topic. You are making me second guess making a SLA front suspension. Although if I do go with the VW front trailing arms suspension I will probably be spending the same amount of money trying to achieve a 12-14 inch of travel.

All, I would like to use a production vehicles brakes because they are better built and more affordable. I wonder if I could build my own steering knuckle out of some plate steel and press fit/weld a spindle into it that will recieve a production vehicles hub.

I am going to start another thread about using a production vehicles brakes on a dune buggy. I will post the link if you all care to join/contribute to the discussion.

[Prometheus]

The brake thread I started.
http://www.thesamba.com/vw/forum/viewtopic.php?p=5179421#5179421

[Chuck Lewis]

Florida Buggy,
Can you give some details on the welding of the axles?
Thanks, Chuck

[Mr. Unpopular]

The S10 axle and bus axle were very close in diameter. We slid some pipe over the axle, centered over the joint, and welded it up. Before sliding it over the axle, we put some holes in it in various spots to plug weld, then ran a full bead at either end. I had my doubts that it would hold up, but no problems so far, and he runs the buggy pretty hard. He even bent the crap out of one of the rear arms and the axle was fine.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV