Super Beetle single A arm front suspension.

[The Pirate]

Ok thanks for the tip.

[volkdent]

What sort of steering rack changes have you made to compensate for the change in lower pivot point for the control arms?

Jason

[The Pirate]

So far I have made none. As it stands the free program I got refuses to unzip so I trashed it. Going to purchase some new software.

I have been working it out on paper for now. Took a ton of measurements ect ect.

The pivot points aren't so much lower as they are farther out. From what I am seeing so far the roll centes will not move to much out of their original planes. The spindle and ball joint are still in the same locations and thus far see no conflict with the rack at all. Everthing looks like it will clear at full drop and at full compression along with all increments in between.

Will have some pics of the drawings up soon.

[volkdent]

The inner pivots on the tie rods will have to be moved out accordingly then. You will have bump steer issues otherwise.

Jason

[The Pirate]

Hmmm. A conflict has come up. I built the suspension in mock up with all the parts and the tie rods bump at one point. going to have to redesign a little. I will have revised plans up later this week or early next week. Plus I have found a way to make it a bolt on mod with just a little welding of reforcement plates and capture nuts ecet...

[The Pirate]

Still working on this should have a solution soon. Just need to finish the rebuild on my rack and wainting for a fresh set of tie rods to come in. If this works out I may want to market this sucker.

[volkdent]

Originally Posted by The Pirate

Still working on this should have a solution soon. Just need to finish the rebuild on my rack and wainting for a fresh set of tie rods to come in. If this works out I may want to market this sucker.

You're going to have to have custom arms built if you want this thing to work out right. Because the lower pivot points have been moved outward so far, the pivots on the end of the steering rack have to be moved out accordingly. As your new lower control arms travels through its new, smaller than original arc, the longer arc of the original tie rod will cause toe-in as compression occurs. That is assuming the Super is rear steer, I've never looked at one. If it is front steer, you'll have toe-out.

Jason

[The Pirate]

I am looking into this but so far as I am seeing the ball joint end of the A arm has the same amount of travel and arc size as the original beetle arm. I value your input on this and take all you say seriously. other wise I may already be on the road with my death machine.

The super is front steer in this case as I am using Porsche 944 spindels and brakes.

[The Pirate]

Ok so by its very nature the McPhearson strut assembly will toe in or out as it travels up and down respectivly. This is part of its very design as the distance between where the tie rod joins the wheel and the steering rack gets longer or shorter through the arc. While this distance changes the tie rods cannot as their lengths are fixed. It is a matter of deciding how much toe in and toe out is acceptable.

Here is the math on the suspension mod so far as the travel arc. The original lower control arm is 21 inches from pivot point to the middel of the ball joint. The A arm is 13 inches from pivot points to middel of ball joint. This is a diffrence of 8 inches. The folowing diargam while basic shows what I am seeing for this mod.

The red arc shows the original control arm travel arc.

The black arc shows the A arms travel arc.

The red line shows both the long arm and the shorter A arm. The black dot is the point of demarkation.

The gray lines show the max travel and angel of the original control arm.

The blue lines show the max travel and angel of the A arm.

The two arcs over lap in the range of the suspension travel enough to keep the toe in and out within acceptable ranges.

So far the largest change is the amount negative camber the wheel will gain in hard cornering or when the suspension bottoms and the amount positive camber the wheel will gain when the suspesion reaches full drop. This is due to the sharper angels the A arm reaches.

I may need to add at least 4 inches to the A arm to minimize these effects.

I am not planning to use this car as a racer or a competition car. As long as it handels well I will be happy.

[The Pirate]

Still working folks. Here are the updates. Through good advice here and just plain observation it has become clear that the A arms have to be moved closer for various reasons. The A arms are being moved in 4 and 1/2 inches from my original plan. This means the arms are now to short and will need to be legthened by this much. I had sought to avoid this so as to keep most of the off the shelf parts stock and easy to find replacements. On the other hand though if a person manages to bust a lower control arm it is probably due to an accident or such. I havent seen a conrol arm wear out due to normal road use yet. I am currently wating on a set of fresh tie rods and for the paint to dry on my rebuilt rack. I am also experementing with some diffrent break MCs to see if I can get the A arms even closer to center. As soon as a few things are worked out I will post some pics and begin a step by step.

[The Pirate]

Ok so after a small break in work it is back to the A arms.

New developements:

1- The arms will be built from the ground up using either round tubing or square tubing. It depends on what grade steel tubing I can get my hands on around here. If any one has suggestions on what grade to use as well as where to get it, please chime in. Sizes are yet to be determined. I would like to use DOM tubing but cannot find it in square form. I would prefer a square solution. Trying to amalgimate 2 types of factory suspension peices has beed determined to be unweildy.

2- Decided to use a type 3 master cylinder as it will give better clearance for the arm as well as allow each brake to have a connection directly to the MC.

3-The A arms will use the bushings from the 1982 Audi 4000 A arms and the normal beetle sway bar bushing.

4-Total distance from original mount point of the beetel I arm is now about 2 inches to minimize adverse effects on the supension.

That is the plan for now.

[The Pirate]

I am currently building a jig to hold the struts and rack in place as if they were in the car. I am doing this for 2 reasons. One is that I am driving the car that will donate the body for this project. Two is that it allows me unobstructed visual acess to what is going on as well as easier hands on acess. To get the A arms just the right length the strut spindle assembly will be set at absolute neutral camber. This will alow me to get the length of the A arms just right. Once they are fabricated and attatched to the car the camber adjustment will be readded at the top spindel to strut bolt. This is the same set up that the 944 usses and can be adapted to the beetle. All one needs is the ecentric bolts off the 944 as well as ovaling out the top strut to spindel hole on the beetle strut. Will have some pictures soon.

[volkdent]

Is it going to look like this when you are done?





Found these on this site, linked from http://www.beetspeedengines.nl/hoofd_frameset_1.htm posted by Jeza


Jason

[The Pirate]

Sort of but not exactly. I do like the soloution for the sway bar though. Iwill try to get a diagram up at some point. Thanks for the input!

[The Pirate]

So my current question is refering to the picture posted above: What is the part used to attatch the sway bar to the A arm? What is it called and where can one be obtained? Plus what type of ball joint is being used? Where can one get a ball joint like that? I am currently looking into refining a few things in my basic design and I want to explore some more options.