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  #1  
Old September 13th 2006, 11:50
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Super Beetle single A arm front suspension.

Super Beetle single A arm front suspension.

Since I am putting on the 944 porsche brakes on my car I have decided that due to the heavier nature of the porsche set up that I would like a beefier controll arm. I had first considered fabricating one from scratch, but then thought some off the shelf technology would make finding replacement parts easier in the future. I found some Audi 4000 A arms that may work.

I may have some questions for the pros here as this is my first front suspension mod.

Here is what I know so far.

The frame head for a super looks like an Capital I just with larger lines on the top and bottom lol. The S beetle control arm attaches to the midded of the I shape in the middel of the I kind of like this I-. How ever to mount the A arm the arm will have to be mounted to the ends of the I like this I>. This puts the pivot points a good 4 to 5 inches farther from the center of the car than the original S bettle control arm. It will have the same amount of travel as the original S bettle control arm. How ever the A arm has no provisions for camber adjustment at the ends like the S bettle arm does. To get around this I will be either using the lower half of a porsche 944 strut assembly as the camber adjustment is built in there or adapting the S beetle strut to do the same.

Here is where the questions come in.

1- Will having the pivot points moved farther out from the center of the car cause problems I need to know about?

2- Has any one done this before? If so what parts did they use?
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  #2  
Old September 15th 2006, 18:15
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hello? Echo echo echo echo............

(puts beetle in gear and drives deeper into the freakish desolation of this thread)
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Old September 15th 2006, 21:14
alt+f4 alt+f4 is offline
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I say for the benifits and strength v.s. the amount of time and work its not worth it. to change out the arms you would need to set it up to have proper roll centers, and a whole lot of other stuff. Now I am normally one of those guys that wants to convert or fab up stuff myself, but the super is a good design as it is. If you want to strengthen it just make some box ins like Racelook did.
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Old September 16th 2006, 17:16
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What do you mean by "roll centers"? I will be able to better explain my idea and design when I get a chance to draw up a diagram and post it. Plus If the I shaped control arm was such a good design why didnt VW use it on the early rabbits? My main concern is that the A arms are shorter and have to be mounted farther from the center of the car. Yet once this is done they will have the same amount up and down travel as the original I arm and the same arc of travel as well. I guess the question I currently have now is.

Again what do you mean "roll centers"?

Will the same springs work on the struts or will I need some softer or harder springs?

Will having the pivot points farther from center cause the way the car rides or sits on the suspesion to affected in a negative way?

Thanks for any help .
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  #5  
Old September 16th 2006, 17:31
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Ok I know what roll centers are now. And my idea may work. The main thing is that the a arm has the same ball joint position and amount of travel as the original I arm. The length of the A arm and its mounting location are subodinate to the ball joint location and travel of the arm. I finaly found a nifty website for this conversion as well as a handy free program for working out suspension geometry. Thanks for the tip.
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Old September 16th 2006, 18:03
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I've modified my 1303's front end to include strut rods grafted into the original lower control arms. This seemed the lightest, easiest, and least compromising way to strengthen the front suspension, and turn the front swaybar into a non-structural component.

Still gotta finish the rest of the car to see how good it is...
Attached Images
File Type: jpg lfctrlarm4.jpg (65.4 KB, 285 views)
File Type: jpg framehead6.jpg (73.1 KB, 260 views)
File Type: jpg frontsuspension2 copy.jpg (52.7 KB, 287 views)
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Old September 16th 2006, 19:29
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Ok those are nice. But it looks like you took notches out of you frame head to channel those struts into? That and they look like they may interfear with the frame moving up as the body comes down. Dont they bottom out in that channel? I will use paint to draw up a general sketch to show what I have in mind. Plus a little more wight in the front is ok with me as the super is a little to light in the front. That And I want to be able to get parts with out having to fab them incase of breakage.

Gave me some ideas.....
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Old September 16th 2006, 20:56
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During mock-up the struts bottomed out with a full 7mm between the channels and strut-rods. I put a ~7 degree downward angle at the root of the strut-rods, and a 12 degree upward bend about 10" away from the rod-end to keep them from bottoming.
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Last edited by yetibone; September 16th 2006 at 21:41.
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Old September 17th 2006, 03:07
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Also yetibone how do you plan to fit a sway bar?

here is a very basic idea of what i am planing. I will be using Audi A arms. This is just a rough draft and may be changed during design and application.
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File Type: jpg frame head.JPG (28.2 KB, 234 views)

Last edited by The Pirate; September 17th 2006 at 04:02.
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  #10  
Old September 17th 2006, 15:37
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Front sway bar fits in it's stock location. It no longer bolts directly through the control arms, but with drop-links.
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File Type: jpg droplink2.jpg (71.6 KB, 235 views)
File Type: jpg DSCN3579 copy.jpg (49.0 KB, 247 views)
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  #11  
Old September 17th 2006, 21:42
Jeza Jeza is offline
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A freind of mine remade his lower arms, but turned them into really long A arms.

Have a look at this thread on the subject and the pics I posted then.

http://www.germanlook.com/Forums/sho...ghlight=s1fter

Having said that, I don't have a problem with my setup -944 NA brakes on standard setup but urethane bushes and Topline swaybar. Another fellow I know has the same setup being pushed around by a 2.5 SOHC Subi motor, and he hasn't mentioned any problems either.

Cheers
Jeremy
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  #12  
Old September 18th 2006, 03:14
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Thanks guys this is great. I will document my mod carefully for all of you.
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  #13  
Old September 19th 2006, 17:29
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Ok here are some pictures.

A arms -1982 Audi 4000 A arms with mounting bolts.

Ball joints -are bolt in, same size and length of the Porsche 944 ball joints.
The ball joints are cheap even for quality ones. About $30.00 US each.

The beetel strut can easily be modified to have the camber adjustment on the top mounting bolt to the spindel like the 944 Porsche. all you need to modify it is a round file and some time and work.

Now all I have to do is figure where exactly to mount the arm and fab the mounts. The hardest part is the precise position. I am guessing I want to position the A arm so the camber adjustment is right in the middle. That way I will have adjustment either up or down. To find that I will need to keep the face of the spindel 90 degrees to the ground. I also will need to find a way to simulate the way the suspension will behave with the cars empty weight.

hmmm

The A arms are shown roughly where they will need to be to match where the beetle ball joint ends end. About 21 inches from the center of the mount on the frame to the center of the ball joint. I will be leaving the orignal mounts so If i ever want to change back I will be able to.
Attached Images
File Type: jpg A arm1.JPG (68.8 KB, 200 views)
File Type: jpg a arm2.JPG (83.4 KB, 166 views)
File Type: jpg A arm3.JPG (84.6 KB, 181 views)

Last edited by The Pirate; September 19th 2006 at 20:42.
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  #14  
Old September 19th 2006, 21:03
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Ok so now here is the basic plan for the way to mount these. In the following picture the solid black bar represents a peice of heafty tubular steel that will be welded in place on this tubular steel there are mounting points welded on. I left those uncolored to show the joints. Finaly for a bit of added strength and just to give them something to do a third member bolts from the old mount point to the tubular steel. I may be able to make tha whole rig bolt on but I doubt it.

The arms them selves are remarkably light considering the front end weight of the car they came off of. The great thing about this approach is that it stays completely out of the way of the master cylinder. Hmm power brakes now maybe?
Attached Images
File Type: jpg a arm2- basic plan for mounts.JPG (84.3 KB, 203 views)

Last edited by The Pirate; September 19th 2006 at 21:29.
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  #15  
Old September 20th 2006, 02:20
alt+f4 alt+f4 is offline
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Since you have the same spindle mounting area but are moving the main pivot out wards that will effect you roll center. With the pivot being that much closer to where the strut is centered you might not get enough neg camber gain under compressiion durring high g cornering.


with your software you have try to set it up to get your roll center as close as or below the ground as possible. and just as a guid line try to get the virtual pivot to the opposite wheel on the outside of the center of the wheel.
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