4x4 front steering knuckle for trailing arm

[Druck1]

First post after in this section. I need some help from the forum. For many years I have been hoarding a complete 4x4 syncro drive train. I am now starting to think about putting it on the road. Maybe a Schwimmwagen replica. I would like to use trailing arm front suspension to keep things reasonably VW. Below is a sketch I made of a possible solution. The basic idea is a steering knuckle fabricated from easy to access parts, to which a micro stub axle set is bolted. Uniballs are used instead of king pins or ball joints. Link pins connect the knuckle to the trailing arms. Shims used to set camber angle.

The biggest drawback would be the need for a custom front beam to achieve the needed separation to avoid castor change through travel. I hope the drawings are clear. Any comments are appreciated. Note: I just estimated the CV joint center position at 2.5". If anyone has the real dimension, that would be helpful.
If this idea is workable, I will figure out steering arm geometry next.

[65BAJA]

This could be interesting. In for the results.
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[Brian]

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[petrol punk]

Off the top of my head, the first issue I see is lack of steering angle. 25* doesn't seem much. I don't know what stock steering angle is, but I think the guys I've talked to building desert cars were getting at least low 30's steering angle on their inside wheel. Also a 1" spherical bearing with 7/8" misalignment spacers might not produce much steering angle either.
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[Druck1]

good comment.
there must be a uniball out there with +25* angle. Probably 3/4 bolt/link pin.

[syncrobuggy1]

Really old thread but did you ever build this? looking at doing something similar.

thanks

[PhillipM]

Steering angle is your issue, even with high-angle joints I have to run misalignment spacers too and very careful setup to get enough steering lock.

[Druck1]

Picking up this post as I am getting back on the project After 5 yrs.
Several years ago I did get the front end fabricated per the above drawings. The key piece is the steering knuckle (see below pic). Uniball joints with misalignment spacers. This allows steering angle of about 40 deg. For reasons I forget (parts fabricated +4yrs ago) we used 3”x3” trailing arms. Custom front beam that is narrowed to provide stock track width with these arms; coil over vs torsion springs.
I now plan to model the suspension after a class 5/1600. Stock arms, torsion leaves/bars. Stock width adjustable beam, but 7.5” separation. Will go with rack and pinion steering. Looking for a mid-‘80’s GM rack now. This provides offset pinion and center load. Anyone have one?
I will most likely seek professional help to make sure castor angle, bump steer, Ackerman angle, etc are addressed.

[TDCTDI]

Since you are effectively using a ball joint, why would you not use them where they would have the most rotation in the direction where you need the most rotation?

The angle of the trailing arms cannot exceed the angle that the CVs are limited to.
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[Druck1]

Yes, this configuration allows max flexibility. I think I will be CV limited in suspension movements and steering articulation. I see a post today on 40 deg 934 CV’s. Might be overkill my needs

[TDCTDI]

The point is that you are trying to use the “ball joints” in the direction that they are the least efficient in steering angle but also where the would be weakest.


It really wouldn’t take much force to separate the joint or break it if the steering was at its limits & you struck an obstacle that would force the joint beyond its range of motion an it doesn’t appear that this would be a serviceable joint once it failed.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[Druck1]

I appreciate the comments
The application is unconventional. I believe there will be sufficient steering angle, so next up is to perhaps incorporate travel stops so that neither the uni ball nor the cv joint functions as the stop.
I am still working this out and open to other ideas. I would like to retain the vw beam/trailing arm configuration vs go with A arms

[BFB]

someone else manufactured a buggy front knuckle like this using uniballs but it wasnt intended for 4x4.
id think running them like this may not be "optimal" for strength but if you hit something hard enough to shear that uniball, i think that'll be the least of your worries
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