Bump steer, will this help?

[4agedub]

Has anyone experimented with something like this on a beetle?

Oval midget style steering


It seems like everything will clear, but will it work?

[GS guy]

I think only if you grafted on a straight axle front end!

[Marc]

One way to maximize tierod length is to connect both sides as above, but retain the stock steering box/pitman arm and long tierod. Where the two tierods attach to a single steering arm use Heim joints (this becomes a single potential-failure point so it's got to be robust).

[Ol'fogasaurus]

This is a very old way of doing things (read pre mid-‘30s or early '40s). You would probably end up with the drag link wanting to flex it is too long and create some geometry problems (OK for certain types of race cars but on the street it is not that desirable for good road handling manners. Racing moved away from beam axles many, many years ago because of some of the limitations of a solid axle). You also have to deal with the Pittman arm arc plus the arc of the spindles working at the same time; it works but it primitive. The drag link and spindles must remain level at both ends of the Pittman arm swing.

Cross link steering (common with Vega (the diagram you have from Speedway is very old. Vega steering was used but it is not designed for the weight and loads racing may put on it)/Ford truck or first gen Falcon and Mustang steering box conversions [some of them are mounted on their sides for the style you pictured] to early Fords w/beam axles) will also have multiple cross-link and spindle arcs to deal with.

With either of these methods you will want to add a Panard Bar of some sort to keep the axle centered under the car because of the movement encountered by the required spring shackles to the beam. You will also need to have either split wishbone, radius rods or hair pin rods to support the axle keeping it perpendicular to the chassis.

You see this type of conversion done with rat-rod VWs and you get the under-bite/extended/suicide look of suspension where the spring perch is mounted ahead of the frame. I know that there are several companies that make a VW to I-beam conversion and should be easy to find if you look around: for example: http://www.speedwaymotors.com/SoCaLook- ... ,4040.html. Actually there are several names for it depending on how the tire rods are mounted; e.g., behind the spindles, in front of the spindles but down low or in front of the spindles but mounted above them (I seen to remember that the versions mounted in the rear are called Suicide or Bull-dog. I always thought the link between the two spindles when mounted to the front were too subject to accidental [or on purpose] damage being out front). I guess the look is OK as long as that is the look you want.

Beam axles do have some handling benefits; e.g., the transferring the up and down loads from one wheel to the other, but a lot of that can be accomplished in the IFS by using sway-bars; they transfer some of the up-and-down loading from one side’s suspension to the other side as long as there is some kind of support in-between. VW uses sway bars that do not connect in the middle because the torsion tube accomplishes some of the same functions that connecting the sway bar to the middle via pivot supports. Even in the late ‘40’s and early ‘50s they were adding sway bars to the beam cars.

You will also have to figure out some methods of shock mounting and locations as beam axles use several different methods going from lever style shocks (movable linkage required) to tube shocks.

Since I saw racing in your signature: If you want to go solid axle there are many different methods that do not use a transverse spring although I do not think parallel leaf-springs are any better, maybe worse.

There are also several companies that offer IFS conversions to BJ beam cars that are either bolt in or almost bolt in; I think Mendeola (http://www.mendeolasuspension.com/) may be one of them but there are several others that are easy to find on a search. I was going to post a URL for one other but it seems to have taken a dump and it has been replaced by a real estate site.

Lee

Clarified and added some additional information.

[buildabiggerboxer]

Hey up 4agedub, hows it going ? do you have bumpsteer then?

[4agedub]

The idea is to keep the original beetle suspension and adding one bar from the left to right stub axle and a single arm to the steering rack.

Hey up 4agedub, hows it going ? do you have bumpsteer then?

Big time, this is one of our biggest problems at this stage. The steering arms are fairly long and go directly onto the steering rack that is mounted in the middle of the car, but still the bump steer is really bad.

[Ol'fogasaurus]

The idea is to keep the original beetle suspension and adding one bar from the left to right stub axle and a single arm to the steering rack.

I'm confused now (or maybe the light just came on). Are you playing with McPherson Strut, BJ or K&L front suspension? Is your steering located on the right and are you dealing with a stock VW steering box or have you converted to center steer rack and pinion (you used the work "rack" which is often miss-used generically to mean steering box), I don't think an end steer reac and pinion is going to help you much unless you have limited suspension travel needs?

It sounds like you are still playing with a stock box but if you have gone to a rack and pinion conversion; have you checked the angle that the steering box is sitting at? It is the same with the VW box, there is a notch on the box and a stud on the beam to locate it; I think it was put there to help eliminate as much bump-stop as could be done in an assembly line situation.

Unless I am still missing something; I think, if you go to a tie-rod between the two spindles then add a single drag link from the steering box (which ever style you have and short side or long side drag-link) that you are going to have to modify the frame head a lot to accommodate all the arcs involved (probably at least three to five if not more). I think the tunnel is one of the reasons that VW put the box where it did as the tunnel is the main support for the full length of the pan.

Lee

My opinion is worth slightly less than you paid for it.

[buildabiggerboxer]

Ah, i see now, its a big job to bump steer a t/beamer, the leaves need to come out to allow the full range of travel, bump steer makes you look like a novice, i know that..... you know the basics of having the tie rods at the same angles as the trailing arms? spherical rod ends help a lot as you can shim them up higher or under sling them. any pics of your install? wish i could help more.
i cant be too enthusiastic at changing the beam set-up much, as the more i play with it the more i'm amazed at what they will do, being easy to run low is a very good feature and roll camber change is not a big enough problem to cause worry, so i'm building a new beam with a bigger stretch, im going 2.5" wider, and planned a polo rack, but thats canned as the whole package is crammed into and around the stock steering, worst thing is its a bit slow. plenty of drag bugs run as you suggest, it looks strong enough to survive the contact, its used in stock cars and off road racing lots, but i recon ol'fogasaurus is right with the naps hat being in the way, generally, id be inclined to change as little as possible and sort the bump steer out mate.... best regards anyway, Johnny

[Ol'fogasaurus]

My stuff is off-road but there are a lot of similarities... in certain ways. I was hoping that some of the Auto X'er, road racers and others might chime in (Mr. Camper, are you there?). The pix you posted to start with sent me off on another bend (no pun intended) and maybe some of the others too.

Lee

[Marc]

...you know the basics of having the tie rods at the same angles as the trailing arms?...

On a torsionbar ACVW front end, it's even simpler. The wheels move straight up and down as the suspension travels so there's no arc to match the steering linkage to. Just get the tierod(s) as close to horizontal as possible over the normal range of suspension travel. The ideal tierod length on such an arrangement is infinite, so longer is better.

The wheels do move through a slight arc as viewed from the side, so the tierods should be as close as possible to perpendicular to the car's longitudinal centerline through the range of travel as well for minimum bump steer.

[Ol'fogasaurus]

I bow to Marc's greater knowledge and experience (but I do hole onto some reserve because the steering box does have some adjustment/movement capabilities on the beam and the because of the eccentric being able to change the caster and camber so much; there has to be some arcs in there to stub your toe on. I think the length of travel is another factor) and I agree with the as long of rods as possible part.

Lee

[4agedub]

steering rack.jpg

I'm running a link pin beam with GM steering rack. The steering arms are connected to the middle of the rack.

The idea is to connect the rie rods between the two spindles with a single drag link to the rack. I'll leave the suspension as is. The suspension travel is limited.

[GS guy]

Right idea with the as-long-as-possible tie rod lengths, but I believe the inner pivots need to be a lot closer to the torsion beam. The tie rod ends at the spindle do follow an arc (moving up and down), so basically the tie rods need to be able to follow that same arc without turning the spindle.

Similar center load off road buggy racks locate the rack right next to the beam, with corresponding "close-to beam" inner tie rod ends.

I used to have a bump-steer calculator spreadsheet that could predict a balljoint beam bump steer characteristics with various placement of the inner tie rod ends. With it, I was able to get almost nil bump-steer with either an end-load or center-load rack, but placement was critical and always about as close as you could get the pivot points to (and just behind) the upper torsion tube. Granted, this was just an on-paper exercise.

I'd first try moving your rack around up closer to the beam with temporary rigged (but rigid/well clamped) mounts and check bump-steer. I think you can crank the adjusters to full soft/up position and drop a bunch of weight on the front end to keep it down while lifting and lowering the front hub? You should be able to significantly improve bump-steer by simple rack relocation.

[buildabiggerboxer]

from the pic I would guess the rack is far too high, and as gs guy states, too far rearwards, and also duplicate the view of shifting it around with temporary clamping and brackets untill the bump is gone. the centre of the rack will be almost down touching on the naps hat when its getting near to zero bump.

[Ol'fogasaurus]

As an example of converting to rack and pinion, this is a mount available for a stock bug http://www.mooreparts.com/store/product/4019/AC425168/ (I am not pushing this company; it is just one that I can find things easier in).

Having read about mounting these to get the bump steer out; it is first mounted in place and tacked, the suspension is then cycled through its travel (I would expect sands torsion springs) and measurements taken straight ahead and the steering turned. The mount, it then adjusted up or down to try to pull the most “bump steer” out. I would suspect that you are going to end up notching your frame head at least some. Using a center load rack is going to give you the longest tie-rods you can use. I would suspect that this would be the same for the stock steering box except that you still end up with a long and short tie-rod.

http://www.manxgallery.org/gallery/Baja ... a_1?full=1

This came from http://www.manxgallery.org/gallery/BajaManxter?page=1 and might help some. The rest of the pictures might help some too.

Lee