How bad is the bump stear on your buggy?

[oprn]

I am well aware that the torsion bar suspension VW designed and put on their cars was notorious for having a bump steer problem. I have been driving my Manx clone around a fair bit the last few weeks and don't recall any of my previous Bugs being this bad. Hitting a pot hole with one front tire at highway speeds gives me ponder as to whether or not a bump could put me in a bad situation in traffic at speed on a rainy day.

The front end is late model ball joint, all in good shape with a new steering damper and just a little play in the steering box. I suspect part of the problem is from the wide stance the Keystone rims and related adapters that are on this buggy. I really would like to retain the rims as I like the looks. I am wondering about re-drilling the drums for the bolt pattern on the rims. That would decrease the offset by about 1.5 ". Has anyone done this and would it change things enough to be worth the effort?

What else have you done to address this issue?

[jspbtown]

Just curious as to what you are running for tire pressures.

[wythac]

^x2. Plus: find a willing local with stock VW rims and tires to let you borrow a pair to test on your car. Doing so will tell you a lot

[oprn]

12 psi front and 17 rear at the moment.

Actually I have some stock rims and tires on a type 3 I could dig out of the hay shed. Been there a while, not sure what shape they are in.

[oprn]

That's odd! I thought this would foster much more discussion as it is common to all VW torsion bar front suspensions.

[jspbtown]

I don't think there is that big of a problem to be honest with bump steer with buggies.

I might suggest that you make sure your steering box is tight on the torsion tubes and that you have your alibnment checked to make sure it is within spec.

[JCS]

CHECK OUT THE DISCUSSION UNDER BUGGY SUSPENSION. It sounds like the same thing I ran into just buying a freshly built buggy. Look at your trailing arms on the front end. If they are not close to being parallel with the ground, you need to soften up the suspension.

Back in 1970 I built my first buggy and there I learned about removing one set of torsion leaves. Or you may want to have a $25 set of torsion adjusters (which lowers the front as well) welded into the front end. It will make a lot of difference. Front end "bump" is dangerous. Do not drive fast until you get it resolved. I had a 23 Ford "T" bucket with a fuel injected, 2.2 liter vw on the rear. It had coil over shocks all round but they were set a bit too stiff in front. This car would accelerate like a rocket but if you hit a bump the front wheels will come off the road a bit....just long enough that you could turn the steering wheel a slight amount. When the wheels come back down, you may be going in a different direction. I never drove this car near it's limit. I now also have a Beck 550 Spyder which could use a little softer suspension in the front. And of course, rack and pinion steering would also make it much more safe under speed.

Read my post about a Formula V sway (stabilizer) bar that I had out of a mid 1960's FV car under the "Buggy Suspension" thread. I do not know if these are available any longer but you can research it.

The comments about tire pressure are good too but will not solve the situation completely. Softer tire pressure will soften the ride but the tires will still bounce like a basketball. You need your suspension to "give" to a bump and then let the shock absorb the energy so the car does not bounce as well. Softer tires alone will not do that. If you follow racing at all you will see that suspension travel and shocks are key to a car driving well. Roger Penske has his own research lab and manufacturing facility for shocks alone. His cars get all the new developments.

If you use weld in lowering devices, please make sure your caster is adjusted as well or your car could wander going down the road and you will be constantly adding steering input...not safe. There are inexpensive caster shims available to help get caster back in specs. You could not ride a bike without hands if there is not sufficient caster on the forks. Research caster, caster shims etc.
Be Safe!

[oprn]

[JCS]

WOW...........I replaced the lower torsion leaf strips with the Formula V rod today and took the car out for a ride. WOW I say WOW what a difference. The ride height is a little lower so that the trailing arms are almost parallel with the road. Yesterday I had lowered the tire pressure to 15 on the fronts and 20 on the rear since they are wider tires. That helped "some" but softening the front torsion suspension really did the trick. Now when I hit a bump the suspension takes the energy and then the shock dampens out that energy.
The car tracks so I can run 50 mph with no hands. I took it on an especially bumpy blacktop road and there were no more noises caused by the car taking all the energy from the bumps or the tires bouncing like a basketball. After I lowered the tire pressure yesterday I took it on the same bumpy road and there were several rattles and bangs due to the energy transferred to the car from the road and no suspension and shocks helping to dampen it all.
I highly recommend you try this on your buggy, especially if your trailing arms are not near parallel with the road. The bar I used may be the same as is listed on the other suspension thread. If you have a light weight buggy and your trailing arms are not parallel to the road, find one of these bars. I put mine in the lower tube today. That was the same as in the Formula V.

Just a note; a car does not have to have great power to raise the wheels off the ground and cause bounce. All your car has to do is have stiff suspension and hit a bump. The wheels will come off the ground, even if only a bit. So you have your hands on the wheel and they turn the wheel slightly. When the wheels make good contact with the pavement, the car will go the direction the wheels were turned, the driver sometimes corrects and sometime will over correct, the car gets squirrely and the car goes out of control, sometimes in ditch, off the road, sometimes upside down.

I will put some photos on the other thread. I took photos of the bar and the ride height.

[JCS]

(Good idea with getting the trailing arms parallel, I hadn't thought of that. Softening the suspension though may be counter productive as it would lead to more movement and thus more bump steer. Torsion bar adjusters may be the way to go.)

Softening the suspension to get the trailing arms parallel with the ground will NOT cause more bump steer. That is where the shocks come into use.

(Yes that would help some only by virtue of the tie rods being the same length. The bump steer would still be there but would be equal on both sides. presently with VW's unequal tie rod lengths the bump steer is worse on the left side.)

I was just making the point that rack and pinion steering would "make it much more safe". Rack & pinion will not increase bump steer.

[oprn]

I would be game to try one.

I wonder if they are still available.

[hillmotorsports]

Read my post on the suspension thread. Same info applies. Most buggies are too heavy up front to be supported by a single torsion leaf assembly.

Paul
_________________
Rosemarie and Paul Hill
Morrisburg, Ontario

(With way more projects than spare time!)

[JCS]

I built a fiberglass buggy back in 1970 and took one torsion bar set out and put in a pass through bar. It drove great for as long as I ever knew the car.

[oprn]

Could be the guy was off roading the buggy too.

[oprn]

[AMAC1680]

[slalombuggy]

My buggy does not suffer from bump steer at all, and I don't run a steering dampner.

I have a 3/4" steel bar that has replaced my upper spring pack and acts as a swaybar, my trailing arms are almost parallel to the ground, I use Formula Vee offset link pin bushings for negative camber and I also use a quick steering coupler mounted on top of the pitman arm so that the tie rods are much closer to level with the road surface, which I think is the biggest improvement. For shocks I use cheap EMPI gas shocks that are very low pressure, but I like them better than the plain oil shocks I tried or the KYB GR-2s I ran for years. I run 25 psi in my front tires and the car is very stable and I can drive with just one hand on the wheel even on our crappy streets. On smooth surfaces it's a dream and I have let go of the wheel at over 120mph with no surprises.

brad

[JCS]

Interesting posts guys. I am sure everyone has a little different situation and there are so many different uses of buggies. Mine is just for occasional street use and I have found a sweet spot. I have just had this thing for 3 days and although I have had many bugs etc I have not had a buggy since the early 70's...........yes that makes me a pretty old man.

[Q-Dog]

I don't think I have enough suspension travel in the front for bump steer to be an issue.
_________________
Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[oprn]