TheSamba.com :: View topic

Thu Jul 23, 2020 8:07 am

Finally started to deal with bump steer.......my tie rods are both way high at the Pittman Arm.
'68 ball joint front end.
Could I have an incorrect Arm here?
Why would they be so high, and what can I do about it.
Manx style buggy BTW.
Could almost flip the rods at the Arm, but not quite.

Thu Jul 23, 2020 8:47 am

I've also got one set of caster shims on........how much does that effect it, given that the shims push the bottom of the bar out?

Thu Jul 23, 2020 9:49 am

Does the centerline of your steering column line up with centerline of steering gearbox input shaft?

Thu Jul 23, 2020 9:53 am

Thu Jul 23, 2020 1:33 pm

Bump steer cannot be eliminated in the stock VW suspension without some re-designing. All you can do is try to minimize it. You are on the right track by looking at the angle of the tie rods. The more extreme the angles the worse bump steer will be. Your present angles are likely due to the Buggy being lighter on the front than the stock Beetle was so lowering the front end by rotating the inner leaf spring anchor, cut and re-weld or install adjustable centers or remove some leaves to get it down will make it better.

Ideally you want the 1/2 way travel position over a bump to make the tie rods level to get the least bump steer. It's a bit of a moving target as not all bumps are as harsh and changing passenger and fuel tank levels effect it.

Stiffer spring rates help but most people find the stock springing too harsh already in a buggy. Large wheel off sets on the front exaggerate the problem too.

To eliminate it totally you would have to move the steering box to the center of the beam so that you have equal length tie rods.

Thu Jul 23, 2020 3:01 pm

I wonder what affect your coil-over springs have. Could they be pushing your whole front beam (including steering box and pittman arm) up too high? As Opie wrote:

oprn wrote: ... Stiffer spring rates help but ...

Thu Jul 23, 2020 5:39 pm

MrGoodtunes wrote: I wonder what affect your coil-over springs have. Could they be pushing your whole front beam (including steering box and pittman arm) up too high? As Opie wrote:

oprn wrote: ... Stiffer spring rates help but ...
Yes of course! Extra coil springs on the front are going to cause a ride height increase. Good catch!

Thu Jul 23, 2020 7:09 pm

I eliminated the leaves in the lower torsion bar about a year or so ago and replaced them with a steel threaded rod......front end was way too stiff. Added the coil overs to compensate.
Should I go back to standard shocks without those leaves?

Thu Jul 23, 2020 8:17 pm

CNSRANCH wrote: I eliminated the leaves in the lower torsion bar about a year or so ago and replaced them with a steel threaded rod......front end was way too stiff. Added the coil overs to compensate.
Should I go back to standard shocks without those leaves?

Please explain a little more.
Sounds like you're saying the front end was still too stiff after you removed all of the leaves from the lower beam?
How tight did you tighten the nuts on the threaded rod?
If the suspension was too stiff why did you add coil overs to help?

If I understand right, by adding a threaded rod to the bottom you could have put the lower arms in a complete bind not allowing any of the components to move freely. Back the tension off of the through rod nuts and see if things loosen up

Thu Jul 23, 2020 9:41 pm

Get rid of those POS coil overs and just run one set of torsion springs in the front. Your front end is stiffer now than it ever was with stock springs.

Rotate your steering box if you can. Or you could do what I have done on a couple of buggies. Put a quick steer adapter on the pitman arm either on top or bottom to level out the tie rods. In your case it would go on the bottom.

brad

Fri Jul 24, 2020 10:03 am

Doesn't a quick steer adapter make for dangerous oversteer?

Fri Jul 24, 2020 10:55 am

Update based on the coil over question.....
Pulled the coil overs to see where I'm at. Without them, I can easily push the front end down and get the tie rods level. So, the coil overs are definately keeping the front end too high.
Here's one concern with going to standard shocks......I can push the front end down to the point the tires are hitting the fenders (Manx style buggy). So if I go with standard shocks, won't I hit the fenders when I hit a good bump?
Is a fair alternative to shorten the coils? They sit about 16" end to end on the buggy......they need to sit about 14.

Fri Jul 24, 2020 11:11 am

Here's my stupid side showing through.......
I really don't fully understand how the front end works........without the coil overs on, the front end is really soft with no bounce back at all after pushing it down. It would go all the way down, but the fenders are stopping it. Is that why coil overs are added after pulling the leaves? With standard shocks, what keeps it at a certain level (ideally with the tie rods level, and what keeps it from compressing too much when you hit a bump?
Adding to that, by putting coil overs on, aren't we doing away with the benefit of having pulled the leaves in the first place?

Fri Jul 24, 2020 11:22 am

I misspoke earlier.......it was the leaves in the TOP of the torsion bar I pulled, not the bottom.

Fri Jul 24, 2020 2:23 pm

CNSRANCH wrote: Here's my stupid side showing through.......
I really don't fully understand how the front end works........without the coil overs on, the front end is really soft with no bounce back at all after pushing it down. It would go all the way down, but the fenders are stopping it. Is that why coil overs are added after pulling the leaves? With standard shocks, what keeps it at a certain level (ideally with the tie rods level, and what keeps it from compressing too much when you hit a bump?
Adding to that, by putting coil overs on, aren't we doing away with the benefit of having pulled the leaves in the first place?
It matters not which tube the leaves were taken from, the result is the same.

Sounds like too many leaves were pulled. Yes the coils are doing exactly the same thing as the leaves were. Cutting coils off will lower the ride height but remember it will make the coils stiffer.

Might be worth a try though and work out just right, won't know until you try it.

Yes a quick steer adapter will make it twitchier at speed.

Fri Jul 24, 2020 2:33 pm

Another thought......without the coilovers, I'm able to push the front down to the point that the fenders touch the tires. There's no springback.......does that mean either the springs in the lower bar are shot, or at the least the set screw's not doing it's job, and the springs are rotating instead of flexing?

Fri Jul 24, 2020 2:38 pm

This looks like a ball joint front end? Yes? If so, run all the large leaves and none of the small leaves in both tubes. Get rid of the coil over shocks and the through rod. This exact set up was a little bit too soft for me, tires rubbed the fenders under braking, so I added one set of small leaves back in.

You don't have to do any welding or other funny stuff, the stock grub screws will hold everything together just fine on a ball joint front end.

Fri Jul 24, 2020 3:04 pm

Thanks, Brian.....we're getting closer. Here's my (hopefully) final question. If I go with standard shocks, I'm concerned I'll hit the body with my tires. Pretty clear that the coils are preventing that now. What am I missing here?

Fri Jul 24, 2020 3:52 pm

These cars are a bit of a compromise. If you want it at a nice street height with a soft ride and no rubbing, you probably need to get the tires fully under the fenders. If you are like me, with wide fronts sticking out past the fender lip, you may have to live with a firmer front suspension.

Some options? install adjusters to fine tune the height; narrower tires/wheels; narrower front beam; clearance the fiberglass; stiffer suspension; widen the fenders; raise the suspension. I chose to keep the suspension a little bit firmer than I really wanted it. Run the tires at 12-14psi. I may install a beam with adjusters the next time I freshen up the car.

In my opinion, unless you are driving it hard off-road, bump steer is not enough of an issue to worry about on the stock beetle front end.

Fri Jul 24, 2020 4:17 pm

It's not making me completely nuts, but I figured it was worth a try. Thanks for all your help, guys.