Opinions about fixing wheel hop - What should I do next? Now with updates!

[Sam K]

My Bug has had wheel hop problems for the last 7 or 8 years and I've never been able to fully cure it. I've tried damn near evrything and it's gotten a little better, but it's still there. Here's my what I have:

The car: It's a 1967 sedan that weighs about 2100 lbs.

Drivetrain: 2332 with IDA's, Jeff Denham heads, and all the good stuff. I've never had it on a dyno, but it will run low 14's to high 13's at 7000 feet. The transaxle is pretty built and has a 3.88 R&P with stock gear ratios. the bclutch is a stage 2 kennedy with a stock solid center disc.

Transmission mounts: Berg harder than stock rubber mounts, Berg intermediate mount with aluminum (solid) spacers in place of rubber ones. Aftermarket cradle with strap. Berg traction bar.

Rear suspension: 28mm torsion bars set with a litttle preload, adjustable spring plates, KYB gas-a-just shocks, and a CSP torque bar. The rear axles are set with a little toe in.

Tires: They are a set of "Fisk american classic" 205/65 15's. They are about 6 or 7 years old and could probably use a good replacing. However it hopped when they were new.

Other things I've tried: I've had solid mounts and CB performance Rhino mounts. I've also tried KYB GR-2 shocks and stock oil shocks. I swapped tyhe floorpan in case the frame horns were weak. 

Things I'm pondering trying: I'm thinking about ading some more bow to the bowden tube (it has about 3/4 inch). I also borrowed a  set of Jaycee spring plate retainers (the ones with the brass bushing). I was thinking about a some new rear tires. I have a Washington Anti-shocker that I've never installed too.

I eventually gave up on racing my car a regularly and bought a 5.0 Mustang to race. I still drive the Bug a lot, but I only race it once a year at the Denver Bug In. I'll be racing it in a couple weeks and I'd love some new ideas. Thanks!

[Bruce]

Urethane grommets at the spring plates.
CSP type frame horn support bars.

[Speed-Randy]

use one of those kafercup stabilizers that make a triangle from the shock mounts to the frame horns, works like a charm. i couldnt believe it till i finally put one on, they will be going on all my cars, i dont run a berg type traction bar and have zero wheel hop.

[Sam K]

I do have the CSP kafer cup bar thingy. As far as the bushings on the spring plates go, I have energy suspension urethane inners and Sway-a-way outers.

[Sam K]

On a related note, I've had some trouble lately setting the torsion bars up. If I set them, at a position where I like the ride height, there is no preload on them so the ride is very bouncy and the bump stops (type 2) sit more or less on their top perches all the time. If I set them so there is a little preload, the car rides great, but it sits about an inch higher than I'd like. I was thinking that if I leave it with a little preload for a while it might settle. Any ideas/opinions? 

[Bruce]

, I've had some trouble lately setting the torsion bars up.

They aren't working for you, so go to smaller bars.  Just because everyone else uses stiff bars, doesn't mean you have to.  I know a few guys going really fast with stock bars.

[Sam K]

I've thought about putting stock the bars back in, but my old roommate took them when he left. What would be a good size to get?

[Mike Lawless]

There will be virtually no preload with 28mm bars to get the ride height where it needs to be. Use either really short snubbers or no snubbers at all. You won't bottom the suspension with T-bars that big unless you're on slicks with big power. There also needs to be considerable preload on the truss bar to allow of flex in the bar. Believe me, they do flex, even when they are tight. Could be that the shocks are too stiff.

All things being optimized, it might just be the tires. Many kinds of radial tires seem to not get along with a stiff rear suspension. You can try different air pressure to gage the result.

[Fastbrit]

Looking back through you post, I'm with the people who say your torsion bars are too big. You're making the tyres do all the work which, being regular radials, they won't. My old ex-Goss chop-top had stock torsions, stock torsion bar rubbers, Type 2 snubbers (cut by 3/8in or so), solid mounts, a traction bar wound up tight and Konis set about halfway. On radials or slicks, there was never any wheel hop at all. Not one bit. Car ran 12.80s on 215/60 radials, 12.50s on slicks, with 1.84 60ft. Car weighed about the same as yours, if not a little more.

[Sam K]

So I have an update for my wheel hop issue. I raced the car at our local VW event a couple weeks ago and as I suspected, there so much wheel hop that I basically had to baby the car put of the hole every time. In fact in one of the picture taken at the track, you can see the breaks in the black marks the car left on the track. I've decided to change the torsion bars back to the stock ones and possibly replace the rear tires since they are several years old. I may change the rear shocks as well. I've got gas adjust on it but I also a set of GR-2's and some cofap ouil shocks as well. Or I could pick up a set of KONI's So many choices.

[Neil Davies]

So I have an update for my wheel hop issue. I raced the car at our local VW event a couple weeks ago and as I suspected, there so much wheel hop that I basically had to baby the car put of the hole every time. In fact in one of the picture taken at the track, you can see the breaks in the black marks the car left on the track. I've decided to change the torsion bars back to the stock ones and possibly replace the rear tires since they are several years old. I may change the rear shocks as well. I've got gas adjust on it but I also a set of GR-2's and some cofap ouil shocks as well. Or I could pick up a set of KONI's So many choices.

I don't know how often you have the opportunity to go racing, but I'd take a load of parts with you and change one thing at a time. Then you can pinpoint exactly what it is that's causing the hop. For example, you might find with the softer bars it makes the tyres work, but with new tyres the H/D bars really allow it to hook up and improve it more than the bar swap. Trial and error!

[Bewitched666]

what tire pressure are you racing with?

[GreenTom]

so trus barit on not? (what about BP bolt on trus bar) can't put the traction bar cuz I have rear end bolted together (its stiff but not as stiff to take the engine) not big engine just mild 1776 but the wheels hop as hell...
or just shold I make one by my selwe 2 bars bolte to the bonnet flore? like on Peter's site?

[Matt H]

I ran all Berg Mounts, Intermediate support with the ruber bushings, Berg traction bar, stock oil filled shocks, bus snubbers, stock torsion bars and bushings, Limiters on the spring plates. Launced great, no hop, with 6" Firestones at 20 lbs of air. I read the section on Gary Bergs blue car in an old Berg catalog and did everything he did pretty much

[folkevogn]

Not sure if you have done it already, but putting some washers where the clutchwire tube is fitted to the bracket on the gearbox might help. This gives you an arch on the clutchwire, witch in turn prevents wheelhop. Without the arch, the clutchwire will pull and release the clutch arm when the fork that the gearbox rests on bends back and forth. Very simple thing to try out....

[Berger]

Additional to what Folke is suggesting; I made a mount on the top of the box to prevent the back/forth movement of the gearbox (#1 picture). A stronger solution than the cup bar, is to have the bars straight up (#2 picture).

Worked nice on my car

[BeetleBug]

Additional to what Folke is suggesting; I made a mount on the top of the box to prevent the back/forth movement of the gearbox (#1 picture). A stronger solution than the cup bar, is to have the bars straight up (#2 picture).

Worked nice on my car

Yes, keep it simple. Same solution I used on my 65. Solid mounts, original torsion springs, original rubber for the torsions, original spring plates, bus snubbers, red koni`s, Berg bar - full weight car.

[Harry/FDK]

There will be virtually no preload with 28mm bars to get the ride height where it needs to be. Use either really short snubbers or no snubbers at all. You won't bottom the suspension with T-bars that big unless you're on slicks with big power. There also needs to be considerable preload on the truss bar to allow of flex in the bar. Believe me, they do flex, even when they are tight. Could be that the shocks are too stiff.

All things being optimized, it might just be the tires. Many kinds of radial tires seem to not get along with a stiff rear suspension. You can try different air pressure to gage the result.

Mike, when you pre-load the truss-bar. Are you actually tie things together, or pre-load "outwards" ?

Thanks,
Harry

[Sam K]

Not sure if you have done it already, but putting some washers where the clutchwire tube is fitted to the bracket on the gearbox might help. This gives you an arch on the clutchwire, witch in turn prevents wheelhop. Without the arch, the clutchwire will pull and release the clutch arm when the fork that the gearbox rests on bends back and forth. Very simple thing to try out....

I've done quite a bit of experimenting with different amounts of "bow" in the bowden tube. I took several 12mm case washers and cut a big slot in them so all I have to do is loosen up the clutch cable a little bit and I can pull the bowden tube back and take washers in or out as needed. It seems to work best with about 1 1/4 inch of bow in it.

I also have a one of those "washington anti-shockers" from Berg that I've been thinking of installing the next time the engine is out, but it seems like a "band-aid" fix as all it does is slow the clutch engagement a little. If I have time this weekend I'm going to put the stock torsion bars back in and see what happens.

[Harry/FDK]

Up.

[Sam K]

So I finally got rid of the wheel hop. I ended up replacing the 28mm torsion bars with stock ones, installed some KYB Gas-a-just shocks and put new tires on the rear. I made four passes in it at the Denver Bug-in today and had no hop whatsoever and 2.0 60 foot times. Woohoo!

[karmann77]

Fantastic result and a great read, just shows that simplicity is the best bet, dont complicate things hey