Killer Flop-Stop Decamber Trick

[FJCamper]

Killer Flop-Stop Decamber Trick

The humble "flop stop" is a much-misunderstood little piece of ingenuity. It's overlooked because its so simple and cheap (usually under $10 when you can find them), but it can be extremely effective and help you tame your swing axles by being a fine tuning device.

The purpose of the "flop stop" is to limit downward movement of the swing axle by raising the spring plate stop.



All you have to do is use two spacers in the flop-stop rather than one. Each Flop-Stop clamp comes standard with one spacer that is 3mm thick.

Installing a Flop-Stop is easy. Jack up one side of your car, leaving the other rear wheel on the ground, handbrake set, and as you raise the car note that the spring plate will lift off its rest.

Don't try this with the other side of the car already up on a jack stand. You need the leverage you'll create by having the other side of the car as low as possible to make the spring plate rise.

Jack up the car enough to slip a Flop-Stop (with one spacer) inside onto the bottom of the spring plate , and slid it forward until it slips into an indentation that looks like it was made for it.

Put a drop of thread lock on the set screws, tighten them, and that's it.



In these photos, we've used two standard 3mm spacers. With two spacers installed, you'll note you can no longer easily jack the car up enough to lift the spring plate high enough to just slip on the Flop-Stop. With two spacers installed, I had to use my spring plate tool to lift the spring plate enough to tap on the Flop-Stop.

Once the double-spacer Flop-Stop was in place and I lowered the spring plate again, I found what I expected to be true, but better. 6mm of spacing gives you an almost level axle attitude. Obviously, thinner spacers could be used to tune your ride height.

I was just expecting less positive camber and axle droop. "Nearly level" was almost too good to be true. This simple mod puts the Flop-Stop into the camber compensator class of usefulness, but at less cost, time and trouble.

FJC

[Acavet]

If I recall correctly the original intent of the devise was to prevent the spring plate from coming off the stop thereby jacking one side or the other of the car in a turn.

If I am reading you correctly what your doing is in effect taking any ability of the suspension to move in a downward movement out of the equation, something you don't want to do for either ride quality or handing.

You may as well just set yourself up a solid rear suspension.

Tony

[FJCamper]

Hi Tony,

The caveat is this is for road racing only. I wouldn't do this to a street car that needs lots of suspension travel. My posts are all about racing, which is what we do.

The less you let a swing axle move (within reason) the better it works in road racing. If you've ever seen the fastest 356 Porsches up on jackstands, their rear axles do not droop.

You may recall Colin Chapman, developer of the Lotus cars, said: "Most any suspension works if you make it so stiff it doesn't move."

The point of my post is to show how remarkably little it takes with the simple flop stops to achive what lots of torsion bar reindexing and double-spring camber compensators do. And its easy to reverse.

FJC

[Acavet]

Maybe I should have read you posting better instead of scanning over it. I wasn't aware that this was for racing only...

I took your post to suggest that this was a easy means of adjusting camber for street cars as well. I've ridden in buggies and kit cars that have had either suspension pushed to the max or suspension that were so stiff there literally was any suspension. A lot of people seem to forget that a suspension needs to move downward as well as upward.

The road isn't just filled with bumps it has pot holes too.

Good luck with your racing and be safe.

Tony

[WickedWagens]

Would suspension limiting straps have the same effect as this? They might be easier to find.

[FJCamper]

Hi Wicked,

Yes, limiting straps absolutely prevent downward axle movement.

I used them way back on my shimmed-Z bar 1968 swing axle Bug (a hard-driven street car) but found the bang-clunk sound and feel of the axle being suddenly stopped as it tried to drop was objectionable. But the straps worked.

I tried Flop-Stops (but with single shims) and they were okay, but still not good enough.

I then fitted a 19mm Sway-A-Way rear bar (I already had a 19mm front bar) and found the sweet spot. The sway bar controlled the axle movement, and at no time did I ever experience wild oversteer caused by the increased rear roll resistance. This was on Sears VW "heavy duty" shocks, fiberglas-belted "performance" tires, and very stock brakes.

And again, this was a hard-driven car, to include forays deep into Mexico and mountain road dicing with the local VW hot rodders there.

The trick to outrunning the Mexicans was to be just a little wilder than them, come closer to the bull's horns as it were. They were brave but not crazy.

FJC

[fusername]

Very cool, look like a cast piece? A friend just bought a mini mill and I may take a shot at making my own. Now when you are cornering does this limit the power you can put down as the outside wheel has less wight on it due to fixed suspension rather than the ordinary body roll?

Also will a shimmed z bar still help in addition? My original plan was moderate sway bar up front and a z bar in the back. Will these add to that combo, or should I dump the z and only use these? Its a fiberglass play buggy, swing and link. Note I have NO mods on the car yet, so I have a beautiful blank slate

[FJCamper]

Hi Fusername,

All the "flop-stop" does is raise the factory spring plate stop. By all means make yourself a set if you can.

Our experience (and remember we're using ours in conjunction with a camber compensator spring U-bolted to the axles) is that it has increased our handling capability on both slalom and road course.

You asked about also using a Z-bar. I think the overall mechanical efficiency of the Z-bar is perfect for the swing axle BUT it takes more bar diameter in the Z-bar than VW gave us to make it effective. Even the little lightweight Formula Vee's have a half-inch Z-bar!

FJC

[mk-Zero]

Hey FJ and others, sorry to revive such an old, but super useful thread. I'm wanting to limit the downward travel of my swing axle since I plan to start tracking the car (autocross for starters, then possibly some road course time eventually). Right now it sits at 3-deg negative camber in the rear with stock (24mm for my car) bars and adjustable spring plates. My question is, what should I limit the droop to? I do drive the car on the street, so please keep that in mind as well. Would +1-deg positive camber of droop before hitting the stop be sufficient? That would give me 4-deg of camber change from ride height to fully drooped on the stop? Or should I aim more for level axles (0-deg camber) on the stops? Thanks in advance for any advice.

[vwo60]

Hi, I have welded a piece of 4mm steel onto my rebound stop on the rear of my swing axle beetle, it works great, to offset the loose downward rear wheel travel i measuring the upward wheel travel avialable to me and modified the bump stop increasing that,so effectively i still have the same travel, I run on the street a 1 degree of negative and the rear tyres are 235/45/17, I have my car set up to handle but with the limited downward wheel travel I can spin the inside wheel coming out of of camber corner's, you can overcome this by changing your driving style.This has worked for me for years along with a sway a way camber compensator are great mods.

[risk]

Same here.. Welded some small 1/4" thick flat stock pieces where the spring plate rests.

When you let off the gas at 100+mph it makes a lot of difference in handling.

[vwo60]

Same here.. Welded some small 1/4" thick flat stock pieces where the spring plate rests.

When you let off the gas at 100+mph it makes a lot of difference in handling.

There are many benefits to the mod and the only down side i have observed is accelerating hard out of a tight turn and spinning the inside wheel.

[mk-Zero]

Thanks guys. I checked my car last night and there's no room between the spring plates and housing for bolt-on style flop stops (I was going to make some), so for now I've ordered some limit straps. They should limit downward travel to about 0-deg camber, which I think will be enough travel with starting at -3 deg. Ultimately I may come up with some adjustable travel limits that bolt to the housing instead of the spring plate or a way to make the straps adjustable. I like the idea of allowing more travel for the street and less on the track.

[vwo60]

If you make the downward travel at 0 degrees all it will do is pick the wheel up in the corner as you need wheel travel downwards to handle as the body does not stay flat.I have about 3 degrees on the stops.

[mk-Zero]

My starting point is -3 deg though. I measured the down-travel from static at -3 to 0 and it was 2.5 or more inches. I don't think I have that much up travel. Anyway, this is why I'm hoping to come up with an adjustable solution, so I can easily add or subtract.