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Yes Lee it's a swing axle jobbie. I'd like it to be an irs really but it's a load of work.

Chaps. I've always set the front wheels plumb verticle. Thinking is straight line stability. I'm thinking the other way now. I do have extra travel camber nuts on it

If I remember correctly...

A higher rated spring has a high resonant frequency. Which means it will oscillate faster & over a shorter range. To control that the damper rates also needs to be increased to stop the spring oscillating (uncontrolled bouncing).

Stock dampers already have a weak rebound control hence why Konis work well (not over damped but the rebound is adjustable from near stock upwards). With a higher spring rate I’d personally go with spax / Gaz / Protech. But they aren’t cheap.

There are a couple of ways to upgrade to IRS but yes, it would be a lot of work but a lot of people have done it in the past.
The bug pan is a "Tunnel style" of unibody so everything is pretty much of everything is tied to the basic (as I understand it anyway) lower part of the tunnel and it is the upper parts (front beam mount being the change from K&L to BJ) and the upper part of the tunnel to convert TO IRS from swing or visa-versa. Changing the top part of the tunnel would be the perfect way to do the change but the one bad part is that the title's/pan numbers are stamped on the rear of the tunnel and legally (most everywhere) you can't move that.

But converting to IRS can be done other ways as people have done it before and will do it in the future .

Lee

Well I did think my swing box was knackered, turned out to be the noisy solid mounts, so money can go on a conversion kit of some sort. Went out in it before, the rear twitchiness make me hair at back of neck stand up. And there's nothing visably wrong that I can see apart from reading above about better shocks, the concensus is white kyb shocks are rubbish. I've driven a lot of swing bugs and there better than mine.

Per along ago recommendation I'm running Bilstein's on my sand buggy. The model I am using are not being made anymore but they are adequate for off-roading and probably street I do but not a lot of silliness I see now days either .

Lee

For a quick(ish) cheap test...

Fit a set of used stock rear torsion bars.

Bruce.m wrote: ↑Sun May 02, 2021 11:28 pm For a quick(ish) cheap test...

Fit a set of used stock rear torsion bars.

Amen.
Stiffer springs equal less grip at that end. Basic suspension tuning.

On the last swing axles, vw softened the springs and further reduced the rear roll stiffness with the Z bar.

With the damaged rear torsion splines, an adjustable torsion center should be considered. This provides a new socket that IIRC is replacable.

Upgrading to IRS is relatively straightforward if you can do the work or have a buddy that can.

I do have a set of original bars.
The quote, stiffer springs equals less grip.... Is a clue to me, as it does feel like it's floating at the back... This is at speed
Plus
When I boost hoof it the tyres are like its a wet or icy day, its semi spinning a tyre because the back won't DIG into the tarmac.
Our tarmac over here has 10mm stones mixed in. Quite grippy. Looking at US tarmac.. Which to me looks real smooth I'd be spinning out in no time.
What is the degree number for a standard bar and spring plate to get a full tyre contact. So nearly zero camber is what I'm looking for.

Was looking around on the web and found this: https://image.mamotorworksmedia.com/pro ... ension.pdf). Not sure about it but there seems to be a lot of detail in it.

Lee

Yaar. I've down loaded the above. I'll have a good read later on. Ta

It does say that without preload on the bars the rear will be unstable.
A 28 mm bar has to be fit with out preload cause if you do preload it it's WAY too stiff and has a lot of positive camber due to bar being an uprated stiff bar.
So my bug with out pre load is working off the shocks only for some part of the swing axles movement

There is a lot of debate on preload ranging from 0° to ??? depending on bar length (I think there are at least 3 lengths) and what you are trying to accomplish/you are doing with your rig. Here is one site (of many) that might help: http://vw.zenseeker.net/Wheels-TorsionBars.htm

I do mild sand dune riding and have found (shortened pan glass buggy) about 26° is max for my IRS suspension. I have gone as high as 30° and that is way too much/firm.

For what it is worth.

Lee

So my thinking is right then. With no pre load, there's a point in the suspension we're zero pre load will make the car dodgy to drive. Like on a bumpy road the rear will lift due to momentum.

I checked in my Haynes manual and got this:

Spring plate angles

Swing axle models

Without equalizer spring 17° 30 minutes

With equalizer spring 29° plus or minus 50-minutes.

Drive-axle models (IRS) 20° plus or minus 50-minutes

Less than that I think the stop on the housing is going to be used a lot.

Opinion:

Again, I think it often depends on the condition of the torsion bars. Metal does get tired and will "droop" with age or abuse. It also depends on what you are doing. If you are off-roading then you might want to add some preload for strength and to keep the suspension from bouncing on the stops.
Also notching the spring plate some can help with more travel but there is a limit to that also. Mine is notched about 1/4th of an inch but I have seen more/deeper notching also. If you are going to do it then start tiny then, if needed, add more. Also remember that the notch will be tapered towards the spring plate pivot.

Quite a few years ago I did a post on setting the preload so a search should find it for you. https://www.shoptalkforums.com/viewtopic.php?t=110857

Lee