Street suspension.(Swing axle)

[Garrick Clark]

Hi. I've finished with the rear end for now. Gotta get it checked at a shop. Today I had a go at the front end. I've got the bug sitting slightly higher at the front than the rear. From what I've
been reading this is ideal for a street car. I've got the camber set straight up. And have the toe in set at 1/8. I just measured  the width from the passenger  centre tyre treads to the driver side centre tread, then did the same at the back of the front tyres. Easy really.
Heres the thing.
Do I need a 3/4 Sway at the front on a 2" narrowed stock height beam with standard front shocks or will a modified to fit standard one be ok

[spanners]

Garrick, first, you have a lot of power, second, its gonna take some controlling on the street, if you are REALLY gonna push it on the street your on the limit of staying on the road  setup as it is its an oversteerer, a big oversteerer. its very close to circuit swing axle set up torsion bar wise at the rear, its very stiff rear and very soft at the front, hence its trying to swop ends at each twitch on the steering. i know most posters here are drag orientated, assuming you are too means compromises, im not a drag racer but know Beetle dynamics and what happens when changing chassis set up, ie, track use, to balance those big rear torsions you need around a 19 or 20mm front ARB, that will stop oversteer in roll, trouble is this is just baggage on a drag strip  weight.. then as others mentioned, decent shocks at both ends, front too needs stiffer shocks, adjustable preferably if your gonna strip run it and need it soft, i alsays set half setting range front and rear and go driving and learn whats needed, the rear tells you its too soft as it will bunny hop after deflection, again, start at half hard and go from there. your tyre sizes aint gonna corner brilliantly, nor is a narrowed front axle, but we have what we have, i run fronts on track harder than rears, race is around 30\32 front, 28\30 rear, i guess yours would run around 20 in the wee fronts 30 in rear, almost stock, the bigger the tyre the lower the pressure it can run, eg, huge  F1 tyres around 15 psi, books are written on VW handling and you have things to try already, but the very best swing axle handling rule is STIFF, LOW and WIDE, do get a BIG front ARB and go from there..
 one contradiction is a laugh, if you make IRS rear as stiff as your swingaxle, like short 28 mm torsions, it will corner like drift car side ways everywhere, biggest IRS bars would be long 26mm x 26- 3\4".. i find 24mm work best and control them with shock settings. dont know what shocks you can get but protech work extremely well. toe settings are around
half deg toe in front and rear. 

[Garrick Clark]

Thanks for the info Spanners much appreciated , I'm understanding the balance side of things now, no good with a stiff rear and soft front,  I'll get the bar next week. As you say that will make the front and the rear stiff and balance it out more on the bends. Once I have this fitted there's not much else I can do with it is there. I cant get rid of the  rear 70 series tyres as the exhaust manifold will be less than 4 " off the road. I think with all I've done it should be a lot safer at speed. 

Regards G.c

[spanners]

Well you can always do more lol, one good thing is the narrowish axle has stiffened the front somewhat because of the shorter leaves, so no bad thing there, you may be able to bring the front wheels out to fill the wing  aperture with spacers, depends on the wheel et, i see you run dropped spindles so more track width help there, worst case senario if its still tail happy would be to soften the rear back to softer torsions, a camber bar or preferably a proper z bar works ok with stock torsions but does nothing with bigger torsions 26mm and up, my challenge cup car used 30mm torsions and no rear bar, but i would brand them race only and very stiff on the street. the rear down theory works to a point, what it realy does is to add caster, it gained popularity as a theory when the the 411\412 and super beetle appeared to be set up thus, but with those it was done for full load luggage carrying ability with their huge front boot or trunk to you gents, but once you get the car really sorted and going proper quick, you will look at aero and you dont want air getting under it at 120 mph into a turn, so despite rumour and several popular writers and publications the cal look guys got it right, slightly front down but lower than they set them, they also run double caster shims, but key is one change at a time, then test.. remember IRS will always need softer rear torsions, you would think they would tolerate huge bars being a more modern design, but as i said, t`aint so.  have fun and good luck with it.

[Martin S.]

And have the toe in set at 1/8. I just measured  the width from the passenger  centre tyre treads to the driver side centre tread, then did the same at the back of the front tyres. Easy really.

I was wondering about 1/8 toe in. The spec is 1/16 total (1/32 per side). Does 1/8 toe in help with handling? What is the difference with more vs. stock spec?

[JeeWee]

And have the toe in set at 1/8. I just measured  the width from the passenger  centre tyre treads to the driver side centre tread, then did the same at the back of the front tyres. Easy really.

I was wondering about 1/8 toe in. The spec is 1/16 total (1/32 per side). Does 1/8 toe in help with handling? What is the difference with more vs. stock spec?

who is making the specs? a bit more toe in will help in better response in steering.
@Martin, why do you have your front toe in right set to 0?

[Martin S.]

The specs were in the alignment computer at the shop I went to.
I didn't align it myself, so I can't say why I have zero on the right and 1/32 on the left.
If I had to guess, the operator maybe thought that 1/32 and zero were almost the same thing (.030" is pretty small) but I have no idea.
It does drive nicely as is, so you are saying it would be more responsive with more toe-in?
Interesting, although I'm not sure I would like it more responsive.

[spanners]

Front toe depends on the cars agenda, but in the real world there's rarely any time or reason to change from what you are regularly running. i would run parallel on fast airfield tracks but 1/16 on tight tracks, the only thing i avoid on my VERY stiff front b/j axle is toe out as it tram lines and feels un predictable braking hard into bumpy turns and most are exactly that.
small differences side to side dont matter as it centres anyway, to be picky, there is a centre register on the 'box which is useful for setting up, i carry a track rod assembly with Pittman arm pre set ready at 1/16" to bolt in in the event of bent steering, but 1/8th is ok and would be good in winter races as we have trouble warming the front tyres, i would run parallel for drags only  looking for minimum rolling risistance🤔.
             

[mac68]

I run toe out on my track only k@L swing axle. Yes its a bit squirmy under brakes but turn in is awesome!

[Garrick Clark]

Hi Chaps.
I'm back doing some work on this bug.
Went out in it today for 1st time since the changes.
The Last change was actually a 3/4 front sway bar. I No some people say don't do it as there too big, but I didn't get any bad vibes from having it fitted. The rear on the other hand does feel dodgy.

These 205 x70 tyres I'm using. I have them at 30 psi. The side wall isn't very stiff to me , they do wobble about. Is this the right tyre pressure.

P.S   I need the 70 series to gain some height in the rear end to stop the exhaust being low.
I'm driving along, no torque, boost comes in, full torque after a couple of seconds then what feels like rear end wobble.

[Neil Davies]

First try dropping the pressures a little. I've always run around 26psi, no matter what the tyre size. 30 might feel a bit squirrelly. If that doesn't work, maybe try a different brand of tyre? What are they at the moment?

[Garrick Clark]

Hi Neil.
I'll have a look at the make.

[Garrick Clark]

Got it better today.
Put more camber in the front end.
Passenger side has more camber than the driver side.
I'll have to take a bit of camber out of the passenger side to get both front wheels to match camber wise .
Re tracked the front again.
Upped the tyre pressure.
Got rid of a bit of steering box play.
I'm 3/16ths toeing in at the back.
I don't think its symmetrical at the back I'll have to get a shop to check it.
So progress has been made. It feels better at speed now.
Not easy is it. A tweak here and there makes these bugs drive from good to bad and vise versa. 

[Garrick Clark]

.

[spanners]

The most common handling/suspension set up problem i see in the shop is bump steer, especially on k&l cars that dont have a register for the steering box location, no amount of cash spent on high end suspension parts will compensate for a car with bump steer, it feels like the rear is wayward especialy over undulating roads and always worse the faster you go, properly set up, if should run straight and true so maybe thats your problem Garrick..

[Martin S.]

I'm 3/16ths toeing in at the back.
I don't think its symmetrical at the back I'll have to get a shop to check it.

Did you find toe-in at the rear was helping? I found the opposite. When I pulled the axles back all the way (toe out) it drove much nicer with more stability in the wind, or bumps.

[Garrick Clark]

Hi Martin.
I've not altered the rear since I last tweak it. Bad weather stopped me driving it.
I've a new box to fit now.
I'll fit that then get a good tyre shop to get the symmetry right then add a 1/16 of toe in.
My other rear end mod is a camber compensator, from what I've read its a must have on a swing axle.
Regards.

[Martin S.]

I was thinking about that too, although I still have the original 68 Z-bar so I'm not sure how well they work together?
One thing I would like less of is the feel of a bounce in the rear suspension over the bumps which the Koni's helped the most.

A couple things I found out after fitting a new box:
Make sure you have a reinforced cross shaft for the clutch! Also get a heavy duty rear transmission carrier and the grey HD rubber mounts. Also add a frame horn rear engine brace to keep the frame horns from bouncing.
Next on the updates for mine are the carrier and the frame horn kit as I feel the engine bouncing slightly over sharp bumps at speed.

[Garrick Clark]

Nice 1 Martin.

I was told that if you fit the camber compensator either the CB one or the Empi one that you need to remove the original Z bar from the vehicle. The kit's that fits to the axles like the CB/Empi ones do stop that rear wheel bounce/tuck effect when going over uneven roads at speed. They say its a no brainer add on part for a swing axle .

[H67bug]

Hi- haven’t read all posts... do you have flop stops fitted to prevent the car lifting too high after a hard launch? It prevents most of what you talk about

Basically it’s a bolt in the spring plate, welded up, against the casting of the tubes


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[Garrick Clark]

I did have some of them fitted but as the back went positive camber the bolts used to hit the spring plate ledge with a knocking noise. that got a bit irritating so I removed them.

[Neil Davies]

I had flop stops on my race car, and they worked fine. However, I remember being told not to run them (or limit straps) on the street as they stop the rear suspension from unloading in a controlled way - instead the wheel travel just stops abruptly  and the back of the car can become airborne.

[leec]

I wouldn't drive a swing axle bug with 100bhp or more power without the spring plate mod. It transformed how both of my beetles drove, particularly coming of hard acceleration

Lee

[andy198712]

when i was being followed in my bug and pressing on, i was told when i braked the car would get some decent positive camber.... and it felt scrary too, very unsettled.... think i need to refit my camber comparator and will have to DIY some flop stops as one of mine went missing

[leec]

If you are getting lift at the rear when you come off the power it doesn't matter how good your alignment is (was) as the height change will throw it all out

[andy198712]

totally agree

[spanners]

The rear suspension toes out on throttle lift off, drag cars have soft front ends so the problem is amplified with front dive, i see drag guys lift off and and de clutch into neutral at high speed and the car loses control...
circuit cars are very stiff up front to combat dive and pitch and lift of oversteer..
 dont wast money on camber compensators on cars with big rear torsions, they do naff all.m

[j-dub]

I wouldn't drive a swing axle bug with 100bhp or more power without the spring plate mod. It transformed how both of my beetles drove, particularly coming of hard acceleration

Lee

Lee,
By spring plate mod are you meaning a way to limit the movement of the spring plate such as the flop stop or limiting straps?

are you referencing this thread?
http://cal-look.no/lounge/index.php?topic=25484.0

Thanks in advance,
Jeremy