A question about Caster

[Yabbadubbadoo]

I've seen a number of cars on picture feeds in FB and the like sporting an aggressive down rake to toward the front like the one below.
I was just thinking it must wander like a drunk sailor due to losing its factory caster angle. Can you or has anyone installed a shim like a beetle behind the lower beam? I know it's more difficult than the circular beam cross section of the beetle and it has to sandwich behind the rubber mounts but is it totally impossible to add some caster when you need it on a type 3?

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Sydney, Australia.
66 Type 3 Fastback

[Tram]

Caster is adjustable at both the upper and lower ball joints enough to prevent tire wear in these cases. The REAL problem with lowered front ends is that the lowering puts a severe strain on ball joints, beam bushings, and steering linkage that no amount of adjusting will cure. The wheel is designed to bounce in an "arc" on a proper height front end and lowering the car lessens the arc, which strains other mating load bearing components.

The other thing that can strain front beams over time is too much tire pressure.

EDIT: I meant to say that CAMBER is adjustable- caster is built into the beam/ car. I don't know of any caster compensation available to the Type 3.
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Немає виправдання для війни! Я з Україною.

[Yabbadubbadoo]

Thanks, yeah I thought so. Caster is built in and camber is adjustable with the eccentric ball joint but I don't know of anyone who's been able to add additional positive caster to help the steering self centre when the car has that pro-stock rake angle to it. I'm aware of the magnified wear of a lowered front end and I thought drop spindles would address that in a moderately lowered car but yeah I don't know of anyone who's adjusted caster to compensate for rake. The other thing rake would do is shift the weight distribution but a little more front weight might be nice to remove some understeer.
Anyhow, I was just curious. I see a lot of cars with wild looking stance and the more I learn the more I figure that they've made a lot of compromises and I suspect many of which they are blissfully ignorant of.
_________________
Sydney, Australia.
66 Type 3 Fastback

[vlad01]

unfortunately it is the case the Tram states.

The only benefit I have personally noticed having a slight rake (not like that! in the picture ) is high speed stability especially when windy as a rake helps form a vacuum under the car which increases with speed.
key is to find a balance between loss of caster and aero gains.

I run stock height rear with front lower by about 20mm? its only a very subtle rake but it does help a bit. I can't feel that I lost any handling with the front only slightly dropped.
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[KTPhil]

[Bobnotch]

[vlad01]

for the rubber collars. I think using the late lower collars is always a good idea as they already add extra caster.

what we need is to have upper collars made with an offset towards the rear of the car because the uppers are centered and have adjustment room available while the late lower ones are already maxed out from factory.
_________________
The best of VW engine development!
https://www.youtube.com/watch?v=BROWqjuTM0g

71 Aussie notchback, the money pit
92 VP vacationer, old faithful never die
95 VR executive, Restored beyond factory
92 VP S Pack, bought it new old

[vlad01]

[jaransonT3]

Here is my investigation of the issue from many years ago....

http://home.comcast.net/~jaransonT3/jaransonT3/LoweringPage.html

I still need to redo this since some of the geometry doesn't make complete sense, but you get the idea.
_________________
Later,
John Jaranson
'66 Square
'69 Square
'70-1 Fasty
https://www.carartbyjohn.com
https://www.carartbyjohn.com/2024Invasion/

[Yabbadubbadoo]

Interesting info jaransonT3.
Tipping my hat to you for going into detailed investigation and doing your own measurements on the topic.
I noticed the different length arms too and had expected the caster to change somewhat but had no idea exactly how much. I assume its something to do with adding turn-in capability under braking before a corner. That's just a guess though.
So dumping a type 3 on its belly even with same lowering amount front and back is going to have adverse affect on caster and straight line stability. It's clear when I see your sketch.
You had referred to a solution involving a remanufactured clamp rubber with added caster. I wonder if it could be a little simpler like mill two strips of polyurethane or Delrin sheet with a slight wedge shape to line the lower rear clamp face.
Kerf it or just heat it to bend around the clamp shape and rivet it in position with four rivets.
Then use the original rubbers for the beam. The lowest clamp bolt will look slightly more open but one or two degrees would not amount to a huge gap.
_________________
Sydney, Australia.
66 Type 3 Fastback

[vlad01]

someone with good engineering knowledge ans skills and access to a 5 axis CNC could mill the moulds to use for polyurethane collars as a starting point.

Eventually you could lead that to full rubber moulding tooling once testing and tooling shape is perfected.

The problem is getting someone to do it as a jobs would cost in to the 10s of $K potentially. If you have access to such machinery and software like solid works then its just a matter of materials and finding free time to play and design.
_________________
The best of VW engine development!
https://www.youtube.com/watch?v=BROWqjuTM0g

71 Aussie notchback, the money pit
92 VP vacationer, old faithful never die
95 VR executive, Restored beyond factory
92 VP S Pack, bought it new old

[vlad01]

[Bobnotch]

[Yabbadubbadoo]

Bobnotch I was thinking that rivitingbthe shim to the frame head side clamp would be necessary to stop it creeping out of position. Just an idea.
_________________
Sydney, Australia.
66 Type 3 Fastback

[vlad01]

I just checked my caster. It shows about +4º ish as it should be.

so that 2d model in the link has something wrong with it lol.
_________________
The best of VW engine development!
https://www.youtube.com/watch?v=BROWqjuTM0g

71 Aussie notchback, the money pit
92 VP vacationer, old faithful never die
95 VR executive, Restored beyond factory
92 VP S Pack, bought it new old

[Bobnotch]

[Yabbadubbadoo]