Swapping front hubs for more caster?

[my2000apb]

How will the extenders affect a non-lowered car?

its wont have much of a difference

the extenders are to correct to control arm angle, as the angle gets bad the more you lower it

[afterburner]

Yeah but they will introduce additional camber gain under suspension compression in both lowered and standard height vehicles, won't that help handling by introducing more dynamic camber instead of having static one?

[my2000apb]

Yeah but they will introduce additional camber gain under suspension compression in both lowered and standard height vehicles, won't that help handling by introducing more dynamic camber instead of having static one?

as far as I know, camber gain is more dependent on compression stroke length

ideally you want less camber gain on upstroke

you want the c-arms near as possible to level to ground at rideheight

if youre not lowered the c-arm angle will be below level, negatively effecting handling


its a corrective device for an issue you wont have unless you've lowered the car

[stiglet]

Look at your top mount (from the front of the car), then draw an imaginary line from top mount to your bottom ball joint. Now draw an imaginary line from your bottom ball joint to your inner wishbone pivot. Where these two lines intersect at the bottom ball joint, if the angle is acute (less than perpendicular) then camber gain will be ok upon compression. If the angle is more than perpendicular (such is the case on a lowered car) then camber gain will be the wrong way.

McPherson has this flaw (or advantage from some designers point of view) that at a certain point in suspension travel the camber gain will go from negative to positive i.e. you can corner so hard that eventually the wishbone will raise high enough that the above intersection line will pass perpendicular and start to tilt the wheel the other way with more compression. This is something that only really happens with McPherson. The idea is that idiots who like tyre squeal but have no idea how to drive can have a nice progressive loss of grip instead of a sudden "snap" that you might get with a sportier design. The car will tell you that understeer is going to happen about a decade before it actually does. And when it does, it's already shouting and screaming at you like a wild banshee to do something about it. Older Golf's have the same design, hence why the rear can be as stiff as you like and you will pick up a rear wheel on corners and the thing will still understeer (because the front outside wheel is trying to fall over).

This design is actually embedded in a standard ride height Audi, lowering just exaggerates it. If you correct the problem at standard ride height you will get rid of this noob friendly design feature still BUT you then start to introduce another characteristic that happens when you raise the front roll centre loads, and that is that the front roll stiffness is increased in comparison to the rear (somebody mentioned roll axis earlier in the thread) which then again tends towards understeer. Hence, yes it will work at standard ride height but best to do something about the rear ARB too if you want the full benefit and have your Audi handle like a boss

There is a guy in the states who does auto cross with a MK2 Golf and is considered a Golf suspension Guru (I forget his name) and his secret is to run standard or above stock ride height on the front to take advantage of the funky McPherson design. He was actually one of the guys who originally came up with the idea of the balljoint extenders.

[my2000apb]

cool, good to know thanks

[afterburner]

Good explanation, the idea behind my question concerning stock ride height + extenders is based on what you said.

My car is a saloon with avant rear springs and an S4 B5 rear swaybar, so I guess stiff enough in the rear, also I have front subframe aluminum bushings that lower the front subframe by 5mm to allow a bigger exhaust and add some some more sump protection, which in effect acts like a lowered (by not much, but still) suspension. Maybe will think about ordering a kit in the next month or two, I believe it will help.

[my2000apb]

the bushing make the SF go towards the ground more? that's the reverse effect of what you desire

[afterburner]

Exactly, that's why I want to counter the effect of the bushings with the extenders, and add some more angle to them on top of that (actually I have 10mm spacers on my front springs, which counters the bushings, but that's another story... , let's say I like to experiment) - that's the reason I treat my setup as a one having a stock ride height effectively, hence my first question.

[Mr.Crossfire]

No clearance issue because of the angled design:

http://mrcrossfire.kuvat.fi/kuvat/90q/osia/Alusta/20130326_233029.jpg

The camber curve of the front suspension of t89 chassis is presented in the post #63. At stock ride height, the basic riding position is something like halfway vertically looking. Lower the car, and it sets you upwards to start with.

[my2000apb]

Exactly, that's why I want to counter the effect of the bushings with the extenders, and add some more angle to them on top of that (actually I have 10mm spacers on my front springs, which counters the bushings, but that's another story... , let's say I like to experiment) - that's the reason I treat my setup as a one having a stock ride height effectively, hence my first question.

ok makes sense now for sure
I was thinking a more traditional lowered setup hence my confusion

[stiglet]

No clearance issue because of the angled design:

So you moved the ball joint inboard in relation to the hub?

Any idea what the new scrub radius would be?

[Audi_CQ]

I was asked if I have thought about modifying the bump-steer properties of the suspension, especially after installing the extenders. I actually have designed a little device to raise the inner ends of the steering rods to compensate the changed geometry with the lower balljoint extenders. It looks like this:

http://mrcrossfire.kuvat.fi/kuvat/piirustuksia++malleja/bumpsteerkit.JPG

It bolts directly on to the OEM steering rod holding plate thing.

I could have those made, but it is quite easy to DIY if you have some basic tools. The plate thickness is 5mm and the rest of that you figure out yourself.

And you have to make this adapter (or lower outer mount on strut) because the bump-steer is massive without it. Test mounted extenders both front and rear and after seeing how much bump steer it was I wouldn't have driven the car around a track without adressing the issue

PS! The extenders fitted perfectly

[Mr.Crossfire]

The scrub radius, according to my 3d-model is ~11mm with 225/45-17 et35 rim/tyre. Without the extender, the radius is 1mm negative.

Audi CQ, good to hear!

[stiglet]

So it's shifted out by about a centimeter? Not too bad I guess. I might take a couple of these myself if any are available

[afterburner]

I will also get two next month on pay day, if still available