Projekt Kastor

[Error404]

very good andy, what diamter bearing ahve you specced there? Looks a beast

wish I had CAD skills
I'd have everything pink

[newsh]

Of course there's always lowering the back of the car.. The stock springs give a tilted-forward stance to my car, just thinking about this and realised how much better it steers with some weight in the back, leveling out the car would probably give a degree or 2 of change maybe? Would tend to sit down at the back when loaded though..

[Rusty]

Bearing is 40mm casing, 35mm ball.

My car is stripped and sits level! Promounts are a little thicker than 034 items!

[quattro84]

just thinking about this and realised how much better it steers with some weight in the back

This is the reason why the Audi's perform the way they do, the lumpy engine is too far up front!
Still, load transfer is huge on acceleration. Most obvious on the smaller wheelbase cars like the Sporty:


As previously mentioned, this can be overcome in several ways:
Hardening rear damper inbound, which results in overloading the rear tires resulting in loss of grip.
Use of anti-dive/lift/squat on standard McP geometry. This kills the response and feedback from the steering.
Latest WRC cars use a lot of both, resulting in very stiff and 'dead' cars. Keep in mind that these boys use more advanced diffs

After these modifications i am interested in the driveline behaviour, meaning the TorSen diff. Delivering more torque to the rear wheels induces oversteer as well.
(StaSis mod)
The weight transfer also affects on the TorSen diff because torque delivery is based on tire grip.
And it seems that TorSen diffs go loco when a wheel is lifted from the ground and regains it grip at landing...

[Rusty]

Cool pic

I've not bothered with modified torsen or twin torsen setup yet as I believe the car is easier to drive aggressively on the road as stock, it's quite FWD in character and that is fine for now. I find my twitchy BM quite nerve wracking in the wet and the beauty of the Audi is that its very forgiving on the power. The BM is all good fun for T junction lairiness but on tight, slippery roads with traffic you have to feed it carefully, a couple of times in changeable conditions I've been caught out and it's no fun deciding between a car or hedge... then sometimes the diff provides understeer and that well known feeling of things not going to plan... Something in the middle would be nice, hence a few upgrades

[Error404]

rear torsen lets go very progressively, not at all snatchy like your BM is mate (if its anything like an E36 anyway)
Combined with the stiffer rear ARB mod the handing on and off the power is very neutral - on power understeer is virtually non-existant and the rear end breaks away ever so smoothly - its aweome

none of that horrible "i'm going straight on and nothing I can do about it" audi handling sensation at the limt.

[Keeper of The Kitten]

I personally don't think the front strut brace does a lot, the strut towers are practically siamesed to the bulkhead already. But stiffer is good at any mounting point.

Andy I couldn't receive your email, my ISP is messing about with the service and has been all day...

[Rusty]

Rear strut brace to use with those top mounts is done in concept, will design it Thurs. Have gone with the offset versions at the rear because they provide a secure mounting option that is difficult in a non offset version, just need to decide best orientation...

No worries Mr. Cutting, will see how goes it tomorrow.

[Error404]

I noticed a real difference after fitting the front brace.
Try it without, car feels sloppier at the limit

[Keeper of The Kitten]

I've got a 10V CQ so I've done both lol ...but that's fair enough.

I think I should rewrite that as "the front strut brace doesn't improve it as much as it would improve some other cars, due to the position of the strut towers."

Actually I think a brace that attaches (triangulated) to the bulkhead would be a further step, the sort that just joins between the towers will certainly beef up, but the heaviest load will just cause both towers to move. Tying into the bulkhead would eliminate more movement.

[Mr.Crossfire]

Would it be beneficial to also move the top end of the struts inward? You could still adjust camber to factory spec from the strut and hub carrier joint. I'd think it could help to kill the positive camber gain.

[Rusty]

The positive camber comes from the wishbone arc. I guess that moving the top mount in would change the angle at which the wishbone and strut line are tangential and so yes, it would make a difference. The design of top mount I've got could be mounted at 45deg and thus give 5mm offset in fore-aft and side-side, at the rear the same could be applied or have the mount giving 7.5mm offset side-side.

[HPmuirt]

More dumb questions: -

1. How do Golf owners mod their cars to give more negative camber? I assume they have the same Mac strut and lower wishbone setup and I assume that they are designed to give positive camber on loading the outside wheel to give understeer on the limit? Surely it is more than just camber plates plus camber shims or oval bolts?

2. What are your thoughts on using camber shims? Acceptable or dangerous?

3. Will the camber/castor plates you are designing for the top mount area allow me to keep my promounts?

4. As you mentioned in you original post, the best way to add more camber (and possible castor would be to use adjustable ball joints on tubular lower wishbones.

I seem to remember someone working an S1 copies. What happened and could they be build in sufficient numbers to be affordable?

5. Do we actually know what the optimum camber and castor angles would be if we had all of the above available?

Cheers n

Si

[s2driveruk]

I am soo suprised you guys have kept this on topic given Andy's asertion that:

"This method needs a bit of incestigation as the gains are large for a little head scratching."

That does seem rather extreme Andy...keep to the pc and CAD and it will come together I'm sure

[Rusty]

More dumb questions: -

1. How do Golf owners mod their cars to give more negative camber? I assume they have the same Mac strut and lower wishbone setup and I assume that they are designed to give positive camber on loading the outside wheel to give understeer on the limit? Surely it is more than just camber plates plus camber shims or oval bolts?

2. What are your thoughts on using camber shims? Acceptable or dangerous?

3. Will the camber/castor plates you are designing for the top mount area allow me to keep my promounts?

4. As you mentioned in you original post, the best way to add more camber (and possible castor would be to use adjustable ball joints on tubular lower wishbones.

I seem to remember someone working an S1 copies. What happened and could they be build in sufficient numbers to be affordable?

5. Do we actually know what the optimum camber and castor angles would be if we had all of the above available?

Cheers n

Si

1, your S2 can have a lot more camber added as stock by adjusting the front strut to hub bolts and pulling the lower BJs all the way out.

2. There is not a case or need for camber shims on the S2 as there is plenty of adjustment (the golf has a fixed rear axle).

3. No, these are a solid mount that replaces any existing top mount. To make this a more appealing idea I am using monster bearings and also removing as much movement in this area as possible.

4. Lower wishbones are not difficult to make, would allow substantial amounts of adjustment and would not require other parts to be replaced. However it is a critical part (more so than a top mount) and I've not found someone to make them who I can trust. It's perhaps a future project.

5. Not personally, other than experience with other cars which have different driving characteristics and different camber and castor angles and of course, some basic theory.

P.S.:

Cheers for that David