Projekt alpinweiss II part I - weight reduction

[andy10v]

I'd have said that a lighter rear should cause oversteer as there's less grip at the back, think hot hatch lift off oversteer. Overall the car is fine, I'm a little tentitive about full throttle, tight and wet cornering but on thr occasions I've gone a lttle mad it's been fine without a hint of slip. I've lost <10% weight and it feels better as a result. The rear bar is perhaps a bit much on track but on the road it makes the front of the car tuck in nicely and it can be nicely adjusted using steering and throttle, something the stock car could never do IME. When I posted that statement up, the rears were running stock springs and the front HnRs so it wasn't really a fair test. Now it's HnRs all round and I've not noticed anything untoward since, although I've not done many looney launches recently. Overall the big rollbar and a bit of weightloss have done wonders for the car, it would be nice to address the weight distribution a little but TBH it's a lot better than a hot hatch still and has 4wd to help out.

Ok cheers for that explanation. Going to see how I get on with the car stockish first and then might put my spare 90 front bar on the rear.

Have you thought about an electric power steering pump to shift more weight back, ie mr2? Or do you reckon the cons outweigh the pros.

[Rusty]

PAS pump does brake assist on the S2 so unless I go vacuum assist on the brakes then it'll remain as is. Good idea though, not sure where I'd plonk it tho.

[andy10v]

PAS pump does brake assist

Totally forgot about that.

[Rusty]

I wish it didn't, vacuum or bias box would be nicer

[terrybullwon]

I really do not think that you have lost enough weight from the rear to encourage over steer Andy, Untill you remove from the rear the tank, window and whole rear floor plan changes the car will change very little.

[EspenW]

40-60 1.92s avg, 5 runs.
50-60 1.07s avg, 5 runs.

The 50-60mph time is easy to obtain from magazine road tests, etc, and will give a pretty good idea about the usable power/weight ratio of the car, as it covers approx. 5200-6200rpm in our cars.
I see from my data that most of the RS2's tested by Autocar, etc. were timed at 1.2s between 50 and 60mph. Here are some more 50-60mph times from the collection (note: most European magazine numbers are two-up and with a full tank):

50-60mph:

S2 ABY Coupe: 1.40s
ABY Estate: 1.40
Audi V8: 1.70s
Porsche 968: 1.40
E36M3: 1.20
C6 RS6: 0.90
V8 R8: 0.90
R8 V10: 0.70
Aston V12: 0.80
Audi S6+: 1.20
B5 RS4 (stock): 0.95
B5 RS4 (chip): 0.77
Porsche Carrera GT: 0.60
997 GT3: 0.8
Diablo: 0.70
Ford GT: 0.60
Porsche 997TT: 0.70s
Panamera Turbo: 1.00 (0-60 in 3.6s)
E92 M3: 1.00
Lambo Murcielago LP640: 0.62
My RS2 on petrol: 0.70
My RS2 on alcohol: 0.65
E90 M5: 0.80
Boxter RS360: 1.20
Nissan GTR: 0.80
Mercedes McLaren SLR: 0.70
Switzer SPI 750 (Porsche 997TT): 0.50 (0-60 in 2.7)
Bugatti Veyron: 0.50
Switzer Sledgehammer (997TT): 0.32

[Puglife]

The layout of weight makes it difficult to balance in a monocoque chassis roadcar but I've done alot of investigation into weight balance and transferring weight on a Type85 UR Quattro (also Coupe Quattro)....

Losing total weight is only half the battle, balancing the weight loss is the other half...

As james has said your unlikely to get oversteer without inducing it with heavy braking and turn in. Theres still plenty of weight on that back axle.

[Rusty]

I know the alpinweiss feels strong but it seems to do well in that company. As engine tuning isn't on the cards for a long while yet there's only the pursuit of weight reduction or chassis tweaking left. Although, if an RS2 setup popped up I could be tempted, I'd prefer to get the k24 running a big WG spring and improve efficiency at higher revs and a tad more boost. Should be highly effective on track and reliable too... famous last words.

[Rusty]

Well, with about 80kg removed and some track tyres, the old girl perfromed well at Combe. A slightly sharper chassis would be a nice next step but TBH there was plenty of performance there and on a tighter track it would be more than enough to keep up with some mroe zingy machinery. Managed to keep honest a tuner's B7 RS4 on track tyres and the AM Cars 10v quattro rally car. All good.

Subframe bushes next, then hopefully some fancy top mounts.

[Error404]

theres lots of improvement to be had bracing the chassis dude, and its almost free too
Car feels much more stable towards the grip limit, rather than squidging.
I've now got a bit obsessed by it
Looking at more tunnel bracing at the moment, tricky due to exhaust. Needs some thought.

[Rusty]

Yeah, if I have reason to take the 'box out then this is a good option. Hopefully not needed for a while though - £££!

The later cars are strengthened a bit anyway (so an Audi breaker told me "I cut them up, I've seen it" )