Help Stop The Roll!

[Jonmurgie 2]

Am going to be speaking to the AST guys about this but wanted to get a conversation going about how to reduce this:

 

Massive body roll!

 

I've got hold of a 309 ARB (21mm instead of the 19mm 205 one) and will try that out but what else do you reckon? Harder springs? Stiffer shocks?!

 

Thoughts...

[hengti 2]

stiffer springs i guess

 

it might be a good idea to keep some compliance in the suspension though - especially if using super sticky rubber

 

i've heard of light (relatively tall) cars (like the 205) going up onto two wheels and tipping over with v stiff suspension (usually as a result of bouncing off of kerbs). That said, 195 section tyres might not generate enough grip to make this a potential problem

[Rippthrough 98]

Getting closer to the apex might do it

 

How low are you? Any chance of going lower and still keeping the suspension travel + geometry you need?

That would help a little, but stiffer springs/tb's is the only real option there I think.

 

Stiffer shocks won't help as that's mid corner when it's settled I think? Don't know how much difference the ARB will make either, what with the inside wheel already being off the floor, should make some though.

[Guest smokinslim]

Could be wrong but i reakon a stiffer front ARB would make more difference than a rear one in that situation.

[Jonmurgie 2]

I was using A048's all round that day (it's a pic from Llandow) and the line in the pic is cause I've just come out of another 90deg right hander and cutting across that corner into a sharp left hander, you kind of need to see the whole picture to see how that line works

 

I'm not that low really, and considering dropping it a little more...

 

The 309 ARB I mention IS a front one so going to see how that works out. Might just add that and see how it goes at Combe on the 22nd, if still too much roll will go for harder springs (running 286lbs at present)

[easypug 0]

What is you complete specification at the moment, will give people an idea where to uprate and such.

[Batfink 201]

looks fine to me. Think how high the clidiots supporting the BTCC races lift their rear wheels

[Wurzel 16]

Stiffer front springs would be better. If you're using sticky tyres, you'll be able to run stiffer without understeer. The setup might be crap in the wet though as you know. If you want to retain some of the comfort, then not too stiff on the springs but stiffer arb.

 

I've yet to try the 309 front arb on mine since uprating the rear beam and now running the 275lb front springs.

 

I guess it's just a case of giving it a go. The front arb doesn't take much to fit if you have the right bushes and clamps to go with it

[Rob Thomson 6]

Ditch the sunroof - 25kg (apparently) of glass sitting on the roof isn't going to help!

[smckeown 1]

25kgs. Nah I dont believe that. I removed mine and i'd guess 10 max

[hengti 2]

25kgs. Nah I dont believe that. I removed mine and i'd guess 10 max

 

seconded. prolly not even that - i'd guess 3-4kg max

 

i like the old 'bag of sugar' adage when guessing weights (bag'o'sug weighs a kilo)

 

25kilos is more like a bag of carrots ...

[Jonmurgie 2]

Well thanks to Rob I have a complete 309 ARB with NEW OEM bushes and the clamps so will put that on and see how it goes at combe. The full spec of the current suspension is as follows:

 

suspension

front

AST Sport-Line Adjustable Shocks

50nm Springs (~285lbs)

TAS Top Mounts

OMP Upper Strutbrace

OMP Lower Strutbrace

309 Drive Shafts

309 Wishbones

Powerflex Wishbone Bushes

Stud Conversion

rear

AST Sport-Line Adjustable Shocks

23mm Torsion Bars (Lowered)

25mm Anti-Roll Bar

SBC Negative Camber kit

GrpA Solid Beam Mounts

Stud Conversion

 

Am looking into a non-sunroof shell at present but agree that it's probably not THAT much weight.

 

I guess overall you can reduce a cars roll until the tyres give up their grip... in that pic it's running the A048's so super grippy hence the monster roll, I guess that with different tyres it probably wouldn't have gripped so much...

[Miles 331 1 Cars]

We're just going to try a 25mm front ARB, if this works they will be going up for sale complete with Rose Joint drop links

[Henry Yorke 269 3 Cars]

Possibly shift some of the weight about in the car too. Is the battery already in the boot? Also does your cage have thicker door bars as it could possibly be shell flex (I bet the traditional cracks along the top of the rear quarters are getting very long now as everytime I see it, it is cocking a leg on some apex!!). Final thought miht be down to the setting of the toe in on the front that makes it prone to lurching through corners as the inertial weight moves rapidly. Stronger front springs would certainly reduce front end dive, but may induce other handling characteristics.

 

Just guessing as you seem to have the full shopping list of suspension bits for a 205. The only other methods are to go slower or get someone hanging off the side of the car like a racing catamaran!

[Jonmurgie 2]

25mm ARB.. that sounds like a monster! It's a shame there isn't an adjustable ARB out there for the 205 so you can tone it down for wet days and beef it up for dry days...

 

There is a bit more weight to move about the car, your right Henry... the battery has to move (am awaiting arrival of Red Top 20). I haven't checked the usual cracking areas of the shell yet but I don't think it's caused any issues...

[Butler 0]

Bung on the 25mm and disconnect a drop link if it rains. With 285lb springs in the rain, you should be fine without an ARB.

[jonah 1]

Here's a different slant on it ('scuse the pun!)...

 

Is the problem the amount of roll you're getting, or just the fact that it's lifting a rear wheel?

 

Once you've lifted a rear wheel, the rear end suddenly goes from having a very high roll stiffness to having zero. Would have thought this sudden change in suspension characteristics would cause some odd handling traits. So, you could afford to reduce the rear ARB size quite a bit without increasing the total roll at all in the tight bends. You would have slightly more roll in lower-g corners but is this necessarily a problem? The benefit would be the roll stiffness staying consistent over a wider range of cornering forces.

[tom_m 0]

what about widening you rear track, i know you've got a gucci 205 rear beam, but what about bunging a couple of hubcentric spacers on your rear wheels? I'm running 15mm on mine, but you ought to be able to get away with 20mm too

[smckeown 1]

yeah I was wondering if stiffer / weld-in cage or wider rear track would be of benefit. I have no idea so interested in what people think.

[Rippthrough 98]

Sit a fat mate in the boot?

[Butler 0]

yeah I was wondering if stiffer / weld-in cage or wider rear track would be of benefit.

 

Yeah it would, the wider rear essentailly lowers the centre of gravity, and the weld in cage stops the chassis twist, so that benefit is passed to the front of the car.

[Guest smokinslim]

Sit a fat mate in the boot?

Ha ha ..... thus inducing much merriment of the crowd watchin plus a little oversteer to boot lol

[smckeown 1]

Sit a fat mate in the boot?

 

like this you mean.... Pregnant wife fits the bill

 

[Rippthrough 98]

+

[Guest smokinslim]

Sweet...