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Dec 17, 2010 21:59:12 GMT
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Hi all need some advice just brought myself a small FWD french hatchback for next years autotesting 1st timer I have to thank willcarter for that japan cup vid for inspiration What I'm asking how do you get a car to tripod heres what I'm on about How's it all done suspension/anti roll bars many thanks Davy Here's that vid
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Dec 17, 2010 22:14:29 GMT
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It's a trait of most FWD hatchbacks when set up properly. Most cars of that sort are quite front heavy, and as a result use stiff rear anti-roll bars to help transfer some of the cars weight onto the outside rear wheel in cornering, to help prevent understeer. This ARB lifts the inside rear wheel upwards off the ground when the outside rear one is compressed under bodyroll.
Fitted with a stiff ARB and stuck into a corner hard most FWD hatchbacks will do it.
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EmDee
Club Retro Rides Member
Committer of Autrocities.
Posts: 5,920
Club RR Member Number: 108
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Talk about cocking it upEmDee
@emdee
Club Retro Rides Member 108
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Dec 17, 2010 22:33:53 GMT
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you don't even need arbs, i used to do it in a crabby old standard Geo Prism all the time
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stealthstylz
Club Retro Rides Member
Posts: 14,840
Club RR Member Number: 174
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Talk about cocking it upstealthstylz
@stealthstylz
Club Retro Rides Member 174
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Dec 17, 2010 22:37:21 GMT
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Most French hatches will do it. Just gotta learn how to drive quickly.
Matt
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Dec 17, 2010 22:43:22 GMT
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Basically created by having a short shocker that doesn't allow the wheel to drop enough to keep contact with the ground, I've seen it happen going up a kerb
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Shortcut
Posted a lot
I won't be there when you cross the road, so always use the Green Cross Code.
Posts: 3,037
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Dec 17, 2010 22:55:15 GMT
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Years ago, on a misguided crusade BBC Watchdog took after a few french hot hatches (clio, saxo) because people complained that they lifted a rear wheel when turning into sloped driveways. They tried very hard to claim that they were unsafe as they also did this when cornering. Luckily the respective car companies ignored them and they went away.
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This space available to rent. Reach literally dozens of people. Cheap rates!
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Dec 17, 2010 23:01:33 GMT
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It came in handy, actually!
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Dec 17, 2010 23:01:56 GMT
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^^My Scirocco being jacked from the front jacking point. The front wheel's just about on the ground still. The shock is actually no where near its full travel, but the stiff rear ARB is forcing the wheel up against the spring, lifting it off the ground. The front wheel actually has around the same amount of travel as the rear, but just has a much softer ARB. It is possible, but fairly unusual for cars without ARB's to do it. The rear suspension designs of most FWD hatchbacks (Torsion beams and the type of beam axle used on VW's and a lot of others) give a certain amount of anti-roll without the need for a separate bar, so even poverty spec examples that people will say don't have an ARB, do have a similar effect, which is probably the case with the Geo shown above.
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CIH
Posted a lot
Posts: 1,466
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Dec 17, 2010 23:07:09 GMT
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It's a trait of most FWD hatchbacks when set up properly... Well not really. Denying the rear grip isn't as good as improving the front-end. More castor also reduces rear wheel lift. I think it's a wheelbase thing.
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Dec 17, 2010 23:23:38 GMT
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True when I say propperly set up, I'm not talking about the 100% ideal, but the majority of decent handling FWD cars do it as a result of the compromises made by the designer. Obviously it is better to keep the wheel on the ground, but I guess it's always going to be a compromise.
I've always thought of it as helping weight transfer to the rear end rather than denying the rear grip, the ARB is forcing the rear outside wheel into the ground harder, increasing the load on it, and therefore decreasing the load on the front tyres. Obviously this is a compromise, but it's always going to be on a road car.
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ChasR
RR Helper
motivation
Posts: 10,194
Club RR Member Number: 170
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Talk about cocking it upChasR
@chasr
Club Retro Rides Member 170
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Dec 17, 2010 23:44:12 GMT
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True about denying rear grip although it can help improve the front. It will always be a game of compromises on a road car. But having too much rear grip (as my 205 does atm) does also cause understeer. I plan to give the front more grip once again by going down on the spring rate (I could (and should) go higher on the rear, but rear torsion bars are mega ££££).
Seat Leons etc. can be made to do this with a rear ARB.
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stealthstylz
Club Retro Rides Member
Posts: 14,840
Club RR Member Number: 174
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Talk about cocking it upstealthstylz
@stealthstylz
Club Retro Rides Member 174
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Dec 17, 2010 23:59:42 GMT
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A stiff shell helps to, as ably demonstrated by my mates MG ZR rally car. No i'm not lifting it either just pretending that i'm strong. Matt
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Its done by stiffening up the rear compared to the front. Generally done by fitting a fat ARB but has that same effect as fitting stiff springs/torsion bars. On mk1 golfs they often used to use 'droop straps', but if they weren't set up properly you ended up with some very odd, very fast changes in grip levels (read MASSIVE lift off oversteer!). Works on the principle that any weight that isnt on the inside rear is on the outside front, maximising grip on that wheel. It isn't ideal but it works! My 205 can't keep both feet on the ground and I think most people would agree that it corners like a goodun What little french hatch is it?
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Last Edit: Dec 18, 2010 0:14:45 GMT by Adam
1997 TVR Chimaera 2009 Westfield Megabusa
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It's a trait of most FWD hatchbacks when set up properly... Well not really. Denying the rear grip isn't as good as improving the front-end. More castor also reduces rear wheel lift. I think it's a wheelbase thing. Increasing front grip can only be done by softening the front end. Can be detrimental to suspension geometry, especially on little french hatches which have very little camber gain anyway, and zero on the rear. The only good handing FWD cars I've seen that don't cock a rear wheel are the ones on the hills that run something along the lines of 9" slicks on the front and 7" slicks on the back and really good roll control. Even Ralph Pinders little rocket ship picks up the inside wheel every now and again: www.zipp.co.uk/gallery/Prescott-2010-04-25/34+0303.jpg.html
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Last Edit: Dec 18, 2010 0:36:15 GMT by Adam
1997 TVR Chimaera 2009 Westfield Megabusa
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Haha I'm glad I could help. What championship will you be competing in?
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Dom
Part of things
Limey
Posts: 617
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I hope it's not a 2CV, no chance! ;d Well, not a hatchback.
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Mine does it, even I can get it to do it! Not sure why it does it, in all honesty, but if you push it hard into a sharp corner one wheel will leave the ground, and you don't even have to be going that fast.
When I get my lowering springs this habit should go away.
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skinnylew
Club Retro Rides Member
Posts: 5,546
Club RR Member Number: 11
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Talk about cocking it upskinnylew
@skinnylew
Club Retro Rides Member 11
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Dec 18, 2010 13:14:30 GMT
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my Ax used to slide first but now its stiffened up it tripods and slides goodness only knows what it will be like with the extra 100horses running through it
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Dec 18, 2010 16:03:25 GMT
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I also forgot to mention the 'stool' theory.
When a car is on 4 wheels a front wheel can be unloaded by a bump on the opposite front or a depression on the diagonally opposite rear, which is far from ideal. If the car is cornering on three wheels then that is impossible to unload any of the 3 wheels. Its a theory used to good practice on single seaters to get maximum grip on the rear wheels out of slow corners.
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1997 TVR Chimaera 2009 Westfield Megabusa
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CIH
Posted a lot
Posts: 1,466
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Dec 19, 2010 17:16:23 GMT
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Well not really. Denying the rear grip isn't as good as improving the front-end. More castor also reduces rear wheel lift. I think it's a wheelbase thing. Increasing front grip can only be done by softening the front end. Can be detrimental to suspension geometry, especially on little french hatches which have very little camber gain anyway, and zero on the rear. The only good handing FWD cars I've seen that don't cock a rear wheel are the ones on the hills that run something along the lines of 9" slicks on the front and 7" slicks on the back and really good roll control. Even Ralph Pinders little rocket ship picks up the inside wheel every now and again: www.zipp.co.uk/gallery/Prescott-2010-04-25/34+0303.jpg.htmlMore camber and castor would do that. The castor especially would help with the wheel lifting. Extra castor isn't easy to achieve without specialist kits, though, and isn't usually desireable in hill climbing specifically.
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