Tristan Posted April 4, 2011 Report Share Posted April 4, 2011 Hi everyone , back after a long hiatus. I'm rallying a FordKa in the Irish forestry championship , just wondering if any of you are doing similar , I'd like to bat a few ideas re suspension geometry around . Thanks , T. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 4, 2011 Report Share Posted April 4, 2011 Hello....... How adjustable have you made the car? Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 4, 2011 Author Report Share Posted April 4, 2011 Hello....... How adjustable have you made the car? Hi Tony , the ride height , bump and rebound are all adjustable , as it runs ProFlex 2 way adjustable coilovers. The front wishbones and top mounts , plus the rear axle beam mounts are all either solid or spherical bearing. Front camber is not so easily adjustable to be honest , it runs about 1 degree negative each side. The rear is the same . I've fitted shims between the rear hubs and axle to correct the rear toe. Which is set to total of 2mm toe in. I've modified the front top mounts and bottom balljoints so I can correct the caster , not sure of the actual value ,apart from the fact it's equal both sides. The front toe is about 3mm total toe in , more than I'd like but the car has a lot of bump steer , it toes out about 30-40 mins on compression . Previously I had 2mm toe out up front , but the car was unstable on high speed bumpy stuff . I hadn't measured the bump steer at that stage .. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 5, 2011 Report Share Posted April 5, 2011 The toe gain on bump is a real issue...... Having the car to low will change the wishbone/ steering arm radii, roll centre adjusters would be a wise move. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 5, 2011 Author Report Share Posted April 5, 2011 The toe gain on bump is a real issue...... Having the car to low will change the wishbone/ steering arm radii, roll centre adjusters would be a wise move. the wishbone is pretty close to where it would be on a road car , as I need reasonable ground clearance for the forest tracks . RCAs... are they they units that you fit to the baLLjoint Tony? Thanks for your replies btw. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 5, 2011 Report Share Posted April 5, 2011 It would be easier to relocate the steering arm height, moving the ball joint is a whole can-O-worms. Most bump-steer adjusters work at the TRE pick up point. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 5, 2011 Author Report Share Posted April 5, 2011 It would be easier to relocate the steering arm height, moving the ball joint is a whole can-O-worms. Most bump-steer adjusters work at the TRE pick up point. yeah that would suit me better too , for wheel clearance issues . I was thinking of using a Rosejoint instead of a track rod end , and maybe attaching it to the bottom of the steering arm instead of the top? in general , are there any guidlines for rack position and steering arm angle and it's effect on bump steer? I have to sort it out on one of Dad's classic , his Lancia 037 , too . Quote Link to comment Share on other sites More sharing options...
Tony Posted April 6, 2011 Report Share Posted April 6, 2011 Ideally you want the track rod end pickup point ( pin ) to be vertical not perpendicular. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 6, 2011 Author Report Share Posted April 6, 2011 sorry Tony , I don't quite follow? Quote Link to comment Share on other sites More sharing options...
Tony Posted April 7, 2011 Report Share Posted April 7, 2011 Look at the position of the connection point of this track rod end Since the point ( pin ) is not vertical, on bump it will allow massive toe out. Bump steer adjusters allow the point to be relaxed or change the height of the point. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 7, 2011 Author Report Share Posted April 7, 2011 Look at the position of the connection point of this track rod end Since the point ( pin ) is not vertical, on bump it will allow massive toe out. Bump steer adjusters allow the point to be relaxed or change the height of the point. just trying to picture the movement in my head.. is that rack mounted behind the wheel? Quote Link to comment Share on other sites More sharing options...
Tony Posted April 7, 2011 Report Share Posted April 7, 2011 200SX and yes.... This baby is set for Drifting and as low as Grammars nipples. The steering arm is perpendicular and the steering pick up point also perpendicular, rather than at rest, static. The position of the PUP ( Pick up point ) can be changed vertically or transversely depending on the complaint, your complaint would be vertical since you have a roll centre issue on bump. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 7, 2011 Author Report Share Posted April 7, 2011 awed at your knowledge and explanations , as per usual. Quote Link to comment Share on other sites More sharing options...
Tony Posted April 8, 2011 Report Share Posted April 8, 2011 awed at your knowledge and explanations , as per usual. Do you have an angle of approach now? What's your thoughts.......... Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 8, 2011 Author Report Share Posted April 8, 2011 first off , I'm rallying this weekend , so it'll wait til next week! lol I'll make a dummy TRE , using flat bar and a nut, to simulate a rose joint , and try it Under the steering arm , to see what effect . Quote Link to comment Share on other sites More sharing options...
Tony Posted April 10, 2011 Report Share Posted April 10, 2011 You need to make the angle of the steering arm the same as the wishbone while at rest and the PUP on the steering arm vertical, this will give you +- toe gains on bump/ droop. From this platform ( neutral ) it's reasonably easy to work out/ see the gains on bump/ droop/ transition. Personally i feel for hill/ trial/ climb and short track you need a negative migration on bump and transition, but remember on high rated coils you won't get much from relaxed PUP's. Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 11, 2011 Author Report Share Posted April 11, 2011 Okay , yesterday ,well , all I can say is I should have stayed in bed. The PUP is indeed vertical , so that's part of the battle . Quote Link to comment Share on other sites More sharing options...
Tony Posted April 11, 2011 Report Share Posted April 11, 2011 What changed.... How have you made the PUP relaxed? Quote Link to comment Share on other sites More sharing options...
Tristan Posted April 11, 2011 Author Report Share Posted April 11, 2011 no , it's just that it is designed that way from Ford! my post is a bit misleading , I just had a sh1t day , service crew got delayed , navigator got mixed up on the pacenotes , then I broke a CV joint , got going again , only for the oil light to come on. AAAAAAAAAAAAAAAaaaaaaaaaaaaaaaaaaaaaaaaaarrrghhh... Quote Link to comment Share on other sites More sharing options...
Tony Posted April 12, 2011 Report Share Posted April 12, 2011 Oh dear....... reads like a real pants day, joys of racing i suppose. Quote Link to comment Share on other sites More sharing options...
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