Anti dive and Kick up

[Mark Townsend]

Who knows what they are and how can I use either to make me faster?

Mark

[yellowshark]

Dive - anti dive and pro dive(aka kick-up) is achieved by changing the angle (front to rear) of the front suspension arms. On the my Xray this means having the rear mount higher or lower than the front mount.

Anti dive is normally used as a tuning aid to let you use softer springs without a tendency to dive down too much under breaking.

Pro dive as the name suggest promotes dive. As always it depends on the rest of the setup etc etc but it can improve entry and exit steering. The first is achieved by more pressure being extered onto the springs off power , ie greater weight transfer to the front. The latter is something to do with overall caster angle changing which I don’t for one moment pretend to understand how or why.

Never tried them myself but I was talking to an Xray driver at the SLCC last year and a couple of them had been playing around with it at SLCC Eastbourne to beneficial effect.

[lesbaldry]

Mark I have only played with it once on the advise from a very good Scythe driver at the time...so this is my interpretation "wrong or right??"

On fast sweeping power on bends the Scythe suffers from understeer,an increase in castor from 4 to 6 deg cured this but the car suffered from turn in off power, I was advised to add some anti dive(yes anti dive,did'nt make sence at the time) and decrease my camber angle slightly,it seemed to work ,giving the car a better balanced feel, the best of both worlds?!? I hav'nt got a clue about the ,how,when,if and why's about it,when I try to read up about it oppinions varies and I hav'nt tried it since....My only doubts are with the raised rear of the wishbone as I dont think it will handle our bumpy track too well...most of my adjustment to cure probs are done with ,droop,roll centers.camber link positions and springing??..useing anti dive i would expect the car to become sesitive to droop settings??

Increase the castor then decrese it with anti dive ,seems odd to me ,I dont think many chaps play with it too much,I susspect its an adjustment that may be worth a play with on fast flowing smooth tracks,Cotswolds maybe??

As for kick up I played with it during my early Pro 4 days and to be honest I wasnt fast enough to notice any change...cant help here chap.

After seeing your car I think I know what your after,have a play with Akerman and front wish bone pin angle?...easy to do on the 416?

[TryHard]

I'll try and help here.

Kick-up is as Les describes, it does a number of things... 1) increase the castor (increases mid-exit steering, reduces initia), 2) helps the front of the car deal with bumps better 3) helps transfer more weight to the front of the car
Anti-dive is the opposite...

How does it work? Well quite simply, the pic below should help....(excuse the crappy paint thing, I'm at work). Basically, because the arm is at an angle to the track, the wishbone starts to take more or less some of the loading going through the car.

www.thard.co.uk/download/file.php?id=75

Basically, the lower arrow is the load going through into the wishbone. With kickup, all the load will be taken by the shock, whereas the flat arm will means a little of the wishbone will take the load (the small arrow parrallel to the arm). With Anti-dive, because of the angle, more of the wishbone takes the load (bigger arrow).
As we all know, wishbones are pretty damm stiff things (at least a lot stiffer than a shock!)... so it goes that a car with anti-dive will have a stiffer front end than one with kickup, with less weight transfered forward. Obviously, you also need to combine the castor adjustment in with this (If it helps, for a car with 46mm hinge pins, such as the 416, raising one end of a wishbone up changes the castor by 1°).

The same applies with the rear of the car, where you can play with pro- (rear of the arm pointing up) or anti-squat (front of the arm pointing up).

HiH
Ed