derangedrover wrote:Sam,
If you put smaller diameter and narrower width tyres on your rig with its current suspension configuration does it still perform better than stock geometry or does the decrease in available traction from the tyres change how much antisquat you can/could use?
How much weight have you got on the rear axle and whats your split fr/rr?
I was about to make some cranked rear arms but stay with stock geometry but am now thinking about your advise for lengthening the rear links...
Any advise?
Cheers
Daryl
Going back to a smaller diameter tyre (say a 31) would decrease the amount of anti squat I have dramatically because with the smaller tyre the tyre/ground contact point (which is the point where the power is applied to the ground) is so much closer to the rig and is therefore so much closer to the instantanious centre of the links (which is where the power is applied to the chassis. Therefore the line joining the two points is so much more horizontal which giver less anti squat because as power is applied it doesent try to lift the chassis as much.
So it comes back to how much anti squat you think you need. Because having some anti squat is a good thing because it helps getting the power to the ground. Take drag racers. These machines run alot of anti squat because it gives them so much more grip for the launch. I would guess that v8 supercars would run a lot of anti squat as well for the same reason.
Now the steeper the incline, the more the rear suspension unloads, which gives you more rear lift, which in turn gives you more antisquat. Now at some point (of steepness of climb) the amount of antisquat that you started with will become to great and it will then get unstable and the rig will start to hop which is bad.
For example take two identical rigs, one with moderate anti squat and one with very low anti squat. You come to a moderately steep, loose dirt hill climb. For the guy that has very little anti squat to drive it he has to really get into it with the throttle say full noise second gear to make the climb with heaps of wheel spin where as the guy with more anti squat can just idle up the climb in first gear because the anti squat is helping him. I have this exact hill and it really is amazing to see what sort of rigs drive it easily and what has trouble. But take these same two rigs to a steeper climb with more rock and grip and throw in a ledge and a big hole on one side then the rig with more anti squat may become unstable and start to hop on the climb and wants to lift a front wheel and fall over backwards when it gets to the ledge and drops a wheel into the hole. Where as the guy with the little anti squat is still stable on the climb (and can still use heaps of throttle if he wants cause the thing wont start to hop) and when he gets to the ledge with the hole keeps all four wheels on the ground (doesent lift a front wheel) and drives it as well.
So IMO it does depend on what sort of stuff you drive but if you have problems with the rig hopping on loose climbs or lifting front wheels on off camber climbe or ledges or wanting to fall over backwards on the really steep stuff then you may have too much anti squat. (now the down side with less anti squat is that you will find it harder to do the more slippery less steep climbs like loose dirt or mud)
Oh yeah - this is all just my opinion.
Sam