Snatchy B4 on Grass

[jcb]

I was racing on what was a bit of a point and shoot grass track at the weekend, which had two 1/4 to 1/2 throttle sweeping curves shaped a bit little like a ? if that makes sense.

On the sweeping bends I, along with some other B4 drivers were all complaining that the car would snatch mid corner, as though the rear end was colapsing. Has anyone got any suggestions on how to solve it? While not losing the drive and steering needed for drag racing between the hairpins? It's how quite a few of the tracks are in my area so any help would be great

My setup was as follows:

Front:
35wt
Number 2 piston
blue spring

Middle on tower
outside on wishbone (inside was too aggresive on the really long grass)

Camber link inner on tower with one washer, inner on hub carrier

ride height wishbones level

30 degree hub carriers

Rear:
30wt
number 1 piston
silver spring

middle on tower
inside on wishbone

2 degree anti squat

short wheel base

camber link inner with one washer middle on hub carrier


I tried lowering the rear ball stud which resulted in a slight loss of forwards drive and tended to induce grip roll, while changing the wheel base had to either extra short or medium made practically no difference at all, although the extra short wheel base worked well in the damp and on the hair pin bends.


Thanks,

[Chris Doughty]

might be worth trying outside hole on the rear wishbone

40wt front oil might help too

[markwilliamson2001]

You could try leaning the shocks in one hole on the tower, or moving the shocks out one hole all round on the wishbones. Both these worked for me on carpet.

Mark

[markwilliamson2001]

Also try middle on rear hub carrier.
Lengthen front camber link to longest, this also works on high grip tracks.

Mark

[SimonW]

You could try less anti-squat, most of the set-ups i've seen for a B4 on grass is with 1deg of anti-squat. Off the top of my head, Harris and Cragg set-ups i've seen on the net somewhere have this setting. It should allow the car to roll more when on power rather than stiffen up as you throttle up HTH... hope it makes sense too

[Nolan BJ4WE]

Simon,
It's Nolan (you might not know me....lol) Did I pit net to you on Sunday at the Kings Lynn meeting? If it is you, thanks for letting me use your power supply, even if my day did not turn out as I planned.....lol

[SimonW]

Tis' I, no worries m8. Wot rotten luck you had dude.

[Nolan BJ4WE]

Originally Posted by SimonW

Tis' I, no worries m8. Wot rotten luck you had dude.

Thanks for all your help - rebuild the car today. How did you get on in the end?

[MattW]

If the rear is collapsing suddenly, then moving the top of the shock in may help. The rear will lean more, but should be less prone to sudden collapsing. Moving the bottom of the shock out will have the oposite effect - but because there is more roll stiffness, should the rear collapsing also - although will give more steering at high speed i would expect as well.

[rich_cree]

tighten your diff up

[jcb]

Thanks for all the replies, gives me something to try at the next meeting

[Lee]

Personally im not against a bit of snatch on the grass, but i wouldn`t want too much leading upto a grass national

[Chris Doughty]

I think Mr Cree seems to have come from nowhere to pull probably the best suggestion of the lot (as always)

[Lee]

What effect will tightening the diff have chris, how will it stop the rear collapsing etc

[Chris Doughty]

it will stop the car diffing out.

with the inside wheel unloaded going round a sweeping bend with the power on, if the inside wheel spins up, the outside wheel does not get any power, the car slows down and then starts to turn in some more. (and it all goes wrong from there)

this is what I imagine Cree things is happening in this situation.

[Richard Lowe]

Originally Posted by Lee

Personally im not against a bit of snatch on the grass

Don't you have those in the wrong order

[elvo]

Originally Posted by Richard Lowe

Don't you have those in the wrong order