Grip Roll

[gainsy]

Anyone got a front roll bar kit they want to sell me?

[discostu]

before you can cure grip roll you need to know how and why it happens.

[Skye]

Originally Posted by wacattack

Is the car staying flat then flipping suddenly or is the car rolling into the full suspension travel and then flipping? Both scenarios require different solutions

Im not 100% sure to be honest. Visibly it appears to stay flat then flip suddenly. But having seen a slight improvement when I changed the springs from silver/green to blue/silver then this would lean towards supporting the theory of the car rolling into the full travel position wouldnt it?

Originally Posted by markwilliamson2001

Try this setup....
Silver roll bar fromt and rear
40wt oil, no.2 piston in front, silver or blue spring
35wt oil no.1 piston in rear, silver spring
22/23mm ride height
Get some weight in the back if you dont have any, the centre weight 87g for the b44.1 is perfect, for lipos.

Trim your rear wing down a bit.
Start with minipins, and a firm foam. You might find that the thinner carcass minispike tyre is collapsing.
I would cut the inside and outside row off the front tyres. If the grip roll is still there, cut another outside row off both front and rear tyres.

Hope this helps.
Mark

Thanks Mark, thats excellent. There are some points in there that I would never have thought of, I will try this set up for definate.

Originally Posted by blue_pinky

Latest setups on the B44.1's use the silver roll bars both front and back. That'll help no end, all the other things that have been mentioned are also all good advice!

Use bigger/harder inserts in the tyres, I've been using the KWF foams that P-Dub racing sell, much bigger than the standard schumacher foams, so fill the tyres more making them harder and the side walls more stable and grip more consistent.

Failing that...I know some people have used cut staggers on the front of their 4wd's too.

Thanks very much, I would never had considered bigger/firmer foams. I will get some ordered tonight and give them a whirl as part of Marks set up(above).

[Skye]

Originally Posted by discostu

before you can cure grip roll you need to know how and why it happens.

And there lies my problem, as a novice I dont have that kind of experience to know why it is happening!?

Hence being here picking the brains of some of RC racings finest minds!!

[discostu]

grip roll happens when the side of the front tire digs and causes the car to flip (sidebite) the only way to stop this is to remove side bite by laying shocks down on the tower out on the lower arm flatterning front top link softer spring thinner shock oil cutting spikes off tires front anti roll bars less steering lock more camber more caster we are tallking about making the car more progressive as you turn in to first part of the corner.

stu

[dibble34]

Or just run 2wd staggered ribs up front, works for me but not saying it's right

[discostu]

like i said sidebite. dibble your avantar still looks the nuts.

stu

[Skye]

Originally Posted by discostu

by laying shocks down on the tower out on the lower arm flatterning front top link softer spring thinner shock oil more camber more caster
stu

Thanks Stu, that's a lot of advice! Some of it I understood but the bits I didn't understand fully I have left above. If you are able to translate it into an idiots guide that would be greatly appreciated!

[dibble34]

Originally Posted by discostu

like i said sidebite. dibble your avantar still looks the nuts.

stu

yep, can't bring myself to change it!

[Chalkie]

I'd look at your tyres before messing about with the car setup to much, Silverstone is too bumpy to comprimise the setup too much to deal with grip roll. I've found that if you use yellow minispikes at Stotfold when they start to get too worn and go off they are then about ideal for Silverstone, even the stagger ribs on my 2wd have done a couple of runs at moto arena to take the edge off them.

[Skye]

What would you suggest then mate specifically for Silverstone?

[leepez]

Try slackening the front diff off slightly.

[discostu]

Originally Posted by Skye

Thanks Stu, that's a lot of advice! Some of it I understood but the bits I didn't understand fully I have left above. If you are able to translate it into an idiots guide that would be greatly appreciated!

hi skye

ok sidebite happens on intial turn in, when the shocks are stood up more ie further out on tower inner on the lower arm the car will react faster to steering input so as you turn the car will pitch on to the outside wheel much faster and more sudden and make the front reaction less progressive (sharper).

softer spring and softer shock oil gives a simular effect to laying the shocks but doing it this way you will not compromise the direction change or the way the car rides the jumps and high frequency bumps as much you can usaly leave the shock locations the same.

again the more angled or shorter the top link is the quicker the car will change direction though the roll centers so if you lengthen or level out the front top link again you will make the car more progressive on initial turn in

again sidebite is generated fom the side wall or edge spikes of the tire if you use more camber as the car leans will use more of the top of the tire rather the edge spikes it will tend to give a smoother feel. using more camber the car will tend to have less forward traction as the tire is leaning over more to start with.

caster is very simular to the effects of camber without as much compromise on forward traction with more caster when you turn the front tires are lent over more as if the car has more camber. caster and camber need to work in conjunction with each other ie less caster less camber more caster more camber.

a lot of drivers think stiffing the front of the car up will stop grip roll this will make it worse yes it will make the car have less steering but it will also make the car react faster on inital turn in which is where grip roll is generated from.


i agree with trimming tires to keep a ballance without compromise to bump handling, all the factors ive mentioned have pros and cons you will need to have a play and see what works for you.

stu

[Chalkie]

Originally Posted by Skye

What would you suggest then mate specifically for Silverstone?

Yellow minispikes are fine, it's just they need to be at least half worn out and with the outer row of spikes cut off front and rear, these will then work untill they are pretty much bald on a 4wd.
A set of tyres that have done 2 -3 meetings at Stotfold are about right.
Oh yes the other thing worth trying is adding weight towards the rear of the car, this seems to slow the reactions of the car down which helps

[tomtom]

I'm not experienced but I run on a super high grip track so grip roll on 4wd is an issue.
I didn't find it useful to run too stiff oil/springs as it could harm long sweeper and overall stability so I keep a relatively soft shocks but outside on wishbones, inside on tower. Then low ride height, as low as possible to still clear the jumps. Then a bit more camber overall, shorter rear link and it greatly reduce grip roll without compromising too much the rest.

[Frecklychimp]

In grip roll situation the first thing i'd try is a bit more Camber after trimming spikes... but never any more than 2 deg negative on buggys.

Rather than just snipping spikes of.... using a dremel to slick smooth off the area trimmed helps a lot too.

something else worth trying is toe in on front wheels as this will reduce initial turn in and help stop the outside tyre digging in under sudden load

ride height is critical to how the weight moves and induces roll in corners.

I always start with front wishbones horiziontal and rear driveshafts horizontal under race weight conditions with 2WD cars.

[Skye]

Thanks for all the replies!

I think its very much going to be trial and error to see which suggestions work but at least I have plenty of food for thought now!

Thanks for the info regarding Silverstone Chalkie, always good to get information specific to a track. When I get a set of tyres 'in the zone' for Silverstone I will take them off and keep them for Silverstone only.