B4 hooking on carpet

stuey · #1 14-11-2009

Hi, I am having a problem with my B4 hooking on a small high grip carpet track. It looks like the front is rolling too much, and the inside rear wheel is lifting up leading to a hook into corners. I am using half worn yellow minipins with the following setup. I got to this after going from 35 to 45wt oil on the front.
Front: 45wt
Piston 2 Blue spring
Shock inner on tower outer wishbone Link 1A, 1 washer under balljoint
30 deg caster blocks
Rear: 30wt
Piston 1 Silver spring 1 washer inside
Shock inner on tower outer wishbone Link 1B, 1 washer under balljoint
Short wheelbase 1 deg anti squat, 35g lead in rear of car on NiMh cells
Cells split in middle position.
It did improve slightly after going up on the front oil, but I think either I need a geometry change or soften the rear roll to make it more even with the front.
Thanks for any advice

sosidge · #2 14-11-2009

Your setup is pretty close to mine (which I have uploaded here), and my setup is very consistent on the local small, high grip indoor track.

The only thing I'm wondering about is ride height. Are you running the car low to the ground? Because anything less than front arms level (or a fraction below) will make the front of the car very soft in roll. I run the rear at bones level.

stuey · #3 14-11-2009

I have the front wishbones just below level, same with driveshafts on the rear.

sparrow.2 · #4 14-11-2009

What tyres are you running?

Minipins on the front are totally overkill 99% of the time in my opinion. Stagger ribs on the front with a silver spring no.2 piston, 35weight oil works nicely with the shocks on the middly hole on the tower and outside on the wishbone. 30° caster blocks can bite you in the arse if running pins. Back end sounds ok but I usually run grey associated springs.

Front pins will hook on carpet no matter what you do with the setup. (yes, I really don't like pins

) Staggers have a little less grip and you have to run different setups but are so much smoother and quicker in the long run.

But then european setups and british setups are usually miles apart

To get the staggers on the front rims nicely cut about 1mm off the bead of the tyre then seat the cut bit in the outside groove on the rim. Then glue the outside and just leave the inside unglued and seated one row in from the inside of the rim.

stuey · #5 14-11-2009

Yellow minipins, with the outside row cut off. I should probably cut the fronts down more, and on the inside.

spiro · #6 14-11-2009

My setup for high-grip carpet is about the same as the others stated in this tread, with the front arms-level and the rear shaft-level. Most setup is standard FT setup from the manual, but with heavier oils. My setup is 650 front and 550 rear. (CPS) Blue springs front and silver rear. This makes the car a bit to soft in the back, so I'll change to stiffer springs next trackday. I run the schumi minispikes front and back, with spikes completely cut off.

Oh, and the gold anti-roll bar.

Works well.

-S-

steelie600 · #7 14-11-2009

Im using Craggy's Astro setup for southport to the letter, also on high grip carpet. But we have to use control tyres. Proline Dirt Hawgs. Ive got mucho grip infact if i try i can get grip roll but, drive smooth and its perfectly fine and very hard to get symptoms your describing.

Welshy40 · #8 14-11-2009

I find lowering the rear and raising the front helps.

Richard Lowe · #9 14-11-2009

It sounds like the whole car is too stiff in general, and the front overdamped. Instead of the car leaning into the suspension on the outside it's lifting the inside and running out of droop on the back.

I've been playing about with B4 setups recently, trying different running weight and softening/stiffening the shocks as appropriate and think I've now found my lipo setup

You should be on pins all round, staggers on the front are for wimps

I've not done a setup sheet yet, but I'll list how my car is now so you can try it...

Front
35w/No2/Silver, middle on tower, outer on arm, 24mm ride height, no droop washers
Camberlink 1-A, 2 washers on the tower, -1 camber
30 degree caster, in-line axles spaced middle, 2 bumpsteer washers on steering block

Rear
25w/No1/Silver, inner on tower and arm, 24mm ride height, no droop washers
Camberlink 1-B, 1 washer on U brace, -1.5 camber
2 degrees squat, medium wheelbase

Weight-wise I'm running the Trishbits front bulkhead and brace (55g total), and the older style Trish squat block (28g). Cells are the Trakpower Dark 5000 40c (284g).

Setup like that the car has been fantastic on every track I've taken it to, carpet/grass/astro it's been great. I do seem to be Mr Steering though so if you want to calm it down a touch the trailing axles will dull down the initial turn-in and moving the rear shocks to the middle on the tower will make the car square up quicker and give you a bit more rear end grip coming out

MHeadling · #10 14-11-2009

Thanks for sharing the set up Rich! I'll set my B4 like this for the Petit RC event!

sparrow.2 · #11 14-11-2009

Quote:

Originally Posted by Richard Lowe

You should be on pins all round, staggers on the front are for wimps

Fancy coming over to Germany to prove that statement?

Seriously though, if you're up for it why not come over to one of the Longfield Sixdays races? Come show some belgians how much better pins are on the front

elvo · #12 14-11-2009

Yeah Rich, come beat us on pins and I'll pay for all the pizzas you can eat

bigred5765 · #13 14-11-2009

don't rich he will pinch all your powers, i know i have seen him do that on TV,

sparrow.2 · #14 14-11-2009

Here is Elvo with one of the trophy girls from last weekend...

stuey · #15 15-11-2009

Thanks for the input so far guys

Richard, I am thinking that perhaps the rear is too stiff. As the front dips (with steering lock on), the rear inside wheel lifts because the outer rear wheel is not compressing enough. If it had more rear roll, the inner wheel would stay in contact longer and the outer wheel would perhaps generate a bit more grip without letting go so quickly. Does that make sense? I was trying to kill a bit of front grip by going up on oil, when softening the rear might have been better. If I am going along the right track, how best to get a bit more rear roll? Add a washer under the inner balljoint, change the top link length, go down 5wt on oil?
My initial setup seems pretty similar to others I have found, and it was good at Newbury indoor earlier in the year. Thats why I'm a bit confused as to why it does this on a higher grip carpet