B4 hooking on carpet
 

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 :)

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.

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

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.

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

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-

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.

I find lowering the rear and raising the front helps.

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 :p

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 ;)

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

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 :p

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

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

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

http://www.themorningstarr.co.uk/ima...lar-claire.jpg

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 :cry:

Cough* servo saver *cough

Apologies to all the people that think I sound like a broken record :blush:

The servo saver has always been glued, it is soild. I wish it was that easy!

Just make sure it doesn't have pineapple on this time Sylar, bleugh!

What did I have on the front of my 4wd in Belgium?! :p

hmmm, good point there rich, how many fingers!!:thumbsup:
Being honest i thought you were a madman running them too in belgie:lol:

Richard, what do you think about my ramblings on my last post?

I still think it's the front thats the problem :)

The B4 has a lower initial roll centre at the front than the rear, which will make it want to corner nose down. If the front is stiff enough to stop it rolling as it wants to then instead of the front end compressing on the outside it will try to lift the inside at the rear. Hooking like you describe is usually the inner rear wheel running out of droop and going light.

Am I right in guessing you also have lots of understeer mid corner on slippy parts of the track like wood floor? ;)

I'm confused now! It seemed like the front of the car was rolling more than the rear, and it was then lifting the inside rear wheel. The rear seemed to have less roll, which was stopping the outside wheel compressing as much. I started on 35wt/2 hole/blue springs front, and went up to 40wt then 45wt to try and stop the front rolling as much. It did seem to improve a little. I am confused as you seem to be saying that the front is too stiff, and that I should soften it. Wont that make it worse? I have been out for a long time, and setup was never my strong point!
I appreciate the help btw!!

Thicker oil doesn't stop roll. It merely slows it down a bit.

wish i had this problem!

Im running at formby high school, carpet is med/high grip

Running the same set up as mr lowe but I have 30 weight front and rear, 35 lead weight around the front, 40 placed around the rear and short wheelbase. Running trakpower 3600's, have lead weight to use under the batt strap, will consider using/not using depending on advice given!

Problem i'm having is I want the rear to rotate more, or more initial and mid steering, exit steering is fine! Not sure which way to go to improove the problem, or what changes to make to fix it!

Entering the corner it seem the car doesnt want to dig in and pushes, as said exit steering is fine however!

Are you racing again Paul? :thumbsup:

Try longer wheelbase, or shock to inner hole on the front arm.

Do you have the short wheelbase mod on the rear wishbones? If so get rid of it!

Indeed mr lowe :woot:

2nd race back yesterday! feels good to be on the sticks!

I do indeed have the short short mod, has that trend died out now?

will moving the front shocks in soften it up im assumeing?

I thought shorter wheelbase was used on smaller tracks, or am I wrong in this?

its been a while!!! :p

The super short wheelbase is rubbish on carpet, in fact I don't think anyone really uses it over here now :eh?:

That should solve your problem, leave the shocks as-is for now :)

I'm still stuck!

cheers ill give it a go! much appreciated!

Try the setup I posted on the first page exactly ;)

With the roll centres of the B4 it wants to drop the front as it corners - ie corner with the nose down. If you have some 45w maple syrup in there slowing the front ends weight transfer right down it will try to lift the rear of the car instead of compressing the front.

If you start with the posted setup you will have a balanced platform to work from. If you need to get rid of some steering the first thing to do is cut some rows from the front tyres, or even put some less grippy ones on. (Don't use staggers though, that'd be gay :lol: )

Thanks Richard, I will give it a go. I cant see that my original setup with the 35wt in the front is too far off, seeing as it was good on a bigger slightly less grippy track. It looks like I have the rear too stiff on damping, perhaps the extra front grip has tipped the rear past its limits. Appreciate the help :)

I still say try gay staggers instead of tyres with all the pins cut off :p

or dont be gay and use all the pins, animal style :D

Does using rib spikes (oldschool! YEAH!) make you a gay animal then?!? :woot:

Haha it definatly does! although dont be barking around my tree!!

Back again I'm afraid. I may have mis-diagnosed the problem a bit last time. On a fast sweeping corner, it looks like the front inside wheel is lifting as the back end is collapsing. The rear end then breaks away, which may have been why I thought it was hooking. It still has too much low speed steering, but I think i need to take the inner row of spikes off the front. I started on the following setup, which was similar to my first one I tried. (Sorry I didnt have a chance to try your one Richard).
Front:
middle on tower, outer wishbone, link 1A, 1 washer under ball
steering 30deg trailing
shock blue spring 35wt no.2 piston

Rear:
inner on tower, outer wishbone, link 1b, 1 washer under ball
2 deg anti squat, short wheelbase
shock silver spring 30wt no.1 piston

basically Lee Martins Petit carpet setup. except I didnt get a chance to change rear piston to no.2

yellow minipins outer row off

I tried removing the washer under the rear ball to stiffen the roll, no real help. Put it back, put 35wt oil in rear to try and stiffen a bit, no real help.
Added another washer to front link to try and equalise roll front to rear, and put blue springs on rear to try and stop it collapsing, helped a little but reduced rear grip a bit.
I have a feeling the car may have been diffing out from something I read on here, how much spin should it have if spinning a wheel by hand?
The carpet is very grippy, would a soft rear roll bar help keep the rear end flatter through the corner and stop it collapsing?
Thanks for looking

The only thing I can suggest is going up to grey springs on the rear. That will give a setup very similar to what I run on carpet indoors - and my setup is harder than most people's!

I'm surprised you find that the car has too much steering - if find the balance of the blue/silver in the outer holes to be a bit understeery myself - so I wonder whether something is wrong mechanically on the car?

I think its just this carpet seems to grip so much, you really dont need much in the way of spike to get grip. I had no such issues at Newbury earlier this year, could have done with a tad more steering. I remember seeing some cars a few years ago (at this venue, DMS) with literally just a few rows of spikes in the middle of the front tyre on a B4. Most of the 4wd cars run on 2wd fronts as well. I think the small track needs a specific setup, the car cant be that wrong from the setup I tried surely! I could do with some advice on how tight the diff should be though, if that is causing an issue by diffing out.

Stu, I thought this was you when I read this thread previous, but until now you did not make reference to the track so I could not be sure.

Apart from stating the obvious you would expect me to (ie your motor is in the wrong place...LOL) have you in all seroiousness asked Kevin what he is running on the front of his X6 since the front end on the cars is the same.

His car is pretty stable with lots of steering, after all he was right with the quick 4wd's last night. Although the whole car is not the same the front end is and "might" be a good starting point for you to compare with and maybe try.

The carpet is grippy, but it is not THAT bad TBH, but less spike is always quicker around there (unless your name is Jack that is, he seems to LOVE new pins)

Try some poofy european-style staggers :p

You'd really be surprised :woot: