The skinny on skinny tyres

[colmo]

I run my BJ4 (non-WE) on a very slippery polished wood floor. I've done the usual things to improve overall traction, and run on the softest springs I can (AE blacks, front and back, though contemplating firming up the front a bit to counteract understeer).

But I want more - so what about running on skinny tyres?

I've worked out exactly what I need:

Hubs: NTC3 hex hubs such as these ones by Yeah Racing, to cater for the relatively wide axle of JConcepts and Associated buggies.
Front wheels: Kyosho RB5 front wheels (bored out for wider JConcepts/Associated axle), equipped with 2wd Schumacher yellow fronts.
Rear wheels: Kyosho/Academy/Tamiya 12mm hex 4wd front wheels, equipped with 4wd front Shumacher yellows, again bored out for the wider axle.

I believe boring out the wheels is safe enough, as it is the hub and wheel hex that ensures the wheel is perfectly central rather than the hole in the wheel.

I standardised on 12mm hubs because I'm unsure what hub shapes and sizes are used on the front wheels of Losi and Associated 2wd buggies. The RB5 is the only 2wd buggy using a hex hub in the front that I know of. Standard Losi or Associated front hubs on the rear would I'm sure work just as well, along with our more usual front wheel.

First off, have I got everything straight, and secondly, do you think it'll work?

[colmo]

To stick with Losi wheels instead of 12mm hexes, this Losi hex set should suffice. It also has a set of metric 12mm hexes too, leaving both options open.

[Richard Lowe]

I've never felt the need to try anything like this, you never know though!

If you want to try skinny tyres just mount them on the standard wheels but mount the inside of the tyre further in on the wheel - so there is some wheel showing. That way you don't start changing the geometry with different hubs ect.

Black springs are too soft for the BJ4, especially on the front, you should never have to go any softer than silver fronts and green rears. Try the latest setup I have posted in the setups section

[colmo]

Cheers Richard - I tried your setup of front silvers, green backs, and it worked....for one week. Then....something....happened to the hall surface and the grip disappeared. Everyone was grumbling about it.

The black springs have managed to get me round it for now (we don't always have jumps) but I'm desperate enough to try anything!

There is one driver who shows up occasionally (Oople ID: noreargrip) with his B44 (no regulars have any Associated cars) with green springs all round, and TQs and wins without much fuss. He is much better than any of our regulars, though :P

Oh, one thing - is there anything you'd dumb down on your setups to cater for a...lesser...driver?

[sosidge]

Now I'm not Richard and I'm no where near his standard but I have found that on the slippy floor a stiffer setup can work really well. There isn't a great deal of grip to be had anyway so it's better to tune the car for balance.

Try running a grass/astro kind of setup, which on a BJ4 is probably Blue/Silver spring combo and maybe a rear bar. This stops the cars moving around so much and takes the edges off it at the limit.

Very soft settings, in my experience, tend to lose grip suddenly at the limit because you start lifting wheels or compromising the tyre contact patch. They are also sluggish to change direction.

[dodgydiy]

have to agree with sosidge about a stiffer setup working better, a car which slides gently and consistently is much easier to drive fast than an unstable or snappy car. running too soft will take away some of the weight transfer when cornering, just when you need it to try and get some grip so that doesnt help either. i used to use same springs on slippy floor as on grass, just used to lower the car a lot and reset the suspension so suit the lower ride height. i am not a good driver but this worked well enough for me