[THESLOTCARGUY]

what is body roll and why is it important?

 

[Coopdevil]

Movement of the body relative to the position of the chassis. Can help with loading outside rear tyre on corners and with front-to-back weight movement (back over rear axle when accelerating, forwards over guide when braking) and also with decoupling the body from chassis so that bumps in the track aren't transmitted in their entirety through to the immobile body.

Try the same car (magnetless) with screws up tight and then with screws backed off so that you can see and feel movement between body and chassis and you'll see what we mean. Not worth trying with heavy magnet cars as the chassis can end up flexing towards the rails under magnetic pull.

 

[stoner]

that sums it up nicely. john

 

[Mr Modifier]

That's how I understood it to work too.

BUT I must be doing something wrong;

We have a brand new class at our club based on Ninco1 American Muscle. Last week was the first proper racing with fettled cars. In free practice I put in over 100 laps and got my lap time down to about 8.8 seconds with body screws loosened one turn (about 0.5mm play in the body). Just as an experiment I tightened the screws all the way expecting my best lap to get worse - within 5 laps I had put in an 8.6 and after another 30 or so laps had it down to 8.55. This was the fastest lap by a tenth of a second from one other guy and about half a second quicker than the remaining 4. Everyone except me had loosened body screws.

We then raced a series of 10 minute endurance races and 30 lap Grand prix - everybody else had their bodies loose and I didn't. I won 7 out of 8 races and came second in the other. In Endurance racing with fuel I was putting in 50 laps where second place was 6 laps behind.

The track is 20 metres of Sport track with a 4m straight and an R4 90 degree turn at the end, a series of R2 esses and two R1 hairpins - so a real mix of outright sped and technical challenge.

I'm not a brilliant driver, I'm OK but not brilliant. There are 4 of us who are usually very close to each other (within 2 laps in a 30 lap grand Prix with fuel). So I am at a loss to understand why my rigid car did better than the ones with body float.

I completely accept that body float usually delivers advantages so I must be doing something wrong. Any ideas?

 

[Ember]

And how much is too much? Assuming, of course, that it's not causing fouling of wheels or tyres is it a case of more is better or is there an optimum level for body rock?

 

[stoner]

the optimum for body movement or not, is whatever poduces the quickest lap times. you only need a screwdriver and a timing system to make minor adjustments on the fly, to see what the best results are for any particular car. john

 

[rick1776]

Are you racing with or without magnets? It would make for a big difference. Im guessing you race with magnets.

cheers
rick1776

 

[Mr Modifier]

Without magnets. The aim of the class is for us all to learn about tuning cars to perform well rather than rely on brute force and magnets.

In fact of the 5 classes we will run next year only one allows magnets.

 

[MrFlippant]

As Stoner said, it's not the same for every car. Depending on the car and driving style, some will do better with tight screws. Some will do better with just a little body roll, and some will do better with so much body roll that you can actually see it from 15' away while the car is moving. Essentially, it comes down to whether the car performs better with more or less sliding. I had a car that was tall with grippy tires. I had to not only keep everything tight, but also toss a bunch of weight in the chassis to encourage sliding! It was too tippy/grippy in the turns and would chatter like crazy. Still does chatter a bit, but it stays in the slot. It sounds like your Ninco car was better off with less body roll, and that's fine! It's better to test it out and find that it's better with tight screws than to assume it will be better with body roll. I'll bet the other guys do some more testing. ;-)

 

[Mr Modifier]

QUOTE (MrFlippant @ 5 Sep 2012, 16:07) <{POST_SNAPBACK}>..... I'll bet the other guys do some more testing. ;-)

We're racing again in a few hours. I expect the results to be far less in my favour this week!!!