Weight reduction

[Karl]

Yer after i got the SSR type C rims. it made a huge difference!

[DC2-PWR]

just to clarify, you 'got better results' with more weight in, but only because you didn't fine tune your set-up?

if true, then is there a lesson here?

i think cartoon has nailed it...

Massive lesson learnt for me. But I learnt the hard way. Yes at previous track days if I had more weight at the back of my car I'd definetly get a better PB. But now its all sorted, Im a happy chappy

Cartoon helped me gather what was going wrong with my setup, without his help I'd be doing something really different and not solving my problem.

Wow so much hate for weight loss on this thread. I'm a weight loss fan, since our cars have no torque - weight loss is our best friend. I have nothing in my boot, absolutely nothing, and it makes for horrible echoing and droning from the 60rs catback. That's the down side of interior panel removal. But I love the go-kart feeling of a car with minimal weight.

Further steps of weight loss I want to achieve:

- carbon: doors, hatch, hood
- rotating mass: forged wheels, two piece rotors
- unsprung mass: forged one piece brakes, rear LCA's
c

Noooo not a hate, its just how you apply it. Remember to re-tune your suspension properly. It is a must.

When its all balanced and you have zero weight, then you will have only one problem at track, that is seat time

[Karl]

Was thinking. With the battery relocation would you really needed to run such a large positive. As when the car is running all the battery is doing is charging and stabilizing the voltage.

And high current at start up would only be for a couple of seconds and wouldn't deteriorate the insulation

[ChargeR]

maybe you guys place more empahsis in knowing how a change to your car makes it behave differently, but others might simply want to know how fast they can go!

I think this is the fundamental difference between tRipitaka and my points of view and you and Karl. We don't doubt that weight reduction will get great results, but for me I'd rather know for sure where my speed came from.

Moving on though, Cartoon mentioned the effect of weight bias from front to rear. Ideally for peak lateral grip at constant speed and radius you would want 50:50 weight distribution, as it theoretically allows the tyres to develop the most total grip to turn the car.

However constant speed and radius corners are a relatively rare and small part of a typical lap of a circuit. Most of the time you are braking, turning in, tracking out etc. and for these phases of the track a different weight bias is preferable. Smarter people than me suggest that a slight front bias to the weight distribution will result in better lap times for most front wheel drive cars, with more front bias needed the more power you have. If you for example had only 50hp I'd say that nearly 50:50 would be ideal.

Interestingly BTCC cars and others built to that rule set did go a long way toward 50:50, I've heard numbers around 55:45 thrown around. They had long wheelbases and low centres of gravity though, somewhat mitigating the longitudinal load transfer effect compared to our high and heavy street cars.

HERE and HERE are some interesting threads on the topic.

[cordz]

Good read with the thread you posted (http://honda-tech.com/showthread.php?t=842233)

His findings of front heavy FWD cars being faster just makes sense to me. I'm just thinking about the what the car has to do on the circuit:

- Acceleration. Obviously a front biased FWD car will have alot better traction than a perfectly balanced FWD car, more weight in the rear will encourage squatting and therefore take weight off the front wheels decreasing traction when accelerating out of a corner.

- Deceleration. A front biased car will be less prone to locking the front wheels under braking. Locked brakes are a cause of braking power exceeding the coefficient of grip the tyres have. More weight in the front will increase the grip coefficient of the front tyres and help to always exceed front braking torque.

Brandon's DC2R has a stripped rear, and has a supercharger set up K24 up front, to make for a front heavy bias and it has rocket times!

[cartoon]

front biased car under braking is taking a lot of the weight on the front wheels. Causing the rear to lock also. This more touches on suspension set up in regards to rebound and damper settings to assist with keeping the weights where they need to be.

If a front heavy car allows all the weight to shift round it will not have traction under acceleration and lock the rears up under braking.

[cordz]

front biased car under braking is taking a lot of the weight on the front wheels. Causing the rear to lock also. This more touches on suspension set up in regards to rebound and damper settings to assist with keeping the weights where they need to be.

This is also true, so it is important to consider braking bias also.

By decreasing weight and increasing tire grip with semi's or R-compound rubber, you increase your speed between apexes, this in turn requires higher deceleration rate, this then will increase the weight transfer on to the front wheels. As you said, this increases the chances of the rears locking up, so everybody should consider that rear braking force must be adjusted too.

As you also said for damper settings, a softer rear and stiff front will help keep extreme transfer of weight to the front of FWD cars.

[inertia]

Are you referring to the speed in which weight is transferred? As it was my understanding that the only method to reduce longitudinal weight transfer is via a longer wheel base and / or lower CG, as ChargeR mentioned previously when referring to the BTCC cars.

Edit: sorry this was in response to what Cartoon mentioned about damper settings.

Sent from my Galaxy Nexus using Tapatalk 2

[cartoon]

Less weight, lower CG, initial weight distribution, spring rate, suspension settings etc will all play their part in weight transfer.

[DC2R]

size of driver's bum weighs a fair bit too...

Ah well, in the absence of weight loss, just add power... :-p

LoL, Karl, eat one less KFC meal per week and you wont have to take out as many parts

[Karl]

LoL, Karl, eat one less KFC meal per week and you wont have to take out as many parts

LOL i dont eat that crap. Im a gym junky. i only weigh 68kg

[tinkerbell]

Less weight, lower CG, initial weight distribution, spring rate, suspension settings etc will all play their part in weight transfer.

spring rate would dominate chassis behaviour I’d be guessing? (in an integra)

i went from 14/10 setup to a 10/6 setup and immediately people were commenting on how much car was diving and rolling much more than before...

i replied - "yes, and it feels fantastic!!!"

mind you, this is not for circuit racing, but hillclimbing... (NB - after the discussion in this thread, i am removing my rear wing for this weekend’s event!)

[cartoon]

Tinker,
I think to many people think stiffer is better. A completely stiff set up (suspension, sway bars, chassie) can be to stiff for things like hill climbs and such but work in other areas like track (mind you to stiff can be a problem to).

I like the rear to rotate a little and usually have my set up a little different to most even on the track. I'm no expert but ran a good enough time for my first Wakefield day once I allowed the rear to rotate a little.