Weight distribution test on CR2

[flipside]

Hi all!

I recently joined the atomic carbon team to drive the CR2, and have been testing a lot with the weight placement in the car.

I believe that weight distribution is a very important and dominant factor, which can greatly improve handling of any car.

When building the car, and bringing it up to around 1600gr of total weight by adding lead plates under the lipo's, the rear wheels have about 61-62% of the total weight on them. Compared to other cars this is very low, resulting in a lot of steering, but also a loss of rear grip.

When you start adding weight to the front also, the weight % on the rear can even drop to about 60%, which is really insane :-)

Many people also complain about the losi's front end rolling and nose diving too much in turns. Adding weight to the front will only aid in doing this. I also believe weight up front makes steering slower. Compared to a B4, the front end of the CR is already quite heavy out of the box (thick plastic parts!!).

So I have been testing the car without any weight up front, and then tried to remove weight from under the lipo's and putting it more backwards. The ideal solution to do this would be to make the anti squat block in brass. This is not easy to produce, so instead I made the carbon fibre plate that sits under the gearbox in steel. Also made it wider and didn't make the big hole in the middle.

Here is a picture of this weight plate installed in the car. The thing weighs about 70gr.


I also left about 90gr of lead under the lipo's, cut to 2/3rd of the size of the lipo's and moved it to the back (against the steel plate). That brings my car up to +-1650gr depending on which tyres that are mounted.

All this brings the rear weight % to around 64,5%. Ideally 65% is believed to be the perfect balance for a 2WD, so that's pretty close.

I have been testing with and without this plate, and the effect is huge. The car is much more stable in high speed turns, or when you have to turn in hard after the straight for example. It also keeps the nose flatter while turning. To me it makes the steering much more consistent throughout the turn. It also improves handling on low grip sections significantly.

Last weekend I have raced with this part at the petit RC race. Had a part made for Steven (teammate in belgium) and he also confirmed how well this worked for him. He made a solid C final in his last qualifier, which is very good out of 130 drivers... There were very slippery sections and also on these the effect was huge.

I hope to test it asap on outdoor dirt tracks too. I have read people are using exotic setups to get some rear end grip, I really believe that simply using a good weight balance will give the required rear end grip, while being able to use normal oil, piston and spring combinations.

Interested in hearing people's thoughts on this :-) Will keep you posted with any new findings or improvements!

wouter

[Gayo]

You've got to love oOple for that kind of threads! Very informative, thanks Wouter.
I totally agree with you, I felt also on my B4 and X-6 that adding weight to the front of a car makes steering response slower. You have more steering on-power though.

It would be good to know what kind of weight ratio and overall weight is achieved with the yet-to-come aluminium chassis.

So I'll be the first to ask it here : would you sell me one of those fantastic plates?

[Northy]

Couldn't agree more, it is something I tested roughly on Saturday night when I ran the car. Ran it weight wise as I had outdoors in round 1, then for round 2 took all but 5g out of the front bulkhead and fitted as much lead as I could around the motor. The difference was massive I went about half a lap faster and put me on the pace

I have yet to weigh mine, but again, was going to aim for 65/35 split

G

[SHY]

Originally Posted by Gayo

So I'll be the first to ask it here : would you sell me one of those fantastic plates?

LOL! Now you've become like me!!!

[OldTimer]

There is a rear brace in the works to replace the carbon fibre part with a brass version, but its early days yet, as soon as i have more info i will post here.

[Gayo]

Originally Posted by SHY

LOL! Now you've become like me!!!

Usually you add : "yo tengo dinero"
LOL

[ashleyb4]

How do you figure this out???

I got my digital scales put two wheels on it cancelled them out then got another stack of wheels so they where the same height as the ones of the scales used my spirit level to be sure. Then zero'd the scales and put the back of the car on the scales with the other stack of tyres under the front bulkhead the scales read 1115grams did the same for the front and it read 756grams.

How do i figure the percentage???? Am i doing it the right way????

A

[flipside]

Hey, if you have only one scale, do the following:

Make sure you can put the rear wheels onto the scales (my scale wasn't wide enough, so I had to put a bigger plate on top of it). Reset the scale to 0 with that new plate.

Then make something the same height as your scale+plate where you can put the front wheels on.

Weigh the complete car, for example it's 1620gr.

Then put the car with the rear wheels on the scales, front wheels on the other 'thing' you made.

Read the scales, for example 1050gr.

This means 1050gr out of your 1620 total sits on the rear wheels. Or 1050/1620=0,648148 or in % multiply by 100 so 64,8% of the weight is on the rear wheels.

Simple as that!

[olefiloux]

Originally Posted by Gayo

Y

So I'll be the first to ask it here : would you sell me one of those fantastic plates?

héhé!! Gayo would say: would you sell me TWO of those fantastic plates!???