Lead Ballast & Traction

[Hamish]

Hi Guys,

I need to put about 12lbs of ballast into our Formula Ford. We are keen to improve slow/medium speed corner traction especially in the wet. The car weight split is currently about Front 45% Rear 55%. I'm thinking of bolting this lead to the gearbox. A good idea? We would like to dial in a bit of understeer.

Any suggestions?

Cheers

Hamish

[S Lathrop]

Adding weight will not increase grip. More weight just increases the work the tires have to do. I would place the ballast toward the end of the car that has the least traction problem.

Also placing the weight at one end or the other of the car will increase the polar moment of the car, not good for grip or responsiveness. In short put the weight in the middle of the car as low as possible.

[Hamish]

Thanks for the advice and I do understand what you say. It's just that cars like the late 2000s Renault F1 cars, the 1983 Gordon Murray Brabham which had rearward weight bias had mega traction as of course do Porsche 911s. In the UK the Ray Formula Ford has quite a lot of weight over the rear wheels compared to others and they work well in wet conditions and put the power down well in slow corners. All this has led us to think it may be worth us trying to place the weight at he rear. Has anyone played around with this sort of thing?!

[Hamish]

What we are trying to do I guess is not increase grip but just change the balance.

[Jon Jeffords]

Am I correct in assuming you need to add the 12 lbs in order to meet the minimum weight requirement?

[David Ferguson]

If you don't like the answers/advice provided, you could test several locations, and determine the best location yourself. Moving weight isn't difficult, if you are prepared before you arrive at the track.

[DaveW]

Adding weight will not increase grip. More weight just increases the work the tires have to do. I would place the ballast toward the end of the car that has the least traction problem.

Also placing the weight at one end or the other of the car will increase the polar moment of the car, not good for grip or responsiveness. In short put the weight in the middle of the car as low as possible.

To clarify a bit, more weight at the rear will increase oversteer, but decrease wheel-spin on the inside rear wheel. More weight at the front will do the opposite. As Steve said, adding weight at either extremity will increase polar moment, making response more sluggish.

I have a handling presentation I've given in the past - PM or email me if you want to see it.

[S Lathrop]

Hamish;

I gave you an answer based on what is best for rear grip during cornering. Straight line acceleration is a different issue. The weight over the rear might help straight line acceleration but detract during cornering. What is most important to you?

I would take Dave's advice and test.

[reidhazelton]

FFs have a little less hp than F1 and Indy cars. If you are trying to get more rear grip by adding weight you are solving a problem with the wrong solution if you as me. You should have no issues with putting power to the ground in an FF. Adjust the car to get it where you want and put the weight in the middle.

[Hamish]

Am I correct in assuming you need to add the 12 lbs in order to meet the minimum weight requirement?

Yes that's correct.

[Hamish]

If you don't like the answers/advice provided, you could test several locations, and determine the best location yourself. Moving weight isn't difficult, if you are prepared before you arrive at the track.

Totally agreed. I do like the answers, just pondering all possibilities!

[Hamish]

Hamish;

I gave you an answer based on what is best for rear grip during cornering. Straight line acceleration is a different issue. The weight over the rear might help straight line acceleration but detract during cornering. What is most important to you?

I would take Dave's advice and test.

Thanks Steve,

It's slow/medium speed corner traction in the wet that we are specifically looking at.

Cheers

Hamish

[Jeff_8]

I thought it would be simple, just some dive weights and some cable ties. Shift them around on a practice day and note the difference, just like experimenting with tyre pressures.

Jeff

[S Lathrop]

Thanks Steve,

It's slow/medium speed corner traction in the wet that we are specifically looking at.

Cheers

Hamish

Try lower rear ride height, then softer rear spring and make sure you don't have any anti squat built into the rear geometry. The rear ride height is the easy to adjust and reset for a dry track.

The anti squat geometry is popular on small bore cars to counter a push tendency on acceleration.

[Hamish]

Try lower rear ride height, then softer rear spring and make sure you don't have any anti squat built into the rear geometry. The rear ride height is the easy to adjust and reset for a dry track.

The anti squat geometry is popular on small bore cars to counter a push tendency on acceleration.

Thank you so much. Is there an easy way to check or measure for anti squat?

[Steve Demeter]

Carroll Smiths books tell you how. Need a level, protractor and measuring instruments for lengths and some string would not hurt either.

Make sure it is done with the car weighted (driver in it, etc) when you make the measurements.

[S Lathrop]

Thank you so much. Is there an easy way to check or measure for anti squat?

The control arms pivot about an axis formed by the location of the ends fixed to the chassis. Those axis should be parallel between the upper and lower control arms and they should be horizontal to the ground as the car is raced. Any convergence of the axis or angle to the ground will produce a torque effect of the loads transferred to the chassis. Many cars use these torque effects to produce the handling they want. Your task is to make sure these torque effects work in you favor.

[Hamish]

The control arms pivot about an axis formed by the location of the ends fixed to the chassis. Those axis should be parallel between the upper and lower control arms and they should be horizontal to the ground as the car is raced. Any convergence of the axis or angle to the ground will produce a torque effect of the loads transferred to the chassis. Many cars use these torque effects to produce the handling they want. Your task is to make sure these torque effects work in you favor.

Thanks for this very helpful advice, very wise words and much appreciated.