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Equal Cross Weight vs Other Methods

Practical Corner Weighting

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Discussion and questions related to the course Practical Corner Weighting

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I started typing a comment on the wheel alignment video by HPA on YouTube today, but then thought it's probably more useful to ask here.. https://www.youtube.com/watch?v=GZrIvKqWwi4

Andre, what's your opinion on corner weighting for 50% cross weight vs equal ratios for LF/LR and RF/RR? I've even seen some people with FWD's corner weight to have the front weights even, which would result in a light rear on one corner. Their reasoning is once the inside wheel lifts, its the same result anyway and even weight over the front drive wheels is more important for braking and traction efficiency. While I can see the reason in that, I also assume the point at which the inside rear may lift will be either earlier or later in the turn in phase depending on the direction.

I honestly couldn't tell the difference from the drivers seat whether it was 50% or 54% cross weight (I tried adding wedge for a predominately one direction track) so perhaps its all a bit of a waste of time in a heavy production based car, compared to say a light open wheeler with no ABS among other factors.

Anyone have some thoughts on the topic?

Anyone have some input to share?

It depends largely on what one is using the car for, as that may affect where the bias(es) are preferred.

For example, for a drag car one would focus on loading the drive tyres as evenly as possible, for a 'road' circuit car one may try to equalise the balance on both sides for the same F/R ratio, for a solid rear drive axle one may find a better result with a little more RR-LF to counter the drive and over-run chassis reaction, if the vehicle has an under/oversteer limitation one may gain a net advantage with a bias that gives a greater benefits in one direction than losses in the other - some tracks are heavily biased in one direction. On that last, there may also be advantages in different camber, pressures, etc.

Sorry I should have said, circuit racing application. These days I just set it to 50.0 cross and move on, I honestly don't know if it makes any difference but it helps me sleep better knowing I've scaled and aligned the car before a race weekend.

That's a sound move. Get the vehicle set up so it's consistent and you know what it's goingto do, rather than double guessing and falling into a rabbit hole of changes.

If you have the resources, and inclination, you can use test and track days to experiment with significant changes when mistakes won't matter.

For maximum straight line braking, having equal front weights is the way to go.

There is a very good reason to have non-equal cross weights, particularly if a circuit has say more fast left hand turns, and tight right hand turns. Then having a heavy Front Right - Rear Left (say 52-54%) will increase oversteer in the right hand turns and understeer in the left hand turns. This really works at a particular circuit in the USA that I have raced at many times.

So consider trying different cross-weights depending on the circuit characteristics, and what the car needs to go faster...

I have played around with asymmetric camber for predominately one direction tracks, but I hadn't thought of it with relation to speed - I can see how a wedge in a certain direction could help in the situation you explained.

My last car was a spec car which I had basically ran out of things to try to go faster, but with no data allowed it came down to the stop watch and 'feel'. At a certain track an asymmetric setup was 1 one-hundredth of a second faster than my previous PB in qualifying, but I felt it was a fraction more difficult to drive so went back to square. My new car (and class) has a motec ecu and dash with plenty of logging, so I'm looking forward to getting to the point of playing with the 1%er's again, but for now I need to work on the fundamentals. Thanks for the info!

The asymmetric demands of most racetracks mean that symmetric setups are rarely the fastest. But if you're not racing professionally and chasing the last half second of car setup, setting a car up for each track probably isn't worth it unless a track severely biases one direction over the other (IE: Lime Rock Park).

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