GTS cross weight data?

[FormulaMMM]

Only data I've been able to find is below from this thread https://f80.bimmerpost.com/forums/sh....php?t=1290242

Anyone else? thanks

[redrumm3]

That cross weight appears to be without driver. For a proper cross weight, the car needs to be on scales with driver weight compensation.

[FormulaMMM]

Originally Posted by redrumm3

That cross weight appears to be without driver. For a proper cross weight, the car needs to be on scales with driver weight compensation.

Yep I thought the same

[Gomeler]

I'll have my car corner balanced sometime in August when I put camber plates on the front. Will try to remember to take a photo of the scales.

[Day Laborer]

From my camber plates install and alignment, before the European GTS seats (saves 60lbs)

LF: 1031 RF: 957
LR: 862 RR: 905

3755 lbs total - fuel 3/4 tank and driver (170lbs) weight accounted for.

Roughly about 3695 with Euro seats

[FormulaMMM]

Originally Posted by Day Laborer

From my camber plates install and alignment, before the European GTS seats (saves 60lbs)

LF: 1031 RF: 957
LR: 862 RR: 905

3755 lbs total - fuel 3/4 tank and driver (170lbs) weight accounted for.

Roughly about 3695 with Euro seats

Good stuff, thank you

[FormulaMMM]

So using Day Laborer's #'s, GTS is at 48.4% cross w/ driver.

Can anyone speak to the perceptible improvement on track (if any) going from this sort of value to ~50%?

Cool calculator here https://robrobinette.com/corner_weight_calc.htm

[redrumm3]

Probably not going to see a big difference by going to 50%. Theoretically the car will be better balanced, but I would guess most drivers will not feel the difference.

I try to get my race car close to equal cross balance and corner weight then I dial in some rake to the car. I want more weight forward for better front grip to improve turn in. I am trying to dial out understeer and I can use throttle to control the rear end. This is all done in conjunction with alignment settings, ie: toe, camber and castor. Tires and tire pressures can also play into the equation as well. Spring rates can also make a difference, but that's another topic.

Lots of testing to find the sweet spot and these all change depending on the track and weather etc.

[FormulaMMM]

Originally Posted by redrumm3

Probably not going to see a big difference by going to 50%. Theoretically the car will be better balanced, but I would guess most drivers will not feel the difference.

I try to get my race car close to equal cross balance and corner weight then I dial in some rake to the car. I want more weight forward for better front grip to improve turn in. I am trying to dial out understeer and I can use throttle to control the rear end. This is all done in conjunction with alignment settings, ie: toe, camber and castor. Tires and tire pressures can also play into the equation as well. Spring rates can also make a difference, but that's another topic.

Lots of testing to find the sweet spot and these all change depending on the track and weather etc.

Thanks for the feedback. If I can pick your experienced brain a bit more –

Let’s say driver weight is more than above (+25 lbs.), race seat setup installed (-6 lbs.), passenger seat pulled (-52 lbs.). Factory weight calibration no longer really applies and cross values are less optimal, maybe 47-48% range. Is there a point at which you’d look at the values and say it’s probably “worth it” for a dedicated track car?

Take it that you haven’t bothered to corner balance the GTS.

Assuming relevance, I run at a clockwise track where front left takes the heaviest beating.

thanks

[redrumm3]

Originally Posted by FormulaMMM

Thanks for the feedback. If I can pick your experienced brain a bit more –

Let's say driver weight is more than above (+25 lbs.), race seat setup installed (-6 lbs.), passenger seat pulled (-52 lbs.). Factory weight calibration no longer really applies and cross values are less optimal, maybe 47-48% range. Is there a point at which you'd look at the values and say it's probably "worth it" for a dedicated track car?

Take it that you haven't bothered to corner balance the GTS.

Assuming relevance, I run at a clockwise track where front left takes the heaviest beating.

thanks

If it is a dedicated track car I would spend the money and time to have the car corner balanced/ cross weighted. Why not optimize the potential of the car and truly use the adjustability the suspension has to offer. That is the advantage of a coilover suspension setup.

When setting up the suspension typically you are trying to maximize how the car handles in the most important corners on the track, usually ones leading onto a fast straight. You are trying to optimize your exit speed. On a clockwise course they are usually right handed, high load on the left side of the car. You want to make balance adjustments to spread the load. In this case some additional preload on the right side may be a benefit.

You can go too far in the adjustments however if the car becomes unstable in braking or the left handed corners. It's always a compromise. Optimally you are trying to make the weight transfer work to your advantage wherever possible.

My advice would be to have the car corner balanced as neutrally as possible and see how it feels. At that point you will have a good base to work from going forward. You can make adjustments from there.

I haven't corner balanced my GTS, since it is not my dedicated track car. It's hard to find enough time to keep the race car prepared. The GTS is a very capable track car out of the box with little adjustment and I do enjoy it a lot at the track.

I hope this is helpful.

[FormulaMMM]

Just back from track. Think the GTS could benefit from a corner adjustment. Better turn in and mid-corner grip turning left than right. On my clockwise course with 2 right hairpins being hugely important corners, I'd like to have every advantage.

Either that, or it could be my brain that needs a corner adjustment.

Probably time for another trip to Zima Motorsports.

[hellrotm]

That seems a little heavier than I thought these where.