Missing weight value in car physics (heavy cars braking fix)

A common bug in recent F1 mods is that cc-cars completely miss the braking point at slower corners (think Monza first chicane), failing to compensate for the extra weight of modern cars. Why that happened remained a mystery, until...

I noticed the car weight is stored three times in the GP4.exe, but Physics Editor 1.03 only updates two of them. The third one seems to be linked to braking calculations, and updating it seems to fix the issue. I didn't test for any side effects though, so be wary!

This forgotten weight value is located at offset 0x22edd8 in decrypted GP4.exe 1.02 (I don't have a v1.00 to test), and the weight is stored in IEEE 754 double format.

I've made some .cap files (for use with CSM mods, paste in Patch folder) with values for the last few F1 seasons, ready to use, in the link below. These files do not affect and are not influenced by the weight in the .g3p physics file, so you still need those as well.

Download: [www.mediafire.com]

620 kg: 2010
640 kg: 2011-12
642 kg: 2013
691 kg: 2014
702 kg: 2015-16
728 kg: 2017
733 kg: 2018
743 kg: 2019
746 kg: 2020
752 kg: 2021


My unfinished tracks: [www.grandprixgames.org]
Send bug reports and track editing questions to f1virtualblog@gmail.com



Edited 1 time(s). Last edit at 07/06/2022 01:53PM by Prblanco.

You are an absolute genius and this is more than a brakethrough for GP4!!! Thank you very much!!!

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GP Files | GP Videos | Discord: Carl_gpgames#2350

Amazing work on this, this is huge. Thanks

Great find, indeed a brake through.

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My Grand Prix 4 Files
I'm a total dick. How many people can say that?

Nice find! I ended up just leaving car weight at the default in all my mods to avoid this bug, and compensated in the performance file to get accurate laptimes.

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Intel NUC 8i3, 8GB RAM, MS Sidewinder Wheel

very good, Paulo, thank you

Thanks Paolo for this great discover!

Samuele
32BOBO32

Brilliant! Thanks for sharing Paulo

Superb work and thank you very much to share with us Prblanco!

Gp4 still alive!

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PLEASE VISIT: Grand Prix Mods Blog

thanks.

may you please add this topic to the FAQ?

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GP Files | GP Videos | Discord: Carl_gpgames#2350

Any idea how this fix can be applied for non-csm users?

For now we don't have any user-friendly tool that allows us to correct this issue, the only way without CSM is if you're familiar with any hex editor software. If you do, use the info in the first post to know where to edit the GP4.exe directly.


My unfinished tracks: [www.grandprixgames.org]
Send bug reports and track editing questions to f1virtualblog@gmail.com

Hi Prblanco and happy new year.

Could you tell me which years each weight file corresponds to?

Thank you very much in advance.

Quote
superman77m
Could you tell me which years each weight file corresponds to?

For some reason I didn't see this question so, half a year later, here it is:

620 kg: 2010
640 kg: 2011-12
642 kg: 2013
691 kg: 2014
702 kg: 2015-16
728 kg: 2017
733 kg: 2018
743 kg: 2019
746 kg: 2020
752 kg: 2021


My unfinished tracks: [www.grandprixgames.org]
Send bug reports and track editing questions to f1virtualblog@gmail.com