Brake upgrade effects on bias
#1
Brake upgrade effects on bias
I've been exploring various ways to improve the braking capability of the S2000 on track. I've noticed that there are a variety of approaches but very little real data on how they affect front/rear bias. My own experience is that when the brakes are not overheated, the balance is pretty good so I wanted to stay close to stock. To help me, I built this spreadsheet. Lately I've seen a lot of activity on this subject so thought it might be helpful to share here.
A few things:
A few things:
- I am assuming that the stock brake system F/R bias is ideal so normalize all changes to it. If you're not happy with it, then you may not find this helpful.
- I'm pretty sure I have the mechanics of how changing rotor size and piston size affect brake torque. Still, it would be good if others double check that the formulas are correct.
- For pad height, I have tried to find a drawing for each one and estimated the height. Still, I may be a few mm off of what you measure in the real world. It won't significantly affect the bias, but if you have real world measurements that differ, please post them and I'll update.
- I am happy to add additional solutions - just send me the following: piston diameter(s), rotor diameter, and pad height.
- I have not created every conceivable combination on the Front & Rear Combinations sheet. Most don't make any sense given that the bias shifts more than 10%, hence the word "reasonable" in the sheet's title.
- If you're only changing the front, then focus on the FRONT sheet. Same for the rear, only focus on the REAR. If you want to see how changing both affects bias, focus on the combinations sheet.
Last edited by DanielB; 11-15-2020 at 07:36 PM. Reason: Update spreadsheet link
#3
Thanks for this! On the tab about reasonable setups though you missed spoon front calipers and 330mm ballade rear rotors, that would bring it near 100% stock balance again.
Also what would it be for spoon plus 330mm ballade front rotors and 330mm rear ballade rotors?
Also what would it be for spoon plus 330mm ballade front rotors and 330mm rear ballade rotors?
#4
Thanks for this! On the tab about reasonable setups though you missed spoon front calipers and 330mm ballade rear rotors, that would bring it near 100% stock balance again.
Also what would it be for spoon plus 330mm ballade front rotors and 330mm rear ballade rotors?
Also what would it be for spoon plus 330mm ballade front rotors and 330mm rear ballade rotors?
#5
Nice work. Should pad area not be included or is height the only important part?
Here is a couple more to ad:
Wilwood #140-10309 piston size 41.1 28.4 28.4 (6pistons) 327mm disc, not sure about pad height but check this picture for reference.
Essex/Urge BBK piston size 41 38 299mm disc, pad picture.
Here is a couple more to ad:
Wilwood #140-10309 piston size 41.1 28.4 28.4 (6pistons) 327mm disc, not sure about pad height but check this picture for reference.
Essex/Urge BBK piston size 41 38 299mm disc, pad picture.
#6
Nice work. Should pad area not be included or is height the only important part?
Here is a couple more to ad:
Wilwood #140-10309 piston size 41.1 28.4 28.4 (6pistons) 327mm disc, not sure about pad height but check this picture for reference.
Essex/Urge BBK piston size 41 38 299mm disc, pad picture.
Here is a couple more to ad:
Wilwood #140-10309 piston size 41.1 28.4 28.4 (6pistons) 327mm disc, not sure about pad height but check this picture for reference.
Essex/Urge BBK piston size 41 38 299mm disc, pad picture.
Question for anyone using Wilwood calipers that use a 7416 or 7420 pad, would you measure the height of the pad material at the pad center? Wilwood and others spec it at 43 mm but when I measure from the drawings, it looks more like 39 mm. It's not a big deal because it only changes the bias by 1 percentage point, but would be nice to know which is correct.
Only pad height matters. We're using piston area as a proxy for force and the torque applied is independent of the area of the pad. Pad height matters because it affects the effective radius of the rotor. I'm assuming that the surface of the pad is evenly distributed above and below the midpoint of the pad. That's not going to be accurate for some pad shapes, but the impact is small as you can see by my question above.
Trending Topics
#8
I'll add that for some calipers, there are more than one pad thickness available. E.g. Wilwood 4 piston supports both 16 and 20 mm depending on the Pad manufacturer.
For now, I'm only going to focus on how bias is affected since that information was just not easily available.
#10