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Car brakes review and fixes
07-29-2015, 07:08 AM (This post was last modified: 07-29-2015 07:22 AM by NaN.)
Post: #1
Car brakes review and fixes
I've run our cars through vdrift -cartest looking into brake performance, mainly fixing friction coefficients to have more realistic values (0.3 - 0.7) and increasing brake system pressure where required.

There are a few cars that should have much more aggressive brakes now.

I've ran into one interesting case. TC (Toyota Celica ST185 Rally) reports
60-0 stopping distance (no ABS): 124.708 ft
60-0 stopping distance (ABS): 2326.04 ft

No idea what is going on with the ABS there, will look into it.

EDIT:
There are also a few cars with max power not matching torque curve it seems, which results in incorrect top speed estimation.
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07-30-2015, 08:47 AM (This post was last modified: 07-30-2015 10:38 AM by NaN.)
Post: #2
RE: Car brakes review and fixes
The issue with the Celica turned out to be a non issue Wink

I've added some engine rev up code to the testing logic, which happened to interfere with braking commands for some cars, depending on their transmission setup.
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12-14-2015, 08:57 AM
Post: #3
RE: Car brakes review and fixes
NaN Wrote:I've run our cars through vdrift -cartest looking into brake performance, mainly fixing friction coefficients to have more realistic values (0.3 - 0.7) and increasing brake system pressure where required.

I would say that most of the cars are using piston areas that are way too large. In the project I am working on, I just reduced the suggested value of 0.015 m2 to 0.00501, which is that of a pretty impressive 6-piston caliper AP Radi-CAL CP9660:
In order to view links, you must have to reply to this thread. Product Catalogue/2015 Brake Calipers.pdf

To compensate, I've set max-pressure to a higher value of 1.4e7 pascals, equal to 140 bars.

That was indeed my adjustment factor when I was testing at the Nordschleife in the hard-braking approach from Tiergarten to Hohenrain:
2.5e7 -- enough stopping power (with ABS)
1.1 ---- too little
1.5 ---- enough
1.3 ---- too little
1.4 ---- enough

Pressures up to 250 bars are at least within the realm of possibility:
In order to view links, you must have to reply to this thread.

On the other hand, I have never heard of a piston area of 150 cm2. The largest I have found are 70 cm2 -- intended for 410mm disks!

I know there are some 8-piston calipers out there, but I don't think they can cover that much.
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12-14-2015, 02:13 PM
Post: #4
RE: Car brakes review and fixes
(12-14-2015 08:57 AM)arturo Wrote: In order to view links, you must have to reply to this thread.
NaN Wrote:I've run our cars through vdrift -cartest looking into brake performance, mainly fixing friction coefficients to have more realistic values (0.3 - 0.7) and increasing brake system pressure where required.

I would say that most of the cars are using piston areas that are way too large. In the project I am working on, I just reduced the suggested value of 0.015 m2 to 0.00501, which is that of a pretty impressive 6-piston caliper AP Radi-CAL CP9660:
In order to view links, you must have to reply to this thread. Product Catalogue/2015 Brake Calipers.pdf

To compensate, I've set max-pressure to a higher value of 1.4e7 pascals, equal to 140 bars.

That was indeed my adjustment factor when I was testing at the Nordschleife in the hard-braking approach from Tiergarten to Hohenrain:
2.5e7 -- enough stopping power (with ABS)
1.1 ---- too little
1.5 ---- enough
1.3 ---- too little
1.4 ---- enough

Pressures up to 250 bars are at least within the realm of possibility:
In order to view links, you must have to reply to this thread.

On the other hand, I have never heard of a piston area of 150 cm2. The largest I have found are 70 cm2 -- intended for 410mm disks!

I know there are some 8-piston calipers out there, but I don't think they can cover that much.

Yeah, would be nice to have this fixed too (even if it doesn't matter much for the sim: force = area * pressure). I am all for more realistic values.
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04-30-2016, 07:32 PM
Post: #5
RE: Car brakes review and fixes
Hello folks.
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