[Jazzbass]

I created this quick and dirty little brake bias calculator to help me pick the right brakes to put on my Carrera years ago. Lupin's p/v thread reminded me of it so I thought I'd upload it to the board. Here it is:

http://dorkiphus.net/BiasCalc.html

The standard thinking is that an old 911, without p/v should look for a bias ratio of 1.6 to be close to stock. What is the ratio for 944s, Boxsters, etc? No clue.

This page is several years old so it doesn't have all of the latest and greatest Porsche calipers. If anyone wants to PM info for any calipers NOT on this list, I'll add them.

[hoophead]

Nice! - I was just doing the calculations by hand today.

Add 996TT front: 44/36, rear 30/28

[Trak Ratt]

from Bill V's RennLisp page...

[Fritz]

Originally Posted by hoophead

Nice! - I was just doing the calculations by hand today.

Add 996TT front: 44/36, rear 30/28

Right. I was gonna comment on the rear 996TT brakes. They are 30/28 not the 28/28 listed. That would cause a stock bias of 2+. I think it should be closer to 1.7 or so based upon what I've seen. That said, it's still front heavy. Perhaps I should put the bias on the fronts, although I don't see anyone doing that. Good idea or Bad mojo?

[Jazzbass]

Originally Posted by Fritz

Right. I was gonna comment on the rear 996TT brakes. They are 30/28 not the 28/28 listed.

Read again - 996TT brakes aren't even on that page. 993TT brakes are, and I used the 28/28 number from Bill V's info posted by TR. If that's wrong, let me know.

[Jazzbass]

Originally Posted by hoophead

Nice! - I was just doing the calculations by hand today.

Add 996TT front: 44/36, rear 30/28

Verburg's info lists 996TT fronts as 6 puck 28/32/34 not 4 puck 44/36. Which is correct?

[Trak Ratt]

Originally Posted by Jazzbass

Verburg's info lists 996TT fronts as 6 puck 28/32/34 not 4 puck 44/36. Which is correct?

Can't picture V man being wrong on this... plus it's been around long enough someone would have called him on it.

[smdubovsky]

993 rears are 34/30. IIRC same as 965 just w/ narrower throats. I have both at the house and can double check. FWIW, I don't think porsche has ever made a caliper w/ both pistons the same size (at least the spreadsheet of data I've collected over the years doesn't say so.)

[Jazzbass]

Originally Posted by smdubovsky

993 rears are 34/30. IIRC same as 965 just w/ narrower throats. I have both at the house and can double check. FWIW, I don't think porsche has ever made a caliper w/ both pistons the same size (at least the spreadsheet of data I've collected over the years doesn't say so.)

All the original 930 calipers had same size pistons. This was before Porsche figured out why all the brake pads were wearing into little triangles, I guess.

I'll update the page, I just need some consensus on what these sizes really are. SMD - are you talking about 993 rears or 993TT rears being 34/30. Verburg lists the regular 993 rears as 34/30, but is pretty adamant that 993TT rears are 28/28. I even found a post on Rennlist where he says the same, so it's not a typo in the spreadsheet.

993TT rear: 34/30 (not 28/28 like in the data?)
996TT Front (steel): 44/36
996TT Front (ceramic): 34/32/28
996TT Rear: 30/28

[Fritz]

Originally Posted by Jazzbass

Read again - 996TT brakes aren't even on that page. 993TT brakes are, and I used the 28/28 number from Bill V's info posted by TR. If that's wrong, let me know.

My bad. Meant 993. And I like Stephens answer about them being same as the RS. That would make the bias much more agreeable.