 Notes on brake "upgrades", What's worthwhile, what isn't. |
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| lapuwali |
 Mar 30 2006, 01:44 PM
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#1
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Not another one!  Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743   |
A bit bored this AM, so I'm rambling a little...
The 19mm MC used with otherwise stock 914/4 brakes: this results in a reduction in braking force for a given pedal force (forcing you to push harder to stop), and the actual amount is 16%. Some people like the "firm" feeling this provides, but it doesn't mean "better braking". The 19mm MC used with BMW 320i calipers OR Porsche M calipers (same size). This results in a 12% decrease in pedal effort for a given braking force. So, you will feel an improvement, but it's not a very big one. The downsides to this swap is the bigger calipers are heavier (unsprung mass, too), and of course you're doing a lot of work for a pretty small gain. You're also doing nothing to help brake fade. You're likely making it more likely, since you can now load a bit more heat into the brakes more easily. Happily, this also won't have a huge effect on front/rear brake bias, however, since the overall effect is so small. A 17mm MC used with M calipers would produce quite a big change in pedal force v. braking force: 33%. However, this MAY cause a problem in that the 17mm MC is small enough that you couldn't move enough fluid with it before you run out of pedal travel to fully press the pads against the rotors. You'd certainly have to push it a long way to get the brakes to come on at all, and the brakes would likely feel touchy and mushy, but powerful. Rather like overboosted power brakes... btw, "17mm" and "19mm" (and "42mm" or "48mm" for caliper piston diameters) aren't strictly correct. Even in metric countries, brakes are actually specified in 1/16ths of an inch, so 17mm is really 11/16, or 17.45mm, and 19mm is really 3/4 (12/16) 19.05mm. 42mm is really 26/16", or 41.275mm, and 48mm is really 47.625mm. Germans just list the sizes in the nearest metric size, whereas the Japanese perversely use both systems: 10mm for some parts, and 0.50" for others, for example. |
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| Eric_Shea |
Nov 16 2007, 06:18 PM
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#2
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PMB Performance Group: Admin Posts: 19,289 Joined: 3-September 03 From: Salt Lake City, UT Member No.: 1,110 Region Association: Rocky Mountains  |
Drilled and slotted rotors are designed to vent hot gases that build up inder the pads in extreme braking conditions.
The AJ kit is good for cooling rotors. I miss James. (IMG:style_emoticons/default/sad.gif) |
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Posts in this topic
lapuwali Notes on brake "upgrades" Mar 30 2006, 01:44 PM
tat2dphreak better braking = rebuilt shea calipers, good bleed... Mar 30 2006, 01:57 PM john rogers It appears your rambling is just a tad off, when i... Mar 30 2006, 02:20 PM lapuwali http://www.914world.com/bbs2... Mar 30 2006, 04:17 PM rick 918-S ... Mar 30 2006, 10:07 PM lapuwali I haven't done the math, but my gut feeling is... Mar 30 2006, 10:17 PM turboman808 ... Mar 30 2006, 10:30 PM Dan (Almaden Valley) That is why folks putting Dubs on their SUVs shoul... Mar 30 2006, 10:53 PM trekkor I run rebuilt stock calipers with Porterfield r-4... Mar 30 2006, 11:07 PM racerx7 If all your doing is a single brake test from 60mp... Mar 30 2006, 11:37 PM Andyrew Yup. I experienced this with my car at the wcc.
B... Mar 31 2006, 03:20 AM Eric_Shea Cool thread.
Thought provoking stuff before my pr... Mar 31 2006, 11:48 AM jasons This thread is hitting close to home right now. I... Mar 31 2006, 12:25 PM lapuwali More rambling:
When "improving" brakes, you can r... Mar 31 2006, 12:26 PM Headrage I'm currently have the parts to go with a ... Mar 31 2006, 12:30 PM URY914 here are a couple of my thoughts on the subject:
... Mar 31 2006, 12:43 PM Eric_Shea Paul,
When I saw you name up on the list, that... Mar 31 2006, 12:50 PM lapuwali Mar 31 2006, 12:51 PM john rogers More braking on the rear, that is what I thought w... Mar 31 2006, 12:59 PM URY914 ... Mar 31 2006, 01:41 PM jamara
A bit bored this AM, so I'm rambling a little... Nov 15 2007, 05:38 PM
Dave_Darling ... They are solid and not vented, but being a su... Nov 15 2007, 09:13 PM jamara
... They are solid and not vented, but being a s... Nov 16 2007, 01:59 PM Racer Worthy upgrades? Itmes that fight a brakes biggest... Nov 15 2007, 09:03 PM wobbletop Speaking of airflow... does anyone know where the ... Nov 15 2007, 10:37 PM race914
Speaking of airflow... does anyone know where the... Nov 16 2007, 09:02 AM race914
[quote name='wobbletop' post='967228' date='Nov 1... Nov 16 2007, 11:25 AM Dr. Roger The Hoover vacuum company... =)
Kidding!
Bu... Nov 15 2007, 11:52 PM Jeff Hail I was once told by a famous race car engineer that... Nov 15 2007, 11:59 PM nsr-jamie So what are some nice brake upgrades available tod... Nov 16 2007, 07:55 AM woobn8r I have just acquired some nice alloy 4 piston Boxt... Nov 16 2007, 08:33 AM purple Holy thread resurrection, Batman! Nov 16 2007, 02:05 PM jamara
Holy thread resurrection, Batman!
Ha! Y... Nov 16 2007, 03:03 PM shoguneagle Eric,
You are right on when you say "Miss Ja... Nov 16 2007, 06:31 PM dinomium
Eric,
You are right on when you say "Miss J... Nov 19 2007, 01:49 PM |
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