Poll: Brake upgrades..what kind of ratio?, F=big/R= big or F=big/R=little or ??? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Poll: Brake upgrades..what kind of ratio?, F=big/R= big or F=big/R=little or ??? |
Mueller |
Feb 3 2005, 07:27 PM
Post
#1
|
914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
okay...for a factory 914 /4, the front calipers (piston area wise) are 1.61 larger than the rear....(42mm and 33mm)
for early 911's (up to '84), the fronts are 1.6 larger from '84 to '89, the fronts are only 1.3 times larger than the rears....then the ratios vary from 1.4 to 1.7 until the arrival of the 1st Twin-turbo, that car has calipers that have piston areas 2X the size of the rears !!!!! I'm just wondering what combo people have successfully ran.....it's interesting to note that the standard Boxster front calipers if bolted to the front of a 911, the Boxster piston area is only 1.05 larger than the standard 911 fronts.....seems like a darn near equal swap, except for the bigger pads you get with the Boxster calipers (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) |
bd1308 |
Feb 3 2005, 07:28 PM
Post
#2
|
Sir Post-a-lot Group: Members Posts: 8,020 Joined: 24-January 05 From: Louisville,KY Member No.: 3,501 |
um...stock? I'm gonna wait till my rears rust and reak off (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)
|
SirAndy |
Feb 3 2005, 07:58 PM
Post
#3
|
||
Resident German Group: Admin Posts: 41,676 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
'84/'85 carrera on all 4 corners ... the fronts in the front and the rears in the rear ... (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Andy |
||
d914 |
Feb 3 2005, 08:02 PM
Post
#4
|
Advanced Member Group: Members Posts: 2,331 Joined: 12-July 03 From: Atlanta, ga Member No.: 904 Region Association: South East States |
944 turbo front
carrera rears |
Mueller |
Feb 3 2005, 08:04 PM
Post
#5
|
||||
914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
so you have option 4..... i'm trying to figure out what I am going to do for rear calipers.....I've got 4 calipers that are 6% larger than the Boxster front calipers.... I was thinking that I could modify the rears so that only one piston per side was used, but I don't know if the rear calipers would ever work even with an adjustable prop. valve? |
||||
SirAndy |
Feb 3 2005, 08:12 PM
Post
#6
|
||
Resident German Group: Admin Posts: 41,676 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
don't know about the one piston thing but i can tell you that, unless you change your complete braking system, a adjusteable prop-valve is wasted money. you'll end up running it full open anyways. that's why i used a "T" instead ... (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) Andy |
||
Eric_Shea |
Feb 16 2005, 09:58 AM
Post
#7
|
PMB Performance Group: Admin Posts: 19,278 Joined: 3-September 03 From: Salt Lake City, UT Member No.: 1,110 Region Association: Rocky Mountains |
S-Caliper
M-Caliper T-Fitting I just went off the hp rating the factory had with the 76 930 (240) and installed that system. I'm planning on my 2.5 S engine to be close to that. (220-240 range) |
JmuRiz |
Feb 16 2005, 10:19 AM
Post
#8
|
914 Guru Group: Members Posts: 5,434 Joined: 30-December 02 From: NoVA Member No.: 50 Region Association: MidAtlantic Region |
Front - 4 piston Brembo monoblocks
Rear - Stock with 914/6 rotors Replaced the prop valve with a 'T' |
bondo |
Feb 16 2005, 10:25 AM
Post
#9
|
Practicing my perpendicular parking Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California |
I have the second option, but I can't tell you how it works because my car is still a pile of parts. I will be using it with a 19mm master cylinder and a tee in place of the prop valve.
|
don9146 |
Feb 16 2005, 11:00 AM
Post
#10
|
Member Group: Members Posts: 199 Joined: 3-January 04 From: Nashville, TN Member No.: 1,500 Region Association: None |
I have 964 front calipers clamping cross-drilled and slotted rotors in the front, stock calipers in the rear, a 19mm master cylinder, and the brake line "T" replacing the proportioning valve. Balance and feel are excellent with no fade on open track day events.
|
fiid |
Feb 16 2005, 11:25 AM
Post
#11
|
Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
Friction is a function of normal force, not of surface area.... so it is just the piston size that matters, not the pad area. ( http://www.school-for-champions.com/scienc...ce/friction.htm )
I would be a little careful about using the 911 ratios as too much of a data point since their weight distibution is probably a little different (wrong) compared to the 914. The MR2, Elise, Europa, Esprit, X1/9, Ferarri 360 (engine is a little heavy here) might be more interesting though..... It seems like it is possible to correcly balance everything up to and including A calipers on the front with the stock 914 rears - which is what I am doing. If I were you - I'd probably just go to M calipers.... Don't forget - the other way to increase braking is to reduce weight..... Perhaps some fibreglass decklids would help :-) Mueller: Sorry for abrubtly ending the phone call - I'll call you back today sometime... I had to do a demo for the board. |
ArtechnikA |
Feb 16 2005, 11:29 AM
Post
#12
|
rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
'S' calipers front, widened 914.6 calipers rear.
|
v82go |
Feb 16 2005, 11:36 AM
Post
#13
|
Resident Contrarian Group: Members Posts: 249 Joined: 9-December 04 From: Lakeland, Fl. Member No.: 3,250 |
Front= M (911)
Rear=stock (redrilled/5lug) Prop. valve replaced witha "T" |
bondo |
Feb 16 2005, 11:51 AM
Post
#14
|
||
Practicing my perpendicular parking Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California |
I bet pad area affects heat accumulation to some degree. It also definitely affects wear rate. One thing that is certainly a factor is rotor diameter. That page mentions that surface area comes into play when material deformation occurs. I wonder if pads deform enough? It'd be interesting to do some experiments in a real world situation.. do some repeated hard braking, then cut away half the pad area and do it again (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) |
||
fiid |
Feb 16 2005, 12:13 PM
Post
#15
|
Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) I think you hit the nail on the head.
Pad area would effect wear rate, and I bet it has some thermal effects too - like felxing you mentioned. If you assume that the braking force originates (on average) from the center of the pad, then a bigger pad and larger radius rotor whould also move the braking force further out, giving it a greater mechanical advantage (of course - larger tire radius would lose you this battle from the other end).... |
fiid |
Feb 16 2005, 12:14 PM
Post
#16
|
Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
felxing is the combination of felching and flexing, which happens when you get small animals caught in your brakes.
(IMG:http://www.914world.com/bbs2/html/emoticons/chairfall.gif) |
anthony |
Feb 16 2005, 12:17 PM
Post
#17
|
||
2270 club Group: Benefactors Posts: 3,107 Joined: 1-February 03 From: SF Bay Area, CA Member No.: 218 |
Does this ratio take into account the proportioning valve? It must change the "ratio" in the stock system. Most people, when they add 911 front brakes, remove the proportioning valve to make the rear brakes work more. |
||
1973914 |
Feb 16 2005, 12:23 PM
Post
#18
|
Member Group: Members Posts: 353 Joined: 16-May 03 From: Washington, DC Member No.: 703 |
Boxster Monoblocks up front/Vented rotors
Carrera M (Wide) Rear/Vented rotors T in place of rear slave cylinder Monoblocks have light weight with minimal flex. Think of the S calipers but stronger. No prop valve (although i may add one just in case). This of course for 5 lug, but they fit under the 15's. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif) |
bondo |
Feb 16 2005, 12:44 PM
Post
#19
|
||
Practicing my perpendicular parking Group: Members Posts: 4,277 Joined: 19-April 03 From: Los Osos, CA Member No.: 587 Region Association: Central California |
Now that I think about it, pad area and heat MUST be very related. If friction is the same for a smaller pad (or nearly the same), the amount of heat energy must also be the same, because dynamic friction is simply the conversion of mechanical energy to heat. So that same amount of heat would be concentrated on a smaller pad area and overheating it sooner. I guess the same thing would apply to clutches. Too bad our bellhousings are so darn small. |
||
ArtechnikA |
Feb 16 2005, 12:59 PM
Post
#20
|
||||
rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
in my case, i removed the proportioning valve because after changing the caliper piston ratios, it was no longer needed.
go have a look at a Tilton or F1 clutch :-) |
||||
Lo-Fi Version | Time is now: 8th June 2024 - 12:37 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |