Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
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.
 

Welcome Guest ( Log In | Register )

2 Pages V  1 2 >  
 Reply to this topicStart new topic
> Brake system overhaul, Proportioning Valve
Elliot_Cannon
post Apr 22 2003, 11:43 AM
Post #1


Senior Member
***

Group: Retired Members
Posts: 1,922
Joined: 26-March 03
From: Orange County Ca
Member No.: 480
Region Association: None
Hi,
I'm fairly new to 914s and this web site, so I think this topic has probably been discussed before. I'm working to restore this 73 914 and have done the suspension and most of the brakes. All new brake lines, calipers and 19mm master cylinder. I installed BMW 320i calipers in the front. I would like to replace the rear brake proportioning valve with a "T" fitting. I finally have the engine out and will be finishing up the rear brake lines after some welding is done. What do you think of replacing the valve with the "T"??
I've seen some great discussions on this site and have learned a lot and hope to learn more. I can't wait to get this car back on the road. Thanks in advance for the advice.
Cheers, Elliot
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Apr 22 2003, 12:04 PM
Post #2


Resident German
*************************

Group: Admin
Posts: 41,649
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California
i just put the "T" into my car a week ago. no driving experience yet, but the word is that with a major brake upgrade (in my case '86 911 Carrera), the stock bias does not allow enough pressure to the rear brakes. therefore the "T" gives you a better overall brake performance.

Andy
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 22 2003, 03:26 PM
Post #3


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
Elliot,

The T in place will balance out the new braking force you have in the front very well with the stock rears. I'm finding more and more stock prop valves heading towards failure.

B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Anton
post Apr 22 2003, 03:40 PM
Post #4


Royal Orange
**

Group: Members
Posts: 161
Joined: 25-March 03
From: The Netherlands
Member No.: 473
Have you read the Tech Articles on the Pelican Parts website concerning brake physics and practice? I personally would not discard of the prop. valve. In Europe it's even forbidden; a street car will not get its annual approval (MOT, TüV, APK; depending on where you live). There are after-market, adjustable proportioning valves; wouldn't that be better? I must admit that my own 914 braking experience goes as far as a revised stock set-up, apart from a 19mm master cylinder.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
airsix
post Apr 22 2003, 03:45 PM
Post #5


I have bees in my epiglotis
****

Group: Members
Posts: 2,196
Joined: 7-February 03
From: Kennewick Man (E. WA State)
Member No.: 266
QUOTE(Brad Roberts @ Apr 22 2003, 01:26 PM)
Elliot,

The T in place will balance out the new braking force you have in the front very well with the stock rears. I'm finding more and more stock prop valves heading towards failure.

B

Nobody has mentioned the best part - with the prop valve gone (or replaced with a modern one) spongy brakes are a thing of the past!

I love my brakes since I ditched that flaming piece of dog poop. (IMG:style_emoticons/default/wink.gif)

-Ben M.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 22 2003, 03:52 PM
Post #6


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
Anton,

We have found when installing an adjustable valve... we end up running them wide open...so why spend the money on an adjustable one when I end up with it wide open ?? Install the 8$ T. I do agree that the different brake combo's will require something in place of the T, but I have tested every possible brake caliper combo with the T without the T and with adj. prop valve. Your safe with the T in the USA unless you have bone stock size tires on the car.

I threw physics out the window. We test setups with digital pyrometers to read rotor temp. I have real numbers... not theories.

B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bernbomb914
post Apr 22 2003, 03:55 PM
Post #7


one of the oldest Farts on this board
***

Group: Benefactors
Posts: 1,873
Joined: 29-December 02
From: Temecula, CA
Member No.: 36
I need to get a Tee for my Volvo conversion but cant find one around here. went to Glenns swap meet to pick one up but he was out of them. Volvo fronts are awesome and really pull down very smooth and with the Tee it should be better.

Bernie (IMG:style_emoticons/default/MDB2.gif)

Ps Muller is responsable for the idea of the installation. Very inexpensive.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Elliot_Cannon
post Apr 22 2003, 05:02 PM
Post #8


Senior Member
***

Group: Retired Members
Posts: 1,922
Joined: 26-March 03
From: Orange County Ca
Member No.: 480
Region Association: None
Thanks for the info and opinions everyone. I am told that you can get these "T" fittings at a VW dealership. I think I'll look for one tomorrow.
Cheers, Elliot
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
anthony
post Apr 22 2003, 05:05 PM
Post #9


2270 club
****

Group: Benefactors
Posts: 3,107
Joined: 1-February 03
From: SF Bay Area, CA
Member No.: 218
Here's one for $5 in the classifieds.

Dominic is a good guy.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
drew365
post Apr 22 2003, 05:15 PM
Post #10


These are the good old days!
****

Group: Members
Posts: 2,004
Joined: 29-December 02
From: Sunny So. Cal.
Member No.: 37
Could this be why I flat spotted my front tires last event? So for lack of a $8 T fitting I've got to replace $400 in tires. I think I'm going to try not to let this happen again.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 22 2003, 05:18 PM
Post #11


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
Sure.. all race drivers try and find a reason to describe flat spotted tires. (IMG:style_emoticons/default/driving.gif)


B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
drew365
post Apr 22 2003, 05:37 PM
Post #12


These are the good old days!
****

Group: Members
Posts: 2,004
Joined: 29-December 02
From: Sunny So. Cal.
Member No.: 37
Well if I install a T it will eliminate one excuse. Besides, I'm still a member of the Ricky Racer Club. When I run out of excuses I might be a race driver. (IMG:style_emoticons/default/biggrin.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
campbellcj
post Apr 22 2003, 11:27 PM
Post #13


I can't Re Member
****

Group: Members
Posts: 4,545
Joined: 26-December 02
From: Agoura, CA
Member No.: 21
Region Association: Southern California
I did the tee a while back and once I got some good pads installed front+rear, the difference is pretty amazing. You can actually feel the rear brakes "working" where you couldn't before.

I got my tee from a local Bug shop in the SF valley. "Small Car" was the name, I think, in Reseda or thereabouts.

What brakes are you running Andy?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 22 2003, 11:30 PM
Post #14


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
I'm not Andy...

He has Carrera front calipers and stock rears with a 19mm MC.

B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
campbellcj
post Apr 22 2003, 11:42 PM
Post #15


I can't Re Member
****

Group: Members
Posts: 4,545
Joined: 26-December 02
From: Agoura, CA
Member No.: 21
Region Association: Southern California
Pretty close to my setup - SC (A) calipers up front with SC vented rotors & Pagid Black pads; 914-4 front calipers in rear with 914-6 rotors and Pagid Orange pads; 19mm M/C; SS lines; ATE blue fluid. I haven't been to a really brake-intensive track yet, but they feel very good so far.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Anton
post Apr 23 2003, 05:39 AM
Post #16


Royal Orange
**

Group: Members
Posts: 161
Joined: 25-March 03
From: The Netherlands
Member No.: 473
Another question for me is whether the original prop. valve wears out and needs revision at some point.

Remarkably, revision parts for the prop. valve are nowhere to be found. So, is this not necessary? Or, if it is, might this be the reason for a poor rear brake performance (regardless of the superiority of a "T" as you all say)?

Most car parts simply need revision or replacement after 30 years of duty.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
drew365
post Apr 23 2003, 08:28 AM
Post #17


These are the good old days!
****

Group: Members
Posts: 2,004
Joined: 29-December 02
From: Sunny So. Cal.
Member No.: 37
This Andy has early S front calipers and stock rear calipers and rotors. I'm not sure which pads are on it but I know they were supposed to be a combo street/track pad. I will probably use pagid when these wear out.
Chris; whats the difference between the Pagid orange and black?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 23 2003, 11:30 AM
Post #18


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
Anton,

I do agree that the prop valve probably needs rebuilding. Dont get me wrong, not all cars need a T in place. We went thru a ton of hassle on a factory 6 car in the shop to locate a good factory six valve. When I say a car needs a T... its when somebody has done a 6 conversion on a 4cyl car (the stock 6 prop valve is valved for more rear brake) or a V8 conversion in a 4cyl car....or someone has gone to sticky wider tires. It all comes down to your situation. If I was doing a concourse restoration.. I would go thru and find the proper pieces to rebuild the stock prop valve.

Unless you have driven a car with a T.. its hard to explain the benefits. ChrisC above got pretty close with his comments on "I can feel the rear brakes working now"

B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
JWest
post Apr 23 2003, 11:48 AM
Post #19


Senior Member
***

Group: Members
Posts: 1,662
Joined: 6-January 03
From: Fort Worth, TX
Member No.: 97
Region Association: None
Hey Brad, don't you need less rear brakes (more prop valve) with stickier tires? You can transfer more weight to the front so the rears have less vertical load and less grip that the fronts.

What am I missing?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Brad Roberts
post Apr 23 2003, 09:14 PM
Post #20


914 Freak!
***************

Group: Members
Posts: 19,148
Joined: 23-December 02
Member No.: 8
Region Association: None
Your not missing anything James.

I want the car to stop flat and not transfer so much weight forward. Our cars are pretty well balanced and they turn in really well. No need for more transfer (these are my thoughts on this) I have spent quite a bit time playing with adjustable prop valves in 4cyl cars and 6cyl cars. Each time they end up wide open... so I stopped buying them and starting going with the T.

Too much front brake makes the car feel really squirrely under heavy braking like the rear end wantsto swap ends with you.. the T adds just enough rear brake that the car is more stable when you stand on the binders.

B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

2 Pages V  1 2 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 20th May 2024 - 02:59 AM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
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 ...