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 )

> 914 parking brake, Questions
carcentric
post Sep 12 2003, 09:34 AM
Post #1


Newbie
*

Group: Members
Posts: 3
Joined: 12-September 03
From: Renton, WA
Member No.: 1,149



Question 1: Does a 914 rear caliper need fluid in it for the parking brake parts to work?

Background: I'm building a small (250cc Yamaha-based) trike and need a rear brake system that can be operated by a cable connected to the bike's foot pedal (no hydraulics). I remembered that a 914's parking brake is cable-actuated, so the plan is to hook the bike's foot pedal cable to the parking brake arm on a 914 rear brake caliper. (I'd mount the rotor directly to the Comet differential case so one brake will work both rear wheels - should be sufficient stopping power at the sub-freeway speeds the Yamaha can achieve.)

Question 2: Any reason it wouldn't work, or issues I need to deal with?

More into: If pictures help, I've documented the plan at http://www.carcentric.com/YamahaSR250Trike.htm

Thanks for any assistance,
M D "Doc" Nugent
Former owner of 914 Lite 2.5
http://home1.gte.net/nugentmd/914lite.htm
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
 
Reply to this topicStart new topic
Replies(1 - 8)
Brad Roberts
post Sep 12 2003, 09:36 AM
Post #2


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

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



Welcome DOC Nugent.. (IMG:style_emoticons/default/clap56.gif) (IMG:style_emoticons/default/beerchug.gif)

You can use the 914 rear caliper without fluid (I would put some in them to keep the seals wet and cap it closed).


B
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
McMark
post Sep 12 2003, 09:38 AM
Post #3


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

Group: Retired Admin
Posts: 20,179
Joined: 13-March 03
From: Grand Rapids, MI
Member No.: 419
Region Association: None



I'm not sure I would trust that little arm with my life though.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ArtechnikA
post Sep 12 2003, 09:42 AM
Post #4


rich herzog
*****

Group: Members
Posts: 7,390
Joined: 4-April 03
From: Salted Roads, PA
Member No.: 513
Region Association: None



QUOTE(carcentric @ Sep 12 2003, 07:34 AM)
Question 1: Does a 914 rear caliper need fluid in it for the parking brake parts to work?

...the plan is to hook the bike's foot pedal cable to the parking brake arm on a 914 rear brake caliper.

Question 2: Any reason it wouldn't work, or issues I need to deal with?

doesn't need fluid.

just be aware that the parking brake is pressing against only one disk surface. used as a service brake, that -may- be putting forces the disk wasn't designed to see, and differential heating may slowly turn the disk into a big Belleville washer...

the other issue is that the parking brake is kept in adjustment by application of the hydraulic brake. without that continuous adjustment force, you'll be needing to keep re-adjusting the inner pad location. venting clearance (inner pad) adjustment seems to be a weak-ish point of these calipers.

i'm sure it can be made to work, but those are the potential issues as i see 'em ...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
carcentric
post Sep 12 2003, 10:00 AM
Post #5


Newbie
*

Group: Members
Posts: 3
Joined: 12-September 03
From: Renton, WA
Member No.: 1,149



Hey, this forum is FAST with the responses!

A few more data points (if they matter). Expected top speed is 45mph. Expected annual mileage is maybe 500 at the most. No racing.

Thanks for the initial input. I'll almost fill the caliper with DOT 4? (the kind that doesn't absorb water) to minimize internal rusting, and check frequently for weird wear and cupping of the rotor (unlikely, I think, given its use parameters). Anything else?

Is there a manual way to make the adjustments ArtechnikA mentioned? Would a simple pumping of compressed air into the (unused) hydraulic line occasionally do the needed adjustment?

M D "Doc" Nugent
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
scotty
post Sep 12 2003, 11:16 AM
Post #6


The Fun Never Stops
***

Group: Members
Posts: 773
Joined: 20-May 03
From: Portland. Oregon (SW)
Member No.: 718
Region Association: None



...it'll probably still take forever to stop, even though the trike is lighter.

I like to think of the parking brake as a "gradual momentum reducer."
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Dave_Darling
post Sep 12 2003, 11:28 AM
Post #7


914 Idiot
***************

Group: Members
Posts: 15,051
Joined: 9-January 03
From: Silicon Valley / Kailua-Kona
Member No.: 121
Region Association: Northern California



Doc, once again I will recommend Wilwood mechanical spot go-kart calipers.

--DD
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Sep 12 2003, 11:33 AM
Post #8


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

Group: Admin
Posts: 41,854
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California



QUOTE(scotty @ Sep 12 2003, 10:16 AM)
...it'll probably still take forever to stop, even though the trike is lighter.

when i blew my master cylinder going over the bay bridge, all i had was the parking brake. it did a pretty good job in slowing down my >2000 pound car and i was at least going 50 mph.
dependig on the weight of that "thing" you might get away with just the parking brake.
but why not mount a real braking system ????

Andy
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
carcentric
post Sep 12 2003, 09:59 PM
Post #9


Newbie
*

Group: Members
Posts: 3
Joined: 12-September 03
From: Renton, WA
Member No.: 1,149



Answers to questions:

1. "dependig on the weight" - It'll weigh under 750 lbs with me and my wife aboard.

2. "why not mount a real braking system?" - Cost and complexity . . . and cost (I still have a few 914 parts left, so they're "free").

Got your message, Dave. Still looking for the "no cash outlay" solution.

MDN
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

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

 



- Lo-Fi Version Time is now: 31st October 2024 - 05:22 PM