 T fitting instead of prop. valve, what is the rational? |
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| DanT |
  Dec 1 2005, 08:18 PM
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Going back to the Dark Side!  Group: Members Posts: 4,300 Joined: 4-October 04 From: Auburn, CA Member No.: 2,880 Region Association: None  |
Ok, I know this has probably been discussed in many threads before. But, what is the reasoning for replacement of the Prop. valve with the "T" fitting for the rear brakes. Does the prop. valve cause more line pressure to the fronts or the rears when it is operating properly? I want to understand the engineering aspects of this modification.
I will be running "M" calipers with mythical billet hubs in the front and stock 914-4s in the rear. thanks (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) |
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| DanT |
Dec 1 2005, 10:59 PM
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Going back to the Dark Side! Group: Members Posts: 4,300 Joined: 4-October 04 From: Auburn, CA Member No.: 2,880 Region Association: None |
I am sure the reasoning behind the T is that putting larger front calipers while keeping the stock rears, statically makes the proportioning due to size differential...with stock front and rear the rears were too closely matched to the fronts, yielding rear lock up with out the proportioning valve. The factory needed to use vw parts that were available and the P valve was a cheaper easier fix than changing brake calipers.
This same process is used on some late model carreras like the C2 when you upgrade to big reds or big blacks...all of the brake gurus say remove the stock P valve. My buddy did this on his C2 during a Big Black upgrade. It worked fantastic. The C2 (964) like the 914 had too large of a rear caliper in relation to the fronts, stock from the factory, necessitating the use of a P valve. By the way a big black upgrade on a 964 put the caliper that comes on the front of a C2 onto the rear with the 928 S4 front up front (same caliper as a 993) The T fitting makes sense in this scenario as well. |
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Posts in this topic
Dan (Almaden Valley) T fitting instead of prop. valve Dec 1 2005, 08:18 PM
McMark The prop valve limits the amount of hydraulic pres... Dec 1 2005, 08:33 PM rick 918-S Here's my spin on the deal. I'm running la... Dec 1 2005, 08:33 PM Headrage Jeez!!!
http://www.914world.com/bbs2... Dec 1 2005, 10:59 PM rick 918-S Dec 1 2005, 11:21 PM Dan (Almaden Valley) ... Dec 1 2005, 11:26 PM Brando Also keep in mind that with much better gripping t... Dec 1 2005, 11:35 PM McMark You mean, this graph Dave? http://... Dec 1 2005, 11:38 PM McMark Dec 1 2005, 11:42 PM trekkor Good thread. http://www.914worl... Dec 2 2005, 12:15 AM J P Stein Dec 2 2005, 07:15 AM andys Dec 2 2005, 10:52 AM Dave_Darling <... Dec 2 2005, 10:55 AM J P Stein Dec 2 2005, 11:22 AM andys ... Dec 2 2005, 11:39 AM kdfoust <... Dec 2 2005, 12:19 PM J P Stein Dec 2 2005, 01:39 PM nick mironov This is where I got my T-fitting ($8):
http:... Dec 2 2005, 02:04 PM horizontally-opposed Eric... http://www.914world.co... Dec 2 2005, 02:06 PM andys Dec 2 2005, 03:14 PM Eric_Shea First Post... http://www.914world.... Dec 2 2005, 05:20 PM J P Stein Brakes......a decent buy:
http://forums.pelicanpar... Dec 3 2005, 10:46 AM horizontally-opposed ... Dec 3 2005, 01:19 PM SirAndy Dec 3 2005, 02:12 PM nine14cats Hi Dan,
I'll give you what Doris and I were r... Dec 3 2005, 03:20 PM
J P Stein Basicaly, what Bill, Andys & I are talking about i... Dec 3 2005, 04:46 PM |
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