rebuilding brake pressure reducing valves

tencate · Postby **tencate** » 28 Jan 2012 13:58

Has anyone here sent in their brake proportioning valve (aka brake pressure reducing valve) in to Apple Hydraulics to have it rebuilt? They claim they can do it but I know of no one who has had them do it! If so, could you write me off forum?

Before you say it, NO, Ted S does NOT rebuild them when he does his modification. :-)

Anyone need to HAVE one rebuilt? The inner seals are not available from any of the usual sources. Some of us in TWOA are looking into it and we've already done LOTS of homework and come up empty.

Jim

FI Spyder · Postby **FI Spyder** » 28 Jan 2012 14:10

You may be the experiment. Why does yours need to be rebuilt? It's the only hydraulic part I didn't rebuild because of no parts. A friend had his Spitfire master brake cylinder rebuilt by Apple and it came back looking like new.

- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT

DNK · Postby **DNK** » 28 Jan 2012 15:22

Jim- What parts are in it?

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

Beans · Postby **Beans** » 28 Jan 2012 17:19

As far as I know they cannot be rebuild, as the parts needed are not available.

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

DNK · Postby **DNK** » 28 Jan 2012 19:59

How closely do they resemble a TR6 PDWA?

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

Vegas_M · Postby **Vegas_M** » 28 Jan 2012 20:38

They are nothing like a TR6 valve, which is really just a housing for a low pressure warning light. Rimmers has new old stock on sale cheap. Even with shipping it's worth it.

Martin

Martin

[url="https://docs.google.com/leaf?id=0BxOL0HRH5pDeNWRlOTVhZjgtMWE1Mi00ZWNiLWE3ZGYtOWNiODU1Y2JjOGQ0&hl=en_GB"]My TR7v8 Document Repository[/url]

tencate · Postby **tencate** » 28 Jan 2012 21:49

How do you know these things are working? You screw in a brake pressure gauge in place of the bleed screw and measure the pressure with a lovely assistant in the car pushing on the brake pedal.

http://www.youtube.com/watch?v=sYHHopYXmSc (sorry it's fuzzy, used an ipod as a camera).

Here's what one looks like apart (big, small photo below):
http://homepage.mac.com/tencate/propvalve.jpg
there are 5 (I think) seals on the shuttle on the right...

Apple Hydraulics says they can get all the seals inside and rebuild them. I don't know anyone who's done that. Those valves Rimmers sells? They've been sitting in a trailer for 25 years or so. MAKE SURE THEY WORK before you go driving or you'll be trying to stop with nothing but front brakes! Bleed baby bleeeeeeeed!

Jim

DNK · Postby **DNK** » 28 Jan 2012 22:17

If it is just seal replacement I am surprised the TWOA hasn't figured out that basically all seals are replaceable somewhere.
McMasters has a tone of them besides others

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

dursleyman · Postby **dursleyman** » 28 Jan 2012 23:00

Does anyone know if adjustable ones can be had in the UK as I would like a bit more braking on the rear. I have seen they can be bought in the USA but not seen them here.
The rears are all set up OK and working properly but I would like to change the front/rear balance a little,

Russ

1980 TR7 DHC
Dursley
UK

tencate · Postby **tencate** » 28 Jan 2012 23:51

Hi Don.

Some of us have searched high and low for the middle seals (which have a peculiar cross section and ID and came up empty. Believe me, we'd love to find a source of those seals. Anyone here want to help us in our search? We have tried all the usual places, even some speciality seal places that folks suggested. There was quite a discussion about this a year or so ago on the WWWedge mailing list but maybe worth another look. That's why we thought we'd ask Apple Hydraulics.

I'll try and post exact dimensions and cross sections and we can all look again? Let me try and dig that up.

Stay tuned.

As for adjustable, I've got a Tilton (7 fixed adjustments), be sure to get the metric version, about $100, and there are other adjustables out there too but you need adapters often for the metric threads; be sure to get the right kind.

tencate · Postby **tencate** » 29 Jan 2012 00:18

OK, here's what we're looking for. Anyone have any ideas where to source these? I think we're running into the same problem as folks who have tried sourcing the seals between the font brake caliper halves. This O ring sees pressures around 1500 psi peak I'd guess (WAG) judging by measurements I've made off the master cylinder, maybe higher, I should measure the cross sectional areas and do the math. The other inner O ring has a D cross section.

Here's the BIG photo:
http://homepage.mac.com/tencate/OringCrossSection.jpg

and a snapshot below. Any suggestions welcome!
Thanks. Jim.

tencate · Postby **tencate** » 29 Jan 2012 02:59

Ask and ye shall receive I guess. Was just sent this link. So, anyone have a brake caliper seal to send them too? We might be in luck with this.

http://www.physics.harvard.edu/services ... ndbook.pdf

Jim

busheytrader · Postby **busheytrader** » 29 Jan 2012 11:13

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dursleyman

[size=2]I would like a bit more braking on the rear........
<hr height="1" noshade id="quote"></blockquote id="quote">

If you haven't already done it, fitting 4 speed rear cylinders in to the 5 speed rear drums will give a little extra pressure on the shoes. The back plate will need a small hole drilled in it to accept the locating pin on the cylinder which is in a different place.

TR7 V8 DHC Jaguar Solent Blue. 9.35cr Range Rover V8, Holley 390cfm, JWR Dual Port, 214 Cam, Lumention, Tubular Manifolds, S/S Single Pipe Exh, 3.08 Rear, 200lb Spax & PolyBushes all round, Anti- Dive, Strut-Top Roller Bearings, Capri Vented Discs & Calipers, Braided Hoses, 4 Speed Rear Cylinders, Uprated Master Cylinder & Servo, AT 14" 5 Spokes or Maestro Turbo 15" Alloys, Cruise Lights, S/S Heater Pipes, Replacement Fuel Tank. No Door Stickers. Mine since July 1986, V8 from 1991 courtesy of S&S V8 conversion and big brake kits.

john 215 · Postby **john 215** » 29 Jan 2012 12:04

Hi,

On my DHC i removed the standard brake pressure reducing valve and fitted one of Woody's 50 / 50 valve blocks. Then installed a brake proportioning adjuster valve inside the car. This allowed me to fine tune the balance handy with the rear disc set up i am running.

Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!

FI Spyder · Postby **FI Spyder** » 29 Jan 2012 15:13

Great info in pdf file. I saved it. Unless you're racing in changeable conditions I'd like to keep brake fluid lines out side the car and position the adjuster in the engine bay. I would think once you had the right set up for your brake equipment it wouldn't change much. I like my standard brake set up on the Spider, lock all four wheels in panic stop, rear slides out when braking on a curve but tucks back in when brake releases, car pivots back and forth around pivot point controlled with steering input (not steering the car with stopped wheels, just keeping it under control). I was given a set of slotted discs that I'm going to install to see how they work. Not that there couldn't be any brake improvement as far as modulation but not high on my long list of to do's.

- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT

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rebuilding brake pressure reducing valves

rebuilding brake pressure reducing valves

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