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Plumbing brake proportioning valve?


KnifeySpoony

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Anyone know the best way to plumb in a prop valve in the cockpit like Caterham does on it's racecars? I have an AP racing lever type valve, and I'm trying to figure out the best series of connections to splice it into the rear brake line. Looking at a setup like this:

Brake%2BBias%2BAdjuster.jpg

 

Uses banjos to get into the valve, but how do I get into the banjo from the existing line? Forgive me I'm an absolute noob when it comes to brake line stuff.

 

Thanks

Edited by KnifeySpoony
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  • 1 year later...
  • 2 years later...

Another bump, as I have the new brakes on the way to do this. The DPR kit uses flex lines from the valve to the rear (and they won't sell it to me). Caterham intends for it to be a solid line from the valve to the 3way union in the rear, and I have this line.  https://caterhamparts.co.uk/brake-pipes/4656-brake-pipe-bias-valve-to-rear-3-way-union-r300.html

 

It has a flared end - I guess this just pokes out through a hole in the tunnel and directly into the valve?

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Do you know what the fitting is on the rear line?  As a minimum you're going to need banjo bolts, washers, and banjo brake adapters with the appropriate threads to match the valve and brake line.  Should be available from Pegasus:

 

https://www.pegasusautoracing.com/group.asp?GroupID=BRAKEBANJO

https://www.pegasusautoracing.com/group.asp?GroupID=SSBRAKEFITTING

https://www.pegasusautoracing.com/group.asp?GroupID=COPPERCRUSH

 

Have you taken the tunnel top off yet, and what are you going to do for the front line from the master cylinder to the valve? If you're going to modify the original line you're going to have to be able flare the tube and use the correct fitting. 

 

I've fabricated oil and fuel lines before but have never fabricated brake lines. Brake lines are much higher pressure and something you don't want to screw up, but with the correct flares and fittings it should be relatively straightforward. 

 

 

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Remember that if you use AN fittings, the flare angle is different. AN uses a 37 degree single flare, with a nut and sleeve, not your typical 45 degree double flare brake line

 

It's all easy enough, just be sure to have the right bits

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probably little diff as to vibration

 

I prefer AN/JIC for everything except my daily drivers--it's just easier to deal with, lots of adapter fittings, etc. And you can buy premade flex lines in a wide variety

 

for instance, my Westy came with a mix of English bubble flares and JIC   anything I have had apart is now AN   and the formula fords are all AN

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4 hours ago, 11Budlite said:

Do you know what the fitting is on the rear line?  As a minimum you're going to need banjo bolts, washers, and banjo brake adapters with the appropriate threads to match the valve and brake line.  Should be available from Pegasus:

 

https://www.pegasusautoracing.com/group.asp?GroupID=BRAKEBANJO

https://www.pegasusautoracing.com/group.asp?GroupID=SSBRAKEFITTING

https://www.pegasusautoracing.com/group.asp?GroupID=COPPERCRUSH

 

Have you taken the tunnel top off yet, and what are you going to do for the front line from the master cylinder to the valve? If you're going to modify the original line you're going to have to be able flare the tube and use the correct fitting. 

 

I've fabricated oil and fuel lines before but have never fabricated brake lines. Brake lines are much higher pressure and something you don't want to screw up, but with the correct flares and fittings it should be relatively straightforward. 

 

 

Thank you for the links. The rearward line as supplied by caterham has a bubble flare on it. Forgive my ignorance, but which banjo fitting interfaces with this?

 

My plan was to cut the forward line from the MC bend it 90 and put a flare on it (having no prior experience cutting or flaring brake lines).  I haven't pulled the tunnel top off yet to see if access to the line will be adequate, but I assume since these are put in post-build sometimes that it is doable. I am nervous about the whole thing tbh. Having multiple connections with poor access/visibility after it's all buttoned up will make it difficult to assess for leaking. I will have to test it well before buttoning it back up.

Edited by KnifeySpoony
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I suppose I could use a magnet to find out, but would my 90s Cat have come with epoxy coated steel lines?  Should these all be replaced with something else?

Please excuse the hijack. 

Edited by IamScotticus
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A bubble flare on a line will take a special banjo fitting, prob from an old brit car.  They are bigger than the AN ones,  cast brass. they really are an ugly thing to behold

In the pic at top, I'm guessing the threads into the valve are 3/8-24, so you need 2 3/8 to AN3 banjos and banjo bolts, and copper seal washers. If threads turn out to be 10mm, banjo bolts are available, but check thread pitch carefully. Then turn the lines out thru the tunnel and put AN3 flare nuts and sleeves on   job done  you will need a AN flaring tool--they are Not the same as a regular auto tool, they flare at 37 degrees instead of 45 and AN is a single flare, not double

 

I have an older flaring tool from Speedway Motors part # 91089528, but for light use 91089520 should do you fine

 

fittings from Pegasus

3265-20

3241-3/8

3242-001

3235-030 STL

3236-03   STL

 

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The threads into the valve are 10mm per spec sheet.

 

So you're saying that those banjo fittings on pegasus will not mate up with a bubble flare? Should I cut off the bubble flare and put a standard double flare on it?

Edited by KnifeySpoony
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I have the Rear AP brakes on my car and mounted a proportioning valve up close to the master cylinder. I didn't want to be messing with it and trying to drive. Here are my observations. I would make sure you get in the car and see if your leg will interfere with where the proportioning valve is mounted in the picture. Making brake line flairs takes some practice. I have done a lot of brake lines, and it is easy to make mistakes. If you want to make your own flares buy good tools. If you look at the Eastwood web site, they have a number of different types. Eastwood is not the only company selling these tools, but they have a good collection. The biggest mistake is how much of the tube you flare, or the amount of tube gets squeezed into the die to create the flare. AN flares are easier to make and fittings an easy to get. Pegasus has what you need. I installed a hydraulic parking brake on my car. My car was plumbed with DIN brake flares and when I got everything together and tested the system, I had a leak on one of the parking brake fittings. I did not want to move my parking brake or disassemble the entire rear suspension to run a hard line so I used a flexible line. On my car when I looked at the fitting where the flexible line attaches to the two hard lines that run out to the calipers it appeared to be a AN fitting. It wasn't. Take the line off and verify what it is. I would suggest you look at all your connections and determine what type of fitting each connection uses. You will need some adapter fittings to connect everything with AN fittings. My AP master cylinder uses DIN fittings.           

 

 

 

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I considered putting the valve under the bonnet for ease of install (and assuming that it would for the most part be set-and-forget), but I'm not sure where I would put it to keep it down low. I've read that you don't want to run lines above the height of the MC or it can be difficult to bleed. Can you take a pic of your valve setup?

 

The pic of the valve I posted is on a RHD car - on my car, it would be on the passenger side of the tunnel. What hydraulic parking brake are you using? There has been chatter on various addon parking brakes on blatchat for years, but I don't think they have found a good solution.

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