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TR4/4A 67 TR4A, need brake line fitting specs

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moe_morin

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I'm going to install Wilwood RPV's, but I first need to identify what brake line fittings the car actually has. From the research I've done on the web, it seems the TR4A 4-way splitter block has 3/8-24 UNF flare connections all around for 3/16" steel lines with double flares.

I would like verification on this plus, is the flare 37 or 45 degrees? Any help is appreciated.

Moe Morin
 
I'm either to have to plead ignorance here or get some clarification and ask what is the Wilwood RPV and also what is it that you are trying to accomplish?

As for the lines and fittings, for the most part 3/8-24 threads sounds right, but there are a few applications on tandem master cylinder cars that use a 7/16-20 fitting for a 3/16" tube so that front and rear lines aren't crossed, as far as I know that should not apply to a TR4A but given how Triumph ran things down the line, I wouldn't be totally shocked if there was a TR4A with some of those odd ball fittings either.


As for the flares, I believe that the TR4A uses bubble flares that don't really correspond to the SAE standard 45° or the AN 37° flares. This is why I am asked about what you are truing to accomplish in addition to asking about the Wilwood RPV. If this is something that mounts between junction points in the Triumph hydraulic system, if it follows typical Wilwood caliper and check valve practice, those are threaded to 1/8-27 NPT and are typically used with adapters to mate with the 37° AN flares.
 
An RPV is a Residual Pressure Valve as Wilwood calls it, to keep a slight pack pressure on the rear wheel cylinders. I have a single Master Cylinder with 3/16 lines through the car which has a Girling system. It looks to me like they all have 45 deg. double flares. The flare nuts are longer than a similar fitting for modern inverted flare fittings (3/4" overall) and have 3/8" of thread with 1/8" un-threaded at the tube flare. They look like 3/8-24 to me but again, what standard... UNF, SAE or what?

Research on the Web gets pretty confusing and a bit contradictory on this subject. Hopefully, someone out there has the right answers... my head is starting to hurt!

Thanks,
Moe Morin
 
moe_morin said:
An RPV is a Residual Pressure Valve as Wilwood calls it, to keep a slight pack pressure on the rear wheel cylinders. I have a single Master Cylinder with 3/16 lines through the car which has a Girling system. It looks to me like they all have 45 deg. double flares. The flare nuts are longer than a similar fitting for modern inverted flare fittings (3/4" overall) and have 3/8" of thread with 1/8" un-threaded at the tube flare. They look like 3/8-24 to me but again, what standard... UNF, SAE or what?

Research on the Web gets pretty confusing and a bit contradictory on this subject. Hopefully, someone out there has the right answers... my head is starting to hurt!

Thanks,
Moe Morin
Click to expand...

What do they mean slow of mind... I got target lock and was hung up on proportioning valves of some description and didn't think residual pressure valve. A wee bit ironic considering that I have a couple of the 2 lb Wilwood residual pressure valves sitting in my tool box from another project a few years ago. Oh well.

As far as the threads go, while there is a slight difference, Unified Fine and SAE threads are interchangable so that part of the set up is not really a problem. Where we get into issues are with the flares and and the fittings. The Wilwood RPV bodies are threaded 1/8-27 NPT as mentioned earlier being a pretty much a Wilwood standard. They can be supplied from Wilwood without adapters or with (or at least did at one time) a couple of adapters that would be used with your basic 3/8-24 fitting on an SAE 45Âş inverted double flare on a 3/16" (aka -3) tube. For our purposes we generally dispensed with the 45Âş stuff and used adapters for the AN 37Âş flares, but that was just a matter of choice since we were using AN stuff almost everywhere else.

My suggestion would be to consider taking the brake line to a local hydraulic shop along with the valve and which ever adapters you elect to use. Have them make you up a pre-bent tube or modify your existing tube with the RPV mounted where you want it to make it a plug and play operation. Around here I use a place called Royal Brass, I'm reasonably sure that you can find a similar type of operation in your area. A big part of their business is aimed at construction equipment and farming equipment so think in those terms if you are having trouble finding a place.

As for your exisitng flares, in the back of my mind I was thinking there were bubbles on the TR4A but from your description it seems not. Given that, my money would be on 45Âş flares as that is the SAE standard while 37Âş is more of an AN standard and used on some Japanese stuff from what I understand. If I had the tube here, I have tools to determine all of that, but this is also where that local hydraulic shop comes into play, they have tools to measure flare angles, thread pitch and thread taper if present. And remember if you do run across any British tapered pipe threads, they look amazingly like the US stuff, but the thread pitch is ever so slightly different. They're close enough to get each started on the other but different enough to screw things up if you force it.
 
I'm not familiar with Unified Fine... is this the same as UNF? Finding an adapter for 3/8-24 UNF female with 45 deg double flare (that is NOT an inverted flare) to 1/8 male NPT, seems impossible. Maybe if SAE will work as a substitute, that may change things.

Thanks for the help,
Moe Morin
 
Unified Fine is UNF which is interchangeable with SAE. There is also a Unified Coarse or UNC, as well as an extra fine thread version.

As for the adapters, this is why I suggested bundling everything up and going to a hydraulic supply outfit and talk with them about what you want to do. They will have adapters and can do the flaring to mate up with those adapters.
 
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