The distribution brake line block on the rear of an AD master cylinder is not available new (that I can find) so going to machine some. It is the fitting that is held to the m-c with a hollow banjo bolt. Although I use a lathe and mill on a daily basis I am NOT a trained machinist and have run into a problem. The OD of the flare seat is larger than the ID of the fitting threads so a tool to cut the seat cannot pass through the threads without cutting them away. Any suggestions ???
Undercutting behind a thread is going to require interpolation so a CNC mill will be necessary. As for the cutting tool these guys are my go to for such applications:
The MC on my '51 just has a single line attached to it and uses two division blocks over on the right side of the frame, one splitting front to back and another splitting to RF and LF. The one you're referring to is used on only some AD's (52 and later?) I think I may have seen them somewhere, which would be easier that machining your own. Have you looked HERE?
I think you could cut the seat with a tool ground small enough to cut the seat and the undercut on a lathe, feeding it in parallel to the seat angle, either before or after the threads are cut.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
This I believe this is the fitting Evan is talking about.
Last edited by Phak1; 01/05/20238:52 PM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
Undercutting behind a thread is going to require interpolation so a CNC mill will be necessary. As for the cutting tool these guys are my go to for such applications:
You don't have to have a CNC for that. On a lathe it is relatively simple to use a trapezoidal cutter on a boring bar to do it. Set the angle of the blade for the angle of the seat, move it down the axis of the hole inside the threads, then bring it (radially) out at the bottom of the hole and finish the cut. Then reverse to get the cutter back out.
It takes some planning and attention to the geometry for your depth, but can be done manually by someone with moderate skills.
It would take some thought on how to do it with a mill unless you had a few extra axes to play with.
This I believe this is the fitting Evan is talking about.
That looks very similar to the banjo bolt fittings on the rear wheel cylinders on my '51 with Bendix brakes. There should be lots of those around.
[on edit] Here's one (might be different threads) Link
Last edited by klhansen; 01/05/20239:34 PM. Reason: added link
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Looks like there are plunge cutters available for this. The undercut at the back is probably a thread relief groove rather than a taper that is larger than the minor thread diameter.
That looks very similar to the banjo bolt fittings on the rear wheel cylinders on my '51 with Bendix brakes.
With the exception the banjo bolt is bored and and machined for a 1/4 inverted flare fitting.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
Evan, there is a much simpler solution that requires NO special machining. The part can be made on a drill press. Call me. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
If you have one to use as a pattern send it to me. I'll make you about a dozen of them. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
With the exception the banjo bolt is bored and and machined for a 1/4 inverted flare fitting.
Yes, but Evan said he was looking for the distribution block, not the bolt. The line coming off the master going to the LF brake is 3/16 as are the lines to the rear wheel cylinders.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
With the exception the banjo bolt is bored and and machined for a 1/4 inverted flare fitting.
Originally Posted by klhansen
Yes, but Evan said he was looking for the distribution block, not the bolt. The line coming off the master going to the LF brake is 3/16 as are the lines to the rear wheel cylinders.
The line coming from the back of the fitting in question, is 1/4” on a ‘52, and goes over to the passenger side to a distribution block. Front side on that distribution block. (now 3/16”) goes to the front passenger brake and the rear (also 3/16”) goes to both rear brakes.
Originally Posted by Coilover
It is the fitting that is held to the m-c with a hollow banjo bolt.
I suspect the part Evan is talking about, the difficulty in machining, would be the the hollow bolt with the inverted flare machined inside. The block would be easy to make. The bolt not so much!
Last edited by Phak1; 01/06/20231:48 PM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
The bolt can be made the same way. Use a 1/8" NPT thread in the bolt head and an adapter fitting. The tubing size becomes irrelevant, as there are thousands of factory made adapter fittings available in all sorts of tubing sizes. Why do people insist on making things difficult when there's a quick, inexpensive work-around available? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
