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MG TD TF 1500 - Brake Line Fittings

Hello, finished rebuilding the front suspension on my wife's 1951 TD and now have a question about brake-line fittings (installing copper-nickel lines). Sorry, looked in the archive and could not find a definite answer.

As I understand, the fittings to the front brake cylinders use 3/8" x 20 bsf male fittings. However, the replacement 3-way and 4-way connectors from FredHill appear to be 3/8" x 24 unf DIN flare.

So, when ordering fittings, the brake-lines use a 3/8" x 20 bsf on the cylinder side and 3/8" x 24 unf on the connector side with replacement connectors? Seems a little asymmetrical. :-)

Are the original 3-way and 4-way connectors also 3/8" x 24 unf? Mine are probably good and will use them if there are no leaks.

Thanks, any help and recommendations would be greatly appreciated.
W. H. Troyer

I redid the hydraulics in my car. The 3-and 4-way tees were probably original, and they were BSF. I used BSF fittings from FedHill throughout, with the standard 45-degree double flare everywhere.

I didn't look closely at the tees from FedHill, since they were expensive and I didn't need them. But you should be able to get BSF fitting somewhere--maybe Moss or Abingdon? Or, perhaps some of the guys on this forum who collect and sell parts can get them for you.

As long as the threads and mating surfaces for the flare are OK, you should be able to use an old tee--its easy to clean up even a very cruddy brass fitting.
S Maas

Thanks S Maas, much appreciated.
W. H. Troyer

I bought all the lines from Moss and they had no trouble fitting.
Geoffrey M Baker

WH the original flare fittings, tube nuts or flare nuts were 3/8" x 20 BSF 3/16". The 3/8" x 24 are NF 1/4". I ordered the BSF flare nuts & 25 ft of Cunifer line from Brake Connect in the States. The line was usable though would not bend as tightly as it's supposed to without the wall collapsing. The flare nuts (made in China) are too short in their threaded length & bottom out before the flare engages & so they could not be used. See pic. I reused my original flare nuts as they were all in great shape. Apparently the BSF nuts from Fedhill do fit. 25 ft gives you a little left over. Cheers
Peter TD 5801

P Hehir

If you are sticking with stock OEM TD hardware you want to stick with 3/8-20 bsf fittings. The 3/8-24 fittings are for 'other' British hardware, e.g., power brake boosters. FedHill's P30-3 package does the trick. Bud
Bud Krueger

Thanks Geoffry, Peter and Bud. Called FedHill today and ordered all of the parts. They verified their replacement 3-way and 4-way connectors were not OEM threading.

W. H. Troyer

Don't you think you should check what threads are on the wheel cylinders first?
N Tesla

N Tesla, yes, did that. I have a thread gauge and checked all of the threads before ordering parts. The question was about the inner 3-way and 4-way connector threads; NOT the wheel cylinder threads.

We asked the BBS for help/information because my wife's car is almost 65 years old and has been through several owners who might have changed parts along the way (for example replacement 3-way and 4-way brake line connectors DO have different threads than OEM). We are trying to keep her car as stock as possible and replace any aberrations when found if possible. Just wanted to be sure there was not originally different threads on the inner 3-way and 4-way connector fittings.

In my defense, we searched the BBS archive and found conflicting information. And, our restoration books do not have this detail of information. We don't know (i) anyplace else with the considerable expertise found on this forum or (ii) a place with more people willing to help someone new to these cars.

Thanks, Bill.
W. H. Troyer

All the threads on the fittings are the same on my TF. PJ
Paul161

N Tesla, yes, did that. I have a thread gauge and checked all of the threads before ordering parts. The question was about the inner 3-way and 4-way connector threads; NOT the wheel cylinder threads.

We asked the BBS for help/information because my wife's car is almost 65 years old and has been through several owners who might have changed parts along the way (for example replacement brake line connectors DO have different threads than OEM). We are trying to keep her car as stock as possible and replace any aberrations when found if possible. Just wanted to be sure there was not originally different threads on the inner 3-way and 4-way connector fittings.

In my defense, we searched the BBS archive and found conflicting information. And, our restoration books do not have this detail of information. We don't know (i) anyplace else with the considerable expertise found on this forum or (ii) a place with more people willing to help someone new to these cars.

Thanks, Bill.
W. H. Troyer

Bill, the 4-way union and the 2 three way unions would have the same 3/8-20 bsf thread if they are still original or OEM replacements. I don't know of anyone selling replacements that have the 3/8-24 thread, but I sure haven't seen everything yet. A couple of years ago I installed a UK-made power brake booster. For it I had to make two brake lines with 3/8-20 on one end and 3/8-24 on the other. Bud
Bud Krueger

Hi Bud,

I was going to buy all new brake lines/fittings from Fedhill including their 3-way and 4-way brake line unions. But, found they were both 3/8" x 24 unf threading. We considered using the 3/8" x 24 unf threads on the inner brake fittings since we are making the lines ourselves, but decided to keep everything as stock. I called Moss and their brake line unions do use bsf threading.

This is a little tricky for a newbie (us) because some replacement parts (even from Moss) are unf threads while others are OEM bsf. For example, their A-arm bolt sets are also 3/8" x 24 unf threads and they do not tell you. We try to use bsf and have made a list of unf exceptions on her car when we find them.

Regards,

Bill

Fedhill catalog:
P18-3br - 3 way brass tee - 3/8" x 24 unf - DIN flare
P19-3br - 4 way brass tee - 3/8" x 24 unf - DIN flare
W. H. Troyer

Bill, those unions don't appear to have a threaded mounting hole, as do the ones on our cars. I'm not so sure that you wouldn't run into problems mounting them in a TD. Bud


Bud Krueger

Careful. Suppliers don't always get it right. I just installed new lines in my MGA and the line kit from Moss had 2 fittings that didn't fit any part in the rest of their supplied parts nor anything I removed from the car. I re-used the original fittings and flaired the lines at those spots myself.

I'm guessing the guy in China grabbed the wrong fittings, maybe it was Friday.

....
MAndrus

It's a bitch Mitch. The goalposts lie somewhere between Caveat Emptor & the Duty of Care. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 29/10/2015 and 31/10/2015

MG TD TF 1500 index

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