What size fitting on 79 rear brake line that attaches to prop valve?

Jfannin · 07-28-2011, 07:45:16 PM

I am installing a Wilwood valve but evidently made an error on the adapter to link in the rear line. I have a 9/16 x 20 female going into the valve, and I thought the rear line male fitting was that size, but it's smaller.

Skip Fix · 07-28-2011, 10:40:49 PM

I have a short line I used with that fitting on it that must be a factory line maybe MC to prop valve of my 79-had the other fitting the same as a normal 1/4 line fitting. Pretty sure the other rear line going into the prop valve from the rear end is large also as I had to use two adapters to get it down to the normal 1/4 line fitting size for my adjustable prop valve

Personal_Aviator · 07-29-2011, 12:16:13 AM

Check out these guys. Most auto parts stores should be able to get their stuff.

http://catalog.fmsiinc.com/category/brake-system?&bc=100|1001

wardracing · 07-29-2011, 03:08:33 AM

i had the exact same problem, i work at advance auto parts and we had the adapter fitting in stock just go to your local parts store and tell them what you need!

jamieg285 · 07-29-2011, 09:13:13 AM

For the factory prop valve/MC combo (figure in brackets is line size):

Master Cylinder Out (Front) 1/2 - 20 (3/16)
to
Prop 1/2 - 20 (3/16)
to
Front (x2) 3/8 - 24 (3/16)

Master Cylinder Out (Rear) 9/16 - 18(1/4)
to
Prop 7/16 - 24 (1/4)
to
Rear 9/16 - 18 (1/4)

Not sure if that all carries over to Wilwood though.

Skip Fix · 07-29-2011, 11:41:51 AM

Alot of the Wilwood I've seen have the same 9/16 and 1/2 listed,even their Mopar style.

Skaal-tel 79 · 07-30-2011, 07:56:12 PM

stock rear end line is 9/16, can't tell ya the pitch off hand. Why do you need an adapter? You should be able to purchase a tube nut that adapts 1/4 tube to 9/16 sae flare. I've never seen them in a variety of thread pitches.

Maybe you're trying an NPT fitting?

Jfannin · 08-01-2011, 08:08:43 AM

Thanks everyone - I did determine it is indeed a 9/16 x 18. What I'm doing is tying in the Wilwood adjustable valve to my rears. I have everything tied in up to the stock rear hard line, just under the master. I had the hydraulic shop make a line from the Wilwood that ends with the identical male, hoping to find a double female union to tie my two 9/16 x 18 males together, but I have searched and searched all over and can't find one? I checked advance, autozone, and o'reilly on line with no luck. I've also checked several brake parts websites and it doesn't look like such a union exists??? I'd appreciate any help! This is the last part I need to get the car on the road.

Rene Melten · 08-01-2011, 09:39:21 AM

Your looking for a 1/4" inverted flare union/ coupling? Try a plumbing supplier... they do make them, here's an example...http://www.fastfittings.com/product/12024

Jfannin · 08-01-2011, 09:54:32 AM

Thanks Rene - I also just found this morning a part number BQ119 frin BrakeQuip but it looks like they only deal with dealers. I will check out the plumbing stores and also give BrakeQuip a call.

Jfannin · 08-01-2011, 02:09:16 PM

Finally found the part number BQ119 (9/16 x 18 for 1/4 line double female union) at Clarkville Fasteners in TN. $2.91 each and they will take orders over the phone and mail out. Just thought I'd let you guys know. Thanks for all the responses. Hopefully this will end my brake restoration chapter and we can move on to the inner doors...