Help Find Master Cylinder Flared Plugs

[StanfieldNC]

Need to test my master cylinder. Looking for metal flared plugs that thread into and block off the brake line ports.
I don't want to purchase an expensive universal kit. It seems that all kits have 9/16"-18, which I believe is GM.

Does anyone know where I can find the 9/16"-20 plug?
Our plugs are:

• 9/16"-20 ---can't find anywhere.
• 1/2"-20 --pretty common.

 

[Murray]

Cut off fittings and lines from an old M/C. Pinch lines closed, or leave them open for M/C bleeding.

 

[StanfieldNC]

Cut off fittings and lines from an old M/C. Pinch lines closed, or leave them open for M/C bleeding.

Not a bad idea. Unfortunately, I need the actual plugs so as not to allow anything in order out. Need to test the piston for fluid bypass.
]I'm not convinced that pinching lines will fully seal them shut.
I don't have old lines anyway

 

[Kuz]

If you can't find a 9/16-20 inverted flare plug, you could make it work with a 3/8-24 plug and this adapter. The 3/8-24 plug should be easy to find.

 

[SIX225]

Bought these on Amazon. Still haven't had a chance to try them.

https://www.amazon.com/dp/B0CCXMT9JZ?tag=fabo03-20

 

[StanfieldNC]

If you can't find a 9/16-20 inverted flare plug, you could make it work with a 3/8-24 plug and this adapter. The 3/8-24 plug should be easy to find.

This is what I am considering. Wasn't sure if it would leak or not. It shouldn't be this hard. GM guys have it so easy.

 

[Inertia]

Just stick a roofing or drywall nail into the tube with the head trimmed to fitting size, stick it into tube, screw tube/s back into m/c, tighten.
The soft heads act to plug the fitting, as you are looking for.
Use that when you rupture a line/hose on the road.

 

[StanfieldNC]

Bought these on Amazon. Still haven't had a chance to try them.

https://www.amazon.com/dp/B0CCXMT9JZ?tag=fabo03-20

would need an adapter.

 

[StanfieldNC]

Just stick a roofing or drywall nail into the tube with the head trimmed to fitting size, stick it into tube, screw tube/s back into m/c, tighten.
The soft heads act to plug the fitting, as you are looking for.
Use that when you rupture a line/hose on the road.

I get this, but I want to plug the MC directly. No lines attached.

 

[Inertia]

I get this, but I want to plug the MC directly. No lines attached.

Gotcha, - thought you might be wanting to test m/c for by-passing .

Cheers

 

[67Dart273]

Those master plugs are oddball. You used to be able to buy step up/ down adapters for master fittings, if you can get on that steps to a standard plug size, then you can get a plug to fit THAT

You DO want to for certain measure the threads/ inch as some are not standard fittings

master cylinder adapter fittings

 

[66Valiant528]

I got those fittings at Oreallys....the master port to a 3/8-24 so that a 3/16 hard line would screw into them. Like 4 bucks each

 

[StanfieldNC]

Gotcha, - thought you might be wanting to text m/c for by-passing .

Cheers

I'm thinking my MC piston is having issues and the fluid is bypassing the piston. Pedal doesnt engage until 1/2 way and everything is new and bled well.
If I seal it, the pedal should be firm. If It isn't, I'll assume its the MC.

 

[Inertia]

I'm thinking my MC piston is having issues and the fluid is bypassing the piston. Pedal doesnt engage until 1/2 way and everything is new and bled well.
If I seal it, the pedal should be firm. If It isn't, I'll assume its the MC.

Make sure the drum brakes are adjusted, you can use up a buncha pedal travel just moving shoes into contact with the shoes if not adjusted.
You won't get any pedal till all brakes pads/shoes are in contact with disc/drum.
Try putting on the emergency, pump brakes a few times, release and wait a few seconds, then try the brake pedal.
If the pedal seems higher, definitely adjust the drum brakes.

Good luck.

 

[StanfieldNC]

Make sure the drum brakes are adjusted, you can use up a buncha pedal travel just moving shoes into contact with the shoes if not adjusted.
You won't get any pedal till all brakes pads/shoes are in contact with disc/drum.
Try putting on the emergency, pump brakes a few times, release and wait a few seconds, then try the brake pedal.
If the pedal seems higher, definitely adjust the drum brakes.

Good luck.

I just finished a front brake disc conversion from another front brake kit. Everything was working fine, nice and tight, prior to the change. I'm convinced its the master.

 

[Demonracer]

Is the MC you are using for a disc/drum set up, and is it plumbed correctly through the proportioning valve? That would be the first things I would check, if you haven't already.

 

[StanfieldNC]

Is the MC you are using for a disc/drum set up, and is it plumbed correctly through the proportioning valve? That would be the first things I would check, if you haven't already.

Yep. All that is good.