5 lug rear disc conversion has me pulling my hair out

[1991vert]

ok so i did the rear disc, the 3-2 port conversion and all that junk. i installed that FMS plug after gutting the stock prop. valve and it seems to be a piece of junk. you can literally push the plug in, then towards the last 2-3 threads it will catch, but when you try to tighten it, it will tighten, then loosen. i thought i could just j.b. weld the plug in there, but when i did that i got down the road and the pressure cracked the j.b. weld and i got a soft pedal.

so i decided to put the stock plug back in there and fill the center with j.b. weld. it screws in fine and tightens up how it should and i have the o-ring seal on it, but for some reason it keeps leaking. i pulled it and put teflon tape on the threads, and it's still leaking. what gives?

anyone else have a problem with their FMS brake plug not fitting? can i get the plug welded in there?

 

[Fox_84]

I had the exact same problem except before I used and JB weld, I had the center hole in the factory plug welded up. I would suggest finding someone that can weld aluminum and do that after cleaning all that JB weld off. I would never suggest that crap on brake components, it is just TOO RISKY!!! After getting your factory plug welded, try it then. You may have stripped the threads to badly, it is not something you really tighten. It seals because the threads are so fine and perfectly seal due to a snug fit, not tight. If you have stripped it out, I doubt you can weld that plug in there, you might as someone with an aluminum welding setup, but I figure you will have to have a new prop. valve. Good Luck.

 

[1991vert]

i have an adjustable prop valve already installed. was there some type of recall or anything with these plugs?

im thinking i may have stripped it taking it out? im glad im not the only one who has this problem!

what's the reasoning behind not using the stock plug?

 

[1slowfiveoh]

I had the same happen to me. I put a screw into the stock plug so the threads are showing and the head is inside. I took 2 part all metal epoxy and filled the cavity sealing the screw into place. I let it harden over night and cut off the excess screw. installed and no problems.

Good luck!

 

[1991vert]

good thing i paid like $8 for a plug that doesnt even work!

if i left the center not filled would that mess with the brake pressure or something? is that why it should get filled?

 

[Shakerhood]

Ford Racing has a bad batch of Bolts out right now, the Plug should be Brass if I remember correct.

 

[tunedin302]

Ford Racing has a bad batch of Bolts out right now, the Plug should be Brass if I remember correct.

Where did you hear this? Is it a Ford M-2450-A ?

 

[Shakerhood]

I have seen the same thing listed on every Mustang Site out there, the Bad Batch has the wrong thread pitch and if I remember correct are not Brass. I think Ford Switched Suppliers for that Bolt and ended up getting it wrong.

 

[1991vert]

the plug i got looked like aluminum. and yes it looked like the wrong pitch. i have come to the conclusion the o-ring is shot. i put the plug back in with just the o-ring and it leaked. i then used all sorts of sealers and it's still leaking. anyone know where i can get a new o-ring?

thanks,
chris

 

[Mustang5L5]

I've also heard the same thing. My plug was brass and fit fine.

I've heard that some guys are getting the aluminum plug and it doesn't fit correctly.

 

[Mustang5L5]

I've also heard the same thing. My plug was brass and fit fine.

I've heard that some guys are getting the aluminum plug and it doesn't fit correctly.

 

[1991vert]

what do i do about my sealing problem?

 

[Shakerhood]

I would try to locate the corect plug from someone that might have one sitting from the old batch.

 

[twoturbofox]

same thing happened to me, i used the original plug with a machine screw threaded into the center hole. With the original o-ring it should work. You could see if you could locate an early 80's proportioning valve with the 3 ports, although you already did the 3-2 conversion. Maybe replace the oring and try again? you didnt say where it was leaking from, if you didnt plug the center it would def leak there.