Wheel Cylinder brass nut size?

[ScottT]

I replacing a siezed rear cylinder on my 109 and the brass nut connecting the line to the cylinder isn't giving up and starting to round. Are these whitworth? What size are they? Any advice? I have tried an unhealthy amount of PB breaker, still rounding and no loosening.
I am picking up a set of flare nut wrenches tomorrow night.
Thanks

[gudjeon]

I may be wrong, but, recalling from memory they may be UNF or metric for a "newer" unit. The only thing is the end portion is not threaded and an SAE flare nut will not bottom out properly. When I dive into brake plumbing, I replace with new tubing and new fittings.

[jac04]

Even on metric brake systems, the wheel cylinders remained UNF. The nut should use a 7/16" flare nut wrench, although I had to 'tweak' mine a bit to get it to fit correctly. The 'tweak' was driving a wedge into the split to open it up a little - just enough to get it to fit.

[ScottT]

thanks

[ScottT]

insight needed

The brass brake line nut will not budge with the flare nut wrench, it has rounded so much the 7/16 will not catch and yet not enough to go down to next size. What are the options and opinions?
Thanks

[brucejohn]

That stuff frustrates the heck out of me.

I'd replace the line at that point after removing with vise grips. Just my bias, I don't leave anything I know to be second rate on the brake system.

[NickDawson]

The brass brake line nut will not budge with the flare nut wrench, it has rounded so much the 7/16 will not catch and yet not enough to go down to next size. What are the options and opinions?
Thanks

Had the exact same problem on a wheel nut on the 109 front end on my 88.

Ended up taking the wheel cylinder off and using a 7/16" stripped nut but in my drill. It pulled it out no problem. Then I scavenged a new nut off a spare cylinder I had.

[ScottT]

I just tried vise grips and PB and was left with a very PO attitude and metal shards without budging it a mm. I looked at the dremel but decided to go in for the night.

Can I source a line locally? Cutting is looking better and better.
What heating it with a torch, i am go to drain all the brake fluid anyway.

[Nium]

What heating it with a torch, i am go to drain all the brake fluid anyway.

Brake fluid is flammable.

[ScottT]

Brake fluid is flammable.

i did not know that.
thanks

Flammable or combustible?
probably not a good idea either way.

[Nium]

Flammability is defined at how easily something will burn or ignite, causing fire or combustion

If you're really curious MSDS http://www.championbrands.com/MSDS/1420.pdf

I got nothin for how to help with getting the flare nut off I would have thought the vice grips would have done it for sure. Maybe you had the vice grips clamped on backwards . The release lever side of the vice grips should be to the left when loosening. If you look at the jaws of the vice grips the teeth sometimes are directional and are slanted toward the handle.

[ScottT]

Okay I bit the bullet and I am replacing the complete line from the T in the rear to the left hand cylinder on my 109 (Salibury rear.)
How can I disconnect the T and not loose all the fluid? (other than clamping the rubber) Can it be done?
I am really not looking forward to it.

Can you use just a touch, a wee bit of anti-sieze to prevent the nut and cylinder from locking up again?

Thanks