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Testing Brake Lines

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mylesw

Jedi Hopeful
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Hello

Getting pretty close now to having my new brake system installed with new lines, rear cylinders and rebuilt calipers. With the body off, it's pretty easy to change things is they're not working and I would therefore like to test the integrity of my handiwork before putting the body back on. Can someone let me know the best way to do this? I do have a mityvac tool that is still in the wrapper and I was wondering if I would be able to use this to put some pressure on the system...

Thanks for your help.

Myles
 
No way to generate pressure with a MityVac; at least not with mine. It's a very low pressure device anyway, so it's not going to be much help in testing a brake system, IMO.

Never tried it myself, but I would probably just hook up the MC temporarily, and try mashing the pushrod in with my hands. That won't build much pressure either, but it would let you see any large leaks. Beyond that, you could probably fabricate something to put more pressure on the MC ...

I tend to be somewhat paranoid about contaminating the system, though, so I wouldn't use air pressure or anything like that. Shielding gas from your MIG welder might be OK though.
 
I'd go with Randall's idea to rig up the MC and bleed the system, then apply a good steady pressure to it (the MC actuator) for some few minutes with that. If there are any leaks or problems they'd likely show up then.
 
There is no way of pressurizing your closed brake system short of applying the brakes with the system juiced. What would it serve to test them anyway? Just hook it up and check it out. You will find leaks soon enough. If you are using new stuff, chances of a leak are slim.
 
I think it's a concession to thoroughness. I've screw'd together a lot of weird machines and SOME of 'em were better tested in "abbreviated" form. Case in point was an Aston Martin DB2/4 convertible. I wanted to KNOW the hydraulics were well and truly working BEFORE it was all assembled and "pretty". A leak on THAT wagon would have set back the job by too many hours to chance it.

MY cars? Well, let's say it's more a "poke 'n hope" philosophy there.
 
Myles-

If you have extra line, you probably could tie into the junction on the frame as it splits fore and aft. Perhaps clamp mount the pedal and mc right there to manually test.

Plenty of room without the body on the frame, but you will spill a little I think with the temporary setup. Are you planning on silicone fluid, or something like Castrol GT LMA?

Randy
 
Hadn't really thought about going for the silicone option. What are the benefits?

Reason I want to test the lines is primarily because I did all the flares myself and as it was my first time I've no idea if I did a good job or not...

Thanks for your comments and help. I better get the brake master cylinder rebuilt (it's currently in bits...).

Myles
 
Roadster factory had a really good price on silicone fluid this past weekend, so I stocked up. I intend to switch shortly. I'm concerned being in Houston with the humidity that I'm pulling in too much water. I've never used it in practice before though.

Others will chime in better on silicone - I'm sure there are quite a few old posts on the topic. One of the big benefits, I think, for a frame off restoration like yours is that the silicone will not harm your new paint job.
 
I went with silicone in my recent complete brake system rebuild. Like you, I replaced everything part of the system, right down to the clamps on the frame.

No real worries about bleeding or paint peeling from an accident with the silicone fluid.
 
i am with TR6BILL, juice it up and see what happens. i can tell you that i added speed or "speedy" bleeders when i reworked my brakes and was very pleased with them. had a little help bleeding initially but after the car sat over night i thought it had gotten softer...maybe all in my head...so i bled each one a little more. be sure to go in order. i believe you start at the rear, farthest from the master cylinder and work back toward the MC so the last one is the front driver side. its been awhile so someone correct me if i am recalling that wrong.
 
Actually, I think you work nearest to furthest, that way you avoid bypassing any trapped air in one of the legs. But I may have that wrong too!

And I agree, if it were mine, I'd wait for the body then bleed with the final hookups. Any place it will leak is accessible with the body on.

Randy
 
Randy is correct. According to Girling: "Bleeding should start at the left rear side wheel if the car has drum brakes all round or disc brakes all round, but if it has disc front and drum rear bleeding should start at the front left side wheel." (Girling service bulletin text reprinted in a 1964 TSOA Newsletter.)
 
TR4nut said:
Others will chime in better on silicone
Click to expand...
Been using it for many years, in all my Triumphs and most of my other cars. I love it.

As with any change, there are positives and negatives but to my mind the positives far outweigh the negatives (and most of the negatives that folks talk about are myths IMO).

I do believe it has more of a tendency to form tiny bubbles of air that take longer to rise to the surface than the glycol-based fluids ... so I always give the silicone a chance to 'breathe' after adding to the MC. If that comes in the middle of a bleeding session, I take a break for lunch or whatever. But driving the car right after adding is no problem.

It is also very slightly more compressible than glycol-based fluids, but not enough to worry about IMO.

Some major advantages :
1) Doesn't need to be replaced every few years as glycol should be.
2) Will not absorb water and salt (!) through brake lines as glycol will. This means it also does not promote dissimilar metal corrosion in places like the rear brakes that have steel running against aluminum alloy.
3) Will not harm paint if it does get spilled. This may not seem all that important, but I've seen some very expensive, concours-quality paint jobs absolutely ruined by a leaking MC. And every Triumph I've ever worked on has hidden rust where spilled brake/clutch fluid has seeped into joints & seams.
4) My experience has been that seals last MUCH longer with silicone than with glycol. YMMV

One other negative : If you ever try to paint anything, you must use a special solvent (like Acryli-Clean) to remove all traces of the silicone. Otherwise it WILL cause fish-eyes in your paint job, no matter how much you sand, wash, etc. It's hard to get off your hands too /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
Can I buy silicone brake fluid over the counter here in Houston or do I have to order it from one of the british parts suppliers (TRF for example)..?

Myles
 
It's rarely found in parts stores, although I was surprised to see it in the local Western Auto store a few months back. But even when they do have it, the price is typically higher than TRF. WA wanted nearly $20/pint while TRF has it on sale for $18.50/quart.
 
TR3driver said:
while TRF has it on sale for $18.50/quart.
Click to expand...

And this past weekend it was $12.50/quart! /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif
 
Yeah, thanks Randy! Just have to wait until their next deal on shipping at least...

Another question: I was down at the platers this lunchtime getting my handbrake lever and rear lights rechromed and I also gave them my brake and clutch m/c caps to get nickel plated. Cheaper than buying new ones and hope to get a nice bright finish similar to the originals. Anyone done this before or know if there will be an adverse reaction between the nickel and the brake fluid?

Myles
 
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