Brake fluid query

Post by **rayofleamington** » Tue Apr 20, 2004 2:28 pm

57traveller,
I've not seen the DIY vacuum systems, but if you connect to a bleed nipple it sounds like a bad idea. The bleed nipple itself only seals when it is closed, so if you open it it's going to leak air down the thread anyway.
If there is an additional tank prior to the pump so that any fluid pulled out by the vacuum has somewhere to go intead of the pump then I guess it might last longer, but fluid will still get in the air (brake fluid fizzes when you get it close to full vacuum). I guess the pump needs to be robust against fluid, but then the design of it isn't likely to be as efficient. Therefore in automotive development there is always a distinction betweena wet and a dry system (wet means some parts of the system have had brake fuid in them)
Anyway, we're off into semantics a bit here - pressure filling is the generally accepted 'good' way to do a cars brakes during servicing and repairs. I've seen it done on dummy vehicles / demo systems with clear pipes - these are sometimes used to check that the probability of trapped air is low during vehicle maintenance.
The main principle for pressure filling is that the fluid moves fast enough that the air has no chance to settle at the high points and is pushed all the ay out of the system by the fluid flow. This works well on pipes but cylinders can be tricky as unless the inlet and outlet are perfectly positioned the flow in the cylinder doesn't push the air out. Quite often classic car wheel cylinders don't have an 'in' and 'out' so unless you prime a new/rebuilt cylinder very carefully, some air will stay in the fluid.

Post by **57traveller** » Tue Apr 20, 2004 3:42 pm

Ray - probably wise to close this discussion

. Hope we can agree then that Mark Evans's method was a bit suspect, the air was probably being drawn in through the bleed nipple threads anyway

and he would have been better using the more conventional way to commission his brake system.
That's the first time I've seen that equipment using the bleed nipple.
Never seen the other unit either, which connects to the master cylinder reservoir. (it is in Frost's catalogue) That states the fluid is drawn into the reservoir, from where I don't know.

Post by **nick_h** » Tue Apr 20, 2004 7:18 pm

Thanks for the advice, everyone. I think I will use standard fluid at the moment and have a good look at all the seals etc before trying silicone. Is Lockheed fluid still available, and if not what is recommended?

Post by **rayofleamington** » Tue Apr 20, 2004 7:42 pm

Dot4 is fine.

Post by **Scott** » Thu Apr 22, 2004 4:19 am

We use one of the vacuum units that connect to the bleed nipples in our workshop. They work so well, I even bought one to use at home. It's difficult to see when all the air is out of the system as it does draw air past the bleed nipple threads, but air cannot enter the braking system as it's under vacuum.
The one I use is from
http://www.jwl.dk/index.asp?id=321
I couldn't get too far into this as I don't know much Danish. It all sounds like something from the Muppet Show to me

.

Post by **nick_h** » Thu Apr 22, 2004 9:42 pm

The Eezibleed kit has been discussed at length elsewhere as well and it's a useful piece of equipment.

57 Traveller, can you point me to this thread - I have run a search and lots of results but none with specific reference to brakes. I bought my Eezibleed Kit today and reading the instructions looks like I have to drill and tap the master cylinder lid. Has anyone done this or is there another method?

Nick

Post by **les** » Thu Apr 22, 2004 10:01 pm

Yes Nick, unlike most cylinders with a male thread, the minor has a female thread, which is not supplied. You need a spare cap and drill a hole in it to suit the connector, I can't remember the size offhand. Don't forget the fibre washers each side! You shouldn't need to tap a thread the connector has a nut and bolt arrangement, at least mine has.

Post by **57traveller** » Fri Apr 23, 2004 9:13 am

Nick - possibly the information was lost during the recent problems with the message board.
Les has just about covered the best option with the m/c filler cap.
I'll try and post a pic. showing the arrangement.

Post by **57traveller** » Fri Apr 23, 2004 9:43 am

Top of cap.

Unlike Les it was not possible to drill and fit fibre washer plus nut on underside. I think it was drilled and tapped 1/8"BSP to accept the end of the pipe. The newer Eezibleed pipes may have longer cap ends than this which was bought mid 70's.
Couldn't post 2 pics? so see next post.

Post by **57traveller** » Fri Apr 23, 2004 9:49 am

Underside.

Also used an "o" ring as cap seal, only needs to be finger tight and seems more efficient than fibre washer for this application.
The vent baffle has also been removed.

Post by **rayofleamington** » Fri Apr 23, 2004 9:58 am

I presume you also blocked the vent hole (fine hole through the side of the hex)

Post by **57traveller** » Fri Apr 23, 2004 10:24 am

So THAT'S where the jet of fluid came from.

Post by **Cam** » Fri Apr 23, 2004 10:45 am

I found a mobile 'phone case screw fitted perfectly and bit into the aluminium nicely. Torx 6 size I think. (I used to repair them so I had a few lying about! )

Post by **57traveller** » Fri Apr 23, 2004 11:40 am

Right, where's that redundant mobile 'phone. A bit of silicon sealant smeared around the underside and pushed into the hole has worked - so far.

Post by **nick_h** » Fri Apr 23, 2004 10:28 pm

Have completed the conversion tonight, but found that I can't get the backnut inside the cap. However, the thread self tapped into the hole and I was able to nip this tight onto the fibre washer. I have sealed the well inside with silicone and have left this to go off until Sunday when I hope to do the job. This should also block the vent. I have not pressurised it yet apart from "by mouth" with a finger over the pipe and it seemed airtight. Thanks for the photos, 57T, these were extremely helpful. Have you "bored out" the inside of the cap? Mine does not have a generous space like that. Why can't Eezibleed do a Minor cap to suit their kit to save all this messing about?

Post by **57traveller** » Sat Apr 24, 2004 9:11 am

From what I recall Nick, that's how the cap was after prising out the baffle/deflector plate. Fortunately

I suppose the cost of tooling/manufacture far outweighs the return if a Minor type cap was supplied with the kit. But I'm surprised that my kit didn't have one supplied when purchased mid 70's.

Post by **Matt** » Sat Apr 24, 2004 8:15 pm

But you should be able to buy one as an accessory....... rather than it coming with the kit!

Post by **nick_h** » Sun Apr 25, 2004 10:26 pm

Well, I've bled the brakes with the Eezibleed kit and it went remarkably well - 2 hours, including blacking the tyres whilst the wheels were off. I would recommend anyone intending doing this job to invest in the Eezibleed kit. It was Eezi! Such a simple idea too. The cap conversion held the pressure and all the air and muck is now in the old oil bucket and my system has new DOT4 fluid in it. Just need to get a new master cylinder cap as the one I bought as a replacement is now part of the bleeding kit. Now I have the kit I will renew the fluid on an annual basis to minimise the build-up of moisture inside the system, instead of using silicone fluid. Thanks again to all who gave advice on this subject.

Nick