21 replies to this topic

[tiger99]

Doug,

Thanks for your comments. I am aware of the Seig lathe, and may well get one as an interim measure, although I will want a bigger one, probably second-hand, later, when I have somewhere to put it. I daresay it will be equipped with NC sooner or later, as I may want to do a few repetitive tasks. I find "Model Engineer's Workshop" magazine very interested, as although I don't expect to be building many models, it is the most comprehensive source of info that I know of for all the tasks which accompany the lathe, such as making tooling and special purpose attachments.

It must be 30 years since I last used a lathe. It used to be possible at work, but the Health and Safety at Work Act, and the continuing stream of subsequent legistation, meant that employers insurance companies will generally only allow fully trained professional machinists to go near such machines. I do have some training, but apparently not enough, and it was in 1971. The law (not that Act) specifically only requires that a few processes, such as mounting grindstones, are carried out by trained people, and has done for probably 100 years, but employers and their insurers are scared of possible consequences of anyone using a potentially dangerous machine.At work we joke that our soldering irons and wire cutters will be taken away soon.....

None of which is helping to solve yeti's brake problem. I am rapidly running out of things to suggest. Maybe a vacuum bleeder?

[yeti21586]

And back on topic

Dk thanks for the advice, I have adjusted the rear drums and have done one nipple till it had no bubbles and am on to the next rear one now, it's crazy how many bubbles can be in such a small diameter of pipe, pumped nearly a whole lieter of fluid through till it had no bubbles, oh and I also jacked up the back end so the bubbles will rise to the back

YetI

[tiger99]

I do apologise for not warning you that you would need lots of fluid. It does not take much to fill the system, in theory, but most of it comes out again with the air.

Anyway, it seems that you may finally be winning!

[yeti21586]

Yeah cheers matey, getting there slowly, my dad has said we can't use the fluid that came
Out with the bubbles for a week or so to let it settle, does that sound right?


Cheers

YetI

[tiger99]

You should normally never use fluid that has been bled from the system, because in its travels it will have picked up a certain amount of dirt, which will rapidly ruin every seal and cylinder in the system if it gets back in. The surface finish on hydraulic parts is measured in millionths of an inch, and any scratch or abrasion on a sealing face such as a cylinder bore makes the part scrap, as it will leak.

Could you guarantee that your bleed nipples, any tubing used, and the container used for collecting fluid were perfectly clean? I don't mean the average mechanic's idea of clean, I really mean CLEAN. (Lack of appreciation of cleanliness by the average mechanic is why hydraulic cylinder repair kits for most vehicles are no longer readily available, garages were assembling cylinders with new parts, which invariably failed a few weeks later.)

If you are very, very, very sure of absolute cleanliness, you can reuse the fluid. If you let it stand for a while, any air bubbles will come to the surface. Silicone fluid is a nightmare as regards air retention, but you should have no real difficulty with DOT4. Try to pour the fluid in such a way that it does not pick up air.

Never re-use old fluid, of course. When you bleed the system after a couple of years for its scheduled fluid change, just use your bleeder to force fluid through each nipple in turn until fresh fluid appears,and dump what came out. You will not need to let air into the system at that time.

I remember a friend who set about bleeding the brakes on his car, not a Mini. First thing he did was to shake the can.....

[dklawson]

There is not much to add to Tiger's advice. I have re-used fluid when (and only when) I am filling a completely dry system with completely new fluid. In that instance you have an environment like Tiger was describing where there is (or should not be) anything in the system to contaminate the fluid. It's a special case though. I also have only used this method when working with DOT-5 fluid which is substantially more expensive than the common DOT-3 fluid used over here.

DOT-5 fluid does have a reputation for holding air as Tiger mentioned. There is an additional step that helps with DOT-5 fluid when you are filling the reservoir. Take a spotlessly clean long screwdriver and insert it into the reservoir through the filler opening. When you pour the DOT-5 fluid in, pour it against and down the shaft of the screwdriver so the fluid cannot/will-not splash as the reservoir is filled. This minimizes the amount of air that can become trapped in the fluid. You can also use this method with DOT-3 and DOT-4 but it generally is not necessary.

[yeti21586]

Well I bought new fluid as I don't won't to wait to do it, and who ever suggested forcing the pedal down as hard as I could is a genious and a saint!!!! Managed to get the whole thing done

Cheers guys

YetI