Alfa Romeo Owners Club of Australia Forum

Technical => 105/115 Series (105 Coupe/Spider/Berlina) => Topic started by: toerag on August 21, 2009, 10:23:33 AM

Title: bleeding brakes
Post by: toerag on August 21, 2009, 10:23:33 AM
I have 1972 gtv and have had boosters,master cylinder,brake bias reconditioned with stainless sleaves professionally.rebuilt calipers myself.new hoses.The system will not build pressure is there a trick to this?
Title: Re: bleeding brakes
Post by: Colin Byrne on August 21, 2009, 11:01:33 AM
I've had similar problems like this in the past and now use a pressure bleed system.  I just found a plastic cap that screws onto the reservoir, attached an Air line connector to it, open up the bleed nipples at the calipers and set the air compressor to about 5PSI.  Along as you keep an eye on the reservoir emptying it works very well and is slow enough to have a beer while the wonder of air pressure bleeds the system for you(it also uses minimal fluid so you can pretend your doing something good for the environment!).  If you don't won't to go that far, here's a couple of tips that have helped me in the past

-Make sure you fill the reservoir up enough so that fluid goes over internal split(sounds silly but I did it once and it cost me a couple of hours!)
- If you have time open up the bleed nipples at the callipers and let the fluid gravity feed out (this will take a long time), this Is a good way to 'prime' a completely dry system
- When pumping the pedal try and be slow and smooth so you don't aerate the fluid to much

Hope that helps
Title: Re: bleeding brakes
Post by: cjheath on August 21, 2009, 02:51:33 PM
I have an old fridge compressor which I keep stored with a plastic tube pushed over both the inlet and outlet pipes, so I can get strong suction or compression with equal ease... and with that...

I fit the 2m long suction tube onto a bleed nipple, set the pump going, then open the nipple. When the fluid comes out, I wait until it's about to enter the compressor, then switch off. All the air bubbles are now in the tube. Shut the nipple, pull both ends of the tube off, and you can empty the fluid back into the reservoir and do the next corner.

Couldn't be easier. The flow rate is only inches per second in an 6mm pipe, so it's unhurried but not too slow. Just make sure the switch is handy.
Title: Re: bleeding brakes
Post by: Colin Byrne on August 21, 2009, 03:29:02 PM
QuoteI fit the 2m long suction tube onto a bleed nipple, set the pump going, then open the nipple. When the fluid comes out, I wait until it's about to enter the compressor, then switch off. All the air bubbles are now in the tube. Shut the nipple, pull both ends of the tube off, and you can empty the fluid back into the reservoir and do the next corner

Sounds pretty good, I'd just be a little careful about re-using fluid in that way, especially if it has been in the car for some time.  Re-introducing brake fluid that has been compromised by water (hydroscopic) or dirt is not ideal.
Title: Re: bleeding brakes
Post by: 1750GTV on August 21, 2009, 07:07:07 PM
I use one of these - easy and mess-free.

You probably should change the hydraulic fluid annually and use new fluid each time. Once exposed to the atmosphere, the fluid absorbs water which will rust the lines etc. and also reduce the boiling point of the fluid.

Chris
Title: Re: bleeding brakes
Post by: shane wescott on August 23, 2009, 06:25:18 PM
I bought a little bleeder accessory (from Germany) off ebay. It's like a valve on the end of tube which you adjust. The idead is you adjust it so by putting pressure on fluid passes out, but no air can be sucked back in.

I've used it a few times and it seems to work a treat :-)