Brake bleeding.

Post by **smh582003** » Sun Dec 30, 2007 11:17 pm

Am I doing something wrong? I've never done a brake bleed before but I think I did it right.
I started with the n/s rear and undid the brake bleed nipple, I then got my son to push the brake down , then I did the nipple up, he released the brake, I undid it again and we carried on like this until no air bubbles. We did this to all the wheels but when I took it out the brakes had to be pumped. Am I doing something wrong.?
I hope you can help.
Steve

Post by **alex_holden** » Sun Dec 30, 2007 11:21 pm

Are you sure the brakes are all adjusted correctly, and have you replaced the rear cylinders (and if so did you prime them before plumbing them in)?

Post by **smh582003** » Mon Dec 31, 2007 12:08 am

I did the rear brakes a few weeks ago and they where fine. I have just replaced the front brakes and cylinders on the front. No I didnt prime the front cylinders could this be my problem?.

Post by **Orkney** » Mon Dec 31, 2007 6:21 am

Fronts don tneed priming like the rears do as the rears cause a little airlock by nature of the way they are fitted.
Are you slackening the snail adjusters right off before you bleed them?

Its worth doing it again but employing a troly jack ( i use 2) jack the back up on a level surface - rear passenger side first, then drivers side (assuming its right hand drive).
Make sure theres not a upside down U near the rear pipe t joint in the pipe - if so gently make it parralell to the prop shaft and bend back when finished.
Do them that way and eliminate any possible air in the back.

Then drop the back & jack up the front & do those - having that fluid going uphill from the master cylinder makes a Lot of difference. Also keeps things clean & lets you see the sometimes surprising amount of crud that can come out of the system.

Another one that helps is a piece of flexible tube on the nipple - into a jam jar with an inch of fluid in, keep the end of the pipe in the fluid, stops you getting any air back on by mistake if you dont quite do the nipple up completely on a pedal up.

Keep a real close eye on teh level in the MC too, let that go to low and your just putting fresh air back in.

Once done like that you'll know if all is well, the pedal will feel so hard you'll think somethings wrong once the snails are adjusted again

Repeat a week later - just in case of any tiny bubbles left in the fluid which will have formed into bigger bubbles. Also if after that you lose any pedal at all then you need to be looking at the cylinders for possible dodgy seals.

Post by **paulk** » Mon Dec 31, 2007 9:20 am

I use a one man set up with the one way valve (my son is only 3 so not yet much help

)

I've changed most cylinders and the M/C and undone pipes at the rear and each time bleeding has been fairly easy but I have had to do it about 3 times each go. just to get the last of the air out.

Post by **Peetee** » Mon Dec 31, 2007 9:26 am

As Paul says a one man set up* can work if your patient and go round a few times its just a bit expensive on fluid.

* list:
1 (flexible) Person
1 Jam jar
1m clear tubing.
The technique is to position the bottle (containing enough fluid to hide end of tube) within site of person operating brake pedal - hence the need to be flexible

Post by **bmcecosse** » Mon Dec 31, 2007 4:32 pm

Simple pipe into jam jar works for me. Never had any 'airlocks' - usually just rely on gravity to do the bleeding - but that only works if the car is flat on the ground. Otherwise - tube on nipple and in jar - open nipple - two strokes on the pedal - tighten nipple and move on.

Post by **RogerRust** » Mon Dec 31, 2007 8:45 pm

As I've said before, I think the problem lies in the rear cylinder design and arragement.

I know this has been discussed several times but here are some pic to illustrate the problem

This is the path the fluid takes when bleeding the rear cylinder.

There is only a small hole in the cylinder;

My solution is to fill the cylinder with brake fluid just prior to bleeding like this;

I hope thats not teaching my grandma to suck eggs, but I thought it might be usefull.

Post by **bmcecosse** » Mon Dec 31, 2007 8:58 pm

I renewed a rear cylinder recently - absolutely no problem bleeding it! , without any pre-filling!

Post by **Orkney** » Tue Jan 01, 2008 7:54 am

Flippin Eck Rog !!! Cant get much cleaner than that first picture - surprised you didnt getthe brasso on the brake pipe & banjo

Post by **Kevin** » Tue Jan 01, 2008 11:06 am

Keep a real close eye on teh level in the MC too, let that go to low and your just putting fresh air back in.

As Orkney has said did you keep it topped up correctly.

Post by **wanderinstar** » Tue Jan 01, 2008 11:38 am

I do a one man system. But I use a 2 metre length of transparent tube. Looped over wing mirrors when doing front, and open boot lid and looped over bootlid handle on rear. The open end obviously placed through hole in jamjar lid. This holds the tube in jar. Inch of fluid in jar. Just open nipple and slowly pump pedal, watch till all bubbles rise to top of tube and no more bubbles rise. nip up nipple and job done.