Bleedin brakes!!! Using mityvac and still no joy :(

[JohnC]

OK so I had no joy bleeding my front brakes (Nissin 4 pots from a GSXR) using the normal methods, bought the mityvac off ebay and had a go this morning. The mityvac sucks like a prossie with no teeth, and the fluid is coming out by the gallon, but whatever is happening (or not) I just cant get even the slightest pressure at the lever, nor can I get the system free of air.

I feel I'm missing something fundamental here, duff master cylinder or something? It's from a ZZR or ZXR, cant remember which and seems in tip top condition. I've checked all the lines are tight and copper washers ok, the lines are all new HEL and came with HEL washers and banjo bolts.

I know the standard splitter is a suspect when bleeding the brakes but I'd have thought with the amount of fluid being sucked through with the mityvac this shouldn't have been a problem. Is there any way to part bleed the system at the splitter without getting brake fluid all over the shop?

Any other tips or thought much appreciated. I've left the lever tied in to the bars for just now (overnight) as someone said this might help.

[DogsbolloxofZ1B]

I use the mityvac and its a good piece of kit. It sounds as though your master cyl isn't compressing fluid, normally worn seals or bore is worn but this would be a rare root cause. Have you tried pushing the calliper pistons fully home. Then bleed? Is there any other pressure relief on these brakes? Not similar with your bike.

Mike

[njwmct]

Had a similar problem with my front brakes - turned out to be air at the master cylinder.

Try the following:
Pump up the pressure & hold the lever in then bleed from the master cylinder a couple of times by undoing the banjo bolt - just wrap a bit of rag around the area to save your paintwork.

You can also do the same at the splitter.

Good luck.

[PAULJAC47]

Plug the output from the Mc with the banjo bolt sealed with ptfe tape,this will prove the mc then work down the system the same,is the tiny release hole in the Mc clear??...Paul j

[gray]

sometimes you get an airbubble in the brake light sensor in the splitter. To dislodge this , unbolt the splitter from the bottom yoke and turn it clockwise so any bubble rises out of the switch area ,bleed with it in that position , and the air can be bled away. Then bolt it back on once you've got good pressure

[jimmock]

Guyz,

How many times must I tell you this.......


SPLIT BLEEDING!!!!

Bleed to the banjo on the master cylinder outlet.

Then bleed to splitter.
Then bleed to ONE caliper.
Then bleed to SECOND caliper.

Garaunteed result OR YOUR MONEY BACK.

I can see a new book in my "With Jimmy" series coming out soon.......


Bleeding brakes with Jimmy.

[Big Fluff]

Exactly how I do it jim old boy
The biggest usual culprit is the mc.
Fill the mc with fluid, stick a finger over the open port and violently pump fuck out of it until it blows your finger off the port..... mc is now bled !
Continue to splitter and so on!

[Keefleaf]

I can see a new book in my "With Jimmy" series coming out soon.......


Bleeding brakes with Jimmy.[/quote]

I was expecting 'Bleeding Nipples' ,Jimmock?

[jimmock]

I can see a new book in my "With Jimmy" series coming out soon.......


Bleeding brakes with Jimmy.

I was expecting 'Bleeding Nipples' ,Jimmock?[/quote]

Keef,

The book you're thinking of is....


Greasing nipples with Jimmy. !!!!!

[JohnC]

Thanks guys, a lot of good suggestions there.

Jimmock, I did read your sage advice about bleeding from the banjos, unfortunately it made no difference, soz ;)

I've a feeling it's the master cylinder as plenty of fluid is coming out at each banjo bolt down the line.

I'll try PAULJAC47, Big Fluffs and gray advice and see how I get on.

I did see less air in the system when I put some ptfe tape round the bleed nipples, recommended in the mityvac instructions, but still no pressure at the lever.

I've a spare (known to be working) master cylinder kicking about, worse case I'll use this until I can repair / rebuilt the ZZR/ZXR one. The only reason I'm using these is I want a matching pair I can use with my hydraulic clutch conversion.