Bleedin brakes!

Moderator: Moderators

Post Reply
Tinman
Posts: 39
Joined: Mon Aug 04, 2014 9:30 pm
My Bike: Kawasaki zxr 400

Bleedin brakes!

Post by Tinman » Mon May 11, 2015 5:58 pm

I've just put on a set of gsxr 600 calipers on my zxr at the weekend and I'm really struggling to get rid of all the sponginess out of the lever.
I've been through a bottle of brake fluid so far trying to bleed them. I've used a vacuum pump and tried the traditional method of bleeding the brakes.
I've tried tapping the brake lines and calipers.
I've bled the master cylinder too.
I've left a cable tie on the brake lever over night and still can't get rid of the spongy feeling.
The brakes work brilliantly but there's obviously still air trapped some where. Any ideas?

User avatar
banner001
Track day God
Track day God
Posts: 2172
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Bleedin brakes!

Post by banner001 » Tue May 12, 2015 3:58 pm

bad caliper seals can lead to a spongey feeling, as can air in the master cylinder/splitter (if you still have it).

unbolt the splitter and the MC, angle the splitter so that any air inside will travel up to the MC and cable tie it in that position for a few hours, give it a wiggle every now and then to free stubbon air bubbles.

for the MC i detach the oil reservoir and turn the black nozzle that it attaches to 180 degrees so the reservoir is now above the lever, then i remove the MC and angle it so that that black nozzle is a high point, this gets rid of any lingering pockets of air.

or fit steel braid hoses?

it is possible for small air bubbles to remain trapped in the calipers, if i suspect that this is the case i push the pistons into the caliper so that they are almost up to the dust seals, put a block of metal inbetween the pistons that ive had machined to be the right size, then i cable tie the caliper to the bike so its at the correct angle for air bubbles to escape up the brake line and see what emerges at the top.
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

Tinman
Posts: 39
Joined: Mon Aug 04, 2014 9:30 pm
My Bike: Kawasaki zxr 400

Re: Bleedin brakes!

Post by Tinman » Tue May 12, 2015 8:04 pm

Ok. Cheers I'll give that a try then thank. I've fitted new braided hoses and got rid of the splitter at the same time. I was wondering if it could have been the caliper seals also.
Thanks for your reply

Post Reply