6 replies to this topic

[redmini]

:wales: I've recently renewed the seals and pistons in my standard 8.4" calipers, standard seals and stainless pistons. Whan I bled them all through last week I noticed the pedal was travelling half way down before anything happened, I bled them in the correct sequence (furthest away first down to the nearest) and adjusted up the rear drums but still no change. Tonight I noticed a slight weep from the nearside front caliper so removed the wheel for closer inspection, it just needed a tweek on the bleed nipple but as my mate was pushing the peddle down I noticed only one piston was moving (the one on the side the brake line screws into) so I checked the other side and that's the same. I can only assume it's air in one side of the 2 pots, when the new seals were fitted everything was checked out and cleaned thoroughly in new fluid. They worked well before the rebuild, has anybody any ideas as I've bled them countless times now with no improvement to the feel or travel in the pedal. I'm using dot 4 fluid, I dont want to put it back on the road until I'm sure the brakes are okay

[Purple Tom]

Sounds like a daft question but are the calipers the right way round so that the bleed nipples are at the top? I can't remember if on 8.4's the bleed nipple is on one side, but if the calipers are upside down so the nipple is at the bottom then the air won't all be able to escape.

[redmini]

:wales: yes the nipples are at the top, it's the inside pot (without the nipple) that I think the air is trapped :sad:

[dklawson]

If the nipples are at the top you may wish to try this additional step and re-bleed the front brakes. Pry both pistons "back" into the casting... all the way back. Once they are fully retracted put tapered wooden wedges between each piston and the disk. Now re-bleed the brakes. This minimizes the volume for trapped air. Remove the wedges and pump the pedal to fully extend both pistons then repeat on the other side.

[redmini]

:wales: Cheers, I'll give it a go

[bluebottle]

make sure your rear brakes are adjusted right up as well.

[redmini]

:wales: They are, I was going to clamp the rear hoses off to see if that made any difference but they're goodridge braided hoses so I cant. I wont get chance to try the wooden wedge method until tomorrow as my sons have come to stay for the night :cool: :grin: