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Excessive pedal travel


sgilks
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Any experience in this area appreciated...

Just swapped rear drums for discs on the back of SE Westfield (drums were getting too hot on track) and the pedal travels right to the floor giving very modest braking effort even after extensive brake bleeding.  (2nd stab at the brakes will lock a front suggesting to me that front circuit is ok).

There is a slight increase in piston area (single pot sierra caliper vs two piston wheel cylinder on brake setup) but the lack of resistance suggests other problems.

All lines are aeroquip, the hydraulic handbrake has been bled through as well to ensure no air in the in-line m/cyl.

Do the sliding pins wear and introduce play which would back the piston off or are there any other gotchas with this setup?

Any thoughts appreciated!

Thanks

Stuart

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Are the calipers the right way up? I have heard of people mounting them with the pipe and bleed nipple connections nearest the floor..........

Otherwise, remove the caliper, place a piece of wood between the pads, and bleed with the nipple uppermost. Tap the caliper at the same time, to release any trapped air.

If you want to "set up" the procedure, try bracing the brake pedal (pushing it down with your foot, then wedge it down) using a peice of wood between the pedal and the seat/chassis/rear bulkhead/wherever, for a few hours before bleeding. This sometimes helps to shift difficult air pockets. Cracking the nipple aggressively can help, as can NOT using a pressured type easi-bleed. Phone a friend.........

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Phone a friend.........

Or go 50-50. Sorry I could not resist that one

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Or ask the computer to remove 2 wrong answers........ :D  :D

Mornin' Matt...............no work to do?

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Never mind where the bleed nipple is.  Check the drilling from the bleed screw & make sure it enters the cylinder at the top.  I have been caught by this one.

You could try a residual pressure valve in the rear line.  This keeps pads in contact with the discs & therefore reduces pedal travel.

                     tonym

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I did this conversion on a '91 chassis and encountered similar problems. Brake travel decreased by using a 13/16 inch bore master cylinder. Not AP but one from a factor with east west mounting flange and matching pipe fiixing (£60).  Original Morgan M/C replaced with Girling PMA226 I think, check that. Brake feel improved with fitting Green Stuff pads front and rear. Increasing M/C bore moves more fluid, reducing pedal travel but increases the pedal effort required as pressure to caliper pistons is reduced.

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  • 19 years later...
On 10/07/2002 at 12:15, Lionel said:

I did this conversion on a '91 chassis and encountered similar problems. Brake travel decreased by using a 13/16 inch bore master cylinder. Not AP but one from a factor with east west mounting flange and matching pipe fiixing (£60).  Original Morgan M/C replaced with Girling PMA226 I think, check that. Brake feel improved with fitting Green Stuff pads front and rear. Increasing M/C bore moves more fluid, reducing pedal travel but increases the pedal effort required as pressure to caliper pistons is reduced.


Nice one @Lionel

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I just want that imposter with one post from 2002 to be deleted so I can claim my birthright 

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I'd like to know exactly what that replacement master cylinder is and if its still available - cos the Morgan one is over 200 quid from WSC

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