Manky Monkey
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« Reply #1080 on: January 24, 2016, 08:57:37 PM » |
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Opened the garage door this morning & everything was dry, but before my very eyes a mist of condensation formed on all the metal surfaces. Guess it was the change in air temp. You can see the gloss black frame's misted with moisture here.
I'd gone to have another go at bleeding the rear brake. Mr Olds had suggested the fluid in the reservoir might not move if it's lower than the caliper. Hadn't occured to me, but sure enough it is lower by a couple of inches.
The reservoir's the small black billet ali' cylinder in the middle of the electrics box. Even if moving it doesn't cure the problem, it'll be tidier anyway so would be handy to get done before Nathan gets in there to wire the bike up. I'll mount it off the top coil mount, (the grey bit at the front of the box).
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On the last freedom moped out of Nowhere City.
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Manky Monkey
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« Reply #1081 on: January 24, 2016, 09:09:21 PM » |
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So I took some measurements & headed over to Mr Loon's workshop to bend a bracket up from 20mm wide flat strap.
Also took the kickstart lever. It flops around on it's mount a bit & would drive me crazy while I'm riding, so I bought a rebuild kit for it -a new spring, ball bearing, E clip & washer. A simple job once the old ball bearing's out but it was trapped by a burr on the edge of the hole it sits in. Took an hour of carefully grinding flats on the ball bearing with an angle grinder to free it. Clamping the lever in the vice damaged the powder coat so I flatted it back & Mr L will respray it when he does the rear guard.
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On the last freedom moped out of Nowhere City.
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kapri
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« Reply #1082 on: January 25, 2016, 09:51:46 AM » |
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I agree with Dave you are trying to force fluid uphill and there is the ideal opportunity for it to bleedback as well. You may to go to a 2lb residual valve if you lose full travel over night.
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Manky Monkey
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« Reply #1083 on: January 25, 2016, 09:25:35 PM » |
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Hmm. I remember the trauma of sorting the Pop brakes out only too well Kev!
Well I drained the reservoir this evening, (wicked the brake fluid out of it with some paper towel), then disconnected the hose from the reservoir to the cylinder. The cylinder's below the reservoir, so even if it wasn't working, there should've been fluid in the hose. There was, but definitely not a full hoseful. No blockage in the reservoir outlet so it should've filled the hose with fluid just by gravity. Odd.
I've got to modify the bracket I made & cut a longer piece of hose then I'll fill it again. I suspect the pushrod that operates the cylinder isn't pushing far enough to pump the fluid cos it's too short, or isn't returning enough to allow it to refill from the reservoir cos it's too long.
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On the last freedom moped out of Nowhere City.
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BikerGran
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Gran Turismo
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« Reply #1084 on: January 25, 2016, 09:40:04 PM » |
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I had a problem like that with the trike and had to get the pushrod modified.
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You don't stop havin fun because you get old - you get old if you stop havin fun!
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Olds
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« Reply #1085 on: January 25, 2016, 10:00:24 PM » |
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Could be as simple as a bubble of air stopping the fluid from going down the tube. Tapping the side of the tube usually shifts it, but I once had to fill the master cylinder and tube using a syringe before connecting the resevoir. Just a thought.
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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Manky Monkey
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« Reply #1086 on: January 25, 2016, 10:04:42 PM » |
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Yeah, we discussed using a syringe to prime the system the other day. Hadn't thought of air in the hose. Good point.
My brother & I had to guess at it when we set up the brake linkage. Ideally the rod would be adjustable. The pedal doesn't feel like it has any freeplay before the rod makes contact with the cylinder piston, so I reckon the piston isn't returning enough to draw fluid from the reservoir.
I'll remount the reservoir & go from there.
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On the last freedom moped out of Nowhere City.
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terry t
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« Reply #1087 on: January 25, 2016, 10:06:25 PM » |
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You don't have much luck with brakes. do you Andy
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Manky Monkey
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« Reply #1088 on: January 25, 2016, 10:29:43 PM » |
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Hate them.
Hate them, hate them, hate them.
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On the last freedom moped out of Nowhere City.
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merv
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« Reply #1089 on: January 26, 2016, 07:00:55 PM » |
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Hate them.
Hate them, hate them, hate them.
Until you need them to stop you  |
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Why do every five minute job take all day, and
if it can go wrong it will go wrong
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Manky Monkey
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« Reply #1090 on: January 27, 2016, 09:45:38 PM » |
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Brake fluid reservoir mounted a few inches higher inside the electrics box with a new length of hose connecting it to the master cylinder. It's now slightly higher than the caliper.
Pedal linkage disconnected & the master cylinder operated with a screwdriver temporarily.
Result-
it's definitely pumping fluid through the system & the piston seemed to travel less as the air was bled out at the caliper, suggesting it was building pressure as it should.
However, when I reconnected the pedal & linkage, the pedal goes right down without operating the brake at all.
It got too dark to make out what was happening this evening, but I assume either the operating rod's the wrong length or there's just a lot more leverage with the pedal fitted. I'll try bleeding it with the pedal tomorrow.
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On the last freedom moped out of Nowhere City.
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Manky Monkey
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« Reply #1091 on: January 29, 2016, 06:58:45 PM » |
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Decided to buy a rebuild kit for the rear master cylinder. Probably not been touched since it was new in 1980, so worth doing & at least it'll eliminate that as the problem.
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On the last freedom moped out of Nowhere City.
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Manky Monkey
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« Reply #1092 on: February 09, 2016, 08:46:51 PM » |
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Cylinder rebuild kit's arrived from the States, so I removed it from the bike this morning, (a bit of a faff cos it's tucked under the electrics box, between the top & bottom runs of the chain, with a complicated pedal linkage attached to it).
Stripped it & rebuilt it this afternoon, then refitted it this evening.
I'd literally just popped the dust cap off the rear caliper bleed nipple when click -the LED worklamp in the garage ran out of charge & I was plunged into darkness. So I'll charge it up this evening & have a go at bleeding it using the pedal tomorrow. I've had fluid bleeding through the system when I disconnected the pedal & pushed the cylinder piston with a screwdriver, but couldn't get enough leverage on it to bleed it properly. So if it doesn't bleed now, the problem must be in the linkage between the pedal & the cylinder.
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On the last freedom moped out of Nowhere City.
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Manky Monkey
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« Reply #1093 on: February 10, 2016, 09:26:18 PM » |
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No fluid movement when I use the brake pedal to bleed it. So it looks like the rod that pushes up into the master cylinder's too long. It begins moving the piston as soon as I touch the pedal -I'm guessing there should be a couple of mill' of free play, which would make sure the piston's fully returning & replenishing the cylinder with fluid. Too dark again this evening to remove the linkage, but I guess I'll have to shave a little off the end of the rod & see what happens.
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On the last freedom moped out of Nowhere City.
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Olds
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« Reply #1094 on: February 10, 2016, 09:43:46 PM » |
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Any chance of making it adjustable ?
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Getting older but no wiser! Just using bigger hammers.
The answer to most problems, fire and lots of it.
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