Preloading caliper with fluid


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waynedudes
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Preloading caliper with fluid

Post by waynedudes »



I just rebuilt right front caliper, 94 1500 se. I also replaced all the fluid. Can not the brakes to fully pump up. I have I believe I need to remove the caliper and pre load it with fluid. The upper piston is not fully pressing against the pad, as much as the lower piston. I have checked everything else possible? So now I believe I need to remove the caliper and pre load it with fluid? Since the upper piston does not press against the shoe as much as the lower piston does. Do not see any articles on here about anyone having this problem when rebuilding a caliper? Thanks



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Re: Preloading caliper with fluid

Post by WingAdmin »

waynedudes wrote:
Fri May 08, 2020 9:50 am
I just rebuilt right front caliper, 94 1500 se. I also replaced all the fluid. Can not the brakes to fully pump up. I have I believe I need to remove the caliper and pre load it with fluid. The upper piston is not fully pressing against the pad, as much as the lower piston. I have checked everything else possible? So now I believe I need to remove the caliper and pre load it with fluid? Since the upper piston does not press against the shoe as much as the lower piston does. Do not see any articles on here about anyone having this problem when rebuilding a caliper? Thanks
I have always vacuum bled from the caliper, and then left the brake lever pulled tightly and tied in place overnight. This helps air migrate up to the reservoir and firm up the brakes.

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waynedudes
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Re: Preloading caliper with fluid

Post by waynedudes »

I will pull the brake lever tight and tie it with a zip tie. Recheck it in the morning.... Wish me luck!

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Erdeniz Umman
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Re: Preloading caliper with fluid

Post by Erdeniz Umman »

waynedudes wrote:
Fri May 08, 2020 3:29 pm
I will pull the brake lever tight and tie it with a zip tie. Recheck it in the morning.... Wish me luck!
If there is too much air in the system, reverse bleeding may be a better method.

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ct1500
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Re: Preloading caliper with fluid

Post by ct1500 »

When bleeding turn handlebars all the way left which puts the master at its' highest position relative to hose where air can get bound.
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waynedudes
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Re: Preloading caliper with fluid

Post by waynedudes »

What I have already done: Turned wheel all the way left and even jacked up trike on right side. Just to be sure I had the reservoir above the banjo bolt. I also loosened up the banjo bolt to see if any air would come from it. I tied lever back and left it compressed all night. This morning I have about a third of what I should have when compressing on the lever. At least, last night I made some progress! I tried reverse bleeding but did not have the correct syringe to push the fluid in reverse, up the brake line. I tried using a plastic bottle with a nozzle. It leaked brake fluid all over me and the floor. So now I am going to find a large syringe to again try to reverse bleed the brakes. I have never had this much difficulty when bleeding any brakes! But I will find the problem and fix it. Sooner or later.

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Re: Preloading caliper with fluid

Post by Snowmoer »

When I rebuilt all the calipers and master cylinders on my 88, I added fluid to the caliper before hooking up the brake line. I rolled it side to side and added more fluid to work out the air bubbles. It has been a while, but I think the shop manual said to do this. I then pumped fluid through the master cylinder to refill the lines before hooking it up to the caliper. I replaced the lines also, so the whole system was dry. After I hooked the line up to the caliper, I bolted it in place and then bled the system with a Miti Vac. I did not have any air in the system this way. I did it this way on the rear brake system also.

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Happytrails
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Re: Preloading caliper with fluid

Post by Happytrails »

When I rebuilt my brakes and the system was empty I used a mityvac too just to get some fluid into the lines. Bench bleeding the master cylinder got rid of the extra air. Good luck with your brakes! :)
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waynedudes
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Re: Preloading caliper with fluid

Post by waynedudes »

Mystery solved! So I reverse bled the right side caliper. After I finally found a syringe that would work. Still, air somewhere? So I removed the caliper again, disassembled it again, removed seals and pistons again. Washed caliper with brake cleaner, blew everything out with air compressor. Reassembled and bled line as before. Still air somewhere? Up until this time I had not checked front left side. Because with GL 1500, only the right side brake uses the front hand brake? Wrong! Not on this trike.

When the trike was converted, they put a crossover brake line from the right side to the left side! Eliminated the brake line from rear to left front.The rear brake pedal is only for the rear brakes. The front hand brake is for both right and left front brakes. So I reverse bled the left front brake, and watched the bubbles in the front master cylinder. Now I have great front brakes. Only took me about three days to figure it out!



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