75 gl1000 rear brake dragging

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nakedinterstate81
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75 gl1000 rear brake dragging

#1

Post by nakedinterstate81 »

This is driving me nuts.
I rebuild the whole brake system with a brake crafters kit and it's got good braking.
But pushing the bike around the garage is not easy. The rear wheel doesn't spin freely.
It was spinning freely before bleeding, but now it's not after bleeding.
After a forum search, I decided to pull everything apart, clean, relube the pistons and made sure all the return passages of the rear caliper are clear, blasted out the new brake lines and reassembled the master cylinder, making sure that the piston moves freely.
Checked the movement of the pads on the rods and put everything back together.
This was a lot of work, since it involves taking off the rear wheel and dropping the exhaust to get to the rear MBC.
Needles to say, it's still dragging.
So what am I missing here?

Please send help, Cheers!
1975 Gl1000
1981 Gl1100, looking for a used good engine.
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flyin900
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Re: 75 gl1000 rear brake dragging

#2

Post by flyin900 »

Likely the return hole in the master cylinder is plugged. Did you remove the plastic reservoir on the master cylinder and clean out the tiny hole for the pressure return? If the rear line is new then that should rule out any internal collapse from age.
Check that the wheel rotates easily with the caliper removed from the bracket to rule out any issues there.
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Re: 75 gl1000 rear brake draggi

#3

Post by redglbx »

The “spooge” hole on the 1000’s rear m/c is under the silver nut on the side of the m/c, DO NOT DRILL THE SPOOGE HOLE, some use a very small fine wire like a piano wire, I personally use a welding torch tip cleaning tool. They are very small and do tend to plug, if they are plugged the brakes will drag.

You talked about relubing the pistons and seals , so you only used clean brake fluid right ? If you used a mineral based oil/lube it will cause the seals to swell and the pistons to not return due to the seals being swollen. If a mineral oil based product was used then anywhere, all the rubber products are now junk.
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1977 CB750 K7
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1984 GL1200 naked
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nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#4

Post by nakedinterstate81 »

Thanks for the quick reply.
Yes, I cleaned under the plastic reservoir but I wasn't aware of a spooge hole. If it's the one in the photo then it looks like it is to access. Is brake fluid going to shoot out when I open it?
The wheel rotates easily without the calipers. I lubed with brake fluid and the red paste that brake crafters include in the small tubs.
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1975 Gl1000
1981 Gl1100, looking for a used good engine.
nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#5

Post by nakedinterstate81 »

Howdy,
I removed the MC and inspected the return hole in it. I was able to insert a micro brush and watch it come out in the piston bore. No dirt on the brush. All clear.
I remember that I could not feel a lot of travel on the brake pedal. Just pressure.
Could it be that the piston did not retract enough to clear the return hole?
The springs were the same length.

I am reassembling everything again. What would be a good starting point to set the clevis on?
At the end of the pushrod or more towards the MC?
1975 Gl1000
1981 Gl1100, looking for a used good engine.
redglbx
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Re: 75 gl1000 rear brake dragging

#6

Post by redglbx »

Naked, the spooge hole on the rear m/c is located under the silver plug you can see on the back of your m/c, not under the reservoir as it is on the front m/c. One other thing to check is that the rear brake pedal is moving freely, they are noted for rusting slightly and then sticking and not fully returning, give that a check as well, it’s a bit of a Pita because it all has to come apart to clean and lube it but it has to work freely.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#7

Post by nakedinterstate81 »

Hi Redglbx,
The spooge hole was clear.
I took off the brake pedal and spring earlier, cleaned, de-rusted, and lubed it. It's moving freely.
1975 Gl1000
1981 Gl1100, looking for a used good engine.
nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#8

Post by nakedinterstate81 »

MC
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1975 Gl1000
1981 Gl1100, looking for a used good engine.
nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#9

Post by nakedinterstate81 »

Cleaned the MC again, did a quick bleed and went riding for 100 miles. Brakes were OK, not great. Had to double tap to get some pressure, but it released properly and the wheel spun freely.
When I came home I bled and have a stiffer pedal, but it's dragging again. :IDTS:
What is going on here?
1975 Gl1000
1981 Gl1100, looking for a used good engine.
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Re: 75 gl1000 rear brake dragging

#10

Post by gregforesi »

Have you lubed the shaft that the brake pedal rotates on? If it gets dirty/corroded it will cause enough fiction to keep the brake pedal from returning all the way. You can spray the ends of the female piece with WD-40 and see if it helps free it up. It may require disassembly if it is really bad.
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pidjones
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Re: 75 gl1000 rear brake dragging

#11

Post by pidjones »

They always drag a little when spun after any adjustments. Need a quick (around the block) ride for the square piston seals to push them back out.
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nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#12

Post by nakedinterstate81 »

I did ride around 10 miles for an errand but returned because the disk was too hot to touch.
The brake pedal is moving freely and returns properly, restored it last month and greased it.

There was black paint on the caliper pins which I wired off and slightly lubed with the red paste.
I am thinking that maybe my metal tube is dirty ( I used the old one, blasted brake spray through and air) or
the ebay K&L rebuild kit has the wrong dimensions so that it doesn't go past the relief hole.
I compared the kit with the original but I didn't use a caliper. Looked OK.

I should order a Nissin rebuild kit from partsnmore, I can't find oem Honda.
Any idea where to get a new metal tube, or do I have to make one?
1975 Gl1000
1981 Gl1100, looking for a used good engine.
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pidjones
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Re: 75 gl1000 rear brake dragging

#13

Post by pidjones »

By metal tube, do you mean the metal brake line section? There have been posts on it. I think some folks shape a 12" line for VW (metric) for it.
"Love 'em all.... let God sort 'em out!"
Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
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Re: 75 gl1000 rear brake dragging

#14

Post by redglbx »

Just had a thought, I’ve seen some new brake pads that fit tight in the caliper body and don’t move freely,they need to move freely in the caliper and the pins.

I’ve seen and had some that the steel backing plate needed to be sanded or filed to fit properly. The backing plates are just stamped or cut out and sometimes not all that well, so as a rule anymore when I put new pads in I run a file over them to take any burrs/roughness off.

The only thing that retracts the pads off of the disc is the piston boot/seal which only moves the pads back a few thousands of an inch so it needs to move freely. Just a thought.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
nakedinterstate81
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Re: 75 gl1000 rear brake dragging

#15

Post by nakedinterstate81 »

I replaced the two-part brake line with a braided line and used a banjo on the MC after I took out the little insert.
I also took out the pistons and noticed some scratch marks 180 degrees of each other on the top and bottom of the pistons.
That means the pistons are rocking. Got out the micro and measured the piston OD 38.040 mm.
The book says 38.115 - 38.148 standard. The service limit is 38.245 mm.
So the brake crafters pistons are too small!
The caliper bore ID is within spec.
I also removed the shims, which are only touching 1/3 of the pistons.
It's still dragging a little. When I kick down the tire with my foot, it rotates one revolution and stops quickly.
At least a little progress.
1975 Gl1000
1981 Gl1100, looking for a used good engine.
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