Author Topic: dragging rear brake  (Read 1660 times)

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Thislldo

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on: May 11, 2024, 10:32:40 pm
Rear brake on my 2019 Himmy drags. It does not release freely when brake pedal is released.
Fortunately, after stopping, a few minutes later it frees off suggesting that heat is involved. The bike has had the Caluiper Recalll work done.
I understand the type of caliper with pistons and moving pad on one side and fixed pad on the other.
It could be the moving part of the caliper sticking on the rod it should slide on, but it dosn't really feel like that.
Any ideas?


Deathwish

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Reply #1 on: May 12, 2024, 01:01:13 am
Couple of questions. Are you running EBC Sintered pads? When was the last brake flush? While the EBC pads work great, they are very dirty and rough on rotors. I imagine a good disassembly/cleaning, greasing the caliper pins and flushing the old brake fluid out of the system should fix you up.


Thislldo

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Reply #2 on: May 12, 2024, 07:09:41 am
Thanks. The bike only had 4,000 on the clock when I got it 5 weeks ago. So I don't know what pads are fitted. Service record that came with it is thin and does not suggest an owner who took much care over it. 1st & 2nd services, brake recall and got the dealer to fit heated grips! And not much bothered about thorough cleaning, so I shouldn't be surprised.
I've bled & rebuilt brake set ups before but never one with ASB. Any particular things to watch out for?


Deathwish

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Reply #3 on: May 12, 2024, 03:15:11 pm
No. The process for flushing/bleeding the brakes w/ABS is the same as without. Just takes some time. I'd pull the rear cliper and remove the pads so I could really clean the piston with brake cleaner and a brush. Then a little grease on the pins, clean the rotor well and reassemble. Then flush all the old brake fluid out with fresh. Might want to hit the front as well to prevent future problems while you are at it. Wouldn't hurt to pull the rear brake lever and clean/grease the pivot pin too.


Thislldo

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Reply #4 on: May 12, 2024, 04:18:11 pm
Thanks. Thought it was worth checking. Its the advantage of a forum.


Thislldo

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Reply #5 on: May 12, 2024, 07:05:01 pm
As its a lot cooler in the garage this evening, I began investigation.
Brake pin came out easily and pads dropped out. Inscribed Bybre on the backs and not seriously worn.
Without going further, I tried seeing whether the movable caiper half would move. It did ! and easily !
So I popped the brake pads back in to see whether problem still existed.
But couldn't get that far, as I now have zero resistance or sense of pressure on applying brake pressure. So where has it vanished to?
Brake fluid is at acceptable level in the reservoir and nothing else has been disturbed.


Thislldo

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Reply #6 on: May 12, 2024, 08:17:38 pm
Wierd, or what?
Went indoors thought about it. went back out, waved the vacume bleeding device at it threatenly at it but then tried the normal brake bleeding tube and amazingly the  pedal and rear master cylinder start doing proper business with each other and within a few strokes, fluid comes through and firm pedal action is restored.
I bled fresh fluid all the way through and wheel spins freely, no drag and pedal applies brake and frees when it should. So I am a happy bunny ;D
But what the heck was going on when after refitting the pads, I tried the brake action, and there was nothing there?  ::)


Deathwish

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Reply #7 on: May 12, 2024, 11:55:35 pm
Good to hear you're back in business. My guess is when pulling and replacing the pads, you pushed the piston back into the caliper some. If so, then it would feel like you have no brakes when first applying them until the pads are seated again.


Thislldo

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Reply #8 on: May 13, 2024, 08:20:06 am
Could be. But when I refitted the pads and tried pumping on the pedal, there was absolutely nothing. After leaving it for an hour and then having another go, without doing anything else, there was the feel of fluid being pumped at almost the first stroke. So I still don't understand what happened. As you say, just glad it works again.
Thanks very much for your help.


Isla

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Reply #9 on: June 01, 2024, 10:33:24 am
Has your dragging brake issue been resolved? Only asking as by what you have described it suggests that the caliper piston is sticking slightly.
Shunpike Sister riding a bronze/chrome Classic 350 called Biscuit


Thislldo

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Reply #10 on: June 01, 2024, 02:35:22 pm
Thanks. It did re-occur. I pulled the calipeer halves and made quite sure the pins were clean, and had no sign of scoring. Since then, 10 days of regular riding it has not done it again.
If it does I'll investigat thepistons and seals. But problems there on a bike with only 5,000 on the clock, and a lot less than that since the caliper recall.


Isla

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Reply #11 on: June 01, 2024, 05:15:10 pm
Yes true, although things can also seize with lack of use & that is pretty low mileage for a 5 year old bike, not to mention what those miles consisted of before you bought it.

Being very well priced adventure bikes, lots seem to see off road use which is no doubt different to occasional fair weather use, and different again to riding on road through a winter.

Best of luck in any case. Am not a Himmy owner but my bestie has designs on owning one.
Shunpike Sister riding a bronze/chrome Classic 350 called Biscuit


Thislldo

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Reply #12 on: June 02, 2024, 08:43:34 pm
Drat ! it did it again today !
I am coming round to suspecting the piston, as you suggest. Reason for this is, that letting it cool for 20 minutes, the caliper frees up.
From past experience of working on motorcycle brake calipers, I am wary of pulling it apart without having a rebuild kit to hand. The bike is day to day transport and I don't want to be waiting for parts to arrive.
Ideal would be getting hold of a spare, used rear caliper, that I can fettle and swap onto the bike.
But what about the "Brake Recall" business ? Mine had that done. But shopping for a spare, how do I tell "pre" from "post" recall type?


Isla

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Reply #13 on: June 02, 2024, 08:52:49 pm
Some more food for thought...when it binds does the brake light stay lit?

If it does try cracking off the bleed nipple & see if there is pressure released...the brake pedal pivot may be rusty & sticking...or it could be the master cylinder sticking.

The process of elimination! Had much fun with this when besties ST1300 CBS/ABS brakes were playing up.
Shunpike Sister riding a bronze/chrome Classic 350 called Biscuit


Thislldo

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Reply #14 on: June 02, 2024, 10:37:52 pm
Brake light is not staying on.
Bake pedal and all linkages are greased and free moving.
First time the problem occured I bled the system.
Still want to know how to tell a "pre recall caliper" from a "post recall caliper"


Isla

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Shunpike Sister riding a bronze/chrome Classic 350 called Biscuit


Thislldo

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Reply #16 on: June 03, 2024, 08:14:06 am
Thanks. So avoid anything marked Bybre.
But does that mean, anything unmarked is genuine? ::)


Thislldo

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Reply #17 on: June 03, 2024, 12:00:13 pm
Ordered complete caliper rebuild from Hitchcock's so will be prepared to pull it apart and see w2hat's amiss.


Isla

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Reply #18 on: June 03, 2024, 12:22:38 pm
Okay best of luck 👍
Shunpike Sister riding a bronze/chrome Classic 350 called Biscuit


Thislldo

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Reply #19 on: June 07, 2024, 07:03:50 pm
Problem solved :)
Though I have the full caliper rebuild kit from Hitchcock's, I hesitated to rip the caliper of and rebuild it when I was still uncertain that, that is where the problem lay. As GV Motos a well respected Enfield dealer is only half an hour away, I decided to get their view on the problem before going any further.
As soon as I described the symptons, (rear bake binding after braking, sometimes freeing off after a few miles and deffinitely freeing off after a 30 minute stop) He said "sounds like the rear master cylinder problem!"
He explained that is quite common on E4 Himmys and on some early E5, that a small white nylon spacer in the master cylinder swells and causes the caliper to bind. Or something of that sort.
Solution is an improved replacement master cylinder, which to my great relief is less than £40, and they have one in stock.
Fitted it this evening. No hassle bleeding it through, took it for a spin and could not provoke the rear brake to drag. So dfingers crossed. 8)


Timw

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Reply #20 on: June 30, 2024, 07:28:49 pm
I think I might have the answer to your problem as I have just found an issue with my Himalayan. Little history last year I hahad rear brake bind temperarly I thought it was calliper but it seem to fix it self then early this year I was out for a ride and I lost the rear brakes then they suddenly started working again forward to this weekend I decided to do a brake fluid change as a part of the Seville and was unable to bleed the rear brakes I had no rear brakes on investigation I found the rear brake master cylinder piston was randomly sticking so i decided to strip the master cylinder what I have found is the aluminium casing has corroded between the casing and the nylon bush which has caused he slight distortion of the bush causing the grabbing of the piston so not returning correctly hope this helps