Pressurised Rear Brake Caliper - Yamaha FJR Forum : Yamaha FJR Owners Forums
 12Likes
Reply
 
LinkBack Thread Tools
post #1 of 25 (permalink) Old 05-25-2020, 04:41 PM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
Pressurised Rear Brake Caliper

Firstly, thanks for all of the useful posts on this Forum. I have a UK 2005 ABS model, non-linked brakes. During ‘lockdown’ I replaced the front Caliper seals as the dust seals were starting to show. As part of the bleed process I linked out the ABS test points and ran the ABS pump. Everything bled through fine. However, on a test ride the rear Caliper piston seized onto the disc meaning a slow ride home stopping every 500 yards waiting for the disc to cool down. I have removed the Caliper and cannot push the piston back unless I open the bleed nipple. The great posts re clogged ABS units have led to me thinking that there lies the problem. Since getting home I have cycled the pump test half a dozen times and flushed through. The thing is, if I can operate the foot brake, flush through and bleed then I have good flow from the reservoir to the Caliper. So what is holding the pressure in? I’m thinking that if I had a blockage then it would prevent flushing. The ABS block diagram on previous posts is for a later linked brake version so I may not have all of the components shown. Is it just a case that the return flow releasing the pressure goes through a different port and that is blocked? I don’t want to chase down the ABS road if it is something simple. Any advice appreciated.
4Star is offline  
Sponsored Links
Advertisement
 
post #2 of 25 (permalink) Old 05-25-2020, 06:07 PM
Senior Member
High-G FJR Junkie!
 
RaYzerman's Avatar
 
Join Date: Jan 2013
Location: Millgrove, ON, CA
Posts: 6,455
Normal braking bypasses the ABS fluid circuits... possible you have some cholesterol in there somewhere, but with free fluid flow one would think not. Bit of a mystery, I don't have a Gen1 ABS diagram.... you are correct Gen1's did not have linked brakes... but is there a delay valve or metering valve or anything that looks like it, on the downstream flow side of the ABS pump? Other than that, I can only suggest starting at the ABS pump and loosening banjo fittings to see if there is flow at any location on the downstream side, and if you find one blocked..... potentially messy little proposition, have yourself a bunch of isopropanol to clean up.
Edit, note added... are you sure the rear pedal is not sticking and returning to rest position freely?
4Star likes this.

Ray
Keep yer stick on the ice....
2014 FJR1300A - Root Beer (sold)
2009 CBF1000A - Sienna Red
1999 VFR800Fi - Pearl Shining Yellow
RaYzerman is offline  
post #3 of 25 (permalink) Old 05-26-2020, 02:02 AM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
Thanks Ray. I will start tracing back the lines as you suggest. Foot pedal is free moving. I take this off the splines and grease regularly. The only other thing that I have seen on the Forum is the ‘spooge’ orifice. Not sure if that could act like some kind of non-return valve. Everything was working fine before. Fitted new disc and pads, didn’t notice anything odd pushing the piston back to fit the new pads. The one thing that I had never done before was cycle the ABS. Don’t know if this has been done during dealer servicing. I will start investigating later.
4Star is offline  
 
post #4 of 25 (permalink) Old 05-26-2020, 06:46 AM
Senior Member
High-G FJR Junkie!
 
RaYzerman's Avatar
 
Join Date: Jan 2013
Location: Millgrove, ON, CA
Posts: 6,455
There is no harm in cycling the ABS as many times as you like, it may help.....
4Star likes this.

Ray
Keep yer stick on the ice....
2014 FJR1300A - Root Beer (sold)
2009 CBF1000A - Sienna Red
1999 VFR800Fi - Pearl Shining Yellow
RaYzerman is offline  
post #5 of 25 (permalink) Old 05-26-2020, 07:28 AM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
Any harm or point in cycling the ABS with the bleeder open? Help to force fluid out of the circuit?
4Star is offline  
post #6 of 25 (permalink) Old 05-26-2020, 08:00 AM
Senior Member
High-G FJR Junkie!
 
Join Date: Mar 2015
Location: Rolling Prairie, Ind
Posts: 2,666
Let me ask,if when the rear brake locks up and you open the bleed screw is there pressure ? If so then iris probably the spooge hole in the master cylinder or the brake pedal is sticking. if no pressure then it is likely the piston in the caliper hanging up, usually corrosion in the seal groove that push’s the seal out against the piston or the piston itself is corroded and hanging up on the seal.

Also when you ”grease” the brake pedal you are removing the plate that the pedal shaft goes through and cleaning and lubing the shaft there right ? Not just putting lube on the splines ?

I would bet on a closed spooge hole hole myself as they are usually only .010-.013in and can be quite difficult to access and clear, I am just finishing a 76 wing that had plugged spooge holes on both the front & rear m/c’s as well as stuck pistons as well. This is one of the typical by-products of when a brake system doesn’t get bled regularly. I use a set of small “number” drills and a pin vise to clear the hole. Some use a piece of wire. Hope this helps.
cra-z1 and 4Star like this.

Steve P
Red 2014A, the fastest color !
Ride more,, worry less !

Last edited by passx; 05-26-2020 at 08:04 AM.
passx is online now  
post #7 of 25 (permalink) Old 05-26-2020, 09:26 AM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
Thanks for the reply Steve. Didn’t open the bleed when it seized at the road side as I didn’t have a suitable spanner. Dropped by someone and used water to cool the disc enough to ride home without touching the brakes so not under pressure when I got home. Brake pedal gets removed completely and the pivot point gets greased. I have had this before and failed a UK Ministry of Transport annual test so make sure that this has free movement. I did think that it could be the Caliper seals but with the bleeder open I can push the piston back easily with my fingers. As regards the spooge, would this still have an effect with the reservoir cap off? One other thing I noticed and may or may not have any relevance is that with the cap screwed down on the reservoir and bleeding through, when I take the cap off again the black diaphragm inside the cap has been completely extended as though it has been sucked down.
4Star is offline  
post #8 of 25 (permalink) Old 05-26-2020, 09:35 AM
Senior Member
High-G FJR Junkie!
 
RaYzerman's Avatar
 
Join Date: Jan 2013
Location: Millgrove, ON, CA
Posts: 6,455
No problem cycling ABS with bleeder closed or open... maybe open just a crack, not wide open, but.. give it a go.
Bleed with reservoir cap off..... cap is vented so air goes in to fill the void as the rubber diaphram is pulled down by "loss of fluid". I wouldn't expect it's an issue either way, but better with cap off IMHO.
Spooge hole can be a problem in some cases. This is an older bike, maybe time for a rear master rebuild kit?
4Star likes this.

Ray
Keep yer stick on the ice....
2014 FJR1300A - Root Beer (sold)
2009 CBF1000A - Sienna Red
1999 VFR800Fi - Pearl Shining Yellow
RaYzerman is offline  
post #9 of 25 (permalink) Old 05-26-2020, 10:03 AM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
The spooge hole, where exactly is this located please?
4Star is offline  
post #10 of 25 (permalink) Old 05-26-2020, 10:19 AM Thread Starter
Junior Member
Training wheels fitted!
 
Join Date: May 2020
Location: Birmingham UK
Posts: 11
Ray, rebuild kit on order. You’re right, 15 year old bike with 50k miles on it. No harm in a rebuild.
4Star is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Yamaha FJR Forum : Yamaha FJR Owners Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome