Bimota Forum Forum Index Bimota Forum
Forum for Bimota Owners and Riders
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  

DB4 rear caliper bleeding awful 😠

 
Post new topic   Reply to topic    Bimota Forum Forum Index -> DB Series
View previous topic :: View next topic  
Author Message
ladolcevita7



Joined: 02 Dec 2015
Posts: 44
Location: Manchester

PostPosted: Thu Jul 30, 2020 8:23 pm    Post subject: DB4 rear caliper bleeding awful 😠 Reply with quote

Back Again for some help if possible,bike all ready for the roado bar taxing at the beginning of the month and I'm raring to swing my leg over it and hit the road.
Well that is if I can get the one problem that has made me pull my hair out, well what hair I've got left being an old codger.
I've tried and failed miserably on 3 occasions 😠 to bleed the rear caliper, I've removed it and hung it up above the swingarm,well as much I could due to the constraints of the pipe length.
Thanks to 2bims suggestion but to no avail.
I have tried with a vacuum pump and also a one way bleed valve.
So got no rear brake now ☹️
Any suggestions would helppfull or do I just admit defeat and take it the dealer's 🤔

How hard can it be, I've bled brakes on all manner of machine's over the years 🤔

Failed in trying to load a photo ☹️[/img]
Back to top
View user's profile Send private message
brian



Joined: 22 Aug 2011
Posts: 3568
Location: Australia

PostPosted: Thu Jul 30, 2020 11:31 pm    Post subject: Reply with quote

Iíve never had any trouble bleeding a rear brake. Are you sure that your master cylinder is good? Any more info.... why did it need bleeding in the first place? Have you replaced something or repaired anything recently?
_________________
Current motorcycles - '99 Bimota DB4 #104, '96 Bimota SB6 #1165, Ď94 Bimota DB2 J #652, '99 Bimota DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, Ď94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, Ď61 BSA A10 650
Back to top
View user's profile Send private message Send e-mail
pkay



Joined: 16 Dec 2016
Posts: 150
Location: Brizvegas

PostPosted: Fri Jul 31, 2020 1:55 am    Post subject: Reply with quote

Check for air leaks in the system from front to back. Also sit back with a cuppa and take a close look at everything because you'll be surprised what you can sometimes miss eg small split in line, end joint not sealing or sucking air around the bleed nipple. You'll find the last one by attaching the vacuum pump to the bleed nipple - if you notice the pressure drop it's not sealing and letting air in around the thread - happens when they get old. Use Teflon tape on the thread to seal it (I do it on all brake services now as it seems a common issue on old bangers - not suggesting a DB4 is an old banger BTW....... ). On my GSXR-750 I was having a similar issue and had gone through at least one bottle of brake fluid when I noticed rust marks around where the end piece that goes into the caliper joins the rubber line - slightest leak but enough to stuffing my bleed attempts. Didn't notice it for ages, just kept putting the bike in the naughty corner for another day. Also check your M/C is working properly and the fittings are tight. I haven't looked at the set up on my DB4 but on another bike there was a bellows/dust cover across the lever end - couldn't get pressure and when I took this off it was full of brake fluid, the pump seal had failed. Another thing only noticed after the "cuppa check". Good luck Very Happy
_________________
pkay
SB6, YB7 and many other assorted Euro and Jap bikes and one Triumph.......
Back to top
View user's profile Send private message
Jonny B Bad



Joined: 05 Dec 2009
Posts: 505
Location: NE London

PostPosted: Fri Jul 31, 2020 9:21 am    Post subject: Rear brake Reply with quote

Rear m/c uses an O ring as a dust seal. This gets upbraided over time, absorbs fluid and grips the piston, preventing it from returning freely under spring pressure. If the m/c has never been opened, get a repair kit or replace the master with a new one - I presume itís a 13mm. Should be marked as 11 or 13. Iíve just re-furbed both master and calliper, i.e. both bone dry and the system bled up in a couple of minutes with a pneumatic vacuum bleeder.
_________________
What, Jonny's gone!
Back to top
View user's profile Send private message
ladolcevita7



Joined: 02 Dec 2015
Posts: 44
Location: Manchester

PostPosted: Sat Aug 01, 2020 10:31 am    Post subject: Reply with quote

brian wrote:
Iíve never had any trouble bleeding a rear brake. Are you sure that your master cylinder is good? Any more info.... why did it need bleeding in the first place? Have you replaced something or repaired anything recently?


Thanks for the reply Brian,It had 10+year old fluid as it had been storage and I was recommision the bike,so I had to flush it out.
Back to top
View user's profile Send private message
ladolcevita7



Joined: 02 Dec 2015
Posts: 44
Location: Manchester

PostPosted: Sat Aug 01, 2020 10:46 am    Post subject: Reply with quote

pkay wrote:
Check for air leaks in the system from front to back. Also sit back with a cuppa and take a close look at everything because you'll be surprised what you can sometimes miss eg small split in line, end joint not sealing or sucking air around the bleed nipple. You'll find the last one by attaching the vacuum pump to the bleed nipple - if you notice the pressure drop it's not sealing and letting air in around the thread - happens when they get old. Use Teflon tape on the thread to seal it (I do it on all brake services now as it seems a common issue on old bangers - not suggesting a DB4 is an old banger BTW....... ). On my GSXR-750 I was having a similar issue and had gone through at least one bottle of brake fluid when I noticed rust marks around where the end piece that goes into the caliper joins the rubber line - slightest leak but enough to stuffing my bleed attempts. Didn't notice it for ages, just kept putting the bike in the naughty corner for another day. Also check your M/C is working properly and the fittings are tight. I haven't looked at the set up on my DB4 but on another bike there was a bellows/dust cover across the lever end - couldn't get pressure and when I took this off it was full of brake fluid, the pump seal had failed. Another thing only noticed after the "cuppa check". Good luck Very Happy


Appreciate you taking the time for an in depth suggestion to my problem,that I have solved.
The rear caliper is an underslung one on the disc,thus it tends to cause an airlock in the pipe going up to it from the master cylinder,the trick is to remove it and get it above the cylinder so the air bubbles can travel up up and away 😁
I decided in the end to just remove both the caliper and master cylinder as a complete unit.
Placed the caliper in my vice and let the master cylinder with the brake pedal hang down.
And proceeded to bleed the system,this did the trick and all well and good now 👍
It might seem a long way around the problem but it really did not take much to remove the brake system.
As having time on my hands being a retired old codger 😁

Thanks once again for the reply sir👍
Back to top
View user's profile Send private message
ladolcevita7



Joined: 02 Dec 2015
Posts: 44
Location: Manchester

PostPosted: Sat Aug 01, 2020 10:49 am    Post subject: Re: Rear brake Reply with quote

Jonny B Bad wrote:
Rear m/c uses an O ring as a dust seal. This gets upbraided over time, absorbs fluid and grips the piston, preventing it from returning freely under spring pressure. If the m/c has never been opened, get a repair kit or replace the master with a new one - I presume itís a 13mm. Should be marked as 11 or 13. Iíve just re-furbed both master and calliper, i.e. both bone dry and the system bled up in a couple of minutes with a pneumatic vacuum bleeder.


Thanks for the info Johny and I will bear that in mind,I did have a look at mine and it seemed to be ok
But only time will tell 👍
Back to top
View user's profile Send private message
brian



Joined: 22 Aug 2011
Posts: 3568
Location: Australia

PostPosted: Sat Aug 01, 2020 1:07 pm    Post subject: Reply with quote

Glad you got it sorted mate 👍👍
_________________
Current motorcycles - '99 Bimota DB4 #104, '96 Bimota SB6 #1165, Ď94 Bimota DB2 J #652, '99 Bimota DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, Ď94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, Ď61 BSA A10 650
Back to top
View user's profile Send private message Send e-mail
DB1 860



Joined: 23 Mar 2014
Posts: 147
Location: Sydney

PostPosted: Sat Aug 08, 2020 2:36 am    Post subject: Reply with quote

I had a similar problem with the clutch on my DB4... it wouldn't bleed right... turned out the master needed a new seal kit.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Bimota Forum Forum Index -> DB Series All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group

The Bimota Forum has no official connection to Bimota S.p.A.. We just ride or are interested in their motorcycles and support the brand. All trademarks are acknowledged