5th gen brake delink, front brake won't release

[andybutton]

Hi all, first time poster hope you can help!

 

This issue is driving me up the wall. As part of a much needed general overhaul on my high mileage 1999 5th gen VFR 800 I have ditched the linked brake system and replaced it with a HEL kit. The one problem that I haven't been able to solve is that the front calipers will grip just fine but they won't release and I'm now pretty desperate having missed riding all of this summer. Starting from the bottom - I have replaced the rotors, the pads, the seals, the pistons, the hoses (now 2 braided, one to each caliper from the MC) and serviced the master cylinder. I have also checked that the tiny return hole in the master cylinder isn't blocked.

 

What else can I do? The only other thing I can think of is that ratios might be wrong between the master cylinder and the pistons now, I'm only using the 2 outer pistons on each caliper but I've no idea how to do the maths for that. I had to downsize the MC for the rear and that works fine but I just tried that and got lucky.

 

Help!

 

(Photo is prior to delinking. It's a UK 50th anniversary edition but the yellow flashes on the side looked terrible so we've left the Honda racing team and joined the rebel alliance)

 

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[JZH]

What did you do about the bracket on the LHS front?  And the other DCBS-related stuff?  Pictures would be useful.

 

The master cylinder for the front should be perfect with just the two outer pistons on a 5th gen--that's exactly the same thing the front m/c controlled before you de-linked it.

 

When you say "won't release", do you mean they drag, or are full-on?  Did you rebuild the front master cylinder?  My guess would be that the problem is located there...

 

Ciao,

[VFROZ]

Make sure the pin between the front lever and the master cylinder piston is the right way around, it fits both ways but only works one way. 

it it's wrong, it will apply pressure but it doesn't let the piston go back far enough to release. 

[andybutton]

Hi guys, thank you for quick response.

Can't get pictures right now but to clarify, the brakes are dragging rather than jammed on. I did rebuild the mc so I will look at the pin tomorrow.

The lh front bracket (I guess you mean the secondary master cylinder that would ordinarily trigger the system to activate central piston at rear) is filled with fluid and blanked off with a bolt as per instructions in the delinking kit.

All the other DCBS bits are in a carrier bag at the back of my garage! The rear brake has a single line operating the two outer pistons and I had to exchange the mc for a much smaller one due to ditching most of the pipework. This system provides sufficient power to lock the back wheel if I want though but still gives good feel and control. A second line came in the kit to feed the centre piston but I couldn't get it set up right with that and it doesn't appear to be necessary.

Will report back tomorrow after I've examined the pin.

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[RVFR]

Yes,  check that pin in the master,  it's done a few in.  Other than that I'm at a miss to whats going on.

[andybutton]

Well, you were absolutely correct - the pin was the wrong way round. The stupid thing is I had read about this and been super careful to make sure I didn't flip it when I serviced the MC which means it must have been like that since before I bought it! No wonder the rotors were so deeply troughed. The bad news is that it wasn't the magic bullet I was hoping for, they are still dragging. I've bled them again to rule that out. The only ray of hope is that they are easier to release now than before, a firm push on the sides of the calipers has the wheel running free again.

I'm hoping it's just a bedding in issue from all the new components so I'm going to go round the block a couple of times and see if that helps.

I can't thank you guys enough for your help though, it had to be something daft that I was missing but it had really got me at my wits end! Sincerely, thank you.

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[Terry]

Make sure that the sliding pins that the calipers sit on are well greased.

[zupatun]

"dragging"...is not so specific...

 

Calipers won necessarily push in ans pull back...the brake system doesn't cycle in and out...there will be "some" drag...but for the most part the wheel should spin if spun while front is off the ground...

 

Matt

[andybutton]

Heh, one step forward, one step back - got ready to go round the block and found that the rear brake was non-existent. Turned out that the cheap master cylinder that I had got working for the rear brake didn't have a proper hose from the reservoir to the cylinder and the fluid had sweated out through it. Ordered a CBR F4i cylinder/hose/reservoir and will be fitting that instead, also repainting the heat shield where the paint has now bubbled off!

Thank you again for the extra advice guys.
@zupatun - with the front propped up in the air the wheel was still not as free as it should be even after bleeding, I really expected reversing the pin to have a greater effect. It's a lot better than it was but I still don't think it would pass MOT vehicle test in the UK. If I push the calipers together with my hands it's easy enough to release the remaining excess pressure so the wheel spins freely (I can still hear light contact with the pads) but then the brake lever goes limp and it takes 3-4 pumps to repressurize and I'm back to the same situation.
@Terry - I have read so much conflicting advice about what type of grease to use and how much that I've got no confidence with this. Is there any consensus of opinion here?

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[mello dude]

I'm being a bit of an ass but IMHO replumbing the existing  linked brake gear is a exercise in futility such as you are experiencing today. Plus now you are carrying around 5 pounds of unsprung weight on your forks. Most of us that wanted normal brakes have gone to the step of changing the forks and adding Honda sport bike calipers. There are plenty of examples on this forum, but the simplest way for the 5th gen using Super Hawk lowers on the VFR800 uppers. That will allow serveral available Honda calipers to be a straight bolt on exercise. Photos to follow.....

 

I know this doesn't fix your current dilemma - Wish you the best to work it out and get riding...

 

Beers to you

 

[andybutton]

@mello dude Ok, I have read some accounts of that being done, but it seemed more extreme than I was comfortable tackling and the ready made kit *seemed* the simplest solution. Simplest doesnt necessarily equal simple! I also thought it was a US only bike making it a trickier proposition (I now realise we got it over here as the Firestorm.) Please bear in mind I've started this whole project as a complete novice so everything has been a completely new experience, but I'd built some confidence replacing the whole cooling system, the exhaust headers, repairing/replacing a hundred other corroded bits and bobs before ripping out the braking system. This problem has always felt like I'm juuuuust a step away from solving it but it's been stopping me for months now so you might be right!

 

I'm a bit confused by your comment about me having extra weight on the forks though? If anything surely I've reduced weight significantly in all the hoses and valves I've chucked away? Unless you mean the redundant central pistons?

 

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[Terry]

Metal sliding on rubber = silicone grease. But if you had none, a good clean out and any high temp grease should do a decent job.


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[Terry]

11 hours ago, andybutton said:

Heh, one step forward, one step back - got ready to go round the block and found that the rear brake was non-existent. Turned out that the cheap master cylinder that I had got working for the rear brake didn't have a proper hose from the reservoir to the cylinder and the fluid had sweated out through it. Ordered a CBR F4i cylinder/hose/reservoir and will be fitting that instead, also repainting the heat shield where the paint has now bubbled off!

Thank you again for the extra advice guys.
@zupatun - with the front propped up in the air the wheel was still not as free as it should be even after bleeding, I really expected reversing the pin to have a greater effect. It's a lot better than it was but I still don't think it would pass MOT vehicle test in the UK. If I push the calipers together with my hands it's easy enough to release the remaining excess pressure so the wheel spins freely (I can still hear light contact with the pads) but then the brake lever goes limp and it takes 3-4 pumps to repressurize and I'm back to the same situation.
@Terry - I have read so much conflicting advice about what type of grease to use and how much that I've got no confidence with this. Is there any consensus of opinion here?

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If you still have your original twin hoses for the back caliper, you can connect these together at the CBR600F4 master using a double banjo bolt. I know when I de-linked my brakes there was a spare double banjo somewhere in all the original lines that I used. The line that previously went from the PCV to the back caliper will reach the master like it was meant to go there. IIRC the CBR master has threaded mounting holes and you need to drill the threads out when you mount to the VFR, and shorten the pushrod.

[RVFR]

5 hours ago, mello dude said:

I'm being a bit of an ass but IMHO replumbing the existing  linked brake gear is a exercise in futility such as you are experiencing today. Plus now you are carrying around 5 pounds of unsprung weight on your forks. Most of us that wanted normal brakes have gone to the step of changing the forks and adding Honda sport bike calipers. There are plenty of examples on this forum, but the simplest way for the 5th gen using Super Hawk lowers on the VFR800 uppers. That will allow serveral available Honda calipers to be a straight bolt on exercise. Photos to follow.....

 

I know this doesn't fix your current dilemma - Wish you the best to work it out and get riding...

 

Beers to you

 

LOL you sound just like me..    good form,  but yea.. it's for some, others , not so much.

[andybutton]

Metal sliding on rubber = silicone grease. But if you had none, a good clean out and any high temp grease should do a decent job.


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You're a star (I hope!) thank you, I'll get some.

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