I've done a ton of research now on the linked braking system for my 1998 VFR. After all the research and looking at my mechanical ability, I decided to have the local Honda dealer here in Minneapolis complete the brake flush... After 2.5 weeks of having the bike, the tech narrowed the issue down to the PCV valve. He was able to get all the other points to bleed fluid just not the PCV valve. HERE IS THE PUNCH TO THE FACE.. The dealer can't get the PCV part from Honda anymore... 😞
I asked the tech to get the bike as rideable as possible so I can come and pick it up. He stated to just use the front brake on the ride back from the dealer to my house.
Real bummer is that now I have to pay for all the time they spent on it and it's still not fixed.. Partszilla says its discontinued as well.
Any encouragement or thoughts would be super helpful. Winter is coming and I guess this bike is not meant to be ridden this year.
Lastly?? What options do I have? De-link the brakes? hold out for a used one?
Look up 2001 part. I had that happen on another part for my ‘99. Wasn’t available on parts fishe for ‘99, but was on ‘01.
I don’t think I kept my PCV valve when I changed my forks, but if I find it you can have it for shipping. It’s bound to be on eBay though. Those breakers generally take it down to every last nut and bolt.
Look up 2001 part. I had that happen on another part for my ‘99. Wasn’t available on parts fishe for ‘99, but was on ‘01.
I don’t think I kept my PCV valve when I changed my forks, but if I find it you can have it for shipping. It’s bound to be on eBay though. Those breakers generally take it down to every last nut and bolt.
The dealer told me that the 2001 was made different than the 98 and 99 models... But I have no clue if this information is accurate.
I looked up the parts on Partzilla, none of the 5G PCV show as available. The 6G part is available for $60, but I have no idea if that would interchange. So your options are wreckers or a part from a different model. Or you could try and repair it.
The PCV function is designed to stop the rear brake from locking up due to weight transfer. As you crank on front brake and the SMC compresses, it applies more and more pressure to the rear caliper at a time when weight is transferring to the front end. The PCV relieves the excess pressure and allows it to drop and reduce rear brake pressure to the centre piston. I would expect that the function won't change between models but the fine details e.g. spring rate or piston size might.
From the schematic and the external appearance it looks like you could remove the two screws and the spring and I assume that will enable removal of the internal components for cleaning. I'm betting there is a gunk build-up that is stopping fluid flow but no actual parts damage.
In the interests of science and because I happen to have a surplus PCV from my 99 VFR just lying around (delinked the brakes and sold the bike earlier this year) I did some disassembly. Very simple to pull apart to clean the parts and easy to reassemble. The 3 screws holding the cap on have threadlock and needed some persuasion, once that is off there is a large spring that applies tension to the decompression piston. That pulls straight out with a couple of rubber piston seals affixed. On the end of the cut valve is a small circlip, push the cap in and dig the clip out. I used a small self-tapping screw in the end of the cap to extract it. Then there is another smaller spring, and finally the cut valve itself which has another piston seal. This leaves the cast body which you can squirt brake cleaner/air through. Reassembly is the reverse of disassembly (as they say in the Haynes manual).
In the interests of science and because I happen to have a surplus PCV from my 99 VFR just lying around (delinked the brakes and sold the bike earlier this year) I did some disassembly. Very simple to pull apart to clean the parts and easy to reassemble. The 3 screws holding the cap on have threadlock and needed some persuasion, once that is off there is a large spring that applies tension to the decompression piston. That pulls straight out with a couple of rubber piston seals affixed. On the end of the cut valve is a small circlip, push the cap in and dig the clip out. I used a small self-tapping screw in the end of the cap to extract it. Then there is another smaller spring, and finally the cut valve itself which has another piston seal. This leaves the cast body which you can squirt brake cleaner/air through. Reassembly is the reverse of disassembly (as they say in the Haynes manual).
This is amazing and makes me think I might try this first and use the ebay as a back up in case.
Terry, I’ve searched quite a bit on the forum for a discussion thread on delinking. Wondering what the process entails and if others have found it a valuable modification?
I'm indifferent to the linked brakes, they are complicated but functionally they are kinda nice for street riding. If I had a problem with my linked brakes I'd fix it rather than properly de-link as I think to do it properly would be a large undertaking. Plus these are old bikes and there are tons of cheap used parts out there to fix any aspect of this system.
Getting new fluid into all the far reaches is the hard part of the linked brakes and I suppose things get stuck due to the lack of this maintenance.
You might want to take apart and clean both the stuck one and the ebay valve and install whichever one is the least sketch.
When I delinked I also swapped to CBR954 calipers and CBR600RR master, to fit those you need VTR1000F fork lowers as the caliber mounts are different. At the back use a different Honda master and join both brake hoses to that with a double banjo bolt, leave the caliber alone.
You could possibly leave the forks and use the std calipers but you’d need to include the 3rd pistons either externally or by internal drilling, and a master cylinder change.
Update: so I was able to replace the PCV and get it to bleed.
However, now the rear caliper is locking up and not releasing unless I loosen the bleed point on the rear caliper. I tried the blunt blow to the rear caliper in case it was hanging up - did not solve the locked wheel.
I have been able to get the Secondary master cylinder on the front forks to bleed in the past. It has not been rebuilt though.. ??
Im wondering if I need to rebuild the Secondary master cylinder now? Wondering if that is what is causing the hang up of the real caliper on the wheel. Or should I rebuild the rear caliper as well??
If all is well in the caliper (moving freely on the slide pins and the pistons are free) then I think you do indeed need to be looking at the SMC. In order for the rear centre pressure to release, the compensation ports in the SMC need to be clear and allowing fluid to flow back from the caliper. There are two ports, one in the casting as per normal, but there is a second one in the plastic one-way valve that is just under the banjo fitting, you'll know it when you see it. I'd be popping that out and flushing it well and then making sure the whole SMC is clean and the piston is moving freely. There are also some critical dimensions for the clevis to screw onto the shaft, if there is not enough movement the piston can't retract far enough to uncover the compensation port, so measure that before you disassemble it (actually the manual says not to disassmble the clevis from the piston, just to replace as a unit).
First let me state that I've never had issues with the linked brake system. So now let me defend them.
Motorcycle Consumer News used to publish use mc prices periodically. At the end of the article they published top performers in several catagories, one of which was 60 - 0 mph braking distances. The 1998 VFR800fi tied for 6th best at
108.something feet. Motorcycle reviews state that 120 feet is considered great. I'm a firm beliver of linked brakes.
Additionally, when taking advanced rider training at a local track, when practicing trail braking, the coaches explained to me that the linked braking system is effectively trail braking when used.
And I make it a habit to use both front and back brakes together. Makes the brake pads, front and rear, wear more equal.
You have two bleeders on thecrear caliper. So whichever one releases the piston(s) is the culprit. I haven’t had linked brakes in a while, but the SMC operates the center piston? I can’t remember which bleeder.
Could also have the rubber line delaminating inside and blocking return flow.
I would also disassemble and clean thecrear caliper. If the O-rings are not torn I generally reuse them.
I just went through similar pain and the issue was not the PCV or rear caliper but the SMC. I could write dissertation on the what I went through but ultimately it was the SMC that was not allowing the rear piston to release. Good news is that the SMC is still available, although not cheap @$128 but it was what resolved the issue I dealt with. You can try and rebuild and clean out the SMC before spending the $ on a new one but in my case the SMC was a little too far gone for a good recovery. I’m pretty sure my post about it covers what was done and where I ended up.
I hope this is helpful...
D
End of thread · 23 posts recoveredWayback Machine snapshot 23 Oct 2019