Proportioning valve:Is it adjustable?

The rear brake pedal on my Gen 5 doesn't do much of anything unless I practically get off the bike and stand on it with both feet; the front brake takes just two fingers to stop the bike RIGHT NOW.

Can I tweak the proportioning valve to get the rear working a bit better? Right now the rear's not really pulling its weight, and if delinking weren't so involved I'd do it in a heartbeat.

 

No, but you should flush the old fluid out and bleed the system. While you're at it, clean the rear caliper, as this does contribute. When I bought my 5 Gen the rear brake was similar in action until I cleaned up the caliper and bled the system really good.

 

Did all of this when I got the bike approx. 3,000 miles go, and installed new pads at the same time.

I'm an old roadracer and largely unaccustomed to using the rear brake at all, but because this one contributes to front braking I have to get in the habit of using it.

 

You're partially right, the rear pedal does trigger the front center pistons on both front calipers when pressed and the front triggers the rear only IF the front wheel is rotating. The secondary master cylinder on the left front fork uses the rotation of the rotor to trigger the rear center piston. Essentially, only 2/3 of the front (of each caliper) and 1/3 of the rear caliper are used when squeezing the front lever. I normally don't use the rear unless I really need to stop hard, other wise I use the front lever only, as it does do the rear brake ever so slightly. I find the front works well on it's own unless, like I said, I really need to stop hard.

When you bled the system did you also bleed the secondary MC and proportioning valve too?

 

Actually the de link ain't all that tricky, other than locating the parts to do it, even that ain't bad. just takes a bit of checking this an that. I just did this, and oh what an improvement. The rear on this vfr wasn't up to par either, and here its suppose to have two pistons doing the work, most rear calibers are one piston like the 4th gen, that rear brake was just fine, as is the one on the BMW. so kinda weird the vfr with it's fancy brake system can't do better. I too never used much rear except for that little bleed off of speed where I didn't want any dive. After the de link the rear is a bit better, not a lot, but better. I plugged off he center piston so it's two pots instead of what some do hooking the middle one up making it three, if I can real in some time, I'll be looking for another rear caliber, but yea, I feel your frustration. I was going to say the same thing OOTV did, pads and a re bleed Doh!! By looking it over says there's no recalibration for the proportioning valve.

 

Bang-on correct.

 

Well, when I say "I" bled the brakes, I mean I had them bled by a factory-trained Honda mechanic at my local dealer. I'm absolutely certain he did it by the book; I've known the guy for donkey's years and he's the only wrench in town I trust.

It appears from your description of the way braking is distributed front to rear that front-brake use only isn't giving away as much braking as I suspected. I feel a little better now about just ignoring the rear as I habitually do.

Still, it's a little frustrating. I had a GL1800 with LBS and it really responded well to rear-brake use along with the front. The pedal had a lot of feel, too. My VFR's rear-brake pedal might as well not even be there for all it seems to contribute. Only other thing I can think of is to take apart the pedal assembly and grease the pivot. I'm the third owner, and although the previous owner took good care of the bike (I've known him for years, too) greasing the pedal pivot is not, I think, considered routine maintenance.

 

I'm on the same situation... It just feels bad... I replaced master cylinder piston and seals suposing that the exhaust heat had hit on them, but it is still "rough".
The only part i've not cleaned or changed is the proportioning valve...
We need for sure a system to check and refurbish that proportioning valve... Delink should be for the "fast on closed circuit" people, but i'm more a all weather cruiser.

 

UPDATE:

My hunch about greasing the rear brake pedal pivot paid off.

I'm sure the day the bike was built someone smeared a dab of grease on the pivot, but I'm equally sure no one has done it since, until today. The pivot and the lever were bone-dry, so I dabbed a gob of hi-temp disc-brake grease in there (proximity to the headers made me go hi-temp) and now I can really feel the rear brake contributing when it's time to drop anchor. Effort at the pedal is lower, too, though it still requires a heavy boot (which I am fortunate to possess). It's as if I'm experiencing for the first time since getting the bike what LBS really does. I'd still rather have separate brakes, but I can live with this.