Inconsequential ramblings of an Old Git

[mangocrazy]

Fz6 Fazer came with a 16mm Brembo master cylinder, that should give you the intended size bore / physical leverage combo, and the compatibility/clearance with Yamaha switchgear.
https://www.ebay.co.uk/itm/185516056399 ... media=COPY

Mmmmm, choices. That would also give me a span-adjustable brake lever, but would need a different brake light switch cable. And I'm taking the chance that a Brembo 16mm would have the same lack of feel as a Nissin 15.875mm m/cyl. But frankly, I doubt it. And it would work with the OE Yamaha mirror.

I think it's worth giving it a go for £40...

I didn't take the LC for a spin today, but pushed it around and tried the front brake a few times. Feel wasn't great - wooden and graunchy and that is almost certainly down to the (40 year old) Nissin m/cyl. It's getting replaced.

[A_morti]

Graunchy? Don't lose sight of the basics in all this experimentation, it may just need a squirt of silicon based (rubber safe) grease where the lever contacts the master cylinder piston, and/or where the lever pivots in the master cylinder body.

[mangocrazy]

The (OE 5/8") master cylinder has had a new piston/seal kit fitted and the bore cleaned up with fine scotchbrite. It was reassembled with red rubber grease on the seal/bore and on the bearing surfaces between lever and piston, so I've done as much as I can to make the operation smooth. Even after all that, and with no brake fluid in the system, the lever action felt a bit rough and notchy.

So I'll be replacing it with either the Brembo one you linked to (purchased and paid for) as first choice, or a 14mm Nissin if the Brembo doesn't cut it.

I'm really hoping the Brembo one works well.

[Skub]

Brakes and m/c ratios are a veritable rabbit hole. On one of my ZZR11s I think I used more brake fluid than petrol.

[mangocrazy]

Brakes and m/c ratios are a veritable rabbit hole. On one of my ZZR11s I think I used more brake fluid than petrol.

Tell me about it, especially when you are mixing brands between calipers and m/cyls, as I have been.

Hopefully an all-Brembo setup will fix it.

[mangocrazy]

Yesterday I flew back to France for a couple of weeks and today I've been shopping on the VFR. A few months prior to this I'd fitted a new set of taper roller head races and hadn't tightened them up enough, giving rise to pronounced clonking (technical term) from the front end. This was exacerbated by the shock having too much preload and the two ends bouncing off each other. I'd made adjustments to the head races (about a quarter turn of preload) and reduced rear spring preload to solo settings, so now it was time to test it out.

Result is much improved, but when negotiating sharp-edged road humps at speed the clonking on rebound was still present, albeit greatly reduced. Also there was still some juddering when using the brakes from speed, so a bit more preload adjustment is indicated,

Shock felt miles better and the bike steered very nicely, so we're getting there.

[mangocrazy]

I got back from France last night about 8:30 pm and now have unlimited internet access (compared to savagely limited access in France), so I can get back to posting shite on here. I'm sure you're all delighted...

I'm in something of a quandary with the VFR; I've tightened the head races up 2 or 3 times to the point where the steering has been adversely affected; it feels like I have an over-adjusted steering damper on the bike, but the 'clonking' still happens over sharp-edged bumps. I'm perplexed... Next time I go back I'll get the rear on a paddock stand and jack the front off the ground and see what I can figure out. Something is definitely amiss.

When I got back a parcel containing a 16mm Brembo front brake master cylinder was waiting for me, and earlier today I removed the 16mm Nissin item and replaced it with the Brembo. The difference in feel between the two is frankly amazing. The Nissin felt scratchy and harsh, but not particularly powerful whereas the Brembo feels smooth, progressive and has bags of feel and power.

I suppose I shouldn't be surprised - I don't recall many people complaining about the brakes on a Ducati 916 and that is effectively what I have on the LC now. So I owe a debt of thanks to @A_morti - your suggestion was spot on and I thank you for that.

[Skub]

Maybe worn fork bushes giving the impression of loose head bearings?

Sometimes you can get a click from floating discs too.

[A_morti]

@mangocrazy never mind about rambling, thanks for updating the thread and glad you have your fix!

[mangocrazy]

Maybe worn fork bushes giving the impression of loose head bearings?

Sometimes you can get a click from floating discs too.

I did think of play in floating discs being a possibility, and to be fair there is some up and down play between disc/bobbin/carrier, but when you go over a sharp-edged bump you can feel the shock through the bars as well as hear it, and it feels/sounds a bit too sharp for a disc issue. But I'll definitely be checking that when I go back.

Doesn't feel like fork bushes as it's less of a judder and more of a hard knock.

The other thing I was thinking about is whether the top out springs in the forks are missing or gone soft. If I can't find any other problem, I'll need to strip the forks. They could probably do with an oil change anyway.

[A_morti]

Is it necessarily from the front end?
Could be a bad rear suspension linkage bearing.
Shouldn't be too hard to locate if the bike has a centre stand, but potentially a swine if not.

[mangocrazy]

It does definitely feel like a front end issue. I can feel the shock through the bars as well as hear it. And VFRs do have centre stands, but mine doesn't, which does make the whole process a lot more troublesome. The problem is exclusively when going over low road speed, sharp edged bumps like road humps or those plastic speed bumps the French love to put in Supermarket car parks. The front end knocks, the back end goes over OK. I've tried increasing rebound adjustment on the forks, but that hasn't fixed it.

[A_morti]

On general principle, it's more likely to be something that was touched in the last round of works rather than something coincidentally wearing out around the same time. So I'd push worn-out fork bushings and top-out springs to the back of my mind, and start with checking tightness of anything that was touched to get at the neck bearings: fork pinch bolts, yoke pinch bolts, handlebar pinch bolts, etc. Could even be the mudguard moving if the shoulder bolts aren't tight enough, as loose plastic parts can make a heck of a noise.

After that I'd be making double and triple sure the taper bearings are installed properly, seated fully, etc. Tapered bearings do need a little preload on them, if you don't have enough they can slide around in there. In case you don't have two C spanners or one and the fancy socket to torque the castle nuts, they may have backed off too.

If that still didn't get it, then if yours has the CBS with the extra master cylinder on the fork leg, have a good look at it as they can seize (it did on my dad's vfr800) and depending how and where it stuck, that could knock.

Only after all that would I be worried about the forks having suddenly worn out at the same time I changed the neck bearings.

[A_morti]

If you can find an assistant, park the bike against a wall and work the clutch to load and unload the front end. Hopefully that replicates the fault and a well-placed finger can identify it.

[mangocrazy]

The clunky front end has actually been around for a while now, and was the reason I replaced the steering head bearings a couple of months ago. They needed doing, as there was wear in the (old) taper rollers, but the clonking/knocking issue remains even with new Koyo taper roller bearings installed. When I get back to France (probably spring 2023) I'll do as you suggest to track down the source and also strip the front end completely. The bike is an early VFR750 (pre single sided swingarm), so no CBS.

[Mr. Dazzle]

The solution is gonna be rhe same in all cases. Replace something in the forks.

Rebuild the forks, do not pass go, do not collect £200

Now that I've said that you're gonna find the seat is just loose.

[mangocrazy]

The solution is gonna be rhe same in all cases. Replace something in the forks.

Rebuild the forks, do not pass go, do not collect £200

Now that I've said that you're gonna find the seat is just loose.

It could be, I give you that. But the problem could just as easily be in the steering head/triple clamp area or even the discs. But I can't see myself finding out this year, more likely next spring.

[mangocrazy]

I've not felt like updating this thread in the last month or so, mainly 'cos there's little to report. But I haven't been completely idle - The Falco has been measured up for a belly pan (suits you, sir...) and said BP has been ferried to the paint guy who has had my top fairing since February (mutter, mutter). So when he paints the top fairing (when?) he can kill two birds with one stone. It's all a cunning plan to divert attention away from the bars...

The faulty rear wheel speed sensor has been replaced by a used one of unknown provenance, so that could go either way. If all else fails, I'm reliably informed that a Vauxhall Corsa cam position sensor both fits and works exactly the same as a reassuringly expensive Aprilia OE part.

I've also been trying to make sense of the mounting pile of spare brake calipers and clutch and brake master cylinders that are taking up space on the bench. That's making sense as in trying to stop them corroding into a pile of worthless fur. Earlier in the month I stripped the OE 350LC Nissin calipers, cleaned out all the manky brake fluid and red rubber greased all seals and sliding pins, then stashed them away somewhere warm and dry. I also did the same to the 1/2" and 5/8" Nissin master cylinders i've tried on the LC. I remember what a horror show greeted me when I came to try and salvage the LC calipers after they'd been left for a decade or two with old brake fluid in them, and have no desire to go through that again.

In the last couple of days I've turned my attention to the OE brake calipers fitted to the Ducati 888 and the Falco, both of which haven't been touched in 10 years. Thankfully the pistons weren't seized and still moved, so I was able to split the calipers, remove all the pistons without damage and remove all the seals from the caliper bodies. Deep cleaning of caliper halves, pistons and seals will wait until I have unobstructed and unobserved use of the kitchen facilities next week when Mrs Mango has to go to work. There are definite advantages to being retired...

[mangocrazy]

While the cat's away the mice will play...

Made a start on the Brembo Goldlines I removed from the Falco way back when. These had been sitting unloved down in the cellar for at least a decade, so I was very pleased with the way they scrubbed up. Lots of elbow grease, green Scotchbrite, P21S cleaner and a stainless farkling tool got these parts the way you see them.

I reckon they're © Weeksyclean...

DSC_5965.JPG (764.73 KiB) Viewed 352 times

[Skub]

After a lifetime of finding my fly encrusted visor wrapped in kitchen roll,or various bike parts on the drainer,Mrs.Skub had a sink fitted in the garage.