Inconsequential ramblings of an Old Git

[mangocrazy]

Dave reckons that 40hp is a baseline for a standard 350LC. Mine did have a Terry Beckett road tune back in the early 80s, so that should account for the couple of extra hp. I've no plan to start modifying it further - I'll fit the Brembo front calipers and mounting adapters I have waiting in the wings and then that will be it.

In the early 80s I threw loads of stuff at it - AP Lockheed front caliper and master cylinder conversion, box section steel 50mm longer Hejira swingarm, 35mm Marzocchi forks, Ducati Pantah lookalike fairing etc. etc., but I'm not heading down that path again. It stays (relatively) standard and just gets ridden...

[mangocrazy]

As I alluded to at least 3 pages ago, I've bought a set of caliper adaptors for the LC to enable me to uprate the brakes by fitting a pair of mid-90s 4-pot Brembos to replace the single piston sliding caliper originals. And while I was at it, I had the urge to Paint it Black.

After playing this classic single I then decided that the Brembos would look better black as well, and sent them off to be done. Various things got in the way and it's only been this weekend that I've managed to get all the bits I needed, fit them and bleed the buggers. They are now fitted, I'm happy to say.

DSCF3265.JPG (583.93 KiB) Viewed 423 times

They're probably overkill for a 43bhp early 80s bike, but I always prefer having too much rather than too little front brake. Ask me again after I've locked the front wheel a few times...

And I'm already regretting having them painted rather than powder coated. When brake fluid touches the paint it goes very slightly 'sticky'. Still, always the winter to get that put right. Other than that I am a very 'appy...

[KungFooBob]

Are you using the original M/C?

The bore to piston area ratio might be all to cock.

Those Brembo Goldline calipers did come in black as standard on some of the cheaper Ducati models.

[mangocrazy]

M/cyl size is something I'm experimenting with. As standard the 350LC calipers and m/cyl weren't very well matched - the m/cyl bore was too large (5/8") and made the brakes feel very wooden. Most people fitted the 250LC m/cyl intended for a single caliper, which was a 1/2" bore and gave much better feel at the lever.

I've kept the 1/2" 250LC master cylinder and to be honest it is rather on the spongey side - lots of lever travel. I'm going to try it out for a bit but will probably go back to the 350LC m/cyl that I'm refurbishing. I reckon that should be about right.

My Ducati 888 had the very early black Brembo 4 pot calipers with all pistons the same size. They weren't quite as good as these ones, which have the smaller trailing piston. Ducati fitted these as standard to early 916s.

[Supermofo]

I seem to recall the Duke II had a Brembo Goldline caliper, also seem to recall it being better than the radial one on the 690 in terms of feel.

Didn't the TZR 250 have an FZR 1000 caliper? It's a long while ago but them brakes were very good. Not KR1S good but decent enough

[mangocrazy]

I seem to recall the Duke II had a Brembo Goldline caliper, also seem to recall it being better than the radial one on the 690 in terms of feel.

I've heard a number of people say that. The radial caliper on my 690R is the most powerful one I've ever tried, and has good feel. But it is the genuine Brembo M50 caliper, not the Indian made 'ByBre' jobbie. It's also matched with a Brembo radial m/cyl. The best non-radial calipers I've used have been the 4-pot 4-pad Brembos that were used on the 999 and Aprilia Factory models.

Didn't the TZR 250 have an FZR 1000 caliper? It's a long while ago but them brakes were very good. Not KR1S good but decent enough

Could well be. I seem to recall that they were opposed-piston jobs, not the rubbish sliding caliper design they'd previously used.

[Supermofo]

I seem to recall the Duke II had a Brembo Goldline caliper, also seem to recall it being better than the radial one on the 690 in terms of feel.

I've heard a number of people say that. The radial caliper on my 690R is the most powerful one I've ever tried, and has good feel. But it is the genuine Brembo M50 caliper, not the Indian made 'ByBre' jobbie. It's also matched with a Brembo radial m/cyl. The best non-radial calipers I've used have been the 4-pot 4-pad Brembos that were used on the 999 and Aprilia Factory models.

Ah yes you have the R! They have the M50 caliper so are probably top. The standard 690 Duke still has a Brembo caliper but wasn't amazing imo. Could be rose tinted glasses but seem to remember my Duke 2 and 625SMC being better braked. Or it could be I'd come off an R6 which had better brakes

[weeksy]

I seem to recall the Duke II had a Brembo Goldline caliper, also seem to recall it being better than the radial one on the 690 in terms of feel.

I've heard a number of people say that. The radial caliper on my 690R is the most powerful one I've ever tried, and has good feel. But it is the genuine Brembo M50 caliper, not the Indian made 'ByBre' jobbie. It's also matched with a Brembo radial m/cyl. The best non-radial calipers I've used have been the 4-pot 4-pad Brembos that were used on the 999 and Aprilia Factory models.

Ah yes you have the R! They have the M50 caliper so are probably top. The standard 690 Duke still has a Brembo caliper but wasn't amazing imo. Could be rose tinted glasses but seem to remember my Duke 2 and 625SMC being better braked. Or it could be I'd come off an R6 which had better brakes

Could have been pads ? I stuck a Brembo SA into my Dukes and they were absolutely brutal in terms of stopping power.

I don't even know what's in the SMC-R but neither me, @Couchy or @Tricky had any issues at Donington with it, so i'm happy to ignore

[mangocrazy]

I've finally had the opportunity to get out on the LC for the first time since it's been on Dave's dyno and had the Brembos fitted, and the changes have completely transformed the bike. Previously the 'black hole' between 4500 and 5500 had adversely affected just about every aspect of the bike's performance and usability. Dropping out of the powerband meant going down the box at least one gear and probably two. Trying to ride on a constant throttle was all but impossible as the engine would either bog down if it was near the BH or be in the powerband and wanting to take off. It was all or nothing - no half measures.

Now I can ride the bike almost like a four-stroke. The bike will happily hold a constant throttle and will pull from 2000rpm to the red line without fluffing or bogging. There is a slight plateau at 5000 rpm, but it will pull through that without hesitation. And the top end is so much crisper and sharper - and faster! All the changes are overwhelmingly positive.

And the brakes, even though the pads aren't fully bedded in yet, are just so much more effective and reliable. There's some real stopping power now and that will improve further in the short term. The lever action is a bit spongey, but it's perfectly manageable. I do have the original 5/8" bore m/cyl waiting to go on if needs be, but the 1/2" one is doing a job for the moment.

Definitely a happy bunny...

[Le_Fromage_Grande]

I think a 14mm master cylinder would be right for your calipers, 5/8 (15.9mm) might be a bit too big. 1200 Bandits have a 14mm master cylinder that doesn't look that different to the original LC one.

[mangocrazy]

I think a 14mm master cylinder would be right for your calipers, 5/8 (15.9mm) might be a bit too big. 1200 Bandits have a 14mm master cylinder that doesn't look that different to the original LC one.

Yes, that sounds like a good idea. I'll check out a 1200 Bandit m/cyl - thanks.

<edit> Just found out that a Yamaha TDR250 also used a 14mm front brake m/cyl and it's a perfect visual match with the LC one, and also uses the same mirror and brake switch mounts...

[Skub]

I found this a handy reference point.

[mangocrazy]

That's very impressive, but I'm not sure what it tells me. The calipers I'm using have diferent size pistons (30/34) with the larger piston on the leading edge. I guess I'd need to add up the piston areas for 2 x 34mm and 2 x 30mm and then work from there. And unfortunately 34mm pistons aren't referenced on that chart. (But Pi is your friend).

[mangocrazy]

Digging further in the darker reaches of t'Internet I stumbled across this page, written by a chap whose handle appeared somewhat familiar - a certain @A_morti no less:

https://www.customfighters.com/threads/ ... r-s.56704/

Following his maths (seems like the spreadsheet is NLA), came up with the following 'feel ratios' (you'll need to read the page to get the idea):

All figures are based on 2 x Brembo Goldline calipers with 2 x 34mm and 2 x 30mm pistons per caliper and Nissin master cylinders in 1/2" (12.7 mm), 14mm, and 5/8" (15.9 mm):

M/Cyl.........Feel Ratio
1/2"............25.6:1
14mm..........20.96:1
5/8"............16.3:1

According to the author's findings, for dual calipers a 'feel ratio' of around 17:1 is ideal. On dual calipers <15:1 is wooden, and >19:1 is spongey. The author stresses that this is personal preference, not a hard and fast rule.

So according to the above, my 5/8" Nissin master cylinder should give best results. Should...

Anyway, tomorrow I'm fucking off to the South of France for 3 weeks and the LC isn't coming with me, so the point is moot until mid-September. But as I already have a 5/8" Nissin m/cyl, that's what I'll be trying first. If it's crap I'll try a 14mm.

[Skub]

That's very impressive, but I'm not sure what it tells me. The calipers I'm using have diferent size pistons (30/34) with the larger piston on the leading edge. I guess I'd need to add up the piston areas for 2 x 34mm and 2 x 30mm and then work from there. And unfortunately 34mm pistons aren't referenced on that chart. (But Pi is your friend).

I think a ratio of around 27 is a two fingered feel and anything less than low 20s gets a bit wooden. As ever,feel is a bit subjective!

[A_morti]

Digging further in the darker reaches of t'Internet I stumbled across this page, written by a chap whose handle appeared somewhat familiar - a certain @A_morti no less:

I had much of that from an even older site which might or might not still exist. Something about classic bike racing I think. And the rest from piddling about with brakes on a few of my old bikes.

With your 30/34 pistons, the usual 5/8" nissin master cylinder will be a good match, the 14mm will be spongey. I tried both combinations back to back when I put gsxr tokicos on an early blade with rusty calipers. The caliper pistons went up from 27/30 to 30/34 and the original 14mm master cylinder was too small. 5/8" master made it work well.

[mangocrazy]

Cheers, much appreciated. I'd never realised there were so many variables to consider, and how Nissin (and other Japanese) master cylinders are different to Brembos with respect to pivot pin to piston distance and other little gotchas. In the past I've used Brembo m/cyls with Brembo calipers or Nissin m/cyls with Nissin calipers and not mixed the two. But in this case for a mixture of originality and performance I do need to mix the two. When I get back from France I'll get on it and report back.

Thanks again.

[Mr. Dazzle]

Silly as it might sound, just changing whereabouts on the lever you pull makes a difference too! And/or moving the mounting left/right and changing the adjustment so you've still got the same span but you're gripping the lever closer/further from the pivot.

S'just GCSE* physics of trigonometry, levers and hydraulics after all.

*O Level.

[A_morti]

@mangocrazy there is a good reason to stay with the original brand master cylinder. Other brands may not clear your switchgear, and may have different terminals for the brake switch.

[mangocrazy]

@mangocrazy there is a good reason to stay with the original brand master cylinder. Other brands may not clear your switchgear, and may have different terminals for the brake switch.

Yes, I'm staying with Yamaha-specific Nissin, as then mirror mounts and brake light switch mounts all match up and work the same way.