Inconsequential ramblings of an Old Git

[mangocrazy]

I just try and ensure all the evidence has been removed. It mostly works, but when it doesn't I know I'm in trouble...

[mangocrazy]

New Year, same old shite...

Last year I finally hit on a front brake master cylinder/caliper combination for the LC that gave me what I wanted - more power, excellent feel, while still looking (kind of) OE. The only problem was that the (eBay sourced) master cylinder was mechanically and hydraulically sound, but looking a bit crusty round the edges. And the calipers (being Brembo Goldlines) were a bit shouty compared to the black OE Nissins. So on December 6th I sent them all off to a chap I know who does excellent quality powder coating.

They didn't arrive until December 21st, by which time the chap in question was sunning himself in Cuba. So it wasn't until earlier today that the freshly powder coated parts made their way back to me. And when they did, I found that things were not as I'd hoped (I made my feelings known in the BYP thread in General Mayhem). Basically all the mating or sealing faces had been powder coated, not masked. So when fitting the calipers to the forks, there would be uneven powder where bare metal should be, likewise for all the faces where brake lines were to be connected, there was uneven powder instead of bare metal. I was not best pleased.

Faced with the option of sending them back for remedial work (with all the delays and hassle involved) or doing it myself, I reluctantly chose to DIY. Fortunately I had recently purchased some super heavy duty paint stripper (not the feeble imitation on sale in your local B&Q) which munched its way through 2-3mm of powder and clear coat with impressive rapidity. By masking off surrounding areas I was able to contain the chemical reaction to where it was needed (for the most part) and after a couple of (nervous) hours all the offending powder coat had been removed.

But I would have much preferred not to have had to do it...

All the bare metal parts in the photo below had previously been coated with powder, and there are some more faces you can't see. If I ever send any more stuff for powder coating to this guy I will mask all required bits off myself before sending them...

DSCF3532.JPG (831.71 KiB) Viewed 310 times

[Mr. Dazzle]

I started reading that, having already seen the pics, and thought "cool, he managed to mask the power coating pretty well...most don't do that".

Black callipers are normally anodised black though, are they not?

[mangocrazy]

I started reading that, having already seen the pics, and thought "cool, he managed to mask the power coating pretty well...most don't do that".

Black callipers are normally anodised black though, are they not?

You obviously missed the bit about them being Brembo Goldlines...? Every time I've inquired about anodising calipers I'm advised that results from anodising cast parts can be very variable and not recommended.

[A_morti]

I believe BMW anodised those calipers where they used a rebranded version of them, so it can be done.

However, you will see some that have lived a hard life get corrosion coming up right through the anodising, and it can fade in the sun as any anodising can.

[Mr. Dazzle]

Not really thought about it that much, I'm just picturing how the black (now grey) callipers look on my Triumph. They're sorta cast rough texture I think rather than shiny.

It's got Triumph branded callipers which are actually Nissins...I could get new/refurbed Nissins OK, but I'd like to keep the Triumph branding so I was just musing on what I'm gonna do if/when I get them refurbed.

Come to think of it though, i'm pretty sure the black ones on my CBR are shiny smooth paint/powder.

[mangocrazy]

One lesson I have learned is that getting calipers (or any part of the braking system) wet painted is pointless unless a brake fluid-resistant clear coat is applied on top. Before having the calipers powder-coated I had them wet painted by a very well known company that advertises on eBay and specialises in bike brakes (no names, no pack drill) and they didn't do this. As soon as brake fluid came into contact with the paint it went tacky/sticky and stayed that way. This annoyed me no end, and so I sent them off for powder coat.

Powder coat with a clear coat on top is brake-fluid resistant (as long as you don't leave them soaking in the stuff), but your chosen powder coater must mask off all the sealing/mating surfaces as well as the piston bores.

[Le_Fromage_Grande]

Speak to Nick Chambers in the LC club, he rebuilt a pair of FZR1000 calipers for me for less than the price of pattern rebuild kits.

[mangocrazy]

I remember that the Yam calipers of the 80s/early 90s were prone to seizing up with only minor provocation, although I think they've improved a lot in recent years. It's a bit cheeky only providing half the number of seals required for a full refurb though. How do they justify that? Surely you buy a refurb kit on a per caliper basis?

Sticking calipers can be a real safety issue. A mate of mine was on a track day with his Falco, and he was aware that the brakes were binding but thought he could get away with it. He didn't and crashed at around 120mph when braking for Park and the brakes locked solid. So I'd say you were wise to fix the caliper before it fixed you...

[Le_Fromage_Grande]

It's the pistons on old Yamaha calipers that are the problem, they're coated with special chrome that corrodes at the first sniff of road salt, rebuild kits usually have stainless pistons.

The problem with standard LC brakes is that the master cylinder is too big for the calipers, fit a 250LC master cylinder on a 350 and it improves the brakes massively, for any one who wants to think single piston, sliding pin calipers don't work, they seem pretty good at stopping my 1500KG car from 130 mph.

[Mr. Dazzle]

any one who wants to think single piston, sliding pin calipers don't work, they seem pretty good at stopping my 1500KG car from 130 mph.

Powered brakes will do that for ya Try turning the engine off then using them.

S'very rare to get cars which don't have boosted brakes, they're generally either utter shit boxes which don't stop err....for shit....or mega exotics.

[mangocrazy]

The problem with standard LC brakes is that the master cylinder is too big for the calipers, fit a 250LC master cylinder on a 350 and it improves the brakes massively,

A 250LC (1/2") master/cyl improves the brakes a lot and gives much better feel, but at the expense of some sponginess. But even then the brakes aren't nearly as good as modern stuff. The Brembo master cylinder/calipers combination I've got on the LC are streets ahead of OE, even with a 250LC m/cyl.

for any one who wants to think single piston, sliding pin calipers don't work, they seem pretty good at stopping my 1500KG car from 130 mph.

A big fuck-off servo will also help quite a lot and mask a lot of inadequacies.

[Le_Fromage_Grande]

any one who wants to think single piston, sliding pin calipers don't work, they seem pretty good at stopping my 1500KG car from 130 mph.

Powered brakes will do that for ya Try turning the engine off then using them.

S'very rare to get cars which don't have boosted brakes, they're generally either utter shit boxes which don't stop err....for shit....or mega exotics.

I'd forgotten that

[mangocrazy]

I can't remember what size my MC is, it's small, 11mm possibly.
It's spongey and if you really squeeze you can pull the lever right in to the bar, but the brakes are so good it would put you over the bars way before the level hits the stop.

It does feel cobbled together though, I keep threatening to change them.

11mm is really, really tiny. I think most 125s with single caliper setups use either 12mm or 1/2" (12.7mm). ISTR that when I was running a single ISR caliper setup on my Hejira YPVS that the master cylinder I used was a Brembo 14mm, which worked really well.

[mangocrazy]

It's the ratio that matters, rather actual dimensions.

Yebbut it's the dimensions that make the ratio...

The 11mm is a factory part off a YZF125R - I think it's 11mm, but could be 12mm, I forget now.

The standard LC one was dangerous for a single TZR250 caliper set up, if I squeezed with everything I had then it would just about slow me down enough to only bounce lightly off the car in front. The one I have is a little bit too small but there is incredible feel and force out of it because the lever moves a long way and you can really tailor the amount of force, it's got probably twice the amount of movement (due to the ratio) that you might normally expect, so it's a bit spongey but there is a lot of control.

Yeah, give me spongey but loads of feel against wooden and no feel every time. The standard LC m/cyl is bad enough feeding 2 calipers, with only one caliper it would be horrible.

[Bigjawa]

It's the pistons on old Yamaha calipers that are the problem, they're coated with special chrome that corrodes at the first sniff of road salt, rebuild kits usually have stainless pistons.

RE Himalayan ones are anodised alloy. They corrode if you look at them crooked.

[mangocrazy]

It's the pistons on old Yamaha calipers that are the problem, they're coated with special chrome that corrodes at the first sniff of road salt, rebuild kits usually have stainless pistons.

RE Himalayan ones are anodised alloy. They corrode if you look at them crooked.

Brembo pistons are also anodised alloy; great until the surface of the anodising is breached, then it all goes downhill fast. Pistons made of 316 stainless are the way to go - heavier than aluminium, but last pretty much indefinitely.

[Le_Fromage_Grande]

Brembo front brake levers used to be chromed with special easy peel chrome, it used to flake off on your fingers.

[mangocrazy]

Chrome on aluminium is always destined to fail.

[mangocrazy]

So today I've been reassembling the powder-coated bits, particularly the master cylinder. Before it can go to powder coat every single piece, moving or stationary, that isn't part of the actual casting must be removed. This includes the sight glass, brake microswitch, brake lever and (crucially) the piston and all associated parts. Knowing how these come apart and how easily certain parts can be permanently damaged, I ordered up a brake master cylinder refurb/repair kit off eBay. When the kit arrived I was a bit concerned about how good the kit would be as it wasn't OE, but an All Balls copy. As it turned out, that was a pretty fair description...

For a start there were no assembly instructions or even a diagram - I know that I ought to know how to assemble it, but I would have expected something. The parts included in the kit were as scant as they could be and still be referred to as a kit - no piston, washer or c-clip - all those had to be re-used (thankfully mine were in OK nick). They did include a spring, the two seals (subtly differently sized but no indication which went where), a circlip, a rubber boot, two reservoir screws, two copper washers and that's yer lot.

When it came to mounting the wiper seals on the piston, the bottom one went on OK, but the top one was simply impossible to fit onto the piston shaft as the rubber used was just too inflexible. In the end I had to salvage and re-use the old one, which rather negated the point of a rebuild kit. And when it came to fit the circlip which holds the whole plot in place, it wouldn't flex sufficiently to slide down the bore using circlip pliers but jammed halfway and had to be driven into the groove using a hammer and screwdriver.

Moral of the story? Avoild All Balls master cylinder rebuild kits like the plague...