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Discussion Starter #21
One way to test if its DOT 3/4 or DOT5( Fraid your neighbor will not have a good week.)
Go find the neighbors car (as mentioned in post #8) Drain you master cylinder reservoir and pour it on the trunk(boot) lid. If the paint isn't damaged its DOT5. If the paint is damaged it DOT3/4.
K
Will try it on my brother in law's automobile:wink2:
 

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Well regarding the unknown brake fluid presently in the bikes master cylinder.


One way to test if its DOT 3/4 or DOT5( Fraid your neighbor will not have a good week.)


Go find the neighbors car (as mentioned in post #8) Drain you master cylinder reservoir and pour it on the trunk(boot) lid. If the paint isn't damaged its DOT5. If the paint is damaged it DOT3/4.


K
Remind me never to live next-door to you.
 

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Remind me never to live next-door to you.

Just offering practical solutions to a problem.:nerd:


Besides most of my neighbors and I get along.


But I don't think the current Chief of Police is real impressed. His dog (Border Collie sized) attacked my Shih Tzu Poodle (about 15lbs) a few years ago and fractured a front leg on my little guy. I got the County to issue him a Citation.


K >:)
 

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Take a look at the caliper pistons, there should be a rubber boot around them that mounts to the edge of the bore in the caliper. You don't need to disassemble to see this. If one or both are missing then it's a pretty safe bet that your issue is in the caliper.

Rod
 

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nope - these calipers dont have a boot - there is an inner seal and a dust seal - the dust seal is held by a steel ring but it is flush with the caliper face
 

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My '78 front brakes stick also. Just don't ride the thing enough to keep the pistons from sticking.
 

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Hi Rod,

Certainly for Europe (and the US?), Wol is correct, none of the steel calipers and only a variant of the ally calipers had/have 'boots'.

The AP Lockheed caliper pistons/seals can appear confusing:-

. Generally, the pistons in both types of caliper are 1-9/16" OD; when AP supplied pairs of ally calipers with these to the Co-op, they also supplied the 0.7" ID master cylinder.

. I knew that, at the time ally calipers were fitted, Oz had an ADR requirement that calipers had to be fitted with dust seals. To comply, AP supplied the Co-op with the aforementioned variant, which had 36 mm. OD pistons (the mixture of Imperial and metric measurements is correct - AP didn't 'go metric' 'til about 1980) to accommodate the 'boots'.

. The 36 mm.-piston ally calipers were attached to the 5/8"-ID standard single-disc master cylinder. As these reduced the Co-op's parts inventory and allowed assembly flexibility - in that the same master cylinder could be fitted irrespective of caliper/s - the Co-op used the smaller-piston calipers as standard thereafter. Unfortunately, the Co-op's "thereafter" didn't last very long - and spares weren't available for the 36 mm. pistons for many years, so some 36 mm. calipers will have been replaced by owners - so the overall picture is not always clear.

As far as I was aware, there were never dust seals on any steel caliper pistons, they were only ever 1-9/16" OD; however, I appreciate you'll have better local knowledge.

Hth.

Regards,
 

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Hi Fred,

I would not have any problem with flushing the system through with fresh DOT 4.
As a general rule-of-thumb, neither would I. But, although I've used DOT5 for 35 years without any problems, I have been able to restrict it to just two makers - Bel-Ray and Fuchs (a British lubricant blender well-known in the motorcycle world). When there is an internet forum thread about DOT5, one of the 'againsts' usually trotted out is that mixing it with DOT3 or DOT4 "causes sludge to form". Like Rod, I've never experienced it; my concern is that the fluid in the bike is not the problem, it is DOT5 and "flushing the system" with DOT4 you "happen to have in stock" will cause a problem the bike does not have now.

Well regarding the unknown brake fluid presently in the bikes master cylinder.
One way to test if its DOT 3/4 or DOT5( Fraid your neighbor will not have a good week.)
Go find the neighbors car (as mentioned in post #8) Drain you master cylinder reservoir and pour it on the trunk(boot) lid. If the paint isn't damaged its DOT5. If the paint is damaged it DOT3/4.
Curiously, this won't work certainly in Europe. :(

Glycol-based fluids (DOT3, 4 and 5.1) never damaged paint instantly, only if left for some time. For many years, I dealt with Ray Bailey at AP Racing, he was very knowledgeable and experienced (often being the Lockheed engineer to race teams), he was against the use of DOT5 and said he finished any work on a brake by throwing a bucket of water over it to neutralise any residual spilt DOT3/4/5.1.

A few years ago, I wanted to remove some paint from a (ironically, Sparx) handlebar switch cluster, retail 'paint removers' are chocolate-fireguard category thanks to the Safety Elfs, so I decided to try some old DOT3 I had at the back of one of the garage shelves. Despite leaving it for several days, the brake fluid had absolutely no effect whatsoever on the switch cluster paint, I ended up having it blasted off. :(

My '78 front brakes stick also. Just don't ride the thing enough to keep the pistons from sticking.
'Fraid it's more likely another problem. :( While I give all the disc-brake levers a few pulls or pushes once a month or so, I've 'projects' that've been sitting for years :eek: that the brakes work fully.

Hth.

Regards,
 

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Stuart me old China, are you sure we are talking about the same thing? Brake caliper design 101 calls for 2 seals. The first being the square section seal in the bore of the caliper and the second being the dust boot (seal) thats id sits in a groove around the top of the piston and od seals around the top of the bore of the caliper. Without that dust boot (seal) well salted British roads would quickly render the brake Donald. I have never seen a brake caliper without them. They are also shown fitted to both the calipers pictured earlier in the thread.

Well, sorry Stuart my flabber has never been quite so gasted. I googled a bunch of images and did indeed find AP calipers without a boot.

Rod
 

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So, looking at the re build kits I can find I see they come with 4 square section seals and two steel seal holders. My assumptionn is that the extra two seal and holders are there instead of the more topical boot?

Rod
 

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Discussion Starter #32
Brake caliper design 101 calls for 2 seals.
The first being the square section seal in the bore of the caliper
#1 Piston seal ? (see attached exploded view)

...the second being the dust boot (seal) thats id sits in a groove around the top of the piston and od seals around the top of the bore of the caliper...Rod
#2 Dust seal ? (see attached exploded view)

I would add #3 dust seal cover (see attached exploded view) to complete the picture:wink2:
 

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Hi Rod,

are you sure we are talking about the same thing? Brake caliper design 101 calls for 2 seals. The first being the square section seal in the bore of the caliper and the second being the dust boot (seal) thats id sits in a groove around the top of the piston and od seals around the top of the bore of the caliper.
:)

I'm pretty sure I know what you mean by "dust boot", I agree most calipers have 'em.

Nevertheless, if you look at Lockheed Hydraulic Brake Equipment For Motor Cycles, .pdf page 9 - Disc Brake Caliper Overhaul Procedure Sheet 354B - you'll see Lockheed did put in two seals - "Fluid Seal" and "Wiper" - but both inside the caliper, nothing between "top of piston" and "top of the bore of the caliper".

Without that dust boot (seal) well salted British roads would quickly render the brake Donald.
We-ee-ll, yes and no.

Firstly, bear in mind that both steel and ally calipers were intended for Cooper versions of the BMC Mini originally - in the early 1960's, afaik actual "dust boots" simply weren't a requirement on road cars; even if they were later when the ally versions were made available, ally were always for "racing", nudge, nudge, wink, wink. Also, even if "dust boots" were ostensibly required by what e.g. GB called "Construction & Use regs." for road cars or bikes, if their presence wasn't a requirement in later safety inspections - e.g. the British "MoT" ... As I say, afaik it was just Oz that was strict about actual "dust boots" (in addition to the other seals) on disc-brake calipers.

Then, certainly ime, it isn't the hard-chromed pistons - on either Lockheed or Japanese calipers - that are most susceptible to corrosion, it's the shag-awful ally the Japs insist on making their calipers out of, plus the Heath Robinson linkages they inflicted (and continue to inflict) on the motor/cycling world. :Not again Certainly, when all-weather riding, I never experienced the problems on steel-caliper Triumphs that I experienced on Jap bikes. :bluduh

looking at the re build kits I can find I see they come with 4 square section seals and two steel seal holders. My assumptionn is that the extra two seal and holders are there instead of the more topical boot?
:nah As you can see in Lockheed's own destructions, they're just called "Retainer", just for the "Wiper". In theory at least, you can just change "Wiper" (and "Retainer"?) without any need to break into the hydraulics. :thumb

Hth.

Regards,
 

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Discussion Starter #34
.......Hope this helps. :)
Amicalement,
Hi Stuart, K, Rod, Dave and other fellows

I removed front wheel and brake pads to glance at the caliper and pistons.
After careful cleaning with a rag, toothbrush soaked in DOT4, pistons don't look corroded (see attached pics).
Viewed from rearside of bike, left piston moves freely out of caliper bore when applying gentle pressure on handlebar lever and retracts in caliper housing when forced inside with a clamp.
However, right piston moves out but is reluctant to retract inside caliper bore even when forced with clamp.
There remains a visible piston bore protruding from caliper housing.

Is it normal or should the right piston move completely inside caliper bore?
Should I insist with pliers or unscrew drain plug in order to release some pressure ?
 

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The Pistons should retract evenly, however it's possible to cock the piston over when pushing it back so that it jams. Apply a little pressure from the lever and watch the piston to see if it straightens up before it moves. If not it's time for further disassembly and inspection.

Stuart, not to labour a point but the wiper seals do the same job as a boot by wiping any debris, water etc from the piston to stop it getting to the main seal and damaging it. The MOT regs, whilst vague suggest that all components be inspected and worn parts replaced. So in effect it depends on the tester (as always). Your experience with brake calipers differs from mine. I served my time in Hampshire on England's South coast as a motor mechanic. Corroded pistons caused by missing or damaged boots was incredibly common. Perhaps the motorcycles you looked after were better maintained.

I'll bow out now
Rod
 

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All they do for the mot is sit the bike on a set of rollers that drive up to speed and then brake.
So long as it stops within the permitted time, the bike passes with no inspection of parts

When I used to go to a very old school MOT place that only sold bicycles , they had a winch on the wall connected to a dial.
They dragged the bike along the floor while the rider held the brakes on. My old tiger cub wouldn't stop in a month of Sundays but passed every time - so long as the brakes were already on the wheel was locked solid-
 

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Hi Rod,

not to labour a point but the wiper seals do the same job as a boot by wiping any debris, water etc from the piston to stop it getting to the main seal and damaging it.
Not arguing they don't. What started this part of the discussion was, "Take a look at the caliper pistons, there should be a rubber boot around them that mounts to the edge of the bore in the caliper. You don't need to disassemble to see this"; the Lockheed "Wiper" cannot be seen without removing either the piston or the "Retainer".

Perhaps the motorcycles you looked after were better maintained.
0:) Well, obvs ... :grin2:

The calipers on the Jap bikes I ride/rode or maintained generally require(d) liberal applications of stainless to keep them functioning as the designers - if not the production accountants - intended. :bluduh

Regards,
 

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I had the OP's original problem with my TBird. Granted may be apples/oranges. My Tbird has a Nissin caliper. I believe the body is aluminum and the piston chromed steel. What I found on disassembly was that corrosion had formed UNDERNEATH the piston seals down in the bottom of the seal grooves. It didn't look all that bad, but was severe enough that it was forcing the seals against the pistons SO HARD that they wouldn't retract. I had to use compressed air to force the pistons out for disassembly (Careful! Use a safety clamp to avoid mashed fingers or creating piston bullets!) I had never seen this kind of corrosion in ANY disk brake caliper. My theory is that airflow and water and brake heat on a motorcycle just do weird things.

Once I DID finally get it apart, it took scraping with a dental pick, wire brushing with a little dremel wire brush and polishing with a scotchbrite disk in the dremel.

For reassembly, the oft-mentioned red rubber grease is VITALLY important down in the bottoms of those seal grooves to PREVENT water getting right back down in there. Use a liberal coat!
 

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Discussion Starter #39 (Edited)
......In my humble opinion, if you must change the fluid, unless you can discover from the previous owner what he put in, the only really safe way is to drain the existing fluid, dismantle master cylinder, hoses, pipes and caliper, put new seals in master cylinder and caliper, clean the hoses and pipes, reassemble and refill with new fluid.....
I removed the caliper from fork and removed the seized slave piston from caliper.
Caliper bore under seized piston filled with sludge.
Piston nice and shiny after thorough cleaning, no corrosion, no blemishes, nothing !
Caliper bore looks good too after cleaning and sludge removal.
Suspect previous owner filled DOT5 since I topped up reservoir some time ago with DOT4, hence the sludge in caliper !

Now, I'm not out of the inn yet (French proverb) !

As Stuart mentioned, need to dismantle the brake sytem, repair kits for master cylinder and caliper, new braided hoses, clean pipes before re-assembly and refill with DOT4 in stock :crying:
 
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