Damn, the Spit 1500 tandem master cylinder has leaked over the bulkhead .. another spray job.
Main problem, it leaked 'cos of a small pit in the bore. Now these tandem cylinders are nearly £200, is there anyway it can be repaired .. or is there a cheaper alternative ?
Chris
I did my bulkheads and so on (Heralnd 13/60 convertible) with a bombproof twin-pack in plain black. Looks a lot neater, especially with the amount of grot that gets under the bonnet. Proof against battery acid and brake fluid too.
Not a cheap repair, but you can swap a dead master for a twin cylinder system with a balance bar - there's plenty of space. If you fool about with tyre sizes on a Spitfire, the adjustable balance is useful too.
-- Congrats to STBL on his elevation from TLA to ETLA
The best mod I have heard of is to have your master cylinder resleeved using stainless steel. Add to this a new repair kit and the job is as good as new.
I am sure any good engineering workshop could do this for you for a fraction of the cost of a new cylinder.
Dixie
I understood it to be much more expensive than a new cylinder so only used for unobtainable ones.
snip
I investigated sleeving for a Sprite tandem master cylinder and it was not feasible because of insufficient metal to stand the boring out. I don't know what the Spit ones are like but suspect the bores are close together like mine. However on more than one occasion I have restored the unit by honing it out myself. If the damage is not too bad you can use fine emery on a suitable drill mandrel - I went up to 1200 grit. Indeed I have read that honing is recommended to get new seals to bed in.
and it was not
out. I don't know
together like
unit by honing
emery on a
read that
Brake and master cylinder seals don't need bedding in. Indeed, any roughness in the bores is detrimental to the seals and their life expectancy. Careful honing with a fine stone gives a reasonable good finish in cast ally. But a mirror finish would be the ideal. Mike.
It's always feasible. If it's too thin to sleeve it, you just machine a new cylinder from bar stock, pipe entries and all. IMHO, it's _easier_ than a decent sleeving job.
-- Smert' spamionam
Quite common for dual master cylinders to leak a little from the rear seal the cause usually isn't the pitting but just the oxide and build up lifting thethe rubber seal off the surface invariably just cleaning the bore surce with 1000 grade and Brasso followed by renewing the seal works no need to hone the bore.
The important thing is to keep it packed with clean fresh Giring Red Brake rubber grease, don' presure wash near the cylinder I also sugest you try Silicone brake fluid.
the
these
the rear seal
build up lifting
the bore surce
works no need to
Giring Red Brake
sugest you try
Not a very good suggestion IMO. To safely change a glycol filled brake system, to one with silicone, the brake system should be stripped and cleaned to remove any old fluid, as silicone and glycol based fluids do not mix.
Apart from that, not all seals in glycol based systems are compatible with silicone based fluids. Many are, but unless you know for certain, they should be replaced. Otherwise old seals that are not, could lead to sudden brake failure.
Silicone also needs to be changed much more frequently. Unlike DOT 3 & 4, which are both hygroscopic, silicone doesn't absorb water, so any condensation pools, and can cause local corrosion in lower parts of the system. Which is why it should be changed more often. Mike.
So just bleed the thing, same as you do to to brake systems normally. Or is your next posting going to be trying to sell some snake-oil brake system flush product ?
Natural rubber seals were last manufactured (according to my mole at Lockheed) some time in the late '60s. Ozone has already had them, long before you need to worry about silicone.
And seals are no more likely to experience _S_udden _B_rake _F_ailure if dunked in silicone than in anything else. Sure, they might swell and they might wear, leak or fail. But it's no more likely to be sudden than any other brake-related wear problem.
Why ?
Do you know how often glycol fluids should be changed (2 years, typical manufacturer recommendation). How old is _your_ fluid ? What's its boiling point these days ?
Has anyone ever _seen_ such corrosion ?
If you don't want water pooling in a silicone-filled system, don't pour water into the reservoir. It isn't going to sneak in on its own.
-- Smert' spamionam
Andy,
Whilst in the first instance you maybe partially correct in your response to Mike G he is also correct in his views and if you go onto the Net you will find out why, please read the following,
not
normally.
You must be naive if you think that will remove all the old fluid.
snake-oil
Is that an attempt to be insulting?
you
seals
mole at
them,
FYI there are many manufacturers of synthetic brake seals, and at least as many different compounds to make them from. Not all those sold for vehicle braking systems are compatible with silicone based fluids.
_F_ailure
swell
be
How is cloud cuckoo land these days?
years,
?doesn't
don't
its own.
That's exactly what does happen. You don't need to pour water in. Condensation will quite happily do that for you.
Why do you think 2 years is the recommended change interval? To answer my own question, it's because the water that inevitably condenses in the system, and gets absorbed into the fluid over time, will corrode the components, and can seriously affect braking performance if it turns to steam under heavy braking etc.
In any case I'm not prepared to have an argument about it. I'd just suggest that you look into the subject a little more thoroughly, before making inherently unsafe suggestions in a n/g.
You'll find all the recommendations I made are fully supported by those who probably know more about vehicle hydraulic braking systems than either of us are ever likely to know. Mike.
"Campingstoveman" realised it was Sat,
10 Jan 2004 19:18:56 -0000 and decided it was time to write:
Very interesting page - goes straight into the favourites.
It'll remove as much as anything short of a complete strip and rebuild. Now I'm not _against_ such a thing - brake systems are pretty easy to do large-scale work upon, in comparison to the hassle factor of touching just one component and still having to bleed it afterwards.
Ah, the _other_ canard. SBR seals are perfectly compatible with silicone. Please cite some credible ref. to suggest otherwise.
Why do you think that reservoirs have a crud trap at the bottom ?
Look at the figures for silicone fluid's water absorption. Assuming two years as a reasonable benchmark for DOT 3 fluid, you need to keep silicone in service for decades (ie far longer than the seal life) to have an equivalent degradation from water absorption. Just take a look at the Ohio site that Campingstoveman posted
No one is claiming that water is a good thing to put in your braking system. However I see silicone fluids, and see their self-evident superiority in avoiding this, but you (and many others, which I've always been puzzled by) start constructing these entirely specious arguments _against_ silicone, and thus _in_favour_ of glycol !
There _are_ problems with silicone. Lubricity is lower, and this might cause a problem with some ABS pumps (check with the makers).
Compressibility is higher, so if you're driving a non-servoed single-seater on a track, then you might get a different pedal feel.
But if you're concerned about water problems, boiling point or general long-life issues, then silicone all the way !
-- Smert' spamionam
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