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Brake calliper refurb


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Hi Rob,

have you got the little 'O' ring that goes inside.

 

Not sure if they are anything special.

 

If you are using DOT5 then the material is less important.

Not sure what DOT4 will do to common rubber 'O' rings

 

Roger

Edited by RogerH
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Hello,

 

My first car, in 1966, was a Triumph Herald, and that had calipers that consisted of two halves.

 

There was a brake specialist near where I lived and I took the calipers to him to ask for new seals.

 

For some reason I’d split them into the two halves and the bloke on the counter went berserk telling me that I’d ruined them and that they were now scrap, and he refused to sell me new seals.

 

From what I remember I went to another spares shop and just asked for a set of seals without showing them the remains. The o ring was not part of the kit, and I can’t remember what I did, (Although I have a feeling I cut a rubber washer out of an old inner tube…)

 

The calipers never leaked, but there must be some serious reason why you should not split them.

 

(I do not advise making a washer out of an old inner tube !)

 

Charlie D.

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Hi Rob/Charlie,

there is no logical reason why not to split the caliper.

You can buy various vented disc mods and these require the caliper widening by putting a spacer between the two halves.

 

The only concern is ensuring that the rubber 'O' ring is happy with DOT4.

The DOT5 silicone should have no effect on any 'O' ring.

 

Roger

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Rob,

 

Although there are many/most jobs on TRs that you

CAN do yourself, there are some where it is better to

refer to a specialist.

 

In my book, rebuilding callipers is best left to speciualists.

 

AlanR

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I had to obtain the sealing ring for mine from Moss USA, for some reason not available in UK.

Paul

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I'd agree with Alan here, few owners have the skills or equipment to rebuild callipers properly, and as the consequence of error tends to be potentially catastrophic it's a job best left to specialists unless you know exactly what you are doing and have the right kit and experience.

 

The sealing ring between callipers is a very precise piece of seal in terms dimension, profile, and constituency.

 

Sorry Roger, the seal material is just as relevant to all five major hydraulic fluid categories. (ie 3, 4, 4S, 5, 5.1)

 

You cannot just substitute any old piece of whatever happens to fit, that simply will not do.

 

The seal is crucial and must be absolutely correct for the specific application. No ifs, no buts.

 

Brake failure has a nasty habit of killing innocent people.

 

Cheers

 

Alec

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the only possible issue is that the bolt is some stretch bolt that cannot be reused and must be replaced with some rather esoteric bolt size ... my e10 BMW ones were M9..which isnt so common.

Brake caliper splitting in half during hard application of brakes is one of those failure modes i have never hear of....

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It would appear that Moss in the UK do the seals https://www.moss-europe.co.uk/catalogsearch/result/?search_group=&q=583-820

 

I agree whole heartedly that the correct fluid should be used regarding seal composition

However what is the correct composition for what ever fluid - all the fluids are quite diferent even when you think they are equivalent.

 

Is DOT3 the same as DOT4 - no it isn't

In a number of areasd DOT3 is specified but not DOT4 - Why.

 

Well DOT4 has Borate in it that may well affect some rubbers.

 

DOT5 being silicon is inert in many areas so most rubber composition will survive quite well.

Sadly trying to find 'the ' answer is proves to be clouded with information form self interested parties.

 

It would be nice to read the facts.

 

Roger

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The reason for not splitting the caliper is not only the non availability of the correct "O" ring its also the fact that the bolts that hold the two halves together are different and the torque figures for each (Also different) is not generally published.

Stuart.

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The o rings are available from moss and the part number is as described above available from Buckeye Triumphs internet documents

Got the part number ( 583-820) and rang moss and they sent them, no questions asked (24 1 2017)

from memory they ( Buckeye) define the bolt torque settings

I, needless to say have split callipers, refurbished them with new pistons seals and use Dot5.1 brake fluid and I race the car

Happily the problems I have had do not include front calliper failure

Michael Hunter

Edited by MichaelH
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Hi Stuart,

a few years back I fitted the EBC vented discs.

The kit comes with seals and the bolts. !!!!!

 

The build, in itself, went OK except that when torquing up the supplied bolts the first one started to stretch and stretch and stretch - rather like rubber.

I think the load was about 60lbs/ft.

 

I contacted EBC and some old chap (either old or poorly) said it may be a good idea to use a lower torque loading, say 40lbs/ft - it was only a guess after all.

 

I used the original bolts - thankfully they were just long enough.

 

If they can;t get the torque loading right I have my doubts over the seals - but so far they have not leaked.

 

Roger

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