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Master Cylinder Confusion


cliff.b

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1 hour ago, johny said:

So the actuator rod must be positively located in this MC however at least youve proved its not under load and can function correctly👍

Yes. Still a bit spongy but happy to drive it now so will prob let pads bed in further. If, as you suggest, the actuator rod is positively located, I presume I can't use it if I decide I want to fit the new standard MC?

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Sorry I think we might have misled you a bit as looking in the Vitesse online workshop manual the MC has an internal circlip that retains a washer which allows the pushrod to move but not come out. When the pedal is released the internal spring traps the pushrod between the piston and washer/circlip so it cant move. You might be able to rotate it with your fingers but there shouldnt be any back and forward play.

The only possible play will be between the clevis and brake pedal which of course then does indicate that the MC isnt under pressure and all is correct.

I think if the clevis is fixed (threaded ones are available) the washer cant be removed so that rod can only be used on the same size bore MCs and wont be transferable to your new one... 

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13 minutes ago, johny said:

Sorry I think we might have misled you a bit as looking in the Vitesse online workshop manual the MC has an internal circlip that retains a washer which allows the pushrod to move but not come out. When the pedal is released the internal spring traps the pushrod between the piston and washer/circlip so it cant move. You might be able to rotate it with your fingers but there shouldnt be any back and forward play.

The only possible play will be between the clevis and brake pedal which of course then does indicate that the MC isnt under pressure and all is correct.

I think if the clevis is fixed (threaded ones are available) the washer cant be removed so that rod can only be used on the same size bore MCs and wont be transferable to your new one... 

Ok, thanks for the explanation. So I will need to see if an actuator for the standard MC is available if I want to use it?

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Not sure as perhaps where the washer and circlip sit is the same size in all MC and also the pushrod is universal so that just the bore/piston size varies. That seems logical and then one pushrod can be used for all...

It would be interesting to see if anything is already in place on the new MC?

Although I dont think a workshop manual specific to the 1500 Spitfire is available you might find some of the others available free from vitessesteve.co.uk useful...

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3 minutes ago, johny said:

Not sure as perhaps where the washer and circlip sit is the same size in all MC and also the pushrod is universal so that just the bore/piston size varies. That seems logical and then one pushrod can be used for all...

It would be interesting to see if anything is already in place on the new MC?

Although I dont think a workshop manual specific to the 1500 Spitfire is available you might find some of the others available free from vitessesteve.co.uk useful...

Ok, many thanks with all your assistance with this 👍

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16 minutes ago, thescrapman said:

Different angles on the brackets I correct, it is due to reduced clearance under Spitfire bonnet for the bigger MC, possibly the dual circuit one. 

Which yours may be supposed to have.

Oh, I see. Makes sense. Anyway, brackets now swapped over with the Brake cylinder now on the re-inforced one. 

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  • 2 weeks later...

Just a follow up to close this off, I have now found & remedied multiple brake faults at each corner necessitating replacement of both front calipers & pads, freeing off both seized rear brake cylinders, replacing rear shoes, a sheared brake adjuster & several missing cotter pins, tightened weeping brake joint, corrected significantly maladjusted hand brake & carried out copious bleeding. Ironically, the only thing that didn't appear to have a problem was the master cylinder which was my first guess for causing the issues.  

I am pleased to report that the brakes are now working pretty well and I will just make a final adjustment to the rears after they have had a chance to bed in a bit. So many thanks for all advice offered. I have reminded myself of several things that I had forgotten over the years and have learnt a lot of stuff that I never knew in the first place 👍

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  • 2 weeks later...

Well I thought the brakes were sorted but it appears not.

Developed a nasty noise from the o/s rear and a reduction in braking performance. Took the drum off this afternoon and found the brake adjuster was rubbing against it. The retaining studs had pulled away from the adjuster (see pic). The nuts weren't overtightened and I removed the bolts from the backplate easily using a small spanner & screwdriver. I'm trying to remember for sure but I'm pretty certain this is the adjuster I fitted a couple of weeks ago from Rimmer's. 

IMG_20210507_172800_006.jpg

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49 minutes ago, johny said:

that looks a very poor construction and has all the signs of being another example of the low quality of some of the parts available these days. Let Rimmers know and see what they say....

Yes, that's what I thought. I assumed the studs would have been threaded rod into a tapped hole, not a bolt cast a few mm deep into some dubious looking "metal". Apart from the failure that has occurred there is very little to stop the bolt turning if any degree of force was applied tightening, or more likely un-tightening in a few years time. If it lasts that long, of course. 

I do intend to contact Rimmers. Ironically, I could have bought more cheaply on E-Bay but decided that I would rather get brake parts from a known company. I suspect I would have actually got exactly the same thing, No doubt made in the PRC to look like it's supposed to but without regard to functionality.

Hopefully their new aircraft carrier is the same lol

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yes for me secondhand, if available, is often best (if original of course) or cheap as possible so when it falls apart you dont feel so bad! The only way we can change the situation is by hassling the suppliers...

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very poor design and construction, why would any competent designer cast a cheese head bolt in when a tapped stud would have provided extra meat and been so much stronger, trouble is with PRC goods your the tester! I'll be interested to see if Rimmer's advise there've had other cases!

Fortunately I recently replaced the daughters Spits ones during a service with a couple of rebuilt old originals & the removed ones have now been rebuilt as spares for the fleet or if called upon to help other local club members

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I've been thinking about this overnight and despite my concerns about the design, I couldn't see how this happened. Surely any lateral forced would be taken by the "boss" that protrudes through the backplate?

However, to gain confidence in the brakes after the problems I had experienced I had  been making repeated heavy braking from increasing speeds prior to the noise starting.  This clearly caused the drums to get very "warm" as the paint on them had blistered so I am thinking, could this have happened due to expansion of the bolt heads forcing the adjuster away from the backplate?

 

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i would think the alloy would expand more than the bolt head 

sorry that design is just crap , just doing the nuts up would stress the thing to destruction and not through over tightening  

its just a disgraceful look alike  in a box 

ive not done a search but something rings a bell that way back a similar problem occurred 

pete

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23 hours ago, cliff.b said:

No doubt made in the PRC to look like it's supposed to but without regard to functionality.

Maybe the WC (Western Capitalists) distributors of products, looking for the cheapest price that it can be made?.

23 hours ago, johny said:

yes for me secondhand, if available, is often best (if original of course)

Yes, if you can get it at the time (or end up with a load of used parts I bought cheap, that may never be used?) 

Edited by daverclasper
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Cliff if your stuck in getting a good replacement I have a surplus original in good condition less the two wedge pistons (missing/lost) but has the tapered threaded adjuster that I'd send over to you free, just to keep another Trumpie going.

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1 hour ago, Peter Truman said:

Cliff if your stuck in getting a good replacement I have a surplus original in good condition less the two wedge pistons (missing/lost) but has the tapered threaded adjuster that I'd send over to you free, just to keep another Trumpie going.

Thank you, I would appreciate that as not too happy to fit another new part until I understand the quality issue. Can I send you my address?

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