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Mk3 Spitfire brake master cylinder


Amy Wade

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Hi peeps, 

I'm in need of a new brake master cylinder & so far I've received 2 different ones which are both wrong, the car has single circuit brakes.

So far I've had one which I bought at Stoneleigh earlier this year, the reservoir on that one is too big a diameter & fouls the wiper mechanism.

The second one I purchased clears the wiper mechanism but is too tall.

Does anyone know what master cylinder I need to order? I can't find one identical to the original. 😒

First photo is the old one, second shows the height issue of the second one & third one shows the problem with clearance with the wipers. 20231013_141611.thumb.jpg.009cf80e8296a155d95ea518dacfa36f.jpg20231007_133131.thumb.jpg.31c4d38f2042afe400454faf593c2db9.jpg20231013_141652.thumb.jpg.5d241fcfa9399f1fa671585e43ea70e6.jpg

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A slight tangent... are the clutch and brake master brackets the right way round? They aren't the same, if I remember rightly mine were the wrong way when I got the car meaning the clutch one was low and the brake one too high....

I found an old blog post about it: https://yorkshire-spitfire.blogspot.com/2013/08/mixed-up-things.html

Might be different on the MK3 though?

 

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14 minutes ago, yorkshire_spam said:

A slight tangent... are the clutch and brake master brackets the right way round? They aren't the same, if I remember rightly mine were the wrong way when I got the car meaning the clutch one was low and the brake one too high....

I found an old blog post about it: https://yorkshire-spitfire.blogspot.com/2013/08/mixed-up-things.html

Might be different on the MK3 though?

 

They're the same as in the photo in the link you posted.16972055721168382548343691679229.thumb.jpg.6bda79645d3cf526f371fd88c20b29db.jpg

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Not the answer you are looking for but it's not too taxing to clean up and rebuild the original master cylinders. Hardest part is ejecting the piston assembly from the bore - I managed to force mine out using air pressure from a foot-pump. New rubber seals and aluminium lids are available

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27 minutes ago, PeteStupps said:

Not the answer you are looking for but it's not too taxing to clean up and rebuild the original master cylinders. Hardest part is ejecting the piston assembly from the bore - I managed to force mine out using air pressure from a foot-pump. New rubber seals and aluminium lids are available

Unfortunately my original is long gone, the bore would never have been able to seal due to heavy pitting and scoring.

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39 minutes ago, glang said:

check part GMC224 at Rimmers - two versions, expensive and very expensive, but correct....

That's the same as the one I bought at Stoneleigh, the reservoir diameter is too big, the wiper mechanism passes through the bulkhead directly behind the brake master cylinder on a Mk3, it would be fine on a Mk4/ early 1500 where the wiper mechanism passes through the bulkhead to the right of the master cylinder. 🫥20231013_174818.thumb.jpg.97a70d5d8f1e0f08e8ca5692e455aee6.jpg20231013_174833.thumb.jpg.401696f97046a79ef34f413677095738.jpg

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Something is niggling away in my brain about master cylinder brackets and angles, and maybe being different between some models. (the brake one always has a reinforcing bar AFAIK)

Of course, you could get your original cylinder resleeved in stainless, but not a cheap option.

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1 hour ago, glang said:

Looks like you need an original from Rimmers then at 114 pounds shown below! The only alternative is a cheapy 5/8 master cylinder available on eBay but the reservoir is clutch size so quite a bit smaller...

image.png.80a9c5341f9eae16885538d7d8969339.png

Ouch, that's more expensive than the dual circuit ones (which definitely won't fit) I'll do as Wendy suggested and try Flitcetts in the morning, if they can't help (and beat the price) it looks like Rimmers will be getting an order.

Thank you for the help 😊

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4 minutes ago, glang said:

Yes all the original type integral big reservoir m/c are rare with the Vitesse 0.7" difficult to find and the last GT6 0.75" like gold dust...

So I should hang on to my 0.75 cylinder. Been in a cupboard since I took it off my Vitesse, it did 10 years on that.

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On 13/10/2023 at 18:34, glang said:

but the reservoir is clutch size so quite a bit smaller...

Have a suspicion that that exactly what would have been there from the factory. Two identical 5/8” master cylinders with the small, extra angled reservoirs.  
 

No real downside so long as you check the fluid levels regularly. Used to be possible to get plastic screw-on extensions to gain a bit of capacity but possibly too tall in this case.

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16 hours ago, Nick Jones said:

Have a suspicion that that exactly what would have been there from the factory. Two identical 5/8” master cylinders with the small, extra angled reservoirs.  
 

No real downside so long as you check the fluid levels regularly. Used to be possible to get plastic screw-on extensions to gain a bit of capacity but possibly too tall in this case.

Nick,

No, they weren't the same. Triumph changed the brake master cylinder for the Mk3 Spitfire to one with a larger reservoir at a right angle to the bore. The one Glang posted a pic of looks right.

Even the Mk1&2 had different master cylinders for brake and clutch. The reservoir on the brake cylinder was about 12mm taller. 

Regards,

Paul

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6 hours ago, drofgum said:

Nick,

No, they weren't the same. Triumph changed the brake master cylinder for the Mk3 Spitfire to one with a larger reservoir at a right angle to the bore. The one Glang posted a pic of looks right.

Even the Mk1&2 had different master cylinders for brake and clutch. The reservoir on the brake cylinder was about 12mm taller. 

Regards,

Paul

As I'm only the third owner & the previous owner seemed to be averse to changing parts, I have no reason to believe mine originally had anything other than the one Glang posted. I was toying with the idea of a clutch master cylinder but decided against it, I  don't think a weeping wheel cylinder would take long to empty the small reservoir 

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