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| How To ID Master Cylinders https://ausmini.com/forums/viewtopic.php?f=2&t=100968 |
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| Author: | cooperess [ Wed May 19, 2021 3:26 pm ] |
| Post subject: | How To ID Master Cylinders |
I bought a 1969 Mini Mk2 Cooper S partially rebuilt. The owner said the master cylinders had been rebuilt. How do you tell which master cylinder is which or doesn't it matter. Attachment: Master Cylinders DSCF0654.JPG
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| Author: | gtogreen1969 [ Wed May 19, 2021 3:43 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
There is a non return valve in the pressure outlet. Try to insert a wire into the outlet and you should see the difference. Also its preferred to use 0.7" for the brake master to provide more braking pressure and 0.75" for the clutch master as it moves more fluid. |
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| Author: | drmini in aust [ Wed May 19, 2021 3:44 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
Brake MC is 0.70" bore. And may have a restrictor valve in top. Some plastic clutch MCs were 0.70 but 0.75 preferred. |
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| Author: | gtogreen1969 [ Wed May 19, 2021 3:48 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
The bore size maybe cast into the side. Attachment: .7 inch Lockhead Brake Master.jpg
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| Author: | cooperess [ Wed May 19, 2021 4:23 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
I think they are after market as there are no marking anywhere. |
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| Author: | cooperess [ Thu May 20, 2021 10:10 am ] |
| Post subject: | Re: How To ID Master Cylinders |
gtogreen1969 wrote: There is a non return valve in the pressure outlet. Try to insert a wire into the outlet and you should see the difference. Also its preferred to use 0.7" for the brake master to provide more braking pressure and 0.75" for the clutch master as it moves more fluid. Tried the wire test, there does seem to be more resistance in one. Is the more resistance the brake MC? |
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| Author: | gtogreen1969 [ Thu May 20, 2021 12:51 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
cooperess wrote: gtogreen1969 wrote: There is a non return valve in the pressure outlet. Try to insert a wire into the outlet and you should see the difference. Also its preferred to use 0.7" for the brake master to provide more braking pressure and 0.75" for the clutch master as it moves more fluid. Tried the wire test, there does seem to be more resistance in one. Is the more resistance the brake MC? |
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| Author: | cgo [ Thu May 20, 2021 2:05 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
My 1970 Mini came with one Girlock and one Lockheed cylinder, both 0.7" bore. The Lockheed brake one being cast Aluminium alloy with the non-return valve and the Girlock clutch one cast iron. The cylinders looked awful but on inspection, after dismantling, the bores were in good condition and both had been resleeved. They hadn't been stored very well as evidenced by the reservoirs. Have no idea if they are original. Is there a pattern to who supplied what in the 70s? Also, I imagine Girlock would be manufactured later than Lockheed. |
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| Author: | DavidE [ Thu May 20, 2021 3:19 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
cgo wrote: My 1970 Mini came with one Girlock and one Lockheed cylinder, both 0.7" bore. The Lockheed brake one being cast Aluminium alloy with the non-return valve and the Girlock clutch one cast iron. The cylinders looked awful but on inspection, after dismantling, the bores were in good condition and both had been resleeved. They hadn't been stored very well as evidenced by the reservoirs. Have no idea if they are original. Is there a pattern to who supplied what in the 70s? Also, I imagine Girlock would be manufactured later than Lockheed. My memory has it that Girlock was the company name that emerged from the merger of Girling and Lockheed. |
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| Author: | Bill B [ Thu May 20, 2021 3:24 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
I think it might be worth dismantling both master cylinders. If they have been stored for a while the seals may have dried out and would benefit by some rubber grease or brake fluid to help them to prime when you go to bleed each system. Then you'll see the intensifier/non-return valve in the brake cylinder. They varied slightly in appearance from manufacturer. Some had a small metal dome held by the moulded rubber, some didn't have the metal part - just rubber with a small hole in it. This is from a PBR brake o/h kit. Attachment: Intensifier valve Brake master cylinder.jpg
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| Author: | winabbey [ Thu May 20, 2021 4:45 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
Be aware that traditional brake fluid (non-silicone) is hygroscopic (water absorbing), so if brake fluid was used as a lubricant during assembly and they have been sitting for some time then you really should dismantle to check that all is well inside. |
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| Author: | cooperess [ Sat May 22, 2021 12:26 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
Here are my components. The size on both end rubbers is 11/16" and inner diameter is nearly .70". Guess they are both brake master cylinders. Both sets of internals look exactly the same. Any comments would be helpfull. Attachment: Mini Master Cylinder Components DSCF0660 (2).JPG Attachment: Mini Master Cylinder Components DSCF0660 (1).JPG
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| Author: | gtogreen1969 [ Sat May 22, 2021 1:08 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
Both of those have the non return valve and are setup as brake masters. Just leave out the non return valve from one of yours to turn it into a clutch master. If you have clutch throw issues later you may want to look at a 0.75 clutch master sometime down the track. Or look for one now to prevent double handling. Here are the internals for the clutch master. Attachment: Clutch master - Plastic tank.jpg
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| Author: | cooperess [ Sat May 22, 2021 3:18 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
Attachment: Mini Master Cylinder Components DSCF0660 (2).JPG Is the non return valve the one I have arrowed?
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| Author: | gtogreen1969 [ Sat May 22, 2021 3:23 pm ] |
| Post subject: | Re: How To ID Master Cylinders |
cooperess wrote: Attachment: Mini Master Cylinder Components DSCF0660 (2).JPG Is the non return valve the one I have arrowed?Yes Here is a section through a brake master. Its a tin type but it shows the non return valve at No16. Attachment: Brake Master Cylinder Parts.jpg I didn't have an exploded view of the plastic tank brake master so i just added the non return valve to this pic. Attachment: Plastic Brake Master Cyl.jpg
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