Modifying Morris Minor Master Cylinder for Disc Brakes

Today I remove the rubber seal from the check valves in the master cylinder on the Morris Minor for use with disc brakes.
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This Week With Cars - Episode 0080

[@johnquilter7620]

Well done video. I thought you would mention that the through the master cylinder bolts can be fitted with the heads on the inboard side so that they are easier to remove next time but your trick to getting them out over the torsion bar was very clever. And I thought as long as you had gone to the trouble of getting the cylinder out it might have been worth while to fully clean it, hone it, and fit new seals.

[@1963TOMB]

As stated by others, I'd also consider having the bore sleeved in stainless steel, or preferably, brass (brass is kinder on the seals).

[@JourneymanRandy]

Pretty simple. I would have believed that a new compatible master was necessary. I didnt know a drum master could be converted to disk brakes. Take care Steve

[@donmacdonald7758]

Nice upgrade, ya gotta love the old Morris Minor. Well worth the time.

[@MrPropanePete]

I'm a former motor mechanic from decades ago, and worked on these cars in Australia. It wasn't in the video but I assume you honed out the master cylinder bore and fitted new cups, etc. We used to drill out the bore and press in a stainless steel sleeve with an inside diameter that was equal to a standard cup size. More costly but the master cylinder would last for years after that. English cars always seemed to have whitworth nuts and bolts rather than a bolt screwing into a captured nut or a thread. And the nuts were often tucked away in a very tight and dark area hard to get to. When you worked on a Morris, a Vanguard, an Austin, a Wolseley or a Hillman, you nearly always ended up with skinned knuckles, particularly in winter.... However, I still have a soft spot for those old English cars, despite the permanently scarred knuckles...

[@Scrubworks]

It's very easy to obtain new master cylinders for these now, at least here in the UK, since AP still makes them. I'd probably just use one of those. You can also swap to a Morris Marina pedal box that puts the brake master in the engine bay like a normal car, and also gives you the option of a servo and hydraulic clutch.

[@mebeasensei]

You are not kidding!!! Imagine all the labour costs?? THose holes tucked behind the torsion bar under the car! The cylinder under the floor! The list goes on! Did the unions design these cars? lol Compare this to an Holden or Falcon of the mid 60s, which would have been on the roads at the time these Minors needed repairs in Australia, and were starting to appear cheap in car lots as the first Toyota Coronas and Mazdas appeared. No wonder they were a labor of love. Like a Royal Enfield. But I guess they were fairly well made finish wise? I think it wasn't until the '70s when Brit cars went to dunny of quality?

[@tomt373]

My favorite BSW (British Standard Whitworth) "spanner" for removing the MM's master cylinder was an 8 inch Sears Craftsman crescent wrench, with a 5 lb. drill hammer to loosen the nuts, no skinned knuckles.

[@grahameblankley3813]

Hi, we have a 4 door minor, owned it 30yrs now, first mod I did disc brakes from a Morris marina the hubs had to be machined to suit the bearings & the master cylinder bored out to sleeve it with stainless steel & remove the seal as you did & changed the others, it's amazing what you can do on night shift in the engineering! You got 1 more sub, from Coventry UK 🇬🇧👍.

[@edsalerno2790]

You made it look easy, I would of used words not found in the auto dictionary currently. Well done.

[@gazza116]

its called a residual line pressure valve, its there to hold a low pressure in the brake system to hold the cyl cups against the wheel cyl walls.it also gave you a brake pedal on first application .

I could've done with this advice when converting my Austin A35 from drums to discs. Same set-up.

[@Scrubworks]

The way I've removed these before is to cut the heads off the bolts using an angle grinder, then slide them out the chassis rail from the other side. Then, put new bolts in the other way round. The reason the bolts are in that way in the first place is because they have special low-profile heads so that there's no danger of them fouling the torsion bar. You can achieve this with the bolts put in the other way round by using washers to space the heads out and making sure the threaded end doesn't foul the torsion bar.

[@chrisennis2245]

The reason they are in this way is so they don't fall out if the nuts come off. No hassle to do the job to original spec.

[@Scrubworks]

@@chrisennis2245 It's a considerable hassle. Nowadays with nylock nuts there is no reason to put the bolts through from the the suspension side. Even without them it's not hard to tighten up a pair of bolts properly.

[@peterscandlyn]

Quick, if a little awkward. Up here for thinking. Cool, worthwhile conversion.

[@grahamcrooks3581]

Drum brakes require a residual line pressure valve to work well. Problem with this conversion is that the rears cannot be converted to disc. I'd prefer to upgrade the front brakes to 8 inch drums, [earlier ones had seven inch, after 1961 eight inch. ] This is a 20% improvement in braking on the fronts, which is as good as disc in every respect other than fade resistance.

[@johnnytenjobs]

Good video. My dad and I spent a weekend messing about with disks on the front of his Traveller. I went home leaving him to do the hydraulics which he was happy with until he saw those master cylinder bolts behind the torsion bar!

[@stuarthalliday6169]

Take care which master cylinder you use. I tried it on an aftermarket unit and it locked the pedal every 3-4 engagements. I missed the small print on only using genuine parts for this modification. Loved the video, many thanks

[@TheEulerID]

Given the effort involved in getting to the damned thing, then I'd have put new seals in the master cylinder. They aren't expensive.

[@awesomeguy8392]

And cleaned it up

[@jonka1]

And lubricated it with silicone grease to slow the corrosion under the rubber boot. And treated the inside of the box section to slow the inevitable corrosion.

[@Pinzpilot101]

Another very wise upgrade will be telescopic front shocks.

[@jjmac3561]

You should really use a larger diameter master cylinder to safely operate the discs, you are going to have to move a lot more fluid to get the pistons in the caliper to move. A remote reservoir would be a secondary option with the original master cylinder. Why didn't you fit a new seal kit while you had it apart? That should be the minimum requirement on an old cylinder. How do you keep residual pressure in the rear brake line now that you have removed the rubber seal from the check valve?

[@jonka1]

He doesn't.

[@ludvignyman6940]

Is it possible for you to make some kind of comparison between the original brakes and the disc brakes? Regarding brake efficiency

[@ThisWeekWithCars]

With the disc brakes fitted it felt like it could do a front wheel stand.

[@johndavey72]

Alex lssigonis designed the Moggie (mini designer). He must have been in a bad mood when he thought this one out! l saw the pick up ! What a pain in the ***!

[@jaydwolf]

I pulled my master cylinder apart (a new replacement) and the end is not like yours it has a cup and a spring on the output end? no seal to remove? how do I modify this one I can send pictures.

[@allanmanley6340]

The Morris Minor I had all had its master cylinder on the firewall. Maybe because it was a right hand drive.... (Minor 1000)

[@jonka1]

Yours must have been modified. They all had the cylinder buried in the chassis member which meant zero chance of anyone checking the fluid.

[@ramaraonamburi7772]

Nice job done on nice car. I suppose many people will like its chubby cheeks and pot belly just like me. I think no other car will have shapeclike this. Really Awsome design people will become craze even if it re

[@chrisgiles8068]

Does this vid suggest no need for a servo?

[@mebeasensei]

You seem to be neurologically typical and not OCD. I would have started cleaning the master cylinder and the floor cavity. No wonder you get stuff done. (No, I wouldn't. I would have bought kit, made a mighty effort to install the discs and then given up and cried when I realised the master cylinder needs modification too..

[@ThisWeekWithCars]

I used to be that way but after hundreds of cars i have realized what is actually important.

[@grahamparr3933]

This appears to be the last video on this, can we assume you now have a moveable pile of rust?

[@ianatkinson8464]

😎

[@SvenDansk7]

What a pain in the ass place to put a MC. What were they thinking?

[@SvenDansk7]

@Doctor MENGELE Well I'm a Ford guy so I like my distributor accessible. Worked on a GMT400 454 once and literally couldn't see the dizzy. Had to use a mirror to even find the damn thing. I've never had a problem with the front mounted one in my F100, but then again it's about 17 feet off the ground.

[@UPTHETOWN]

@Doctor MENGELE Nope, this is a myth, my moggy, minis and 1100 never had a problem in the wet, plus the UK is not the wettest country. In fact the wettest countries in the world are much closer to Ozzieland

[@DMJ52]

Doctor MENGELE You have never owned a French car then ?

[@Witheredgoogie]

@Doctor MENGELE Those engines were pretty much a pioneering design, hardly anyone (if any) had put the engine and transmission east/west rather than north/south before, so the distributor had to go somewhere and most of the design money went on designing front wheel drive, something everyone uses now but was hardly known in 1959.BL could take the flak for the teething problems which others could improve on.

[@johnquilter7620]

@Doctor MENGELE There WAS a factory splash shield fitted to later model Austin Americas.

[@ramaraonamburi7772]

I mean if it come back

[@JosephOlson-ld2td]

Lucas Electrics and Girling brakes were junk > upgrade when possible

ur junk

[@JosephOlson-ld2td]

@ "All of the parts that fall off of this vehicle are of the highest quality British craftsmanship"