Brake conversion

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IslipMinor
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Re: Brake conversion

Postby IslipMinor » Wed Feb 13, 2019 2:22 pm

the 7/16" bolts used for securing the caliper direct to the stub axle
Phil,

Does the Minor conversion kit for Marina discs and calipers bolt the caliper directly to the stub axle? I thought there was a sheet metal bracket that bolted to the stub axle (with 4 x 5/16" bolts!), and the caliper bolted to the bracket with the two 7/16" bolts?
Richard



paul 300358
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Re: Brake conversion

Postby paul 300358 » Wed Feb 13, 2019 3:53 pm

You also have to consider the fact that the J type bracket is looped around the back of the backplate fixing, if you remove all the bolts, the bracket still cannot spin.

Rust bucket
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Re: Brake conversion

Postby Rust bucket » Wed Feb 13, 2019 4:07 pm

Hope i'm not going on too much about this subject but are Marina hubs and Midget hubs the same depth, ie measured from the front face to rear where they bolt to the disc.

philthehill
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Re: Brake conversion

Postby philthehill » Wed Feb 13, 2019 4:18 pm

Richard
The Marina/Ital caliper is fixed to the mounting bracket by two 7/16" UNF fitted bolts which in turn is attached to the Minor/Marina/Ital swivel by four 3/8" UNF (not 5/16" UNF) fitted bolts with reduced depth heads. (the 5/16" holes in the Minor swivel have to be drilled out to suit the Marina/Ital mounting bolts. The mounting bracket fits completely around the seal boss and has a return lip to increase its strength.
Below is a photo of the Marina/Ital caliper bracket attached to the Minor swivel using the Marina/Ital fitted bolts with the spring washers & nuts replaced by nylock nuts.

My reference to 7/16" bolts referred to the way the Midget caliper is attached directly to the Midget stub axle. Also referenced in one of my posts above.

My concern is that the number of bolts have been reduced to three, they are 5/16" not 3/8" and the 'J' bracket does not circle the stub boss completely and yet the brakes are more powerful; this increases the rotational shear forces on the three 5/16" bolts. The four 5/16" bolts are more than adequate for drum brakes - but BL considered those 5/16" bolts to be inadequate for use with discs brakes and increased the size to 3/8".
Phil
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Rust bucket
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Re: Brake conversion

Postby Rust bucket » Thu Jun 27, 2019 5:54 pm

Bit of an update on my brake coversion after a while, in the end I went for Wolseley 1500 drums as it was much easier and cheaper.
All fitted now but still have a persistent problem of pressure building from time to time, sometimes it's all ok then the peddle will get too hard with almost no play and the front brakes will bind and get hot.
They are Minor cylinders on the front not wolseley, my last thought and the only thing I can do now is remove the top hat in the master to maybe stop pressure building in the system.????

philthehill
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Re: Brake conversion

Postby philthehill » Thu Jun 27, 2019 6:28 pm

There is no need to remove the top hat seal (the re-couperation valve) as it is required with drum brakes to keep the cylinder piston seals against the cylinder walls especially Morris Minor 1000 rear cylinders.
The only reason it is discarded when disc brakes are fitted is that the valve allows a small line pressure (8lb) to build up in the circuit - if the seal is not discarded that line pressure would not allow the caliper piston(s) to return to the free non rubbing position.

By all means check the top hat seal but my first inclination would be to examine the wheel cylinder for proper operation and free movement.


Rust bucket
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Re: Brake conversion

Postby Rust bucket » Thu Jun 27, 2019 7:06 pm

Ok thanks for that, I did take a piston out of one cylinder and it was a little mucky. Fitted some new seals to it so it could be all four are getting a slight rusting and sticking.


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