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Creating access to rear M/C cover screw on RHD Magnettes

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Wray Avatar
Wray Gold Member Wray Lemke
., South Carolina, USA   USA
Hank Mauel did this nice write-up on his solution to the pesky problem of removing the MC cover on the RHD Magnettes. It should have its own thread so here it is.

This quick tutorial explains and shows how to create an access point for the rear screw on the reservoir top on a RHD Magnette.

My recently sleeved/rebuilt Master Cylinder went back in with little difficulty, but the thin paper gasket was weeping/wicking brake fluid to the outside edges, then dripping down to the frame rail below. Since the MC is just below the battery tray on the RHD cars, there is no way to remove the rear screw in order to replace the gasket.

I decided to create an access hole in the battery tray, right above the rear screw, remove the reservoir cap and cut/install a new gasket of Buna N sheeting.

Step 1
After removing the battery, I used a popsicle stick (Photo 1) to locate the front edge of the rear screw. (first line on the stick) and then added half the head diameter of the other screw heads to get a mark (second line on stick) that would get me pretty close to center above the rear screw. I then marked the location with a felt tip pen and drilled a small pilot hole.

Step 2
A small pilot hole was drilled after covering the top of the MC with a paper towel and a piece of 3/16 cabinet plywood to protect the top of the MC from metal bits and the pilot bit in the hole cutter (Photo 2).

Step 3
Photo 3 shows the hole saw commencing the cut. I used my 18V Makita drill at a slow rpm. You will note in all the photos that the hole has to be cut through a rolled section of the battery tray. First contact is made at the leading edge, then down into the flat recess. This required that I start with the pilot bit extended to reach the pilot hole. As the depth progressed I had to stop and adjust the pilot bit to shorten it’s protrusion beyond the hole cutter so as not to drill through the plywood “guard” and hit the top of the MC. The progress can be seen in Photo 4.

Step 4
Photo 5 shows the hole…a 1” diameter…and the 3/16 plywood shield with just the tip of the pilot drill bit having broken the surface. Once again the “7 P’s of Project Management” paid dividends! I cleaned up the cut edge with a small hobbyist needle file.

Step 5
Photo 6 shows the now accessible rear screw on the MC reservoir cover.

Step 6
Photo 7 shows the MC reservoir top taped to a piece of BUNA N sheeting that is 1/16” thick with a Durometer reading of 55. I carefully cut around the cover edges using a new sharp pointed Exacto knife to create a new gasket outline.
Photo 8 shows the completed gasket after using the existing paper gasket to locate and cut the screw holes with a ¼” hollow punch…sometimes referred to as a gasket hole punch. I also used the punch to create the rounded corners for the filler hole and then cut the gasket material from corner to corner.

Step 7
Photos 9 and 10 show the finished installation, using the access hole to replace the rear screw and the BUNA N gasket installed. New stainless steel star washers were used to avoid corrosion. I covered the MC again and then touched up the raw edge of the cut metal with a Q tip dipped in some Birch Grey paint.

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Ian Williams Avatar
Derbyshire, Derbyshire, UK   GBR
Nice job there Wray

If my m/c has to be removed (again) due to limp brakes I shall do this...


Ian

Muzz Avatar
Muzz Murray Cowley
Tavistock, Devon, UK   GBR
1958 MG Magnette ZB "Maggie"
I did this just the other day.

I have been trying to get a good brake pedal after fitting discs and 3 stainless flexible pipes.

The Mrs has nearly gone through a whole book whilst sat in the car operating the brake pedal
over the 3 days of faffing about!

I am lucky I have a pit and just move the car back and forth over it to get to front or rear bleed valves.

However I decided to get a Gunson Eezibleed and pressure the system that way, only to find the top
of the master cylinder was puffing air out along with a fine spray of brake fluid.

I tightened the bolts but of course couldn't get to the rear one and it still leaked.

Right then! Make a hole, take off the m/c cover, make a new gasket from cork, put it all back together with a smidge
of hylomar blue to help it seal and Robert is your Fathers brother!

After lunch and tested for leaks, all OK so bled the system again. Very easy and quite a good pedal.

Took everything off taking care not to drip fluid as the m/c is toppers.

Still not a great pedal this morning, gone a bit softer, but out for a little run and I still need to get it better but good braking in a straight line
so that is an improvement. Need to bed in the discs and pads yet so after another bleed it should get better.

Just hope it will hold a firm pedal afterwards.

Off out Sunday on the Drive it Day so a fairly long trip around the countryside and that should show me how it all works out.

Such fun!

Cheers

Murray

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Wray Avatar
Wray Gold Member Wray Lemke
., South Carolina, USA   USA
Just to clarify, Hank did all this work, I just posted the procedure with the pics for him. He was kind enough to share with me via email.

In reply to # 3494796 by Ian Williams Nice job there Wray

If my m/c has to be removed (again) due to limp brakes I shall do this...


Ian

Ian Williams Avatar
Derbyshire, Derbyshire, UK   GBR
Hi Murray

Yes, I am building up to asking the missis to help with mine (and not looking forward to the response)

My Easi-bleed gave a "reasonable" pedal but the next day it was not so good. Does make me wonder about the M/cyl...

It's been suggested to me that just bleeding using a rubber tube on each bleed nip with a non return valve works just as well. Cant comment yet but will try.

Yes. I remember when I tested my easi bleed prior to bleeding it tried to empty the MC. I added some instant gasket around the existing paper one to solve this.

Not looking forward to returning to this job !

Wray Avatar
Wray Gold Member Wray Lemke
., South Carolina, USA   USA
I bled a clutch slave in about four minutes on a Spitfire using bleed screws I got from the local parts store. It was amazingly easy to do. Tube on the bleed screw, put the end in clear jar with a little fluid, open the bleed screw a little, pump until no more air comes out. Worked a treat.

Darvie43 David Hill
Narellan, NSW, Australia   AUS
Hi Murray,
I thought Charlie was your aunt.

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david.g.h Avatar
david.g.h David Harrison
Stratford upon Avon, UK   GBR
1929 Austin 7
1932 Austin 7 "Cabbage"
1956 MG Magnette ZA
1989 Porsche 944 S2
I used "Automatic bleed valves" (screws) on the wheels on Rally cars for years & they worked a treat. I didn't think they were still around. Helps to have a supply of nipple covers (probably don't look for these on the internet !) as it is easy to forget to replace them !

exbrat202 Avatar
exbrat202 Mac Pile
Royal Wootton Bassett, Wiltshire, UK   GBR
1956 MG Magnette ZA "Vera"
I found them under "double entendre" devil smiley

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enigmas Avatar
enigmas Vince Stok
Melbourne, Victoria, Australia   AUS
Murray, you can also bleed the system free of air at any union whilst depressing the pedal and loosening the union while the pedal is depressed. If you've fitted a booster to the circuit and it's mounted high up do this at the unions as well.

Another cause of air being drawn into the system is a pitted or longitudinally scored/scratched/bellmouthed master cyl. Honing old cyls is counter productive and just bell mouths or worsens the stuation. If the master cyl is original it'll need reconditioning with a stainless sleeve. Good insurance on any single circuit system.

Also ensure there is adequate free play at the pushrod, otherwise the piston doesn't fully return causing some of your issues.
If all things are correct, on a simple, single circuit system such as on a Magnette, the brakes should be able to be bled free of air within a half hour, if you start at the master cyl. The only thing you really need to remember is that air becomes trapped at high points in the system...look for these.



Edited 1 time(s). Last edit at 2017-04-23 10:22 PM by enigmas.

david.g.h Avatar
david.g.h David Harrison
Stratford upon Avon, UK   GBR
1929 Austin 7
1932 Austin 7 "Cabbage"
1956 MG Magnette ZA
1989 Porsche 944 S2
Just bought 4 brake & 1 clutch auto bleed screws on fleabay for £14....now do I have any nipple covers....?
D

tadge44 David Clark
High Wycombe, Buckinghamshire, UK   GBR
Search under "grease nipple caps"

david.g.h Avatar
david.g.h David Harrison
Stratford upon Avon, UK   GBR
1929 Austin 7
1932 Austin 7 "Cabbage"
1956 MG Magnette ZA
1989 Porsche 944 S2
See #9 above!
D

Ian Williams Avatar
Derbyshire, Derbyshire, UK   GBR
Hi Murray

I often had the air leak around the top cap of the easy bleed...it often needs an extra rubber seal from the kit (or one made) and this solves the leak..
In reply to # 3494806 by Muzz I did this just the other day.

I have been trying to get a good brake pedal after fitting discs and 3 stainless flexible pipes.

The Mrs has nearly gone through a whole book whilst sat in the car operating the brake pedal
over the 3 days of faffing about!

I am lucky I have a pit and just move the car back and forth over it to get to front or rear bleed valves.

However I decided to get a Gunson Eezibleed and pressure the system that way, only to find the top
of the master cylinder was puffing air out along with a fine spray of brake fluid.

I tightened the bolts but of course couldn't get to the rear one and it still leaked.

Right then! Make a hole, take off the m/c cover, make a new gasket from cork, put it all back together with a smidge
of hylomar blue to help it seal and Robert is your Fathers brother!

After lunch and tested for leaks, all OK so bled the system again. Very easy and quite a good pedal.

Took everything off taking care not to drip fluid as the m/c is toppers.

Still not a great pedal this morning, gone a bit softer, but out for a little run and I still need to get it better but good braking in a straight line
so that is an improvement. Need to bed in the discs and pads yet so after another bleed it should get better.

Just hope it will hold a firm pedal afterwards.

Off out Sunday on the Drive it Day so a fairly long trip around the countryside and that should show me how it all works out.

Such fun!

Cheers

Murray

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