MadaboutKitcars

Or CBS do one for £6.60 inc VAT

http://www.cbsonline.co.uk/product/Master_Cylinder_Clevis_CLEVIS

5/16 UNF thread though.

[Edit] - aha! must read the thread properly. £8 delivered is cheaper!

For anyone interested:

I am not sure whether the Dual servo requires a seal to be maintained between the servo and the master cylinder. The Metro unit definitely does, but the Dual probably does not.
I have made this back plate as a trial for testing, and will deliberately leave a leak to confirm whether the seal is necessary or not.



This photo shows the exposed chamber of the Metro, whereas the Dual clearly has a sealed chamber.


Jason, and anyone interested
I know you are attending metal work classes, so you could make a back plate.
Dimensions are:
Plate - I chose 6mm mild steel: 5mm would be OK
Outer diameter: 108mm nominal
Inner diameter : 40mm for my Sierra master cylinder: generally to suit your own master cylinder
Recess diameter : - if required +5mm on diameter
Recess depth : 1.5mm when using 6mm plate
A cut out will be required for the vacuum elbow : drill 30mm diameter offset centre from perimeter approximately 5mm

Holes for servo fixings :2 x 10mm dia. on 87mm PCD
Studs for master cylinder : M8 x 20mm projection for my Sierra master cylinder, but generally to suit your master cylinder
Offset of servo holes to master cylinder studs : for my Sierra master cylinder approximately 75 degrees, generally to suit your own master cylinder

You may require a spacer between the servo output push-rod and the master cylinder : my Sierra one will require approximately +6mm

And it has to be a 3/8" UNF !

Jason

If I make this back plate to suit your BMW master cylinder and buy the adjustable clevis pin, are you up for testing it? - I can deliver it all to Northampton on my travels.

The only sticking point could be whether your brake pipes can move 2" further? Though I seem to remember you have used flexible pipes, so this should not pose a problem.
There appears to be quite a lot of interest in this, so you'll be doing all of us a favour, as I will not get my car on the road for several months yet.layball:

Sure - why not. I don't think there'll be an issue with by brake hoses... Not sure about the fluid feed lines from my remote resevoir. But I can get some more and rig up some longer lines during the test.

Good man
What is the hole size for the studs to secure the master cylinder?
What is the centre to centre dimension of the holes
What is the thickness of the master cylinder mounting plate? (to determine stud length)
Relative to the vertical, what is the degree of rotation for the centre line of the studs? - from your website it looks around 30 degrees. As you have a remote reservoir, I guess this is not too critical within +/- 5 degrees?
What is the diameter of the male part of the master cylinder which enters the servo?

I'll do some measuring tonight when I get in from work.

I will tell you that it's not a BMW master cylinder as far as I can tell, as I purchased it from Marlin. It's also mounted to the Metro servo without a mounting plate / adaptor, so the stud dimensions / pcd is as per the metro part.

I don't think it matter too much about the degree of rotation. What it is at the moment is as it fell from mounting the servo in the best degree of rotation to allow easy rounting of the vac hose and to keep the low pressure fluid entry ports relatively topside.

Jason
I've had a look on your website, and I'm sure it is a Ford master cylinder.
I can get the studs sorted out from the metro servo. I just need to be sure the male part of your master cylinder will go through the hole I have already made.

Did you have to make a spacer between the servo output rod and the master cylinder?

Yes - can't remember how big though... I believe I followed Robin's schematic. Hang on...

http://myweb.tiscali.co.uk/martinclan/images/spacer.gif

One of them!

Great.
The Dual has an adjustable output rod, so can compensate for the 6mm spacer, making it a direct swap.



I have ordered the adjustable 5/8" UNF clasp, so this should adjust the pedal height.

The prototype adaptor plate is now made:



And fits:






The adaptor angle has been set to allow my own master cylinder to attach vertically, as I am fitting the standard Ford Sierra reservoir directly to the master cylinder.

Cor, you're keen.

Here's some more info:



Adaptor pin / sleeve, as per Martin's diagram (10mm OD, 8mm ID, 2mm 45deg chamfer, 20mm overall length)



Casting number on the cylinder. No idea if it's of any use



Pic of the stepped nature of the servo end of the master cylinder. The larger portion is 40.5mm in diameter, the smaller 36.3mm in diameter. It's the larger of the two steps that creates the seal between the servo and the cylinder. The mounting holes are 8.5mm diameter, and have PCD of 70mm



The cylinder from the end looking back, showing the layout of the high pressure brake hoses (stainless) and the low pressure feeds. The studs are at 25 degrees from the vertical

Do you need anything else?

Hi Jason

I had the day off today and am quite pleased with the prototype adaptor, though I'll have to make a minor modification to the angle of rotation for the master cylinder, and then it should be OK.

I just hope when you test it you feel some real benefit!!

Just looking at your photos I may have a problem with the rotation of the master cylinder as it may cause your pipework to foul the side panels - you may need to test the brakes with the side panels off!

All the rest I think will be ok.

I have trial fitted the whole arrangement in my Cabrio, and apart from not getting the angle of rotation exact - it is more critical in my Cabrio as I have the standard reservoir mounted directly to the master cylinder, it fits much the same as the Metro version.





I have not achieved the exact angle of rotation to ensure the reservoir is vertical. This will prevent the bonnet closing, so the final design will need to err towards the engine.
Otherwise looking good!!!!

Jason

I think we are now good to go. You will need to fettle the servo hole mounts in the pedal box, as the stud centres are 85mm compared to the Metro at 90mm. My holes were fairly large anyway, so it required very little alteration.
Then as you say the only other issue could be the reservoir feed pipe length?

Can you PM me your Mobile & address please?
Mike

PM sent.

I think I can get away with the lines I have, If I make a gash bracket to move the res foward into the engine bay... I'll have to see.

The only issue with that is how much slack I have on the line feeding the clutch master cylinder as my res feeds both clutch and brakes.

Ok, good.

The bad news: I have received the clevis pin in the post this morning but it is too short for my set up.



One other small issue may be the size of the pin through the clevis - it is 3/8" too. Not sure what Marlin supplied on their extender arrangement, as I threw it away. My pedal has a 3/8" hole so not a problem for my Cabrio, but others may need to consider this.

The good news: I've found a supplier close to our Birmingham offices so hope to collect a longer version tomorrow.

It was a long time ago but I think the Sportster brake pedal has an 8mm bolt.

I found this very old picture which may help you understand the dimensions?


Trial fitting brake servo on pedal box by marlinpeter, on Flickr

GOOster and Vikki have taken delivery of the Dual 7" Servo and a "Long" 3/8" Clevis for road going trials.
Thanks Jason.



We must now wait and see.........................

PS - I got to see Vikki in the flesh today - a very nice example indeed, even without paint - and her seats are NOT pink!

Have just found this link via Google.

Speedway Motors in the USA do a Stainless Steel version!

http://www.speedwaymotors.com/Dual-Diaphragm-7-Inch-Stainless-Brake-Booster,37181.html

Well, it fits. I haven't got it completely attached yet, as I've had to come in for lunch (and some pills - I've got a stinking headache for some reason)

I'll have another look at it later.

And it's now all hooked up:





I opened up the mounting holes on the pedal box with my step drill, so it was just an unbolt and remove the old servo and bolt in the new one. The long clevis works a treat.

I will need longer fluid feed lines, if this all works out, as I unbolted the reservoir and it's just resting up against the bulkhead.

The elbow / one way valve on the servo needed to be removed, so my vac hose and elbow could be connected. Unfortunately, in removing the provided elbow it came apart - so I need to replace that for you, Mike.

I've tested for leaks, spraying the vac entry and the adaptor plate / servo / cylinder interfaces with brake cleaner, and no issues there.

Now all I need to do is try it out on the road.

Jason

You should be on X Factor -


"and the result is.............................................

Looking good....

The stepped design of that servo seems to fit really well in the available space.
I see you've fitted heat protection to the brake reservoir supply hoses which is a good idea, given that it above the exhaust.

Jason

Will that be necessary? - if you have used the Metro elbow, I should be able to do the same? I was also planning to use the BMW non return elbow away from the inlet manifold, as it comes out the back of the inlet manifold.

Mike

No - the provided one way valve / elbow on the servo isn't required - I just feel bad for destroying it...

BTW - the elbow I have isn't the metro one. I never got one with my unit. I just used a (IIRC) 10mm 90 degree elbow and straight vac tube all the way back to the BMW one way valve and 'air pump' attached to the throttle body.

I am sure we are all holding our breath to see the results.
Don't have flexible pipes myself they are all copper tubes, so will need a bit of work to make it all fit but if results are good, then it will be worth it.
Good luck Jason.