James
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| posted on 24/7/03 at 04:28 PM |
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Pedal to Sierra Master Cylinder
Just want to check I'm doing the right thing with getting my brakes to work!
So far my plan is the following:
to mount the MC directly onto the bulkhead. I've extracted the pushrod from the servo. This I will weld to the bracket that is held to the pedal
by the clevis pin.
Pushing the pedal pushes the rod and that activates the MC.
Is it really that simple? If it is I'd be surprised as nothing's been simple so far!
What stops the push rod coming 'out' of the hole in the end of the MC when the pedal is released?
I must have forgotten something!
Any info greatfully recieved!
Thanks,
James
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bob
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| posted on 24/7/03 at 05:21 PM |
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James
You need to put a stop on the pedal,basically to stop it returning too far.
This will then trap the rod between the M/C and pedal/clevis pin.
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macspeedy
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| posted on 24/7/03 at 06:31 PM |
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one thing make sure you re-enforce the bulkhead as a person recently failed on that, apart from that about what i did.
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Rorty
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| posted on 25/7/03 at 06:14 AM |
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James, it might be beter to nab a push rod from a wrecker's. Not only will it have the correct radiused end on it, but will also be threaded for
adjustment.
The adjustment is critical to avoid damaging the piston(s)/seals. Also, the piston hitting the end of the cylinder, shouldn't be used in lieu of
a strongly welded pedal stop.
As Bob says, there must also be a return stop/spring mount to ensure the pedal is at the correct position in relation to your foot/lined up with the
other pedals. 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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James
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| posted on 25/7/03 at 10:46 AM |
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quote:
Originally posted by Rorty
James, it might be beter to nab a push rod from a wrecker's. Not only will it have the correct radiused end on it, but will also be threaded for
adjustment.
The adjustment is critical to avoid damaging the piston(s)/seals. Also, the piston hitting the end of the cylinder, shouldn't be used in lieu of
a strongly welded pedal stop.
As Bob says, there must also be a return stop/spring mount to ensure the pedal is at the correct position in relation to your foot/lined up with the
other pedals.
Thanks for the advice guys!
Bob,
Thinking about it there is a stop- it's got the brake light switch attached to it! Doh!
Macspeedy,
I've used just of sheet steel- it's pretty stiff as it is but I'll weld a 19mm RHS across it- should be enough! 
Rorty,
I've got the pushrod from the Sierra itself so that should be ok- the bracket that connects to the pedal still has the threaded end of the Micra
pushrod screwed into it (I remember thinking it'd be a good idea to keep it at the time!) so I can use that too!
Cool! Sound like I may be onto a winner for once!  Now all I've gotta do is get the actual pedal right to fit the brake!
Thanks again,
James
P.S. Does the pushrod end of the MC need to be sealed/protected from dust etc? Because I can use the butchered Servo casing to do so if need be?
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Dick Axtell
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| posted on 25/7/03 at 02:27 PM |
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quote:
Originally posted by James - P.S. Does the pushrod end of the MC need to be sealed/protected from dust etc? Because I can use the butchered
Servo casing to do so if need be?
Yes - it is advisable to fit a cover on the pushrod end of the mcyl. Usually there are some available at one of the shows e.g. Donny.
Don't forget that with your proposed arrangement, you MUST ensure that the mcyl returns sufficiently to allow full recup flow (i.e. brakes
release). Using the pedal & pushrod as a backstop will be critical, so I recommend building some adjustability into your pushrod assy (if
it's from a Micra, there should be M10 thread + locknut).
Go carefully.
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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Jon Bradbury
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| posted on 25/7/03 at 03:21 PM |
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James,
On the Robin Hood DOHC kit I am building, I dismantled the servo and extracted the pin and rubber boot. A piece of wire is used to measure through the
foot pedal hole where the pin is attached to the inside of the brake cylinder actuating rod, which is hollow. I cut the rod accordingly and ground off
the ridge at the end and approximated a radiussed end as Rorty suggests. (I could have welded the radiussed bit off the rod end that used to go into
the master cylinder - I found it inside the servo and it looks rather like an engine valve). The rod is then fitted using common sense and the
Sierra's original plastic doughnut / spring clip. Works a treat, although I'd love an adjuster.
This procedure works for me, but note that my donor is an "H" reg DOHC Sierra Saphire and your brake might be different.
Regards
JonB
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Simon
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| posted on 25/7/03 at 03:58 PM |
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James,
In response to Jasper's request late last year, see this:
http://forum.locostbuilders.co.uk/xmb/viewthread.php?tid=1923
ATB
Simon
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Peteff
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| posted on 25/7/03 at 11:27 PM |
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Put a return spring on the pedal so that you are not relying on the M/cylinder spring to push it back or you may find the brakes don't come off
completely and drag on the discs.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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