Andover Norton MC Bleed Instructions

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stevejovais

stevejovais

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Question about MC install - Just received the Andover 13mm MC, 06.1939/13 and was ready to swap out the old MC for the new. Until I saw the instruction sheet for the MC bleed process, which requires dismantling the unit, soaking parts in brake fluid, etc. I've been away from the wrenches for a while, and was quite surprised that a brand new unit would require dismantling and reassembly before it could be installed. Sure hope I've misunderstood. Any comments on this would be appreciated!
 
I suggest "bench bleeding" first. With the master clamped in a rubber/plastic/soft jaw equipped vice, the brake light sender installed find an old piece of steel brake line or a plastic nipple with male barb. In either case the idea is to channel the output back to the reservoir. Stroke the master until the return fluid is free of air bubbles. Now the master is blead.

The hard part is bleeding the caliper, do a search--lots written about this aspect.

Best.
 
RoadScholar said:
I suggest "bench bleeding" first. With the master clamped in a rubber/plastic/soft jaw equipped vice, the brake light sender installed find an old piece of steel brake line or a plastic nipple with male barb. In either case the idea is to channel the output back to the reservoir. Stroke the master until the return fluid is free of air bubbles. Now the master is blead.

The hard part is bleeding the caliper, do a search--lots written about this aspect.

Best.
Click to expand...
Thank you, RS! Appreciate the reply.
 
It's especially hard to bleed the MkIII's rear caliper, due to the confabulated circuitous piping scheme that is OEM...
 
FWIW, I replaced both master cylinders on my MKIII with 13 mm versions. I simply disconnected the MC and put a brakes line clip ( they look like clothes pins but have rubber tips to block the fluid) on the hose or hardline to prevent the fluid from leaking out. Reinstalled the new MC and put in just enough brake fluid to cover the bottom. Then force bled from the caliper with a syringe. Working the lever slightly while force bleeding helped to get the air out of the “front” side of the MC. Bleeding took about 10 minutes. If you let all the fluid out of the system it then becomes a headache.
I spray everything that can be damaged by the brake fluid with soapy water and then cover with plastic and towels to prevent damage.
Pete
 
"Until I saw the instruction sheet for the MC bleed process, which requires dismantling the unit, soaking parts in brake fluid, etc."

Seriously? :eek:

I've purchased/installed a LOT of master cylinders on all sorts of vehicles and never heard of a recommendation to disassemble a MC to prep it for service. In fact, that's the opposite of any instructions I have ever seen for installing a MC; it's just asking for a failure! It would make me seriously wonder about the quality of the item and the assembly/preparation for packaging!!!
 
I last installed a rebuild kit for a leaky MC. I believe I purchased it (the kit) from Andover Norton. Instructions included advising
soaking all parts in brake fluid prior to installation. It was no problem whatsoever. I also am baffled by the difficulty
some people encounter bleeding air from the brake system. Having serviced two MCs and replacing fluid on
a couple more occasions, the service manual instructions worked easily. I did tape the brake lever back overnight
to allow small bubbles to evacuate. Easy peasy.
 
Maybe I misunderstood the OP. If it was a rebuild kit soaking the pars in brake fluid is a normal procedure. But it is not normal to buy a new item and have to disassemble/service/reassemble it before installation. ;)
 
Hey all, thanks for the replies. A tech at Andover Norton confirmed that disassembly/reassembly is not required for the 06.1939/13 MC body they offer. Missing from the tech's reply was why they include a document describing that procedure when they ship the unit.

My '73 Combat has just returned home from a long refurbishment project, and unfortunately the front brake failure was not addressed during that 14 month span. Looking forward to getting the brake sorted, and breaking in the rebuilt motor. Cheers, y'all!
 
One of my friend's bleeding trick is to use a brake fluid filled oiler. He connects a hose to the caliper bleeder and push slowly oil in, while someone keeps the brake lever open. This oil going the opposite way of the normal one-way, push up every little air bubbles to the open MC. I've never tried this, but my friend is still alive. I suppose all his motorcycle brakes work properly..LOL:p
 
Sergio said:
One of my friend's bleeding trick is to use a brake fluid filled oiler. He connects a hose to the caliper bleeder and push slowly oil in, while someone keeps the brake lever open. This oil going the opposite way of the normal one-way, push up every little air bubbles to the open MC. I've never tried this, but my friend is still alive. I suppose all his motorcycle brakes work properly..LOL:p
Click to expand...
Should be no need to keep brake lever "open" as pulling lever towards handlebar means the MC piston seals are moving past the fluid holes in bottom of resevoir, effectively sealing off free flow of fluid, which is exactly what's supposed to happen as you pull the lever.
Leaving lever in rest position has the fluid able to flow up or down through the tiny holes to or from the caliper.
 
stevejovais said:
Hey all, thanks for the replies. A tech at Andover Norton confirmed that disassembly/reassembly is not required for the 06.1939/13 MC body they offer. Missing from the tech's reply was why they include a document describing that procedure when they ship the unit.

My '73 Combat has just returned home from a long refurbishment project, and unfortunately the front brake failure was not addressed during that 14 month span. Looking forward to getting the brake sorted, and breaking in the rebuilt motor. Cheers, y'all!
Click to expand...
I wonder if these instructions are meant to allow them to sell assembled MC's in a dry state. They may sit on the stock shelf for many years prior to selling and any assembly fluid might do harm long term exposed like that.
It is generally advised to pre soak all seals when assembling brake parts.
 
Tornado said:
I wonder if these instructions are meant to allow them to sell assembled MC's in a dry state. They may sit on the stock shelf for many years prior to selling and any assembly fluid might do harm long term exposed like that.
It is generally advised to pre soak all seals when assembling brake parts.
Click to expand...
I bough a 'complete' 13mm rear cylinder from them which I stored indoors for a few years before use. On fitting I found the seals to be U/S :-(
 
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