Surface finish for bore of brake master cylinder?

[gustafson]

Gonna increase your pedal effort with the larger bore.

 

[mjr6550]

I don't think the pedal effort comment is correct. Pedal effort equals pressure. Pressure over the larger area equals more force. More force means you stop faster. So, does that mean you actually need less pedal effort.

Or because its Sunday morning I need more coffee?

 

[e-fishin-c]

Finish honing with Sunnen J87 or finer the last few thousands.

mrj, You have it backwards, brew some more coffee

 

[gappmast]

A J85 or J87 should work well leaving a 16RA finish. I would recommend removing about .002" to make sure you are at base metal like e-fishin-c stated.

 

[gustafson]

I don't think the pedal effort comment is correct. Pedal effort equals pressure. Pressure over the larger area equals more force. More force means you stop faster. So, does that mean you actually need less pedal effort.

Or because its Sunday morning I need more coffee?

Nope

YOu are trying to move more fluid per inch of travel for a given force on the brakes

more effort


People do the reverse when removing vacuum boosters

 

[jim rozen]

There's no pedal here, guys.

 

[plastikdreams]

There's no pedal here, guys.

Well technically there's nothing but words and pictures here...

 

[jim rozen]

Smart money says, it's a hand lever.

 

[Laverda]

After poking around on the web, I have learned if I am gonna bore it, at the same time sleeve it so any future corrosion problems will be avoided. There are two opinions as to what to sleeve it with. Stainless or brass. The majority favor brass as it has less friction compared to stainless and I will be long since dead before the brass corrodes.

Now what I can't find out is what grade of brass to use? The companies that do this as a business don't say. Also it seems that brass tubing of the correct size is available that won't need honing? You bore the cylinder and glue the brass in with Loctite and you are done?

So is this special brass tubing already to size available and from where? I need 5/8" and 1/2" ID

The front master cylinder, no seal kits are available so I have no choice but to bore it.

I just took the back master cylinder apart today and it has bad pitting so I will have to sleeve it as new ones are not available but seals are.




Here is a picture of the back one. The front one is in the ultrasonic cleaner at the moment.

And here is a picture of the bike the brakes are on.

 

[jim rozen]

At one time Small Parts corp. sold "telescoping brass tubing" in inch sizes. 1/32 inch wall size. So I would bore the cast iron MC up, and ream so I had the correct clearance for green loctite, 620 I seem to recall. I put a few very shallow cicumferencial grooves on the tubing OD as a jc maneuver.

Coated the OD of the tubing and the ID of the bore and slipped it on in.

Yes you need to drill the ports out through the brass, and I used some 600 grit on a wood dowel to de-burr.

I chose brass on advise of a man named Joe Rogers who posted here long ago, and did this for a living. I did not hone or otherwise modify the brass ID in any way.

The bike got a new piston with rubber cups then, probably 15 years ago. Still in use, that re-build still holding.

 

[jim rozen]

1) the man's name was Joe Way apparently, and

2) shit, apparently Small parts is no longer a going concern.

 

[john.k]

Ive done cylinder repairs for non road stuff by using a long bronze bushing from a bearing shop.........Case dozers in particular have two master cylinders working the either side steering brakes ...done lots of them...........I wont do onroad brakes ,as here I am criminally liable for doing non Transport Dept approved stuff that causes a injury.

 

[john.k]

At one time,all brake cyl relines here were bronze......then for som ereason bronze was out,thin stainless is approved ....now relines used to be closed shop ,because getting $100 for a few minutes work wasnt all bad....and still ,I cant source the thinwall stainless tube.

 

[Milland]

1) the man's name was Joe Way apparently, and

2) shit, apparently Small parts is no longer a going concern.

Ultra-Formable 260 Brass Round Tubes

Brass C260 Seamless Telescoping Tubing | Component Supply

Not sure I'd trust them without a light ~600 grit flap sanding on a spun wooden dowel, and a thorough cleaning afterwards.

 

[BillE]

At one time,all brake cyl relines here were bronze......then for som ereason bronze was out,thin stainless is approved ....now relines used to be closed shop ,because getting $100 for a few minutes work wasnt all bad....and still ,I cant source the thinwall stainless tube.

The place down here that does a large proportion of the hydraulic cylinders for a fair swag of brake/clutch shops, won't touch aluminium ones. Typical charge would be around half that for the usual reline of a car size one at least. Stainless liners must have taken over around 30 years ago?

 

[richard newman]

2) shit, apparently Small parts is no longer a going concern.

I seem to recall that Small Parts was acquired by Amazon. Maybe that stuff is available from them. They were aa great source for, well, small parts.

 

[ken moss]

I would not use that type of hone to do that type of job. what I would use is Sunnen hone ken

 

[tdmidget]

The bore diameter is no problem. Sleeve it with a brass tube. Someone out there has the 9/16 cups available. For rubber seals the finer finish the better.
This web site is an archive of a guy who retired from this kind of work. He left it up due to the wealth of info about odd ball cylinders and techniques. It also lists successor shops that can do this work.

Sierra Specialty Automotive.

Antique and custom hydraulic brake and clutch cylinder restoration specialist

www.brakecylinder.com

 

[john.k]

Id be interested why the DOT here banned brass sleeves.......I know the fluid in the cylinders would turn greeny/blue with minimal corrosion,but never seen any kind of fail............the only fail Ive seen was the army had hundreds of power master cylinders resleeved in stainless,and the operator drilled excessively big compensating port holes,and never broke the sharp burr left......consequently rubber seals would develop a long groove and leak at short mileage.............now ,this wasnt all bad ,as the army never bothered to replace the rubber ,but simply scrapped the cylinders........I bought hundreds of the stainless sleeved cylinders as army scrap,cleaned,honed and painted them,and sold them for $150 each exchange.