24 replies to this topic

[tiger99]

The original piping will be bundy, which is ok as long as it is not corroded. It is basically made from a double wrap of thin steel strip, which is fully brazed, and then tin plated, which unfortunately does make it rust badly if scratched. But it has excellent fatigue properties, and will never fail due to pressure cycling. The danger is pinholes or complete fracture due to corrosion. Some European manufacturers have used plastic coated bundy, which might seem to be a good thing, but is not, because it corrodes at the ends, where the plastic is stripped back, and also invisibly corrodes at any pinholes in the coating. It is treacherous stuff. Cunifer will not corrode significantly.

Several "quality" manufacturers now use cunifer as standard, but no manufacturer has used copper since the 1940s, because it proved to be dangerous. The reason that it is not specifically illegal is that there was no need, because no-one was using it. That changed some time after Cunifer was introduced in the 1970s, when a certain supplier who shall be nameless, hard on the heels of the success of Cunifer, decided to make a fast buck by offering copper. As usage of copper increases, the danger increases, and I expect that the law will be changed soon to ban copper, in line with Eurpoe, the US and Australia, as it has been implicated in accidents.

[kez_19]

so does this mean that the GMC227 that minispares sell is for a front disk and rear drum setup then????

michael

[mini-luke]

Minispares actually advertise their brake pipes as copper (http://www.minispare...id=42206&title=) but if you read the description they're actually copper-nickel. Seems a bit strange to be honest.

[tiger99]

Yes, see item 58 here:

http://www.somerford...page=page&id=57

I always use the Someford web site as the information is more comprehensive, and the diagrams are useful, but check around for the best price.

Note that this is a stepped bore cylinder, the unions are both metric, 10mm and 12mm to prevent them being connected wrongly. Item 71 on the same page is a conversion pipe kit, as both your existing unions will be 3/8" UNF. Anyway, it is the correct, up to date master cylinder for a disc system, which is what matters. The stepped bore is used to get as much pressure as possible at the front, and less at the rear, so the total volume does not have to increase as much as it otherwise would, so the pedal will not be quite as hard as it would be if the entire bore was sized to feed the discs. It is actually the smaller bore which feeds the discs, but it has a longer travel than the large bore, low pressure part which feeds tha rear drums. (The pressure limiter remains the same, so front/rear balance is only changed under light braking.)

Somerford don't say whether the pipes in the conversion kit are copper, cunifer or bundy. Bundy is fine there as they are not exposed to corrosion, but copper, no way..... Some people use braided flexibles there to allow the master cylinder to be easily moved during maintenance, although it is more necessary with a servo. Teflon, with stainless steel overbraid, e.g. Goodridge, is perfectly acceptable. Minispares have BAU5655MS which is cunifer, and ideal, or make your own if you have a flaring tool.

[tiger99]

mini-luke, that may be correct in some cases, or a mistake, but in certain cases Minispares are definitely supplying copper, and have no scruples about doing so, but charge a higher price for cunifer (the price of the raw material is only very slightly different, the extra cost should be pence only!), so beware!

[RobWill116]

Thanks again tiger. I've been using somerford to check this out, a lot more detailed than other sites.
Gonna order new master cylinder and piping in the next week or so once I've been paid. Not going to buy the conversion kit though, just going to flare it all myself or get some braided for master to pressure limiter.

If anybody else is looking for the master cylinder...
http://www.ukclassic...r-dual-line.asp
A lot cheaper than minispares, a bit cheaper than jonspeed on ebay

[tiger99]

That is a lot cheaper! It certainly pays to shop around. Google is your best friend. And yes, making up your own pipes is what I would do too. I always have some cunifer lying around.

[RobWill116]

Ordered my new master cylinder and cunifer piping, received that week. All waiting for me to finish uni exams and sort everything out. Will update with results

[RobWill116]

New master cylinder is fitted. Just gotta re-pipe everything when I get chance! Figure out why the brake fluid boiled, the link pipe was resting against the live battery cable, which is held to the underfloor by the same clip as the brake pipe. I'm changing exhaust system anyways so I wil resolve this and repair the melted cable

[tiger99]

That is a most unusual failure, but clearly can, and did, happen. So all the apparently conflicting symptoms are now resolved, and you can be confident that the fix will work.