Master Cylinder Reconditioning Kits

[David Morris]

Hi All,

A Jowett colleague has just rebuilt his full hydrailic Javelin master cylinder. Here is a word of caution. Initially, he ventured onto eBay and purchased what was being sold as a Javelin/Jupiter master cylinder reconditioning kit. There were several vendors who all seemed to illustrate the same kit of four parts.

Armed with this kit, he proceeded to strip the master cylinder and here he met a snag. The kit contained just four components, and certainly one of the rubber components that he extracted from the old cylinder was missing from this new kit. The condition of this component, called a sealing washer in the parts manual, was poor and he could not reuse it.

Fortunately, he dug around in his garage loft and found a refurbishment kit that had been sourced from JCS soume time previously. This kit was much more comprehensive and contained this sealing washer, along with many other components that were missing from the eBay kit. Using this kit, he successfully rebuilt the cylinder.

So, a word of caution. I recommend that you order your rebuild kit from JCS. However, personally, I would not try to do a rebuild myself. I have always purchased a warranted rebuilt master cylinder from either JCS or other reputable rebuilders. They pressure test the rebuilt cylinders, which gives me confidence in their performance. Braking safety relies partly on the master cylinder, which is vital in a single circuit system. There are other causes of failure in master cylinders, apart from the rubber components, such as scored or rusty bores and the piston.

I thought this might be of interest?

All the best,

David

[Keith Clements]

There has been much discussion on JowettTalk about the problems with master cylinder kits AND refurbishments performed by companies.

There are many parts in a master cylinder any one of which might be faulty including the wrong size or material if supposedly new, poorly manufactured if new, perished or rusty if new old stock, worn or scratched if reusing your own parts or if a rebuilder has used old parts, and finally a rebuilder may be incompetent or just negligent.

Because there may be so many things which could be wrong and because sometimes what is wrong does not show itself until after some time in service, I would urge everyone to take great care in sourcing parts and engaging a rebuilder of a master cylinder. I would dismantle and carefully inspect any rebuilt M/C before using. There is really no such thing as a guarantee so dismantling is not going to invalidate it.

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[David Morris]

Hi All,

I completely agree with Keith. There are lots of pitfalls with the brakes on our cars, apart from the master cylinder. Weeping wheel cylinders and defective hoses are just two areas.

Personally, I added a clear plastic extension that is commercially available, to the top of the brake fluid reservior to replace the existing cap.You just fill the reservior so that the fluid level can be seen in the neck of the extension.

Then, glance at this every time you open the bonnet. It gives you a warm reassurance!

All the best,

David

[Nick Webster]

This just a small point, but it is part of the brake system. Beneath the driver's footboard by the pedal levers there is a short rubber pipe connecting the brake supply reservoir to the master cylinder. Often this looks a little worse for wear and as mine was, changed in the past. As part of a wider brake overhaul I decided to change this and looked on Ebay for suitable pipe. I was concerned to find several instances of fuel hose to latest J30 spec being sold as suitable for both fuel and brake fluid. This is not so - fuel hose should be made of nitrile and dot3/4 brake fluid, EPDM. True, there is no pressure on this pipe and nitrile serves for a while probably by virtue of wall thickness but eventually, as mine was, it will start to sweat and soften with the risk of the internal walls contaminating the brake fluid. Eventually after carefully searching through I found a vendor (who specialised in rally car equipment) who listed the hose by use and material. If I was having work professionally done, I would query the source of all parts used.

Nick

[David Morris]

Hi Nick,

Absolutely right! We had a section member who had this short pipe fail, resulting in the brake pedal going to the floor and zero brakes.

I know how this feels, as I had the brake pedal going down to the floor, driving through Edinburgh on our way to the Crieff Rally. However, this was not a pipe failure, but the large nut coming loose on the end of the pedal shaft, that is the pivot shaft for the brakes and clutch pedal. Fortunately, I was able to find and re-tighten this nut in a car park by the Forth Rail bridge.

However, from then on, this was checked for thghtness when ever I was underneath the car!

All the best,

David