NEW FULL-HYDRAULIC WHEEL CYLINDERS

[Mike Allfrey]

A WORD OF CAUTION!

I have received, very promptly from Jowett Car Spares Limited, a complete set of new full-hydraulic wheel cylinders - all six of them. That is the good part.

Now for the not good parts. The wheel cylinders are branded 'County' and, the set that I received are not suitable for use in a Jowett motor car. There are three reasons for this situation:

1. To fit the front cylinders the stud holes had to be opened out. It appears that the studs are slightly out of position in the cylinder casting.

2. The new cylinders have pipe fitting ports that have no raised cone for the flared pipes to seat against when the union nut is tightened.

3. At the rear cylinders, the handbrake tappets cannot make contact with the brake shoes. Such a condition renders the handbrake unusable.

The last two concerns are closely related to road safety and could have serious consequences in the event of an accident.

Club members must be warned about purchasing new items that are not at all suitable for fitting into a Jowett's brake system.

Be careful,

Regards,

Mike Allfrey.

[Keith Clements]

Thanks Mike for alerting us. Hopefully JCS will resolve.
It is likely others might be tempted with what appear to be equivalents.
If these are the only available replacements then we should look at how to modify.
I will have a close look at the ones bought for the Le Mans race car as spares.

[Mike Allfrey]

Thanks Keith,

The piece below resolves the concerns.

The problems related to the County wheel cylinders have been resolved at last! Today I visited a local brake and clutch company, BGT Brake & Clutch Services, at 18 Cambria Road, Keysborough, Victoria, 3173. At the counter, I explained the problems that have been experienced so far. There are two solutions to the problems:
1. In the rear wheel cylinders, use the original pistons if they are in good condition. Or, if those that have been supplied with the new cylinders, machine the brake shoe slots in the pistons so that the dimension from the inner face of the piston to the bottom of the slot is exactly the same as the original. Doing this will ensure that the handbrake tappets will contact the brake shoe web.
2. Also mentioned was the fact that the seal spreaders and spring may need to be swapped. The spring supplied with the County cylinders is longer than the original.
3. At the pipe union ports a copper ‘olive’ is definitely required so that a reverse flare pipe can make an effective seal when the union nut is tightened home. I purchased enough to fit the front bridge pipes and the rear axle pipes. The part number for the copper olive is BX244. The olive must be fitted in the union port with its cone surface facing the pipe and union nut. I get the impression that the olive will spread its sharp edge to form a tight fit in the housing – we shall see. Refer to the photograph, 130-007, attached.
To me, it is of extreme importance that Jowett Car Spares Limited and the Jowett Car Club of Australia Inc., issue with every new County brake wheel cylinder a set of written instructions detailing Items 1 and 2 above to ensure that the cylinders are suited for the purpose intended. We also have to understand that customers who purchase these wheel cylinders may not have mechanical skills needed for correct installation.
To continue, every new County wheel cylinder must be supplied with one copper olive, Part Number BX244, to enable fitment of standard Jowett/Girling reverse flared pipes and union nuts.
This is our responsibility and must be carried out before any more cylinders are sold. The instructions must be printed on an official Club Letterhead and be clearly printed so that they can be read easily – and, hopefully, properly understood. The Club’s Associations Incorporation Number (ACN) must also be prominent.

The above should be placed in Jowetteer, so that all members are aware.

Regards,

Mike A.

[trymes]

Things like this are the reason why, whenever possible, I choose to have my original parts re-sleeved in brass or stainless and then rebuilt. Never a concern about fit, and they come back better than new. I have seen many similar threads for many different cars, where new replacement parts aren't quite right, and work must be done to make them suitable. Better to rebuild what you have, IMHO.

Here in North America I recommend White Post Restorations and/or Apple Hydraulics, but those shops will be of little use to anyone in a different part of the world, which describes almost all of the members of the club!

Tom

[Mike Allfrey]

Thanks Tom,

Indeed, my Jupiter's original wheel cylinders had been locally reconditioned, with stainless steel sleeves just last November. The right-hand front wheel cylinder suffered a breakup of the plastic air excluder (seal spreader, seal support) which jammed in the coil spring and caused the brake to bind severely. Having seen in Jowetteer that new wheel cylinders were in stock at Jowett Car Spares, I decided to treat the Jupiter with its first, in my ownership since 1962, set of new wheel cylinders. Mostly for peace of mind due to the possibility of another same-type lock up.

That was when I discovered that the new cylinders would not fit straight in.

All of that now appears to be resolved and, yes in future, I have no doubt that the owner will have them sleeved.

By the way, the new set arrived here in Southern Australia in five days, much quicker than getting old units reconditioned - last time that took two weeks. So, a bit of a win all round for me.

It is now imperative that the Jowett Car Clubs, UK and AUS ensure that the wheel cylinder kits contain the parts required and the printed instructions for fitting are included with each wheel cylinder that requires adaptation. I will be happy to assist with that.

Regards,

Mike A.

[Nick Webster]

Automec, who are probably the leading supplier of brake pipe kits in the UK (including Jowetts) go out of their way to explain that their pipes have what they term a universal flare, which most recognise as a Lockheed type double formed flare. They explain that this seals reliably even where a bulb flare would have previously been used, whereas vice versa does not apply. Arguably then this default is the safest. In fact of course the follower that holds the pipe in place should actually be shaped differently for use with each of these fittings and my thought is that difficulties in holding stock and supplying two different types has a lot to do with the trend towards double flare for all applications. Ironically, I have always preferred the Girling bulb flare rather than the Lockheed double, which tends to deform out and can jam in the hole making removal and re use difficult.

Nick.

[Mike Allfrey]

Thanks Nick,

Down here in the Colonies we have to make do with what is available.

With the Girling type flare and union hut, I have been involved in situations where the union nut had been excessively over-tightened to the extent where the leading end of the nut had 'flared' to a diameter that took the aluminium threads with it as it was unscrewed. Not on a Jowett, but on a combine harvester - but still the same set up.

It is my firm belief that a number of us should be installing new wheel cylinders as a matter of course. The reason for this belief is to generate a pool of cylinders that can be easily reconditioned by future generations, be they Generation A-1 or whatever term will be trendy at that time!

I am different from most Jowett owners, in that I consider the new wheel cylinders to be cheap and, once sorted, easy for the reasonably skilled home mechanic to install in his Jowett motor car. Here's hoping that we can make that pool of easily reconditioned wheel cylinders grow to the extent that we can keep our Jowetts on the road.

Think about it, one set of new wheel cylinders at 260 quid in seventy-plus years is, in my book, damned good value! I think my Jupiter agrees on that point.

Thank you Jowett Car Spares Limited - even if the bank transfer goes 'walkabout' for a while!

Mike Allfrey.

[Nick Webster]

As a matter of interest here is a broken pipe that I changed on a Javelin I was recommissioning after it had been laid up for a couple of years. I have found back axle pipes in trouble before and wonder if the slight movement of the slave cylinder has anything to do with it. It was hard to spot because it was only leaking under pressure - the clue was the bubbled paint on the axle. Of course the pipe broke like this when I took it off. Note that the pipe with wax protection looks quite good, but I suspect had rusted where water was trapped in the crevice where the pipe entered the securing fastener. I made the new pipe in Kunifer which I prefer to use if possible, though it requires a relatively heavy duty forming tool.

Nick

[attachment=1]2022-12-27-b.jpg[/attachment

[Mike Allfrey]

Thanks Nick,

In the past, I have always used Penrite Copper-Eze thread lubricant on the union nut thread and around the brake pipe where the nut sits after tightening home. Here in Melbourne we do not have anywhere near the rust problems that you have in Britain. That method has worked for me.

I agree with your comment about the pipe flexing at the union nut when the rear wheel cylinder moves. The right hand rear probably suffers more because it is a shorter pipe. The same applies to the pressure pipe at the master cylinder, which pivots a small amount as the brake pedal is stroked. The rear brake wheel cylinders, if properly installed, can slide on the back plate - mostly when changing from forward braking to reverse braking. I was told at college that when brake pipes are made-up for use in areas where small amounts of pivoting occur, to be generous with length at any bends in the pipe.

The wheel cylinder concern on the Jupiter has been resolved. An article about the entire episode has been written for The Javelin our newsletter. I hope it gets into a coming edition.

Regards,

Mike A.

[David Morris]

Hi All,

What a useful thread! I wonder how many owners know that you need to leave the rear wheel cylinders with enough 'slack' on the two fixings to the back plate to allow the rear wheel cylinders to slide back and forth?

The wheel cylinder and the plate next to the backplate need to be lubricated, so they can slide easily. The nuts were originally secured with small split pins. However, replacement wheel cylinders seem to have lost this refinement? I always used at least Nylock nuts. Never use ordinary nuts here! The temptation is to do them up too tight and anyway, they are liable to work loose if deliberatly left slack..

All the best,

David

[Mike Allfrey]

Thanks David,

All similar wheel cylinders are held in with Nyloc nuts and plain washers, in fact, I understand that the later Javelins and Jupiters had wheel cylinders secured by Simmonds nuts. The castellated nuts were used with Thackeray (Thackray?) washers. The Maintenance Manual does state that Girling white grease should be used to lubricate the sliding parts.

In addition, I was taught to install the front wheel cylinders, first nipped up, then the Nyloc nuts backed off half a turn. After assembly and bleeding, the brake adjusters (all four) should be set to lock the drums. The brake pedal should then be pumped hard four times to centralise the brake shoes. After that activity, the front wheel cylinder Nyloc should be tightened. Then the brake shoes can be adjusted in the normal manner.

We all need to keep an eye on our brake systems.

Regards,

Mike A.

[Forumadmin]

This is a 'Read me First' post for brakes.
viewtopic.php?p=46816#p46816

Note point 7.

Other brake issues are discussed in the rest of the topic.

[Mike Allfrey]

Thanks Keith,

I have read all of that information. And used it.

Mike A.

[Keith Clements]

Mike, I am sure you have! The comment was directed at David and others reading this topiç. There is always the problem of keeping all the useful information on a topic together and in a concise form.

[Mike Allfrey]

Thinking still about wheel cylinders.

The front wheel cylinders have two ports, one at 90 degrees to the cylinder's bore, the other at, say, 45 degrees. In the original cylinders, the 90 degree port featured the convex machined seat for the reverse flare pipe and union nut. The 45 degrees port had a tapered seat for the bleed screw.

Does any one know which port the front brake hose should be screwed into? My guess is the angled downwards port, leaving the upper port for the bridge pipe - I think the guess is correct. Any comments?

Regards,

Mike A.