Jupiter restorations.

[Andrew Henshall]

One major problem with your son's suggestion David; the starter motor on the Javelin/Jupiter rotates in the opposite direction to the majority of starter motors!

The best solution to retain the ring gear is to Scotch key it to the flywheel. I've seen numerous examples down this way, and the benefit of this method vs welding is that it can be removed at a later date for replacement or to simply rotate it away from the worn spot.

Andrew

[Srenner]

There is a modern gear reduction starter made to work with the Jowett. One must check that it engages deeply enough to avoid chewing off the extreme edge of the ring gear.

Agree with Andrew the proper fix is not welding. We have frequently milled three holes using a rotary table and the hold the gear with button head socket screws. Seems like over half of the old race cars I have serviced used this fix.

[David Morris]

Hi David,

Glad you have bottomed-out the engine problems. Once you have sorted the Bradford, I m sure you will get the Jupiter engine back to 100%. As you say, it's a question of sorting out the sticking valve ( or valves? ), fixing the ring gear to the flywheel and curing the water leak. All I can recommend is to use the NZ head gaskets during reassembly, if you are not already using them? Check the liner protrusions ( no more than 0.005" ) and the valve stems for any signs of bending. Have you used new valve guides? If not, there may be a build-up of carbon inside the guides or on the valve stems, especially just under the heads. You can check the wear in the guides by putting your finger over the cylinder head end of the guide with a valve stem inside the guide and pulling the valve out sharply, there should be a sharp 'pop' as the valve is pulled out. If there is just a dull 'umph', then the guide and/or the valve needs replacememt. You can drive the guides out from the head, having made up a drift with a spigot to go inside the guide. When making this drift, you can arrange a shoulder on the drift to use upon insertion of the fresh guide, to ensure the correct insertion depth.

With the heads off, do check the condition of the heads, especially on the narrow land of casting between the two valve seats . It's often hard to see, but this is a very vunerable area for hairline cracks to develop. We have a pile of failed heads in our spares shed, for just this reason. Cracks here give water leakage and other problems.

Enough of telling grandmother how to suck eggs!

All the best,

David

[David Kemp]

While waiting for gaskets I decided to start back on my brakes. The new slave cylinders do not fit! They have been incorrectly machined , so now i am rebuilding the old ones by honing & using the internals of the new cylinders.

[Keith Clements]

David, where did you get the slaves and who manufactured them? Where was the machining incorrect?

[David Kemp]

The studds are off line of where they should be.
& i have no intetest in modifying my 70 year old backing plates to fit didgy parts. I bought them off ebay .

[Srenner]

NZ Spares sells original slaves that have been sleeved with stainless steel.

[David Morris]

Hi All,

The unfortunate lesson here is that there are a number of sellers on eBay offering front and rear wheel cylinders at competitive prices. However, some of these may not be compatible with the originals and probably the best source would be JCS?

All the best,

David

[David Kemp]

I have removed my cylinder head & as suspected water is coming from the push rod passages.
All i can think of is internal corrosion of the crankcase or gasket failure. Anyone had either? Any other ideas?

[Forumadmin]

And are you sure it was coming from the push rod tubes?

If you have the head off then it should be fairly easy to see if the gasket has failed.
If you take the tappet covers off then you should be able to see if any water is in there. If so it is likely to be a cracked block.
Pictures would help diagnosis.
And yes most of us experienced Jowett owners have had water coming out of most places.

[David Kemp]

I am working smarter as I get older, I needed to salvage some parts from this Javelin diff. So I have made a crane out of a discarded people hoist, & bolted it to my Howard garden tractor.
This is far less strenuous than physically trying to move it, as I would have done 40 years ago!
My Jupiter now has the rear brakes fitted, with a bit of luck the front brakes will be fitted this coming weekend.

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[David Kemp]

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Before & after. I will make a test pump out of the master cylinder before installing incase they leak.

[Mike Allfrey]

To: David Kemp,

While Keith Clements was here in early April, I gave him a full set of my Technical Notes Series. There is a heap of information in there, provided they are read through and understood.

Any Questions, please ask.

Mike Allfrey.

[David Kemp]

Thank you for your help.
Though everything that can go wrong has, I am an optimist & use it all as learning experience.
The big thing I have learnt is the best way to get it done properly is do it yourself enough times to be the expert
It is a long week end here , which gives me three days to play with my Jowetts.
House cleaning or garden duties can wait another day.

[David Kemp]

Part of the learning experience is that not all Girling slave cylinders are the same, & as shown have different bleed nipple design that do not interchange.
I can confer with Mike Allfrey & Jowett notes that County brand slave cylinders are NOT bolt on fitment. Do not buy them, pay more & get something that does.

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