Jupiter restorations.

[David Kemp]

Thanks Nick , I feel you are correct. after discussion with another Jowett fan I feel Meadows are all wide ratio.

[Keith Clements]

FROM SERVICE BULLETINS in the TECHNICAL LIBRARY

Bulletin Issue Date: March 1953
Item No. 129. Gearbox Ratios – Javelin

From Javelin Engine Number E3 PE 24179, the teeth on the constant mesh drive gear were decreased from 19 to 18. The teeth on the layshaft cluster constant mesh drive gear were increased from 33 to 34. This alteration was introduced at gearbox number 8153 and it gives a lower gearbox and overall gear ratio as detailed below:

Drive Ratios from Engine Number E3 PE 24179

Gearbox Ratio Final Drive Ratio

Top 1 to 1 Top 4.875 to 1

Third 1.5 to 1 Third 7.340 to 1

Second 2.38 to 1 Second 11.60 to 1

First 3.88 to 1 First 19.00 to 1

Reverse 3.88 to 1 Reverse 19.00 to 1

Drive Ratios from Engine Number E0 PC 11270 to E3 PE 24179

Gearbox Ratio Final Drive Ratio

Top 1 to 1 Top 4.875 to 1

Third 1.37 to 1 Third 6.700 to 1

Second 2.17 to 1 Second 10.60 to 1

First 3.56 to 1 First 17.40 to 1

Reverse 3.56 to 1 Reverse 17.40 to 1

[Nick Webster]

Given the introducton date the J close ratio box must be a comparatively rare animal then. Hardly surprisingly, given their history, the majority of J boxes I have seen also carry a R number. Reconditioned I assume. The original number is still left visible. Are there cases where reconditioned boxes with low original numbers have been rebuilt as wide ratio boxes? And if so apart from counting the gears, was there any external mark to indicate this?

I appreciate that overdrives as an unofficial modification will probably have a range of different ratios depending on origin. I do not generally move in "Jupiter" circles and am therefore unaware of the favoured overdrive. On some cars of the 50s overdrive was operational on as many as three gears and provided a useful mid-ratio. Is there merit - or even possible - to fit the Meadows box and use overdrive to fill ratio gaps? I realise if you don't have overdrive, this is quite a modification and therefore a hammer to crack a nut.

Nick

[David Kemp]

As I don't intend to race, most people I speak to believe I could not tell the difference between wide or close ratio box.
However as I live where hills don't really exist, & I intend to retire out west, where hills really don't exist, overdrive would be perfect.
However putting in overdrive at this stage is more than I wish to tackle, the answer people have suggested is putting in a higher diff ratio. Again I feel this is a future project as I am just trying to get my car going with what I have.

[Keith Clements]

The gap between second and third is what I noticed most on long hill climbs. Whereas the gap between top and third affects overtaking.
Both are eliminated with overdrive which I use on three gears. On the lower ratio third box (close) the difference between od third and top is negligible.
There is a lot on JT about them just search 'overdrive'.
Overdrives can be fitted to Javelins. The maker of the box is irrelevant.
You can have a box made to your own ratios at great expense.

[David Kemp]

I thought I had two meadows boxes, however on disassembly, I have two meadows cases.
The 1st box is meadows through & through.
The second has Jowett gears, which as Scott described are less elegant than the Meadows.
Second box also appears to be close ratio.
Inspection of both show the same wear. Layshafts are shot & gear selector shaft/gear case are worn.
The Jowett gears also show uneven wear on the syncro ring of the spigot shaft.
Meadows has no reverse lock out on it's mechanism, is this a problem?
Meadows has a very small chip on the reverse idler, can I use the Jowett gear?They seem the same, or is a very small chip not worth the worry.(it can be felt by dragging my finger nail on it).
The only selector forks I have came with the Jowett box, do they interchange with Meadows?
Does anyone have the link to the Kiwi or Oz thrust bearing modification?
On another note the Jowett box was locked up, whilst Meadows turned freely.
Front spigot bearing on Jowett box fell off, while Meadows needed a puller.

[Forumadmin]

Try a search 'thrust bearing tony george' Tony descibes how to make the tool and there are pictures of it in operation, assuming you mean crankcase and not gearbox or front wheel that is. That contribution was put on the website in 1999!
If you mean gearbox, then I bought redesigned and manufactured thrust washers from JOAC.

[David Kemp]

Good morning, I have seen posts saying to lengthen the cylinder head studs for more strength.
How much longer should they be?
Is there enough room in the block to screw the new studs in or does the holes in the block need to be deepended
& retapped?

[Keith Clements]

A risky operation and is not something I have ever done, except on the oil filter housing bolt holes..
Taking studs out is usually a risky operation to start with, and retapping is even more risky.

[David Kemp]

In case you all are wondering what has been going on, my resto has not stopped I am currently waiting for
my engine crankcases to be repaired the my cylinder heads finished. Both are still in workshops due to covid19.
I have my gearbox cases back & once I receive the new parts from our spares I can reassemble them.
I have decided to rebuild both gearboxes, as the machining was not much dearer to do two boxes as one.
In the mean time I have been cleaning up the brakes so I can drive my car once the engine is going
Attached is the hand brake compensator, cleaned inspected ready to go.

[David Kemp]

This is probably more appropriate for the key discussion, however, I ordered a key from a Morris Minor parts supplier it has arrived & after a clean up my switch is perfect.
The white bezel does look a little off colour. I normally use shoe polish on brown or black plastic.
Does anyone have another suggestion?

[Srenner]

These days I use a buffing rag wheel and compounds for polishing metal. Just the cloth rag wheel tends to make them have a bit of shine.

Color looks fine. Over the decades the plastic gets a bit ivory in color, not white. Float a little black paint into the lettering!

[David Kemp]

Does anyone know what threads are on the gearbox studs?one side is fine the other coarse, neither seem BSF.

[Srenner]

American SAE Coarse 1/4" x 20 TPI.

[David Kemp]

Thanks Scott, just when I thought I knew all the threads on my car I find SAE.
I now have SAE, Whitworth , BSF, BA,metric & assorted pipe threads!
All I need is BSC & I will have a complete set!