Floor change, Jowett Jupiter

[IanHingston]

Greetings,
Its some way of being roadworthy, but I'm considering putting bucket seats and a floor change into my Jupiter (SA 221). Anyone got any details of a conversion from column to floor change?

[Keith Clements]

I do not think you will better the column change with a floor change. I have driven two Jupiters with it for a short stint and did not get used to either.
The column change allows finger tip change without really taking your hand off the steering wheel. Combined with an overdrive switch accessible with the other hand and close to the steering wheel plus clutch switch for downshift you can do rapid changes into and out of bends.

You also loose the option of going back to a bench seat and carrying 2 passengers. For long journeys I used that space to carry a bucket that could hold drinks, maps and all manner of useful paraphernalia that could be stowed nowhere else in the cockpit. The bucket doubled up as a sump oil or gearbox oil tray, coolant catcher or wash bucket during maintenance.

[IanHingston]

Keith
It's great to talk to someone with experience - and advice - in knowing what I am trying to achieve. One of the reasons I thought to put a floor change in is to utilise a Triumph 2.5 gear knob with the O/D switch on it as I have fitted a Type J O/D unit (I must write an article for the By Jupiter magazine on my association with Jowetts, my 40 year desire to buy a Jupiter and progress I have made to date on a Jupiter which was stored in an open ended barn for over 35 years with a bent body, broken chassis and seized engine). My alternative is to fit a Bradford column switch opposite the column gear change and use the Bradford horn button as the O/D switch but it will probably obscure the instrument panel a bit.
If I stay with the bench seat, I think seat belts would be wise to stop sliding around the seat on cornering.
(All this assumption from someone who has never driven a Jupiter - plenty of Javelins, but never a Jupiter, yet!)
Pardon my ignorance, but I don't understand "Clutch Switch." Is that a local mod for racing and rallies?

Thank you for your advice. It definitely will be considered.

Regards
Ian Hingston

[Keith Clements]

The use of a microswitch on the clutch pedal allows a pre-select function for the overdrive. It is there to make sure that when you depress the clutch it takes you out of overdrive. Thus to change up say from overdrive third you do not have to do two operations to change into top. Just depress the clutch and change gear. Without the clutch switch you would have to simultaneously switch out of overdrive and change gear, which is surprisingly difficult to do and maintain engine revs within acceptable limits. Usually you change up when the engine revs are at their max. If you then drop it out of overdrive before the clutch is engaged your flywheel will fall off as happened to John Blankley on a stage in Slovakia. If you take it out of overdrive after you have changed up then your engine revs will be too low and you are off the power peak.

I use a switch with a long (5cm) finger. To go into overdrive it is pushed down (which latches the overdrive in) but then I immediately bring up again so that when the clutch is depressed the latch relay falls out and the overdrive disengages. Using a switch which has both on and off positions rather than a switch which is momentarily on does give a bit more control as very occasionally you may want to go from overdrive top to overdrive third or from top to overdrive third. The system and its operator are not fool proof so perhaps an engine rev limiter might catch the wrong change quickly enough, but I doubt it. Most people do not change gear close to the crank/flywheel/valve spring limit of course. Unlike a gearbox whose syncho rings tend to complain, an overdrive will do what you tell it to.

[ajackson]

Dear Ian,

Please write your article! Will be of interest to all.
Also how about posting some photos of your project to show where you have got to.
Sounds quite heroic.

Best,
Andy