Javelin gearbox oil, level

[Robin Fairservice]

A silly question. When the gearbox oil level is checked, does one push the dipstick all the way until the crook touches the case? Or, does on stop at the point where the return of the crook come to?

[Drummond Black]

To correctly check the gearbox oil level the car must be on the level. Let it stand for a few minutes if it has been running. Remove the dipstick and wipe it clean. Replace the dipstick back into the gearbox to its full extent. As you say the crook must be touching the casing. Leave it for a few seconds then remove and check oil level. Repeat the proceedure to double check oil level BEFORE adding oil. After adding oil make sure that the oil level is NOT above the top mark on the dipstick. The Javelin gearbox tends to leak at the best of times but will only become worse if overfilled. Good quality engine oil is best.

Hope this helps. Drummond

[Leo Bolter]

To help eliminate oil weeps, here's what works for me (well, my Jupiter and Javelin gearboxes, actually!).

Divert a small amount of the crankcase depression to the gearbox!

Here's how!

1/ Drill and then braze a short drilled nipple (1/4" OD) onto the oil filler bung.

2/ Drill and braze a short drilled nipple (also 1/4" OD) to a suitable 1/4 BSF bolt.

3/ Replace one of the screws holding down the pushrod cover near the right hand carburettor with the bolt (the second to rearmost one where the threaded hole passes right through into the case).

4/ Take a piece of spring curtain wire and stretch it out enough so the plastic covering will pull off, then after that is done, pull it some more so it will fit down the inside of a piece of cheap plastic (clear PVC) tubing.

5/ Place the tubing (with the spring wire inside) onto the the nipples after laying it carefully so it doesn't foul with anything and after cutting it to length.

NOTE: the spring wire will stop the cheap tubing from collapsing where it takes any tight bends when it gets hot i.e. where it takes a tight bend as it goes onto the gearbox nipple.

This "mod" is very effective and is a nice little job to occupy one on a lovely autumn Sunday . . . .

Cheers, Leo

[Drummond Black]

Leo This is a new mod to myself. I understand the reasoning......

Does it not suck oil mist OUT of the gearbox and hence reduce the oil level ???

Drummond

[Robin Fairservice]

Thanks Drummond for your answer. Thats what I was doing until I started to wonder, because the alternative would have meant that I had to put more oil in.

[Leo Bolter]

Does it not suck oil mist OUT of the gearbox and hence reduce the oil level ???

That's a fair question, Drummond.

There doesn't seem to be a problem . . . there's no accumulation of plugs of oil in the low places in the tubing run that I have seen. The presence of these would indicate significant mist pickup.

Although I haven't measured it, I would anticipate that the actual air flow from the gearbox would be pretty minuscule, especially after initial engine starting. This provided the usual felt pad in the gearbox breather was in place and that the gear control shafts clearances were in reasonable condition.

The two major flow restrictions in the mod would be the two 1/16" holes (approximately, from memory) at the bolt and the bung nipples.

There's no noticeable change in the engine idle speed either . . . Hey! maybe the mod doesn't actually WORK at all!

I guess the only theoretical downside to this mod. would be that it may cause dirt and dust to be gradually sucked down the gear control shafts and so accelerate wear at those points . . . but there's not many of us who are brave enough to venture into Rallies across Africa . . . . boy, I envy that adventure you and Amy had back then Keith! What memories . . . .

[Keith Clements]

You may have noticed somewhere in these archives that for the desert I fitted breathers from the tappet covers and gearbox upto an air filter made from a bit of old intake air filter. The gearbox also had a high level filler tube next to the rad for ease of filling.
I also fit a rubberseal on the input shaft to the box so at least that leak is cured.

[Brian Cole]

All sounds rather challenging to me, and how do you rebuild a gearbox if no new spares are available? Is the whine of the gearbox usually caused by worn bearings or noisy cogs? Is it common to most Jupiters? Having never driven any one elses car I am not in a position to know. Would fitting an extended oil filler tube have the same effect as using the crankcase depression?

Further to oil leaks and filling I have carried out a simple mod to make reading the gearbox dipstick easier. I always find it difficult to read the trace of clear oil on a shiny dipstick. Hope i'm not reinventing the wheel but what I have done takes only seconds, spray the lower end of the dipstick with matt black, the trace can then be easily read. This is also useful for the engine oil. I think the response on this site is truly amazing! Keep posting!

[Forumadmin]

On the African trip we had big problems with dust. The gearbox was completely knackered by the time it was going home and finally gave up just after Seville, Southern Spain. I had taken precautions. The oil filler was extended with a plastic tube up to the top of the radiator and had a filter breather on the top up hole. This allowed quick refilling as doing over 500 miles of competitive driving a day needed regular top ups. The problem was started when the reverse selector shaft worked its way loose and lost all the oil and allowed muck in. Amy used her French to obtain some oil, but I think it was either olive or date palm. The Molyslip had saved the box from lack of oil, but the ingress of sand gradually did its job over the next couple of thousand miles.

The negative pressure idea will possibly stop minor leaks. One hopes that the standard breather vent is open and not clogged with sealant thus causing positive pressure and forcing oil out through the many leakage points on the gearbox. I think Mike Alfrey lists over 30! Those 30 points with negative pressure could potentally suck in muck! The breather hole theoretically allows expansion when the oil heats up.