Austin gearbox part 2

[crankedup]

Drained out the old oil from the 12/4, cupful was all that was in it :yikes: This could account for why my double de clutch changes were OK when gearbox was cold but crunchy when hot.

Lifted the floor boards and poured in 5 pints of fresh oil. To my dismay the oil was steadly flowing out of the gearbox, looks like from the rear of the housing/drive shaft point. Don't know if I have overfilled as the flow is now a fast drip. Lost about 1.5 pints of my fresh oil I reckon.

How many pints of oil should an old car gearbox hold, I am concerned because no oil in box to start with.

[M3 Mitch]

I am not an expert on this car but sounds like you have an output seal leak to me. Older rigs tended to hold more oil rather than less, I would expect it to hold about a quart anyway.

If you can find a shop manual for this car it would probably be worth having.

[crankedup]

Thanks M3 Mitch, I am trying to track down a manual for the old girl but its proving mighty difficult to find it. I've lost 3 pints of oil out now (into my oil collector container) and its a drip drip dripping still.

[arh]

I would say your output seal is shot, you did use the correct oil as modern oil can destroy the phospher bronze bearings in these old boxes. the seal is probably made of rope or similar and don't last long. I reckon it will take about 2 litres or there abouts. The joys of prewar motoring.

[Crankedup]

Thanks ARH for info, I did talk to Castrol who advised that I should use their monograde 30 same as engine. Of course I do not know what has been used previously.
Looked up for club spares and they list felt gaskets for front of gearbox and same for rear of box. Think I shall buy both sets as I am bound to need at some point. I assume that these are all the gaskets for the box.
Its a little disappointing after the selling dealer assured me that the car would be fully serviced before I collected, its obvious that he has'nt bothered. Usual thing I guess but I am enjoying the car anyway regardless.

[ettore]

Penrite are the best people to speak to regarding any vintage oil requirement but, IMO, the best thing for you to do is ring up the Vintage Austin Register. They will probably have a technical rep` or at least will be able to suggest a 12/4 expert for you to talk to. In my experience Vintage people are more than delighted to help a fellow enthusiast, particularly if they are new to the fold. They will probably be able to suggest a couple of names local to you - I found this particularly helpful with my Seven ( I am a technical buffoon).

The actual problem sounds like some form of gasket, a pretty cheap fix that you may be able to convince the dealer to pay for? If not, it should be a relatively straightforward (if heavy!) bit of work on a 12/4. They are normally about the most indestructible bits of mechanical equipment that man has yet produced!

[crankedup]

Thanks Ettorie, I have now had a conversation with one of the tech' type people in V.A.R. I almost certainly overfilled and I need to replace the seal.

I am also going to have a chat with Penrite oils as you suggest. Worthwhile comparing with Castrol recommendations and oil cost.

Thanks again everyone for your comments and help.

[ARH]

sae 30 is what I use in my austin, penrite mostly bacause the man in farnham sells it. As for serviceing you are better doing it yourself as you will get to know the car much better and you can ensure the correct oils are used.

isn't vintage engineering different I guess you have cable brakes? try setting them up. took me 4 hours the first time I did it, but the MOT rollers proved it to be a good job.

[crankedup]

Yes it is an amazingly different motoring world in entirity. Simply taking up the floorboards to get to the gearbox filler exposed ALL of the essential elements. I am no mechanic tho and concerned that I don't overstretch my capability. However, I do want to work on my car as much as needs be for this is half the fun of ownership I feel, and as you suggest get to know your car.

Strangely the dealer who sold me the car told me how much he enjoys driving/owning and selling vintage, when I asked him what oil he proposed for the engine he said 'oh a 20/50 will be fine'. Hmmmm.

My driving speed is 30mph and the car is 'happy' at that. Take her to 35mph and its starts getting a little rougher, I think 40mph would be top wack, but I'm not intending that, so 30-35mph is fine and dignified by me.

[arh]

I use duckhams 20-50 in my austin engine, with no ill effects.

I have had my austin seven reading 70 mph on the speedo, scarey.

[ettore]

I reckon that once you`ve settled the 12/4 in, you should find a comfortable cruising gait at around 45-50. It is strange how all proper cars have a natural cruising speed at which they feel comfortable!

Further to ARH`s point I have been in a Seven travelling at 85mph (via a following car`s speedo) - I can assure you it felt a hell of a lot quicker!

[crankedup]

Thats interesting using a 20/50 in a pre war engine. I have read and heard that the use of modern multigrade oil will eventualy clean away all the bits of stuck gunk within the engine which will result in leaks and oil ways being blocked. Apparently its the detergents used in the modern oils that have the cleaning effect and the old engine tolerances being so much more than modern engines the multigrade is deemed unsuited.

Of course what I have read and heard is of course opinion, but this was Castrol's line and a respected Mag'.

70mph in a 7 I take my hat off to you Sir.

[crankedup]

85mph in a 7

Perhaps I need to put my foot down a little further in my 12/4, sort of go through the vibration barrier as it were.

[arh]

My 7 has a very lightweight body, which helps. It also had no build up of gunk inside the engine to shift as I only built it not last winter but the one before. It is modified, hi lift cam, mildly ported, cambridge head, three branch exhaust and a morris minor su carb.

It is still happiest at 45mph though. And it will easily keep up with our morris minor 1000.

[arh]

My 7 has a very lightweight body, which helps. It also had no build up of gunk inside the engine to shift as I only built it not last winter but the one before. It is modified, hi lift cam, mildly ported, cambridge head, three branch exhaust and a morris minor su carb.

It is still happiest at 45mph though. And it will easily keep up with our morris minor 1000.

[IOLAIRE]

crankedup said:

Yes it is an amazingly different motoring world in entirity. Simply taking up the floorboards to get to the gearbox filler exposed ALL of the essential elements. I am no mechanic tho and concerned that I don't overstretch my capability. However, I do want to work on my car as much as needs be for this is half the fun of ownership I feel, and as you suggest get to know your car. Strangely the dealer who sold me the car told me how much he enjoys driving/owning and selling vintage, when I asked him what oil he proposed for the engine he said 'oh a 20/50 will be fine'. Hmmmm. My driving speed is 30mph and the car is 'happy' at that. Take her to 35mph and its starts getting a little rougher, I think 40mph would be top wack, but I'm not intending that, so 30-35mph is fine and dignified by me.

A wee bit of advice if it's any good to you.
A gearbox of this age might not actually have a seal on the output shaft; it could have a scrolled thrower which is a finely etched thread that turns into the box when travelling so that any oil trying to escape is "screwed" back into the gearbox.
The problem with these, and I used to do lots of them on XK120s and MK7 Jags, is that the support bearing for the shaft would wear and then start wearing the thrower housing as it was made to a fine tolerance and then it would really leak with a vengeance.
The solution was either to drill out the casing and have a bush fitted and reamed to the size of the prop, or better still have the casing machined to take a standard, modern seal, which will give you a perfectly oil tight gearbox.
As far as oil level is concerned, most of these boxes either had a filler cap on top with a side level plug, or most commonly a filler cap on top fitted with a small dipstick with the level marked on it.
But it was fairly common for these dipsticks to break off the cap and fall into the gearbox, so you end up with no way of judging the correct level.
If you can find out the exact quantity of oil that should be in it, you can weld a new dipstick on, fill the 'box up with exactly the correct amount and then mark the stick with a groove and that's you sorted!

[crankedup]

Thanks Iolaire for some interesting stuff there, who said that vintage cars are very simple and basic?? not so

[tvrgaas]

Crankedup said:

felt gaskets for front of gearbox.

Do you need to soak them in tallow?

[crankedup]

tvrgaas said:

Crankedup said: felt gaskets for front of gearbox. Do you need to soak them in tallow?

Good question and one to which I have no idea at all of the answer! I suppose that as soon as the felt gasket gets wet with oil it would be hopeless in doing the job its supposed to do. Anyone know the answer??

Altho P.H. is a great site we are short of experts (other than an notable few) when it comes down to tech' stuff on vintage cars. It seems that those sites that concentrate on oldies do not have chat forums.

[arh]

felt seals should be soaked in oil overnight, then fitted. even then they don't work that well.

just buy a big drip tray.