Draining Ferret Fluid Coupling?

[sexton]

Hi, I'm working on a Ferret at the Oshawa, Ontario museum and have just found out the Dexron ATF presently in the fluid flywheel is the wrong oil. It's too heavy, with a viscosity grade of 30, whereas the recommended OM-13 oil is much kighter at ISO 10 or 15 viscosity grade.

 

I'm wondering if that is why the coupling drags so much idling hot at ~500 rpm in 1st or 2nd gear.

 

Anyway, I want to drain the ATF, but I have only found one reference to draining and that says the engine and gearbox need to be split. The Ferret manuals don't say anything as the oil is not routinely changed, except at overhaul.

 

There are a lot of threads on flywheel oil seal/gasket leaks, and the oil seems to end up in the hull, so it sounds like the bellhousing has a drain hole.

 

Can I just remove the filler plug and rotate the flywheel 180 deg and let it drain into the bellhousing and onto the hull floor?

 

Thanks.

 

Malcolm

[Whittingham warrior]

The fluid fly wheel can be drained as you say. There will be two drain plugs set at 180 degrees to one another so to balance the fly wheel. There is a special tool basically a hexagonal box spanner with a central threaded shaft to screw into the plug, although a socket can be used. However, don't let the screwed plug fall inside the bell housing as it can be troublesome to extricate. Then it's a question of filling to the brim, replace plug, run engine, recheck level of fluid and refill if need be.

 

Mark

[Grasshopper]

To save mess, it may be possible to use a suction device and hose to extract the oil through the filler hole.

[Diana and Jackie]

I agree with Vince, much preferable to making a mess - and before you start have you tried to loosen the drain-refill plugs? as they can be a right pain in the backside, especially if fall down inside the gearbox/engine through not using the special tool.

 

Diana

 

To save mess, it may be possible to use a suction device and hose to extract the oil through the filler hole.

[sexton]

We have a spare engine and gearbox so I am going to see exactly how the oil will drain out of the bellhousing into the hull if I remove one drain plug when at the top and rotate the flywheel to slowly drain it. I'm hoping I can rig a drain trough from the gearbox drain access hatch in the bottom of the hull to catch and direct the oil.

 

If that's not practical, I'll try sucking it out. I won't be able to get below the centreline so that will require multiple sucks and refills to dilute but that's no problem.

 

I got the drain plug out with a 1" deep socket, a long 3/8" UNC bolt through the socket, and flats ground on the socket so I could put a wrench on it.

 

Malcolm

[Richard Farrant]

I agree with Vince, much preferable to making a mess - and before you start have you tried to loosen the drain-refill plugs? as they can be a right pain in the backside, especially if fall down inside the gearbox/engine through not using the special tool.

 

Diana

 

 

If a plug does fall down inside the bell housing then you will have to pull the gearbox back and draining the flywheel will then be easy. I doubt you will suck the oil out due to the vanes on the driven and driving members obstructing the suction pipe.

[sexton]

Just to close the loop on this one, there are large holes in both the gearbox bellhousing and the gearbox-to-engine adapter at the 6 o'clock position, so oil draining out of the flywheel plug will flow through those holes down into the hull. Unfortunately, the holes are completely inaccessible as they are well aft of the gearbox drain access in the hull, so I can't catch the drainage - very messy. So that's out.

 

I can get stiff 1/4" tubing far enough down into the flywheel to suck out maybe a quarter of the oil. So 3 sucks and refills will dilute better than 50%. I think I'll try that.

[joeferret]

Just to close the loop on this one, there are large holes in both the gearbox bellhousing and the gearbox-to-engine adapter at the 6 o'clock position, so oil draining out of the flywheel plug will flow through those holes down into the hull. Unfortunately, the holes are completely inaccessible as they are well aft of the gearbox drain access in the hull, so I can't catch the drainage - very messy. So that's out.

 

I can get stiff 1/4" tubing far enough down into the flywheel to suck out maybe a quarter of the oil. So 3 sucks and refills will dilute better than 50%. I think I'll try that.

 

I tried to vacuum my fluid flywheel oil out with a 12 volt suction oil pump I have...Like Richard stated the vanes will stop the tubing from going low...I was able to get out about 16 ounces of oil on first try.....

[sexton]

Thanks for the info, joe. 16 oz is one US pint, right? The fluid coupling capacity is about 12 US pints so my estimate of getting 25% out in one suck seems to be way off. Oh well, I'll give it a try anyway.

[Starfire]

Just make a mess and then park up in a hill and let it all drain out of one of the access panels, along with all of the other gunk that has accumulated in there. As you need to drain ATF, it'll flow out fairly well anyway, being so thin. If you're really worried about it, spray a couple of cans of degreaser in their first and slosh it around with a spirited drive.

 

Cheers,

Terry

[sexton]

Cheers, Terry. That was my backup plan! It sure ain't sparkly clean under the engine now. I'll drop in some of those oil absorbing socks as well.

 

Malcolm

[sexton]

To follow up with this thread, I drained the ATF from the fluid coupling and replaced it with ISO 10 hydraulic oil. The results were disappointing. It is still impossible to change into forward or reverse with neutral engaged. The only difference I noted with the thinner oil was that the rpm drop when a gear is engaged from neutral (with the transfer case already in forward or reverse) is not so large.

 

 

What puzzles me is the old hands here who have been driving these Ferrets since we got them circa 1980 tell me they have always had to select forward/reverse with first gear engaged. It won't work in neutral.

 

 

Since my thinner oil experiment didn't work, I can only see two reasons the transfer case input shaft is rotating too fast in neutral to prevent forward/reverse from being selected - the fluid coupling is binding for some other reason than oil, or a band in the gearbox is a bit tight and partially engaging a high gear when in neutral.

[Richard Farrant]

As you change from F to R or visa versa, hold the gear pedal down and move the lever smartly without hesitation.

[Starfire]

I've only ever once managed to get my Saracen go to into forward from neutral on the transfer case. Usually if I miss the shift, I have to stop the engine and select a gear before restarting. It does idle too high though - the Saracen should idle at about 400 RPM or something silly like that.

 

To go from forward to reverse and back again, you have to either select neutral in the main gearbox, or hold down the gear change pedal and then smartly (as in fast and fairly hard) move the transfer case selector from one position to the other.

 

Cheers,

Terry

[Bob Grundy]

A little advice please as we are on the subject of fluid flywheels. I have split the two halves of it and now need to use a sealant upon re-assembly. Can I successfully use Delta 555 or must I use the recommended Loctite 573 ?

Thanks

Bob

[joeferret]

Thanks for the info, joe. 16 oz is one US pint, right? The fluid coupling capacity is about 12 US pints so my estimate of getting 25% out in one suck seems to be way off. Oh well, I'll give it a try anyway.

 

Yes 16 ounces is 1 us pint...2 pints = 1 quart..

[sexton]

As you change from F to R or visa versa, hold the gear pedal down and move the lever smartly without hesitation.

 

Richard, no dice. It doesn't matter if the gear change pedal is up or down in neutral, the bevel gear teeth clashing is too severe to attempt selecting forward or reverse, gently, firmly, or anywhere in between.

 

I did some experimenting, as the the teeth clashing of the bevel gears in the transfer case with the gearbox in neutral has a distinctive frequency. I selected and engaged each gear in turn and gently pushed the forward/reverse lever forward until the teeth just clashed. In first, the clashing is very slow and forward can be engaged easily with a firm push. In 2nd, 3rd, 4th and 5th, the clashing frequency gets progressively faster as you would expect. The clashing frequency in neutral most closely matches the clashing in 4th, so I suspect the 4th gear band is binding on the drum a bit, preventing the gearbox output shaft from coasting down to a standstill. I need to read up on the band adjustment and give it a try.

 

Malcolm

[paulob1]

it is a bit of a balancing act, but I find that if you engage neutral press pedal and engage a gear, press pedal, and at the same time forward or reverse and it works without crunching...you get a neat snicking sound as she engages drive..

[Richard Farrant]

Richard, no dice. It doesn't matter if the gear change pedal is up or down in neutral, the bevel gear teeth clashing is too severe to attempt selecting forward or reverse, gently, firmly, or anywhere in between.

 

I did some experimenting, as the the teeth clashing of the bevel gears in the transfer case with the gearbox in neutral has a distinctive frequency. I selected and engaged each gear in turn and gently pushed the forward/reverse lever forward until the teeth just clashed. In first, the clashing is very slow and forward can be engaged easily with a firm push. In 2nd, 3rd, 4th and 5th, the clashing frequency gets progressively faster as you would expect. The clashing frequency in neutral most closely matches the clashing in 4th, so I suspect the 4th gear band is binding on the drum a bit, preventing the gearbox output shaft from coasting down to a standstill. I need to read up on the band adjustment and give it a try.

 

Malcolm

 

Hi Malcolm,

This is odd as by holding the gear pedal down will release pressure from the bands, but it seems one maybe overadjusted and dragging. Your next step would be to lift the pressed metal cover on the gearbox to inspect the bands and their adjustment. This is the cover with approx. 15 screws in, only remove this cover. Do you know what oil is in the gearbox? It should be SAE30 engine oil.

[paulob1]

I've only ever once managed to get my Saracen go to into forward from neutral on the transfer case. Usually if I miss the shift, I have to stop the engine and select a gear before restarting. It does idle too high though - the Saracen should idle at about 400 RPM or something silly like that.

 

To go from forward to reverse and back again, you have to either select neutral in the main gearbox, or hold down the gear change pedal and then smartly (as in fast and fairly hard) move the transfer case selector from one position to the other.

 

Cheers,

Terry

 

on our sary you cant change it very easily at all from reverse to forward but you are right very smartly and very quickly but I find if your moving it into or out of gear it helps too..son has it sorted the best...

[David Herbert]

In these gearboxes selecting neutral SHOULD prevent any of the bands being tensioned when you release the gear change pedal. Therefor pressing the gear change pedal all the way is exactly the same as engaging neutral but harder on your left leg. There will always be some drag between the brake bands and the drums, if only from the oil that gets between them, which is why it is virtually impossible to select forward or reverse from F / R box neutral with the engine running. However with the vehicle stationary and foot on gear change pedal it should go from F to R or R to F quite smoothly IF you do it quickly. Too slow and the gearbox internals have time to start to spin and you will never get it into gear. Engine speed should not make much difference but obviously the slower the better.

 

If things are not as I describe I would look for a band not fully relaxing when in neutral. Possibly a broken spring in that band's mechanism or the lining damaged and wedging between drum and band. All this assumes that you have the correct oil.

 

Good luck,

 

David

[Richard Farrant]

It has dawned on me that some early Ferret pre-selector boxes might have been constructed similar to the early Saracen ones (as well as WW2 Daimlers), whereby they were not fitted with a Neutral strut. If you take the pressed steel inspection cover off, check to see what happens to the bands when you engage Neutral, if you see 4th and 5th adjusters move partially, then this could be a reason for the reluctance to engage. My Ferret EMER's are updated and do not mention this, but my Saracen EMER Technical Description is dated 1955 and stated that approval had been given for a major modification to the selectors.

The problem on the early Saracen box (and it is highly likely early Ferrets are similar) was that when the Neutral was selected it reduced clearance between 4th gear band and drum as well as 5th gear clutch and caused drag in Neutral.

 

Something to check.

 

regards, Richard

[sexton]

There will always be some drag between the brake bands and the drums, if only from the oil that gets between them, which is why it is virtually impossible to select forward or reverse from F / R box neutral with the engine running.

 

 

 

David, you seem to be saying F or R can't be selected from neutral with engine running and gearbox in neutral. Is that what you meant?

[sexton]

It has dawned on me that some early Ferret pre-selector boxes might have been constructed similar to the early Saracen ones (as well as WW2 Daimlers), whereby they were not fitted with a Neutral strut. If you take the pressed steel inspection cover off, check to see what happens to the bands when you engage Neutral, if you see 4th and 5th adjusters move partially, then this could be a reason for the reluctance to engage. My Ferret EMER's are updated and do not mention this, but my Saracen EMER Technical Description is dated 1955 and stated that approval had been given for a major modification to the selectors.

The problem on the early Saracen box (and it is highly likely early Ferrets are similar) was that when the Neutral was selected it reduced clearance between 4th gear band and drum as well as 5th gear clutch and caused drag in Neutral.

 

Something to check.

 

regards, Richard

 

Richard, Certainly something to check! (This is a 1954 Ferret.) Thanks.

 

Malcolm

[Richard Farrant]

David, you seem to be saying F or R can't be selected from neutral with engine running and gearbox in neutral. Is that what you meant?

 

Malcolm,

This is what we have been saying all along. You have to go straight from Forward to Reverse ( or vice versa) when shifting the transfer box lever, no hesitating or trying to engage from the central position (with engine running of course).