Interesting observation

So, I've got my 550 up on the hoist with the wheels off. I start the car IN NEUTRAL, the clutch is NOT depressed. Yet, the rear wheels start spinning forward. I can stop them with my hand but clearly, something is propelling them forward.

I could understand it better if the car was in first and the clutch was depressed....I could blame clutch drag. But, what could possibly explain this except perhaps mainshaft drag/inertia/friction?

 

With clutch engaged, gearbox primary axis (input) turns at engine speed, and due to oil viscosity, some energy is transferred to secondary axis. Gears are engaged but even if synchro is not, and they turn free on secondary (output) axis, oil viscosity creates minimal torque transfer. Just normal.

 

You said it: the gear is in neutral, and the engine and gearbox are cold, right?
That means the input shaft inside the gearbox is turning.
The box is full of oil and the viscosity of the oil is dragging the other gears.
As the oil warms up the viscosity will diminish and the wheels will stop.

 

Yes, this is normal - it is the principle on which an automatic transmission works (slush box).

 

Interesting indeed….

The rear mounted V-12 transaxle is sort of different. Most manual trans rely on “splash”, while F-car manuals (stick) have an oil pump, kinda like an auto. The weird thing is the pump only works when the engine is running and the clutch is engaged. For instance, if I’m reading the cross-sectional drawing below correctly, the tranny and the diff have NO lubing in neutral if the clutch is disengaged (coasting) or if you’re being towed with the engine off. In other words, when you step on your clutch in neutral, at say 180 mph, your diff and gears are no longer getting any oil sent to them!

No one’s confirmed this, but that was my conclusion when considering whether you can tow a V-12 manual with the rear wheels on the ground. The owner’s manual, for the 456 GT at least, is silent on how you can tow 6 spd manuals.

Everyone recommends towing only on a flat bed, but there are plenty of manual trans cars that the OM says can only be towed on a flat bed that CAN be towed safely drive wheels down. Apparently, the F-car is not one of them, even though the OM doesn't specify. The diff and gears get no lubing w/o the engine running.

One more thing. Ever notice the 6 spd shifts a little better after “warm-up”? Since the trans is being lubed whenever the clutch pedal is out (engaged) and the engine is running, might it be beneficial to let a cold trans idle for a while with the clutch engaged? Seems to work for me……Regards…..Mark
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Never wondered about this, actually... not broken down yet so no worries.
I guess 'towability' depends on where the fluid level is. Since the bottom half of the differential will be submerged (look at the position of the filler plug), it and the gears on the shafts that still turn will splash up the oil and around through the casing, like in any normal manual gearbox. As you won't be towing at 100 miles an hour, and it won't be under load, the gearbox will not create much heat so can do with less cooling and lubrication. I suppose the oil pump is probably mainly there so the oil can be cooled in an external oil cooler. It all depends on wheter at least some parts will be submerged so oil is scooped up and splashed around. With autos, that is where the problem is, all the oil is sitting in an oil pan on those so you do not get the splash lube. it would be my guess this is not a problem on these cars.

 

166&456:

Look carefully at the schematic. The shaft that's turning in tow is the upper shaft.

As far as I can see the lower shaft only turns if the car is in gear or the engine is running.

Likewise, I agree the diff will pick up some oil. But it won't get back to the pinion bearing at the end of upper shaft.

This failed on my car and cost the previous owner about $20K USD. Although rare, I think I've heard of 2 other such cases on F-chat.

Although, I don't think the trans design is a problem (and towing for a few miles will not kill the trans), isn't it strange that the furthest point from the oil pump has been where the trans failures occurred?

I'm not suggesting, based on the limited data available, there's a cause and effect here. Just posing the question and appreciative your and any thoughts. That's what this forum is about, right?

Regards...Mark

 

Yes it is, Mark! Interesting, I did not know about pinion bearing failure on these boxes, sofar I had only heard about the reverse gear coming off its shaft and wreaking havoc between the other gears, grinding everything to bits...??

I wonder where the oil pump pumps its oil to (apart from the oil cooler). I don't think there is any forced lubrication involved in these boxes such as in an engine.
That upper bearing will see plenty of oil splashed up by the differential wheel for the work it will be doing in a tow situation. The front (input shaft side) of the gearbox will also still have three gears stirring the oil, as they are constant mesh, driven from the upper shaft.

The pinion bearing is however a likely failure point on any differential as it is an extremely heavily loaded part. Believe me you'll notice it when it starts to fail, I had a pinion bearing go bad on a BMW I owned. At first it was only audible with the windows down, the sound reflecting from walls and other cars, but went from slightly noisy to unbearably noisy in very little time. It was a sound quite like an untuned radio.

 

Very few manual transmissions have pressure oiling. The vast majority live just fine their entire lives with no oil pump. To say that at any time the 550 transmission is going without lubrication is totally ignoring how 99% of the manual transmissions in the history of the automobile work. If you look in any transmission when it is running it looks like a blender inside. I assure you, everything is getting lubricated.

 

Still interesting...

So what's the verdict? Is the oil pump only for cooling or does it provide critical lubrication?

Regards... Mark

 

Both.


Very important when going down the road at 7000 rpm in top gear. Lots of heat and stress. Coasting? No need.


Ferrari has used that oiling design on every 12 cyl transaxle since the 275 and every 8 cyl transaxle since the 308QV.




Every 550 gear box problem I have seen was a direct result of either poor quality gear oil or not regularly changed. Same goes for about 80% of all Ferrari transmisson failures I have seen.



You are trying to make the case for something that is not there.

 

Actually, Brian, I'm not trying to make a case for anything. I just mentioned the failure as a sidebar. What I was trying to figure out is whether the F transaxle works like, as you say, 99% of all manuals and can be towed rear wheels on the ground?

Appreciate the input... Regards...Mark

 

Sorry guys:

I really hadn't thought about this in at least six months, but I recall I had pretty much convinced myself that the transaxle doesn't rely on "splash".

Note: a full tranny doesn't allow the diff to touch the oil...Soooooo...if the bottom shaft is not turning, how does the oil get to the diff and upper shaft?

Again, sorry, what am I missing?

Regards...Mark
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Push-Button Driving!




[ame=http://www.youtube.com/watch?v=QWRoHFb6DHU]You Bet Your Life! GROUCHO MARX Secret word: Skin - YouTube[/ame]




1:11 - 2:30

 

Great Barry....

I think my cousin had an Edsel with one of those. If only Ferrari was so innovative.... Wait...don't they have paddle shifting now? 'Bout time they caught up...

 

What DeSoto did then is still light years ahead of Ferrari's F1 paddle shifter, Mark. That test driver shifted from Reverse to Drive with just one touch of a button!

 

And this 1942 DeSoto was the first car to have pop-up headlights...




[ame=http://www.youtube.com/watch?v=10JFLyew-40]1942 DeSoto Custom Business Coupe original custom - YouTube[/ame]




DeSoto marketed the feature as "Air-Foil Lights...out of sight except at night."

 

[ame=http://www.youtube.com/watch?v=YoUQNrA9KDg]You Bet Your Life - DeSoto Commercial (1950s) - YouTube[/ame]

 

Barry, guess you already know I'm a big Groucho fan...........It's a shame Elvis' death overshadowed his passing........
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It would seem to me the main job of the forced lubrication of the gearbox is to push the oil through the cooler, as the gears are anyway bathed in oil.
If you look at it from this perspective, then the entire design makes more sense.
Heat is generated only when under power and that is when the oil pump is doing its job.
During towing the differential and the gears are turning, but there is no heat being generated, so it does not really matter if the oil pump is not turning.

 

This maybe a little tangential but hopefully imparts a useful perspective to the overall understanding.

My carb'd 308 used splash lube in the box. Has a PRV on top of the case. Over the years I guess this became clogged. Before i got to know the car well (and I tracked it fairly extensively) I looked at the PRV after a track event and depressed it. It was like letting air out of a fully inflated car tire such was the pressure build up. This was one week later...

Added a breather and catch can / drain back. Needed a pump and cooler.

I had a Noble which I also tracked. Killed the gearbox (it was not well matched to the 500 HP application). Rebuilt the box. Added a cooler with a temp sensitive pump. Never had another problem.

So, yes, gear oil gets hot when subject to heavy use and needs to be cooled. Its natural viscosity will typically cause some drag as others have noted. For a short distance I am sure the car can be dragged safely. Towing a distance? I'd only use a flat bed or a trailer.

On a separate question, does anyone know why most (all?) Ferrari manual transmissions seem bulky on the 1-2 shift until the box is warm?

Philip

 

Nope. 1936 Cord had them. https://www.youtube.com/watch?v=YimaE-4Wt6w

 

Dave- was thinking the same thing, ie Cord was first. Didn't some Dussie's have them too? And, is the 456 the last car to have them? Last Ferrari, for sure...

Phillip and Alfredo- The benefits of the cooler and pump are clear. As I understand it, the cooler on the 456/550 doesn't even get used until the oil viscosity drops. The engineers apparently understood that the trans shifts better with warm oil and keep it out of the cooler until warm.

The purpose of the pump can't be just for the cooler because the diff doesn't even touch the oil. (Again, note the oil level in the bottom of the transaxle.) The bottom shaft is going to sling oil everywhere, but enough to lube the bearings on the top shaft???? Looks to me like the bottom shaft has to be turning to get oil where it needs to be. My conclusion, (admittedly possibly flawed), is the transaxle has to have the forced lube or it will fail in a hurry. Splash is not enough...

I think Andrew in Ontario has his box out and might could add info here. Andrew? You out there?

Regards...Mark
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I guess the Secret Word was Cord. You both get a hundred dollars to split between you.
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Hasn't Brian already addressed this? I do not think your conclusion is right. I believe:
- Ferrari has been building these things for a lot longer than most of us, certainly me, and I think the v12 boxes have a very low failure rate
- my v8 box relied on splash lube and survived well, albeit the oil got very hot at the track
- the problem the pump is there to solve is the trans oil temp, rather than forced lubrication. The Oil gets very hot and needs to be cooled (as I indicated above) which is why it is activated by either a viscosity valve (densometric, like the F40) or a temp sensor (like my Noble).

Philip