Gearbox and Overdrive Oil Level

[robolab]

Hello everybody

After restoring the gearbox overdrive unit for my BJ8 MK III, I refilled the unit with oil.
Here I found that the required level was already reached after 2.5 liters. In the manual, however, the fill quantity is 3.55 liters. Is this value wrong?

Gerd

 

[roscoe]

Re: Gearbox and Overdrive

Have you run it ?

 

[RAC68]

Hi Gerd,

Keep in mind that the overdrive is a pressure pump and its passages need to be filled. Let the engine/transmission stand for a day (arbitrary) to allow for the oil to seep into many of the trans/OD voids. I would also do as Jon has suggested, and run the car to the point of activating and deactivating the OD before making a final fluid check and fill. If my trans/OD had just been rebuilt, I would stay very close to home and listen carefully when operating my Healey and stop immediately if any concerning sounds were heard or any difficulty in operation.

Hope this helps,
Ray(64BJ8P1)

 

[Bob_Spidell]

Be careful not to overfill; you may get a nasty leak from the front seal if you do (ask me how I know).

 

[glemon]

The gear oil needs a little help getting into the overdrive. Mine (BN1) didn't work after a tranny rebuild. The very experienced British and German car mechanic who rebuilt the transmission suggest lift the front end as far as possible, let it sit overnight, lower and check level. It worked fine after that.

 

[roscoe]

After going through the issues with my rebuild and going through the OD myself, I'd be surprised if everything worked as it should on the first go. If you can't run the gearbox because of your stage in the project just wait until you can and do as Ray suggests. If the gb doesn't have a drip or two, celebrate being in the select and rarefied group of Healey owners whose gearboxes didn't. Probably count 'em on one hand.

 

[John Turney]

After going through the issues with my rebuild and going through the OD myself, I'd be surprised if everything worked as it should on the first go. If you can't run the gearbox because of your stage in the project just wait until you can and do as Ray suggests. If the gb doesn't have a drip or two, celebrate being in the select and rarefied group of Healey owners whose gearboxes didn't. Probably count 'em on one hand.

I must be one of those; I have more than a drip or two. :wink-new:

 

[robolab]

Thank you for the many suggestions, but transmission and overdrive working properly.

For the functional test of the units, I had built a test stand. In this test stand, I drove the OD with an electric motor on the output flange at 1300 rpm and checked the oil pressure at the operating valve with a pressure gauge and tested the switching on and off of the OD.
The only thing that surprised me was the amount of oil that I had to fill in after assembling. I raised the unit at the back to let the oil run into the OD. Then the unit was driven with the electric motor and the oil level checked again. This was ok, although I only filled about 2.7 liters. And in the workshop manual there is a filling volume of 3.6 liters. That must be wrong, right?

 

[Bob_Spidell]

...This was ok, although I only filled about 2.7 liters. And in the workshop manual there is a filling volume of 3.6 liters. That must be wrong, right?

I don't have my Bentley shop manual handy, but I've been through it many times and I don't recall any quantities listed in metric (sometimes have to convert from Imperial gallons, though). Are you sure the manual says liters and not quarts? IIRC, it takes about 3.6 quarts to fill a dry gearbox + OD.

 

[Dandare]

3.6L is about 3.8 US quarts so pretty much the same?

Danny

 

[robolab]

In the German version of the Austin Healey 3000 manual, the filling quantity for gearbox and overdrive is 3.55 liters.
In the original English version it says 6 1/4 pints (7.5 U.S. pints, 3.5 liters). But I only have 5.5 U.S. pints needed. Something must be wrong.

 

[RAC68]

Hi Gerd,

What is confusing is that the transmission box alone is specified to take 6 US pints or 2.8 liters with the remaining to 1.5 US pints or 0.8 liters to satisfy the OD. Your level pf 5.5 US pints is less then what is called for for just the transmission. This gives me the impression that your approach to filling and exercising the trans and OD is either not as effective as it would seem or there is something, internally, blocking the flow of fluid. Since you have indicated having the OD activate and deactivate, I am wondering if, during assembly, used a lubrication grease that has blocked some passages and not as yet opened to flow or, as some, filled the OD prior to final assembly and forgotten to include in the calculation.

As it seems to appear from your initial question and approach, I do not feel it probable that you forgot the additional fill, however, I could not rule this out if it were MY experience (not as sharp as when younger). If the transmission/OD has been installed, I would exercise the transmission/OD in a nearby careful run and drain fluids from the transmission/OD, being careful not to contaminate for reuse. I then would go through the process for a refill and determine if there is a difference. If, and only if, not, I would have no choice in settling my mind but to pull the unit and investigate the internals of the trans/OD.

Yes, I don't think trans/OD removal will be required but it is an obvious option,
Ray(64BJ8P1)

 

[robolab]

Hi,

Many thanks for the answer. But as mentioned before, I tested the functions of the gearbox and overdrive in a test stand. The oil pressure in the OD corresponds to the value of 460 psi required in the manual and the OD can be switched on and off perfectly with the solenoid. I measured the changed speeds with a speedometer. All gears can also be shifted perfectly. That's why I assume that the OD is filled with the right amount of oil.
Therefore I am reasonably certain that the values in the manual are not correct.

My test stand

 

[RAC68]

Hi Gerd,

I appreciate the effort you have extended to validate your conclusion but, since I have not performed the task for quite a while, I have requested comments from friend who rebuild trans/ODs for our Healey club members. Either way, once in the car and running, you can always recheck the fluid level and fill if necessary.

All the best,
Ray(64BJ8P1)

 

[Bob_Spidell]

I've filled my gearbox/OD from dry several times and it always takes a little over 3.5 quarts, or about 3.3 liters. I'm not disputing your result, just trying to figure out why yours only takes 2.7L.

 

[robolab]

The discussion about the filling quantity makes me wonder. So today I drained the oil from the gearbox and overdrive by removing the drain plugs on the gearbox and overdrive. Before that, I checked the level on the Oil level indicator. The amount of oil collected was just over 3.1 liters (3.27 U.S. quarts).
I probably filled a little more than 2.7 liters into the restored unit. But the amount of oil drained is still less than the amount of 3.43 liters specified in the manual.

Thanks a lot for all the answers.

 

[blueskies]

Part of that missing .33 litre could still be in there - on the horizontal surfaces and on the bearings and gears. And maybe you did not have the full 3.43 litres in there. Oil fill amounts rarely exactly equal what any manufacturer states.

 

[vette]

Here's the page from the Bentley Manual. This is the BJ8. Spec for the earlier 6 cyl. cars is very near the same with a difference of maybe only a 1/100 of a litre. I have changed my trans oil a few times some years ago. If I remember correctly it never took the full amount specified in the book. As I remember it was around 3 US quarts.

 

[robolab]

Thanks a lot for all the answers.
My car is a BJ8 and the data in the Bentley manual correspond to that in my German BJ8-manual. The filling quantities given there seem to be of a very theoretical nature.
The statements made by Vette agree with my findings and reassure me.

Thank you all.