Filling BW35 transmission system

[Sam Bee]

My gearbox, engine, radiator associated pipework have all been renovated and a Jaguar torque converted fitted, thus the system needs filling with ATF. The gearbox was test run on a test bed and thus will have a little fuid in it. I have put 4 litres in so far and it is showing full on the dipstick now. The car has not been run since 1994 and just preparing for its 'first start'. Thus I cannot run it to allow normal filling procedure to be carried out. Question is chaps, do I start it as it is or put closer to 8 litres in initially?

[enigmas]

Hi Sam, I imagine others will chime in to this tech query.
Although the topic heading states BW35...then why fit a Jaguar torque convertor or have you upgraded the trans to a ZF4HP22? I know (IIRC) that some Jaguar saloons & Daimlers during the 60s-70's ran the BW35 transmission. If you're not aware there are 3 specifically sized torque converters for these transmissions depending upon engine size and torque rating. The factory standard Rover P5B runs the intermediate sized convertor and the Rover P5 MK3 runs the smallest size convertor.

Torque Convertors.
Just because these 3 torque convertor options are interchangeable with the BW35 transmission in its various guises, doesn't mean that there aren't slight internal differences with the impeller, turbine or stator. Any internal changes with the fin angles on these components will effect how the torque converter functions with a given engine. Manufacturers will often place a factory stamped identifying code on a torque convertor if it is for a specific engine or state of tune.

Yes, any of the 3 versions can be optioned to fit and function, but may not be optimized for the engine, gearing and wheel/tyre combo. That's the consideration.

As for filling the transmission, if the car is on level ground, run the engine slightly above idle speed to warm it, then go through all the gear selector positions, then check the fluid level and adjust as required. Once the car is roadworthy go for a 30 minute drive and change the fluid for fresh if it's a concern.

PS.
The 4.4 litre P76 V8 in my MK3 Rover (OEM Rover BW35 case upgraded with BW40/51 components) runs the largest BW35 torque convertor. The 6 cyl 2.6 litre engined P76 also uses the same physical sized torque convertor but both torque convertors have unique differing Factory stamped ID codes on the periphery of the cases. I'm assuming that the Factory engineers had a specific intention when the torque convertors were coded.

[lagain]

I would put in as much as possible, which will bring fluid up the filler tube.
When my engine was rebuilt many years ago I was told to start it and run it at 2500 revs, which I did and there were fluids squirting everywhere, Perhaps you need a few assistants with responsibility for each fluid. The PAS fluid will drop when the belt turns. If I am not away I could come over

[Sam Bee]

Hi Enigmas, thanks for your thoughts. The upgraded torque converter is to cope with the output of my uprated engine, appoximately 210 -220 h.p. The 'box' is rebuilt to incorporate parts from improved BW65 and BW66 gearboxes. The latter was turned out for the Jaguar XJ6's 210 h.p. engine, with an upgraded converter to match, and that is what I am using. It's a 'one-off', properly designated a BW35/65/66 I suppose but externally you cannot tell it isn't a normal BW35.

[eightofthem (Andy)]

Just to chime in on your original question and not waffle on too much, as you stated it's been "run up " prior so yes the converter is primed and some of the galleries will have fluid within.
I guess you need to run in your engine as well so I understand your concern about fluid level.

Dry capacity of the transmission is around 7.5 - 8 litres, the sump pan will hold around 3.5 litres and the converter will hold the remaining, so you will have at least 1 litre within the converter already along with say 1/2 litre within the transmission. ( if you have a separate oil cooler then it will take more fluid )

I would add at least 5 litres and then spin the engine over without the HT lead on, this will be pumped into the converter ( don't leave it too long to crank over once fluid is added as it's way above the normal level )
Once cranked over add another litre into the transmission and get your engine running as it should be, and set the idle to 600 -650 rpm.
You can then go about finding the right level on the dipstick adding fluid as required.
Don't drive or select gears until the correct level is achieved

Remove the dipstick and dry fully ( do not refit yet )
Set engine idle to 600-650 rpm
Park on flat level ground
Bring engine up to normal operating temperature
Chock wheels and apply handbrake fully.
Cover footbrake and select each gear in turn, begin in Park and through the range to "1" or " L" depending on what year and build you have and then back to Park.

Once in park ( engine still running ) dipstick straight in and straight out again.
You should see a wet mark with a dry bit and then another wet mark, the lower of the wet marks will be the level, ignore the wet mark above the dry section ( that's splash )
Add fluid in small amounts until the correct level is achieved
Go through the above each time fluid is added.

I wish you well with your first start up.

[Sam Bee]

Thanks Andy. Much as I imagined then so good to have confirmation. I did in fact start the engine yesterday briefly and remained static as car is still on my garage lift. I will now proceed as you suggest.

As it turns out, I am well versed in topping up these gearboxes as I have run a P6B for a number of years.

[eightofthem (Andy)]

That's good, you will be fine then, best of both worlds having the P5B and P6B, tough choice though which one to drive....

[Sam Bee]

You are right there, Andy! Different though, as the P6 performs very well indeed on the road, true sports saloon.