Gearbox BWDG250

[pphf]

Hello

I've got a Jaguar Stype from 1964 équiped with an automatic gearbox BWDG250, the same that you may have on the RoverP5.

While I am not very used with this kind of gearbox, I'am not sure mine is working well.

What I've felt is when I accelerate till the engine speed reach about 3500 rpm, the 3rd gear engage just when I stop to accelerate. But if then I accelerate just a few, immediatly the engine speed increase without any increase of the speed of the car. I have to wait a long time without accelerating to get an increase of the speed's car.
I didn't felt the same on the 2nd gear, and 1st gear as forward gear run well.
I hope than my explanations are clear enough for you to help me.

[MK IA Norway Viking]

Good afternoon,
I have also a Jaguar S-type 1965 with manual gearbox and have tried another S-type of my friend that has the DG automatic gearbox. The gearbox is behaving like we expect it should, so there is something wrong with your gearbox.

I also have a Rover P5 3-litre with the DG gearbox, and it is behaving normally.

The shift from 2nd speed to 3rd speed is NOT supposed to be at 3500 RPM but perhaps at 1800 RPM.

You know there is a function called kick-down (which is mechanical, with a rod on the gearbox linkage so that when you depress the accelerator pedal fully, the gearbox will shift from 3rd to 2nd until the engine reach about 3500 RPM - and then shift up to 3rd speed.

PErhaps your gearbox is permanently in this condition ? To find out, remove the rod from the accelerator linkage to the gearbox so that the kick-down function is de-activated and try to run the car.

There is one more function called "2nd speed hold", which is an electric switch connected to a solenoid on the gearbox. You can de-activate this funtion too, and test the car to see if it is working as it should.

If both test do not fix the problem, check the level of oil in the gearbox - if there is too much or too little gearbox oil, the gearbox will not work as intended.

I hope you will find a solution to your technical problem. Good luck !

[Phil Nottingham]

This box used in Mk1 and Mk2 Rover 3 Litres to 1965 despite its heavy weight is actually very smooth and more efficient than the lightweight BW35 that superseded and replaced it. It is however prone to gasket leaks and these can lead to low ATF levels which will quickly burn out the clutch linings in the lengthways wide Torque converter and in the box and also gear bands causing slippage. If ATF is not added quickly it can be too late. The bands can be adjusted by dropping the sump.

There are 2 important differences to the common BW35/45/65 ie

• The kickdown and 2nd speed hold is controlled by a cable and an electric operated solenoid respectively both operating directly externally on the shift valve
  
  The other main difference is that Top (3rd) has a torque converter lockup (as some modern auto boxes have rediscovered eg ZF HP4. This prevents slip but the internal converter hydraulic clutch can slip as also aforesaid low oil level and mal adjusted kickdown cable. This converter clutch likely to be the problem and expert rebuild is required

There is loads on the internet on this obsolete gear box (also used on the big Rootes and BMC cars as well as Jags and late Armstrong Siddeleys - I think) and in the Rover 3 Litre and BMC workshop manuals of the early 1960s.

DG stands for Detroit Gears which expands the search result

[tonys]

You learn something everyday, I've often (well, very occasionally  ) wondered what DG stood for and now I know. Thanks, Phil.