Remove/Replace Auto Gearbox P5 Mk 1

[aussieal]

I started a thread on this on August 10 which got mixed up with one on replacing the rear crankshaft seal

I have reproduced the posts here plus current status:

The rear welch plug in my 1959 Mk1 with Borg Warner DG Auto Gearbox has failed and I am in the process of replacing all welch plugs.
Motor and Gearbox are now out of the car, and I find that the welch plug is partly obscured by the torque converter housing. It would also be good top replace the rear crankshaft seal whilst the motor is out.
To achieve this the torque converter and ring gear need to be removed, and there is no description of how to achieve this in the Rover 3 Litre workshop manual, but what is frightening is the process for reinstalling the ring gear and torque converter, requiring special alignment tools etc. This does not look like a home workshop job. Am I right, or can it be removed and replaced simply?
Failing an easy fix, I will not remove it, not worry about the crank shaft seal, (Rover's all seem to leak oil anyway) and cut the housing to allow the welch plug to be put into position

Post by enigmas on Aug 10, 2015 at 2:52pm
I've got the WSM in front of me and as far as I can see it's quite a straight forward task. Simply remove the nuts at the back of the torque convertor drive plate from the bottom section of the bell housing. There should be an access plate there. The drive plate incorporates the starter ring gear and it also has a spigot that centralises in the rear of the crankshaft flange. If you're concerned about affecting balance, mark the drive plate and torque convertor at a particular point for reference. Similarly mark the drive plate in relation the the crankshaft flange before you remove it.

Definitely do replace the rear main seal if you have the opportunity to do so. These seals don't improve with age and are an instant fail if you want a roadworthy for club rego. As you know club rego is not transferable to a new owner if you ever decide to sell the car. A leaking rear main is a very expensive option for someone who doesn't want to do what you're currently doing! Replacing all the welsh plugs is also very sensible.

Post by harvey on Aug 10, 2015 at 8:55pm
This is purely from memory, but the problem lies with getting the box back on to the converter (or the converter on to the front of the box) if you remove it. Removing the box and converter as one unit should avoid this. (I presume this is possible) There is an alignment tool, and that's required because (IIRC) the stator in the converter isn't held in place in the same way that it is with a BW35, so if the box and converter are right way up, the stator drops down preventing refitting. There are also extra sets of splines over the BW35 due to the direct drive clutch. The way around that is to stand the box on the rear flange, look inside the converter to see if everything looks vaguely in line, and then drop the converter down on the front of the box while jiggling it (technical term) to get it fully engaged. Somewhere in the WM I'm sure it says to do the same thing by standing the engine on the front pulley and dropping the box down on to the converter that way, but that sounds like a lot of hard work, and I may have dreamt that anyway.

If anyone knows better, feel free to enlighten me.

Post by aussiep5al on Aug 11, 2015 at 9:23am
Thanks guys
The removal process looks pretty straight forward from Enigmas description.
But replacement according to the WM is a bit more ticklish in that the Converter needs to be centred on the drive plate using aligning guage B-W3 with the engine in a vertical position (ie standing on the pulley) or using a "dial test indicator and suitable mounting bracket".
This is the part that frightens me, as I have neither the aligning guage or a dial guage, although having slept on it, I think that I may be able to make up a suitable alignment guage before removing the torque converter which will enable it to be centred on reinstallation.
Re Harveys comment, I don't see how the converter and box can be removed as one unit. That is one of the big plusses of evolution to BW 35 which was designed to be removed as a single unit.

Post by enigmas on Aug 11, 2015 at 10:30am
I still believe it's a straight forward task. Make a wooden frame and stand the gearbox on its end...the tail shaft end that is. As. For aligning the stator in the torque converter use a piece of hardwood dowel the same diameter as the stator shaft minus the thickness of the splines. (I used to do this when aligning clutch plates on the rear of flywheels when I didn't have an spare clutch shaft or dummy shaft to align the plate.) Do this on a bench with the torque convertor chocked up on blocks and the spigot facing down. When aligned ...lift it over to the box and slide it down over the splines. Nil desperandum!

Post by aussiep5al on Aug 11, 2015 at 1:00pm
Thanks Enigmas
I am familiar with the dowel approach, I have about 5 dowels in my tool box with tape wrapped around to get the correct diameter for aligning clutches in various vehicles. The issue appears to be centralising the torque converter on the drive plate and this is what is described in the WM. I think I shall make up a template for tool BW3 before removing the converter so that I can align it to that on reinstallation.
I am feeling somewhat more comfortable with the process now

[aussieal]

Today I had a visit from a bloke with lots of Jaguar and no Rover experience. Having inspected the bits he has suggested that the process described in the WM is unnecessary and misleading. The spigots in the crankshaft and the torque converter should cause the torque converter to self align, particularly if the gearbox is fitted to the torque converter before installation as described by Harvey and Enigmas,

The biggest problem will be keeping the stators in place, and we will see how we go with that.

[aussieal]

I have finally got around to completing the work on the P5 (with a diversion to replace the clutch on the Discovery after the operating fork failed, fortunately just down the road, and not half way between Darwin and Adelaide which was where we were last July!)

The following may be of some help to anyone doing a similar job in the future, and is a result of doing things the long way around.

My Rover 3 Litre Workshop Manual (WM) is 2nd Edition issued January 1966, and was not tremendously helpful. It appears to assume that you are removing the gearbox in order to work on it, and does not have a process for when you wish to replace the rear welch plug or the rear crankshaft seal. I got very good advice from an older technician in a local Automatic gearbox specialist who had worked on Borg Warner DG gearboxes in Rovers, Humbers and Vanguard 6's. His advice was that removal and reinstallation should be the same as for any other auto gearbox, ie remove the torque converter and gearbox as a single unit.

First of all, to do any work of this nature on a Mk 1 you must remove the motor and gearbox as a single unit as per section A of the WM.

BUT, do not remove the gearbox as described in operation E1-1. Rather I suggest the following process.

- Remove the timing plate from the LHS of the flywheel housing (looking from front of motor)

- Remove the starter motor

- Remove the 6 bolts holding the torque converter to the flexible drive plate. These bolts are accessed through the starter motor opening in the flywheel housing. DO NOT remove the 2 bolts in the slots in the flexible plate: they hold the ring gear onto the torque converter, and are removed with the torque converter

- Loosen the nuts holding the bell housing onto the flywheel housing

- There are 2 threaded holes in the top of the gear box. These take a 3/8 UNC bolt. Clean the threads and obtain appropriate bolts and support the gearbox on a lifting mechanism ( I used an endless chain on a gantry as per photo)

Attachment Deleted

- Remove all the nuts holding the bell housing to the flywheel housing

- Gently prise the bell housing off the flywheel housing taking care that the torque converter moves with the gearbox/bell housing

- Clamp the torque converter to the bell housing so that it does not inadvertedly fall out. I used 2 bolts diametrically opposed through the bell housing mounting holes and some suitable lengths of scrap metal with holes drilled in them.

- Put the gearbox aside and get on with what has to be fixed. The gearbox is very heavy and I made frame so that I could move it around with a hand truck.

Reinstallation is as usual, the opposite of removal except that the following is recommended

- Be careful to align the pin in the torque converter with the appropriate hole in the flexible drive plate. This is best done by placing these at the starter motor housing position and viewing through the hole

- When fitting the bolts between the flexible plate and the torque converter, do them up loosely, and then spin the motor a couple of revolutions to ensure that the torque converter is reasonably aligned, then tighten them diametrically (ie 2nd one directly opposite the first and so on)

As recommended in other threads, check the condition of the chassis mounts while the motor/gearbox is out, and replace the crankshaft rear seal and rear welch plug. Rear seals for early Mk1s are particularly difficult to obtain and cost plenty and are not well covered by the WM. Later 3 litre seals are readily available and the replacement process is described in operation A1-31 in the WM. You really need to remove the original seals to check which you have.

If you remove the torque converter from the gear box, don't get too frightened by the alignment process in the WM. I simply hoisted the gearbox into a vertical position, bell housing up, using chains and a spreader, and gently dropped the torque converter into place. Surprise, surprise, all the splines aligned and it dropped into place (including the pump drive dog). Perhaps I got lucky! 

[Phil Nottingham]

VERY USEFUL AND THANKS - HAVE MADE IT A STICKY