BW35 strip and rebuild in pictures

[eightofthem (Andy)]

Coming soon a photo casebook of the secret gubbins, and magic show that is the workings of the autobox.
I am no expert in the field of automatics, and always looked upon them as a miricle of wonder, but i find the only way to see how things work is to open them up and have a look.
I read as much information as possible ( and still i could not explain to you how they do what they do)
but i do know how the parts should look, and how they work in relation to each other.
There seems to be much fear over the autobox, when problems occur, so i thought i would post my findings on here so it can be used as a reference.
I have found that the strip and rebuild is something that can be done at home, any tools that have to be made i will try and use items that can be found to hand, all comments welcome, and would you like the pictures in a slideshow format or as cyf has done in single pictures?.
I would like to thank Harvey for all his help on this, and also to Allan Thomas who kindly offered to help me
Anyway a taster

[harvey]

Jan 24, 2013 17:53:57 GMT eightofthem (Andy) said:

I have found that the strip and rebuild is something that can be done at home, any tools that have to be made i will try and use items that can be found to hand,

Most of the tools you'll be able to either do without, or easily make something to do the job, but the ones that you really can't do without, (to install the resealed pistons into the drums) you won't make very easily at all.

[cyf]

Oh Good!!!!Just after the V8, I'll go on the autobox!
I wait for pictures and advices as for me the auto box is quite a mistery even if I know how it works in the big lines.
For my part, I prefer pictures one at a time but it's you to choose what is easier for you

well done anyway

[petervdvelde]

Andy,

Very impressive slide show. I wasn't brave enough and let Ashcroft do the overhaul of my 4HP22. I saw you made the plates using the original gear selector with the 4HP22. Could you make a pattern of it so i can copy it?
regards

Peter

[Warwick]

Single photos please Andy; like Cyf's.
That way you can add commentary and notes where needed, and you can move back and forth between photos when needed.

[eightofthem (Andy)]

Ok, thanks for the replies.
I will start with these. Bear in mind that i don,t want to go into the method of removal from the car, each to their own on that one.
The box has been drained of oil, and the torque convertor has been removed already (I will touch on the convertor when it comes to refitting it).
This is a heavy item so opt for a strong surface to work on it.
Give the outside a good clean ( try not to use pressure washers, as this forces water into places where you don,t want it).
Cleanliness is essential when it comes to rebuilding automatics, as they don,t like dirt, so if you give the outside a good seeing to, it will help you to find the bolts,keep your tools and your hands clean, this is where the tea comes in handy. No need to go as mad as this one,
it has already been stripped once, you can give the case a real good scrub once it is empty ( don,t let the wife catch you using the dish washer, and don,t use the tablets they are corrosive)




Next job is to remove the bell house, it will make it a bit easier to move about, so remove the six bolts from the ring shown ( these are 1/2 )



It will then look like this



Bell house,with bolts ( the three bolts on the left are for the gear selector bracket )




Next up remove the inhibitor switch / reverse light sender, just to stop it being damaged, the terminals are easily broken off.




Inhibitor switch and washer.



Next use the selector to place the transmission in the park position



This is so we can remove the 3/4 output shaft bolt, it is good practice to lock the shaft off by other means, as well as using the park pawl.
I would not like to break the pawl, so i used this method as a back up



And undo the bolt ( 3/4 ) socket, there is thread lock used on this bolt so it may be tight



And off with the output flange



While you are there, pop out the rear oil seal (unless you don,t intend to replace it ) If you struggle to remove it, then leave it until the tail cone is removed so the output shaft will not get in the way.
Just take care not to scag the sealing face of the tail cone when removing the seal, alloy is damaged all to easy and the new seal well..... might not seal!



Oil seal removed.



Next, turn the box on its side and remove the 15 number 7/16 bolts
( there are two special long bolts,these hold the oil cooler pipes via clips attatched to these, you may or may not have them fitted )





Sump pan removed showing the 13 bolts and 2 specials ( cork sump gasket has been removed ) expect to see some gunk in the bottom, it will tell a story of the condition or may hold the secret to the problem.



This is what you will see after the sump is removed. We will tackle this next.




TIME.....FOR.....A.............BREW !

[cyf]

That's brilliant Andy!

[eightofthem (Andy)]

Jan 25, 2013 20:43:30 GMT cyf said:

That's brilliant Andy!

I have you to thank cyf

[Warwick]

Good work Andy. Not much chance of getting a job offer from Haynes however.
Their more recent work isn't up to your standard.

[johnwp5bcoupe]

Reading with great interest Andy a good job well done keep up the good work

[Welsh Warlock]

Good info Andy. Looking forward to the next episode.

[eightofthem (Andy)]

Thanks boys, blame CYF he set the standard ;D
Right next instalment,here we go

This is where we got to last time



Next job is to remove the oil feed and return pipes, these are a push fit, they may be a bit tight as some are shaped, just take your time and wiggle them out, one by one. ( you may need the assistance of a puller or leaver, just try not to mangle them in the process )













Until you have them all out. put them safe for now, they will need a good clean after.
As Harvey pointed out to me, the front servo is of the self adjusting type, some are adjusted manually, and as such some of the pipes going to the front servo have a fluid restrictor in them ( this one does not have a restrictor )



Next up, remove the kick down cable, just pull up some slack and slip it out from the cam ( it fits like a bicycle brake cable does at the handlebar end on the brake levers )





Once out, you could remove the kick down cable from the outer case by undoing the retaining nut, or leave it until you turn the case over.



Next remove the 3, 7/16 (2 long 1 short ) bolts that hold the valve body to the case.



Then ease off the body ( there are three oil pipes that are under the body,at the front of the valve block, these go to the oil pump, and one has an oil seal ) again these are push fit as before, so wiggle them out carefully.



Put the valve block in a clean bag for now, we will look at it later. ( also there are a few variants in valve blocks and in oil filter types, again save these for later.



Next to come out are the front and rear servos. You might find a magnet on one of the bolt heads, it is supposed to be there.
The servos move the brake bands under fluid pressure, the brake bands "hold" the rear clutch drum or planet set depending on gear selection.



So remove these two 9/16 bolts that hold the rear servo in place,one long,one short. The long bolt helps retain the planet set,so if you are like me and tend to put the bolts back in after, don,t wind them all the way, or you will not be able to remove the planet set.
Harvey suggests this area including the bolts, threads and case are inspected very carefully. It seems to be a weak spot with a lot of pressure put on it by the servo action.



Then remove the servo complete, and store it for later. (watch out for the steel lever that sits under the servo, as it is a loose item. There is also one under the front servo, these look to be a git to refit, we will find out later.



That steel lever is the link that applies the servo pressure to the brake band, and sits in here



And here at the servo end



So there is the rear servo, note the right hand bolt, this is the one that helps retain the planet set.



This is the inside view of the rear brake band adjuster.



This is the outside view of the rear brake band adjuster



Next remove the two 1/2 bolts holding the front servo in place.



Front servo unit. Don,t forget to remove the steel lever.



So here we have both front and rear servos out.



Here is the front brake band stop/anchor.




Next up for removal is the rear tail cone. We removed the output flange and bolt earlier, so it is just a matter of undoing the four 7/16 bolts, these are twelve point bolts, although they look like specials. ( you could also remove this when the output flange came off )



Then slide off the tail cone, and bin the gasket. You can see the speedo drive in the cone, and worm drive on the output shaft.



Next slide off the worm drive, some have a retaining clip holding it, this one does not.



Next remove the governor, there are a few variations of these, this one has a bolt with a pin end, which locates into a hole on the shaft.





So there is the rear end of the box. Put this away safe for now, we will look at them later.



So next up is the removal of the internals, and get the case empty so we can clean and inspect it. We will start here next, at the front, with the oil pump and stator support.
Time for a cuppa me thinks

[harvey]

The two struts that fit between the servo's and the bands should be stamped with "215"
The Front band holds the rear clutch drum stationary in SECOND, and rear band holds the gearset stationary in "1" and REVERSE.
Manually adjusted front servos have a restrictor in the release pipe, and the restrictor should be fitted at the valve block end.

[eightofthem (Andy)]

Thanks for your help Harvey

[cyf]

It's seems so easy.... and so clean, as the box is new
Wait for the next

[johnwp5bcoupe]

Andy I may be having a moment and missed something but what is the origin of the box? nice and clean all the nuts and bolts flange etc already painted great info and pics

[eightofthem (Andy)]

Hi John, the box came with a load of spares i bought six years ago, i have been tripping over it since then. The time came to look at it or out it, so i stripped down, and with harveys help made a shopping list of what needed replacing
The box was all stripped and all the bits cleaned and painted, as i was going to leave it for a bit, but i decided to do a casebook on it while it was in bits, you can see things better, and i wont ruin my camera in the process.
It will be rebuilt with lots of new bits.
CYF, this is the easy bit, wait till we do the internals, it takes a lot of time just to clean everything up.

[petervdvelde]

Andy,

Great job! You could start a compagny for making work shop manuals. Very good pictures and small and clear steps.
I bought a ZF box and got it overhauled because i didn't feel confident but with this "manual" i would feel confident.
It looks like you dismantled the box again especially for making this manual. Thats very friendly
Peter

[eightofthem (Andy)]

Right then, i have had my cup of tea, so off we go again.
This is where we left off.



Next up is to remove the oil pump and stator support, but before we do, it makes sense to remove the oil seal, as the pump is held nicely in the case, although you may find it easier to remove the seal when the pump is removed from the stator, your choice.
( all seals and gaskets are available in a kit )

Next remove the six 1/2 bolts from the oil pump, and hold the larger outside shaft,then withdraw it out over the input shaft.



If you look at the other side, you will see the five bolts, and one retaining screw that hold in the oil pump.
( put it to one side for now we will look at this later)



Next up is the input shaft and the forward ( front ) clutch. ( note the thrust washer on the front with the tabs on )



Take a good grip on the input shaft, then withdraw it towards you, and out of the case.
you might find the thrust washer and spacer attached at the rear of the drum.



Put this safe for now.

Next is the front brake band, take a pinch here and slip it off the rear clutch drum.



Then remove it from the case.



Next take a firm grip on the reverse / high ( rear clutch assembly ) by holding the sun shaft
and withdraw it from the case, you



Next up is to remove the centre support and planet set. Now remember the bolt that holds the rear servo in?. Make sure it is wound out or remove it.



You now need to turn the case on its ( sump side down ) and mind you don,t damage any bolts you may have left in place.
You need to remove these two 9/16 bolts if you have not done so already.



All three of these bolts are specials, they have a "pin" type head which locates into a hole on the centre support, if you don,t remove all three you will not be able to remove the center support .



When you have removed all three bolts, put your hand into the centre support and planet set, get a nice hold of it ( it is heavy and awkward )



Give it a bit of a wiggle when you withdraw it, then easy does it as you remove it from the case, you may still have one of the sun shaft bearings inside the planet set, along with the output shaft sun gear bearing attached to the rear of the planet set, so watch you don,t loose these.
You can now see how those bolts hold the centre support in place.



You can also see the oil feed / return holes in the support.



Next out is the rear brake band.
This one is a bit fiddly, take a pinch here and flick,or walk the bottom of the band out towards the front of the case, it has to come out sideways, as there is not enough room to take it out straight.



Then take a hold and remove it out the front.



Then take a look inside the box.
You will see the output shaft, and ring gear.



To remove the output shaft and gear, you need to use both hands.
put one inside the case and hold the gear, while you push the output shaft from the rear towards the front.



There it goes. Nearly there now.



Next up, you need to remove the rear support plate.
This is held in place by five slotted head screws.



And remove it.




CONGRATULATIONS ITS A BOY!!!! ;D
You have just delivered your first BW35.



You should be left with a nice empty case.
All that is left inside is the selector mechanism, and parking pawl.



You need to give the case a good clean now, inside and out.
take care with the selector linkage and park pawl
as these are steel and they will rust if you leave water in there.
Also as this is a good shot of it, if you look at the left hand side of the photo you can see the the park pawl.
This is what holds the car in when you engage park with the selector.
Not much to hold such a big car is it, i will think twice from now on, and use the handbrake as well.




Have a good look at the bridge where the rear servo fits.
This seems to be a weak spot, so look for stress or cracks around here.
( Thanks Harvey for the tip on that )



And that brings this session to an end.
Next we will look at what you have delivered ( the boy ;D)
Doing this is harder than the strip down of the box, i need a cuppa............. and cake

[harvey]

Feb 1, 2013 19:09:35 GMT eightofthem (Andy) said:

Next is the front brake band, take a pinch here and slip it off the front clutch.

Front band runs on the rear clutch.

[eightofthem (Andy)]

Feb 1, 2013 19:18:47 GMT harvey said:

Feb 1, 2013 19:09:35 GMT eightofthem (Andy) said:

Next is the front brake band, take a pinch here and slip it off the front clutch.

Front band runs on the rear clutch.

Bang on Harvey, thanks bud.

[harvey]

No problem.

Seeing this pic:



I should have sent you that bolt as well as the other one. Those shiny marks mean it's been loose, although it will have worn the casing more than the bolt, but every little bit helps.

The rear band and gearset are bad aren't they?

[eightofthem (Andy)]

Hi H.
Yes the band and gear set are shot.
I was looking into using locktite on the servo bolts, to stop them coming undone.
The long bolt was tight, but the short one was well loose, and had bent as a result.
The threads look ok in the case, but you can't really tell by looking at them unless they are very bad.
What is your thoughts on locktite?

[harvey]

Feb 1, 2013 22:38:13 GMT eightofthem (Andy) said:

What is your thoughts on locktite?

I can't say I've ever felt the need to use it, I've seen plenty with the bolts loose, but had none of those come back loose again once they've been tightened.

[Warwick]

I hope you're keeping a good back-up of all this Andy, including the captions. It would be a shame to lose it all due to a minor stuff-up by the photo hosting site.