BW35 strip and rebuild in pictures

[enigmas]

Perhaps it's to evacuate fluid between the plates for faster apply. Interestingly, my factory manual (Part No. W.M. 22. for later model Aussie Fords (XE -ZK Fairlane) has an exploded diagram (p.7-1-37) of the rear clutch hub illustrating the placement of 2 flat plates fitted alternately between the dished ones. Ford continued with the development of these gearboxes right up until the 1980s.

[harvey]

Feb 26, 2013 21:54:43 GMT enigmas said:

Perhaps it's to evacuate fluid between the plates for faster apply.

Yes, without the missing teeth on the steels and the drum, the fluid displaced as the piston moves forward would have to go over and under each plate idividually with gradually less room between them to do it, so the way it's done ensures there is always a path for it to travel along the silde of the drum.

[eightofthem (Andy)]

Here we go again then for the next installment.
We are now ready to refit the front clutch hub with all the bits.
We finished here last time.




The first job on the list is to refit the two seals for the piston.
Lightly lubricate these with new transmission fluid or you could use that big tub of Vasaline,and use a smear of that.



Fit the small one here ( make sure they are like for like )



And the large one here, on the outside of the piston.
Then i used lots and lots of vasaline on all the surfaces where the piston is going to be refitted.




Place the piston into the hub.



Sorry to all for not adding this when the post was made.
You need to improvise overcome and adapt a bit here, unless you have access to the piston installing tool.
I made my own from bits i had hanging around, this is not pretty as i want you to be able to make it yourself from things you have.
I used a bearing race from a washing maching that had broken in half, a brace strap from the same machine, and a large washer.



And welded them together, they need to be square and flat.


Then you will need some threaded bar, and a base for it ( Try a small offcut of kitchen worktop, or M.D.F board, it needs to be about 30 mm thick at least.)
and put a hole in the center of it so the threaded bar goes through it. Recess the bottom hole so it can sit flat on your work surface.
And a few spacer tubes or washers too.


You now have the makings of a nice mini press. You can go as mad as you like with it, just make sure it is strong and sturdy, and the the bit i used on the frame bottom
( the bearing race ) is thin and flat, with an outside diameter of 55 mm. ( you will find out why later, as you will need this again )




Place your hub on your thing ( you may need a sleeve on the threaded bar such as a hose pipe or plastic tube to protect the bushings as you slide the hub down the threaded bar
unless you are the world champion on the operation game)


Set your tool up so it is ready push the piston home by winding down on the top nut on your tool.



Then use ( please guys and girls, if we do ever meet and the wife is in tow, please dont bring up the fact that i use all her most precious items in my shed )
A hair dryer to warm the hub up to a nice temperature, nice and warm, and wind down the top nut on your tool, It literally just fell in, with little pressure on the nut.




When you refit the piston into the hub, make sure you dont pinch that outside seal or it will tear, and you will need a new one.
I tore the first seal on my first attempt without the tool. After i used the tool
I removed the piston and seal when i had refitted it to make sure i had not damaged the new seal when i fitted it this way.
It was all good.



When that is in, check to make sure it has gone in properly, then refit the metal ring into its grove on top of the piston




Next up is the diapragm spring ( the old one was in bits ).
Refit this with the dome or dished side facing downwards towards the piston.



Locate this equally in the hub.


Then refit the snap ring, and check that the spring is located properly by the snap ring.



When you are happy with its location and security, you need to check that the piston is seated.
You do this by using compressed air in the same location we used to remove the piston from the hub.You should hear it click back and fore when pressure is applied
and removed. Use caution with the airline!



When you are happy with that, refit the first of the steels ( it is the thickest one with the dish on the underside).

I tried a few methods of refitting the steels and friction plates followed by the inner hub.
The easiest method i found was to refit the inner hub now, this way you can refit each part in turn, and locate them properly without damaging the frictions.


Then it is a case of friction, then steel, friction then steel etc.
The frictions fit on the inner hub, and the steels fit on the outer walls of the clutch hub itself.





You should be left with a friction on top, and it will look like this.
If you have fitted the thrust washer along with the inner hub it should have the groves up like the picture.


Then it is just a case of refitting the input shaft.


Followed by the snap ring.


Not forgetting the thrust washer, Bronze side down, ears or luggs upwards. These luggs locate on the segments of the oil pump.




And that is it, you are now back where you started.
Remember to give your frictions a good drink of new A.T.F fluid before you refit them, leave them soak for a bit if you like.
Mine are fluid free in the photos, just for ease of handling while taking piccies.





Just another view of the frictions, the ones i had in were smooth, i replaced them with the grooved type, but both are available.




Next to go under the lense, is the rear clutch hub and front brake band.
This is where you will need to improvise overcome and adapt, as you will need to rustle up a tool to aid in the removal of the spring on this one.
I will give you a few ideas when we start this next time.

[harvey]

If you've refitted the piston with a new seal, but without using the proper installer then either you've been very lucky (somehow, although I don't know how, but when you know how tight they are to fit even when using the installer, I can't believe you've done it without)or you will have nipped the seal.

[eightofthem (Andy)]

Absolutely spot on there Harvey, they do not call you the yoda of the BW 35 for no reason.
Truth is I did nip the new seal when fitting it, and had to replace it.
So I made a tool to help refit it, and yes it was tight to fit. Now that I have Been rumbled, I shall put up a pic of the method I used.
I also made sure that all the parts were at a nice warm temperature when I worked on them.
" I would have got away with it if is wasn't for those pesky kids"

[harvey]

It's fresh in my mind because I've just fitted a set, using the installers, and it's surprisingly difficult to get them fitted even using the proper tools.

[Warwick]

Andy,

Are your photos uploaded to the forum, or are they links to an external site like Photobucket or Flickr?

I'm wondering because if they are external links and anything happens to that site or in the distant future you organize them into a different folder, all this valuable stuff may be lost.

The same thing applies to Cyf's car and engine dismantling threads, and various other valuable threads.

David, is there any way that threads like these can be backed up, even if the photos are external?

[eightofthem (Andy)]

Warwick, my Aussie cousin.
Sorry bud I forgot to reply to your concerns last time bud.
I have put all the photos on disc, as well as uploading them onto a host site. I also keep a file on the P.C.
I know what you mean about loosing it all, very frustrating. I would just have to do another one .
They are copied and pasted on to the forum, so they should always be there, as I opened an account just for this rebuild, and I will not use it for anything else.
Thanks for the heads up though. Andy.

[eightofthem (Andy)]

Right then next up to be looked at is the rear clutch hub, and brake band.
We left off here last time.


Firstly if you have looked at the last post on the front clutch hub, you will see the tool thingy that you will need to make.
I will have a chat with the chaps who provided me with the new parts, and see if the correct tools are still available, and at what price, and maybee see if the club would be interested in them.

I used what i had to hand, you could go as far as you want with these. It is up to you.
I had a bearing race that had broken in half from my washing machine, this was the correct outside diameter 55 mm, and it was flat and true.
also in there was a brace strap from the washing machine, and a large thick washer.
I only had my large industrial stick welder with 3.5 rods, which are way to hefty for this. You need a mig, or thicker steel for the tool.




For the base tool you can use a nice square bit of timber such as kitchen worktop or M.D.F board. It needs to be flat, at least 30 mm thick, with a hole in the center for a threaded bar or rod.
You need to countersink the top and bottom of the hole to allow lock nuts to sit flush when you fit and lock off the treaded bar to the base.
I had a nice round billet of steel, so i welded my rod to it, and just used a washer to to pack it up over the weld.
Depending on the length of rod used you may need some extra washers and spacers, or you get fed up with spinning the top nut on / off.
Another tip is to use a piece of hose as a sleeve. fit this over the threaded bar when you fit your hubs over and down the rod, to save damaging the soft bearings.
Once the hub is sat on the base, just slide the sleeve off.


So in action it works like this. I have a few variations of these with various sizes of tubes for other uses.



So once that is done the first item on the menu is the brake band.
It is just like a brake shoe, and wears just the same way, and will cause the same damage if these wear down to the steel backing plate.
Check the amount of friction left,look for damage. If in doubt replace it with a new one.


My box has the self adjusting servo, so should have different type fitted. I will show you that later.
Bear in mind that the brake band actually uses the outside of the hub to clamp onto, and if you let these wear to excesss it will ruin the hub here




And you will then need to replace the hub as well.

Next up is to remove and look at the forward sun gear shaft.
You could leave this until later but it is first out so first seen.
Just ease it out of the rear clutch backwards.


Along with the shaft you should have two needle bearings, and a thrust washer. ( the thrust washer somtimes remains inside the planet set)


Inspect this shaft along the surfaces which run on the internal bearings for any wear.
And check the sun gear teeth for damage and wear, and the input splines on the front of the shaft for wear.
There are two front oil seal rings, and one rear nylon ring which need to be replaced. ( these are included in the overhaul kit )
this is the layout order.


On the front of the shaft you will find a valve, i could not find any reference to this, make sure it is clean and free.


Also inspect the sufaces of the sun gear, as the needle bearings sit against these directly, and seem to attract small particles of nasties.


Once satisfied with its re-usabillty , you need some new bits.


Identify the new seals you need


And refit them on the shaft, in their positions. The front two i alternated the joins, like piston rings, one oneside one the other.


And refit the rear ring seal


If the needles are good refit them. Use some vasaline to hold them in place on the shaft.
Rear first.


Then rear thrust washer, flat side against the needle.


Then the front needle.


Give it a coat of vasaline to protect it, then put it away in a clean bag for now.



Next on to the hub itself. it is a bit like the front hub.


First remove the thrust washer, check it over for wear.


Then remove the steel thrust washer ( note it has location lugs ) Check this out for wear as well.


Next remove the snap ring that retains the clutch pack.





Then remove the clutch pack steels and frictions. The first one is thicker than the rest.
Keep them in order if you plan on reusing them.






One steel one friction, remove them all one by one and lay them out in order.


There are five frictions and five steels.
The frictions are the same as the front clutch on mine, but it is worth checking them.
The steels however are dished.


Next we need to remove the piston spring, this is a chunky spring and is under a fair amount of tension.
It is held in place by a snap ring and a collar.
This is where you need your tool.


Set it up like so.






Once you have it in place load the spring down with the top nut on your tool to reveal the snap ring.
Now you can see why i choose the old bearing race ( or half of it )
You need to be able to get in there with circlip pliers to remove the snap ring.
It is tricky, try to use the chamfer where the thrust washer sits to help it out.


There it goes.
Once you remove it all from the tool, check this circlip out. Replace it if is worn or twisted.


Unload the tension on the spring, you can see how much it has risen with no load on it. Make sure your tool is man enough


Then remove said tool and hub, and remove the circlip, collar, and spring.




.


You can now see the piston. This is next out
As before on the front hub, use compressed air to remove the piston.
Apply it here.



Then remove the piston.
As I mentioned before, you can remove this without compressed air, but it is easier with, and you will need a compressor later.


And it has a seal on the outside rim here like the front did.


And another in the hub here.
These both need to be replaced, and come with the kit.
You can also see the torrington race bearing inside the shaft, check this and clean it out, replace it if worn or damaged.


On the back or rear of the hub you will find three large sealing rings.
These need to be removed and replaced. ( In the rebuild kit there are replacements, but these are steel, so i am going to order some teflon replacements and fit these.)


Remove them
.

Finally check the condition of the bearing inside the shaft.
This one is worn so i am replacing it. ( i will have to order one as i overlooked it first time)


So there we go. I have a shopping list of parts needed.
Give all the parts a good clean, and check over, and next time we will put it all back together.
Time for a cuppa.

[Deleted]

Huge respect to you, your skills and your photography!

This is one job that you do need a good workshop and the appropriate skills but I hope that I will never have to contemplate any BW35 work as I can't imagine the re- conditioners doing work to this standard.

What actually wrecks a BW35? Is it hard use and allowing the fluid to become contaminated? Is it age/mileage?

My original box's still changing smoothly at current mileage 59000 and it has never been tampered with and seems to be working as it should. I did change the ATF and clean the pick up gauze a few years ago.I must admit, I start off gently from standstill and only put my foot down (occasionly) once the car is moving.

[eightofthem (Andy)]

Kind words Crossplies thank you.
I am doing this in my shed!, with limited tools, and it is my first BW35.
Harvey is the man who knows what wrecks them, and he is my Jedi Master.
I am the monkey, he the organ grinder.
I just felt like putting something up here for others to use, who may not have access to specialists, and have no choice but to go it alone.
It can be done, just time and patience required.

[harvey]

There's a mighty long list of things that can go wrong with a BW35, but by far the most common is loss of drive through worn clutch plates caused by failure of the piston seal. Next would probably be rear servo faults. The front clutch diaphragm spring is broken most of the time. I've come across loads of different faults, but I think there are lots more for me to find.
I've seen how the new seals have been installed in this thread, and tbh I think that the seal will have rolled in the groove and although it's working on an air pressure check, I don't think it's going to last long in use, but only time will tell that. You may have warmed up the drum, but not as hot as it will get in use, and if you were able to fit the seal with the drum only that warm, it's not going to seal properly anyway because it will be too loose a fit. As I say, only time will tell.
The seal installers are NLA.

[Deleted]

Mar 3, 2013 13:50:46 GMT harvey said:

There's a mighty long list of things that can go wrong with a BW35, but by far the most common is loss of drive through worn clutch plates caused by failure of the piston seal. Next would probably be rear servo faults. The front clutch diaphragm spring is broken most of the time. I've come across loads of different faults, but I think there are lots more for me to find.
I've seen how the new seals have been installed in this thread, and tbh I think that the seal will have rolled in the groove and although it's working on an air pressure check, I don't think it's going to last long in use, but only time will tell that. You may have warmed up the drum, but not as hot as it will get in use, and if you were able to fit the seal with the drum only that warm, it's not going to seal properly anyway because it will be too loose a fit. As I say, only time will tell.
The seal installers are NLA.

Now I am depressed and a bit confused. I would suggest that anyone who uses the cars power to its full capacity might want to think again before flooring the throttle!

Harvey, if the tool to install these seals is no longer available and you are a bit pessimistic about the one made, how is this overcome in practice?

[harvey]

Mar 3, 2013 17:13:50 GMT @crossplies said:

Now I am depressed and a bit confused. I would suggest that anyone who uses the cars power to its full capacity might want to think again before flooring the throttle!

Don't get depressed, if you haven't got problems, keep using the car, and if you do get problems, worry about it at the time. The reason they have lots of problems is that there are lots of them about, and they're working at their limit behind the V8.

Mar 3, 2013 17:13:50 GMT @crossplies said:

Harvey, if the tool to install these seals is no longer available and you are a bit pessimistic about the one made, how is this overcome in practice?

Find someone with the installers, and get them to fit the pistons into the drums for you.

[eightofthem (Andy)]

Well I had a think about what the installers would look like and what they have to do.
I am guessing they are like engine piston ring compressors, but it needs to be slim to fit into the drum, and would need some sort of locator that is central, and locates in the centre of the drum.
The correct installers are the way to go, but if you have no access to them, hmmmm.
I will have a think about a bit more, over a few cups of tea and some shed time.
You may have a rush on Harvey.

[harvey]

Mar 3, 2013 21:21:05 GMT eightofthem (Andy) said:

Well I had a think about what the installers would look like and what they have to do.
I am guessing they are like engine piston ring compressors, but it needs to be slim to fit into the drum, and would need some sort of locator that is central, and locates in the centre of the drum.

They need to be all of the above, and tapered down on the inside to gradually compress the seal into the piston, the taper ending up fractionally smaller than the bore size, but fractionally bigger than the piston.

[Deleted]

Mar 3, 2013 22:05:34 GMT harvey said:

Mar 3, 2013 21:21:05 GMT eightofthem (Andy) said:

Well I had a think about what the installers would look like and what they have to do.
I am guessing they are like engine piston ring compressors, but it needs to be slim to fit into the drum, and would need some sort of locator that is central, and locates in the centre of the drum.

They need to be all of the above, and tapered down on the inside to gradually compress the seal into the piston, the taper ending up fractionally smaller than the bore size, but fractionally bigger than the piston.

Well, somebody's got to ask! Who is the keeper of the installers?!

[harvey]

Mar 3, 2013 22:10:38 GMT @crossplies said:

Well, somebody's got to ask! Who is the keeper of the installers?!

I have a set, but I can't be the only one.

[Deleted]

Mar 3, 2013 22:16:22 GMT harvey said:

Mar 3, 2013 22:10:38 GMT @crossplies said:

Well, somebody's got to ask! Who is the keeper of the installers?!

I have a set, but I can't be the only one.

Looking through the Special Service Tools in the W/S manual are we talking about Rover Part no 601290 " Rear clutch and seal inserter"? Are any of the other tools "unique"? Sorry to go on about it but I'm just curious.

[harvey]

That sounds like it, although I don't recognise the Rover number offhand. You need the one for the front clutch too because they're different. There are also different types as well so you need the one for the 5 plate clutches. You see other BW tools listed in the book, but the seal installers are the only ones you can't do without or make easily.

[Warwick]

Feb 28, 2013 18:17:34 GMT eightofthem (Andy) said:

Warwick, my Aussie cousin.
Sorry bud I forgot to reply to your concerns last time bud.
I have put all the photos on disc, as well as uploading them onto a host site. I also keep a file on the P.C.
I know what you mean about loosing it all, very frustrating. I would just have to do another one .
They are copied and pasted on to the forum, so they should always be there, as I opened an account just for this rebuild, and I will not use it for anything else.
Thanks for the heads up though. Andy.

Thanks Andy. That's reassuring.

I doubt that I'm alone in thinking that what you and Harvey are doing goes far beyond what most of us would consider to be an excellent explanation of overhaul and rebuild instructions. It goes well beyond what you expect from a commercial workshop manual. It's the photographic step-by-step detail that makes the difference.

Perhaps, when it's all finished, there may be some way that David (Admin) can capture the pages in a hi-res pdf file. Or perhaps there is some admin technique available for David to back up a particular thread in isolation, as a discrete file.

Maybe I'm just being overly nervous but you've both put in an enormous amount of work into something that only exists (in its assembled form) in cyber space.

[eightofthem (Andy)]

Good Point there Warwick.
Although i dont think there will be a huge amount of takers for rebuilding the autobox at home, but at least we now have a good case reference to refer to when problems or explenations are required. And this is a full on strip to the Knackers, some may only need to repair a particular part, so it may help.
As far as the piston installers are concerned Harvey is quite right, yes you can install them into the drum without the right kit, but the chances are they will not seat correctly.
So all the hard work put in to a rebuild could come undone at this stage.
Borg Warner / rover would not have gone to so much trouble to design and make a tool that could be done without.
You could make your own, but some serious engineering would be required. So have a go by all means if you are really stuck, but i think i will give someone i a call that may be able to help me out.
Now where did i put Harveys number.................

[harvey]

EIGHTOUTOFTEN (Andy) said: On the back or rear of the hub you will find three large sealing rings.
These need to be removed and replaced. ( In the rebuild kit there are replacements, but these are steel, so i am going to order some teflon replacements and fit these.



A bit late now, seeing as you've probably ordered up the teflon rings by now, but I'd fit the cast ones that you were supplied with originally if it was me. The ends of the cast ones lock together for a better seal and less risk of them snagging up on fitting.

The dished steels can be fitted either way around as long as they are all the same way around as each other.

[eightofthem (Andy)]

Thanks for the tip Harvey.
I have not ordered any more new bits as yet, i think i will need a few more bits before it starts to go back in the case, so i will leave it untill then and have the lot in one go.
The only reason i was going to use teflon, was that these were an aftermarket fit to ZF 4HP22 autos on the front clutch pack failure rate.
The steel ones wore out the bush alowing fliud to seep into the hub and pressure it, therefore wearing out the front clutch.
I guessed these might do the same sort of wear to the 35 where they run.
SSHHHH on the dished steels, i was getting to that later .
Good stuff Harv.

[harvey]

Mar 5, 2013 18:31:56 GMT eightofthem (Andy) said:

The only reason i was going to use teflon, was that these were an aftermarket fit to ZF 4HP22 autos on the front clutch pack failure rate.
The steel ones wore out the bush alowing fliud to seep into the hub and pressure it, therefore wearing out the front clutch.
I guessed these might do the same sort of wear to the 35 where they run.

Those seals on the 35 run directly inside the centre support so the cast rings won't wear that out in a hurry.