ZF 4HP14 Automatic Gearbox - Information Wanted.

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David
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ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by David »

Hi all, as the title states I would like information about the ZF 4HP14 automatic gearbox used in the BX.

Mainly, I would like to know what actually breaks in them when they stop working in forward gears (But still work in reverse).

As I've still got the gearbox that was in my BX, I thought it would be interesting to open it up, and if it's something simple, maybe have a go at repairing it.

I've had a search on this forum and even google, but there's little information coming back. There is a series of videos on Youtube on how to pull one apart (although I think it's from a different car as some of the components are in different places), but nothing answering just that question.

So, What do you know about it?

I pulled the lid off mine today and had a quick look inside, but as I've currently got another project on my bench & I was working on the floor, I couldn't see anything obvious so I just put it back together.

Even if I can't fix this gearbox, any information that can be collected may be useful to someone in the future, in a similar position.
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Kaapelimies »

David wrote: Wed Apr 15, 2020 11:30 pm Mainly, I would like to know what actually breaks in them when they stop working in forward gears (But still work in reverse).
With luck it's something else but quite a few boxes with this symptom have been repaired by machining a new bronze bushing that keeps the oil where it should be. I have no pictures and have not dismantled the box myself, but that bushing is the last part you can get out of the box. So it's not an easy or quick job, like the newer AL4 with a broken brake band..

I do have a lot of material about 4HP14 (and some other automatics Citroen used), problem is where to upload, as it's not really copyright-free material..
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Jaba »

My GTi had an auto box when I got in in 1999. I was pretty underwhelmed by it and quickly put a manual box in. I sold the gearbox on to Doc Chevron late of this parish and that is the extent of my autobox expertise I am afraid and would have to resort to Google as you have done.

Kaapelimies are you worried about ZF coming after you if you host online their info on a 30 year old gearbox. If so host it securely behind a password and give that only to those with a need that you can trust i.e. us.
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by David »

Thanks for the information.

Where exactly is this bush? Will it be obvious when I find it? I've never pulled an automatic box apart before, but looking at it, it doesn't look too complicated.

There is a band just underneath the cogs that I didn't remove; holding them in, but from looking at it, it looks like it's a nut & bolt on the outside of the gearbox holding it in place. If I wasn't on the floor I'd have tried to get them out too. I've read that the bands are set at the factory, so they don't like being disturbed, but I've also read that if it's undone and tightened by exactly the same turns, then it'll be fine.

There looks to be sealing rubber rings inside the internal parts too, so I assume that they cause problems if they're damaged.

So as said above; is this bush on the primary or secondary shaft? I intend on finding it even if I can't fix it. Would it also cause gear change problems if it is this bush that's at fault? - The last time I drove this box, it just locked up when attemting to engage 2nd gear (with a horrible grinding noise).

As for the upload issues, the blog section of this website can't be viewed by anyone unless they're logged in. Maybe you could speak to an admin about uploading on a section of this website that will be secured in the same way, as Jaba said. (or the blog section itself, but ideally you'd want to ensure the privacy couldn't be forgotten about and altered at a future date).
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by xantia_v6 »

On the subject of making documents available for download from this site, it can only allowed within legal rules of copyright.

It is not that we want to suppress any information, but in order to protect the continued existence of this forum, we need to keep an arms length between this site and any content that could in future be liable to legal action.

If anyone wants help setting up or using an external hosting site, we may be able to give some advice.
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Kaapelimies »

The bush is under the governor. To remove the governor you have to remove everything else. This is the summary of the (finnish) document I have about it.
Here you have a link that has a few repair manuals, I'll have it up for a week or until I remember it's existence and take it down :lol: .

The errorneus changing can be caused by impurities in the hydraulic block. It has a lot of stuff falling off when opened if not done in right positions :!: . Be sure to have several spare ones handy if opening one (never done this myself either).

Edit:
In case you have a Xantia or C5 with AL4-box, here's also a link on how to fix if only has R-3-4 gears from box (can be driven on winter mode of the box).
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by David »

Thanks for the links. They have been informative, although (the English and French ones) only cover basic service information (which IMO should be in the Haynes B.O.L), I can't read Finnish unfortunately.

One thing that doesn't make sense though; When removing the hydraulic block, both documents state to remove it as if it's fitted to the vehicle (so upside down, presumably to keep any springs in, but it wasn't explicitly mentioned), but the English one states that it must be in first gear, and the French one states that it must be in park, so is it more of a case of that it needs to be at one side, but the English one is going off the assumption that you'll want the gearbox unlocked whereas the French one doesn't bother? (As they both state that the selector mustn't be moved when the block is off).

Nether document even mentions the governor though, but after having another look on Youtube, I've established that it's behind the plate on the left side of the gearbox, driven by the "output" shaft, but from the same video I saw, it also showed it being very tight, so I assume that's the reason why it's suggested to remove everything else to get to it? And is the bush part of the governor or is it below it, as neither the video nor any of the documents showed this?


xantia_v6: You've got a good point there; I didn't think about it in that way, just more of a case of "if they can't see it, then they can't complain". Thanks for letting us know.
1992 Citroën BX 1.9 Diesel Meteor 4x4 - The Project.

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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by David »

Today I pulled most of the gearbox apart, just to see how it works. I didn't remove the hydraulic block or sump, but I believe that I have a few answers on this gearbox.

And of course, I got some pictures of the insides.
IMG_3207[1].JPG
This is the most interesting picture. It shows the planetary gear carrier at the top. I couldn't get this out because it has a small allen key nut on the back and I don't have one strong enough to undo it. I think there's a one way clutch behind it too, which must be jammed because the outer castled gear carrier wouldn't turn alone or on the centre shaft when the planetary gears were inserted (which is essentially 3rd gear). It was just jammed solid, which would explain why the gearbox locked up when trying to change gear. The inner cog span freely, which is (indirectly) connected to the output shaft.

Also in this picture is the before mentioned regulator, in the bottom of the gearbox. It is shown sidewards here, showing the sealing rings. I think one of these has failed too, as it is too small to fill the hole. There are 3 in total, 2 rubber and one metal, and if this is the case, then it's why it completely lost drive (although why it happened at the same time as the other failure must be coincidence). The machined groves on the regulator are the gearbox park locking mechanism. The regulator wouldn't come out of the gearbox because there wasn't enough room with that cog still inside.
IMG_3208[1].JPG
Here are the planetary gears themselves There are actually 8 cogs in here, 4 for drive & 4 more for reverse. It uses 7 of the 8 the gears for reverse so it sends the power the opposite way.
IMG_3209[1].JPG
This picture is blurry as the camera had oil on it & I didn't realize at the time.
These 3 cogs sit straight on top of the planetary gears. The outer most one is reverse & the centre cog is 1st. I couldn't experiment further as the inner most cog wouldn't turn.

Edit: I have done some more reading up on how they work, and I think that I've worked out what all the combinations are. There is another clutch pack in the back of the gearbox that I initially missed, although it can just about be seen in the 1st picture. I'm now not sure if it has a one way clutch too or if it's just that clutch pack with something seized in it.

The combinations are: (as shown in the picture above).
1st: is driven off the centre cog with the back clutch locked
2nd: is driven off the centre cog, as with 1st, but the outer most cog used for reverse is also used.
3rd: is driven off the centre cog too, but it also uses the inner most one too.
4th: is driven off the inner most cog & the outer most one.
Reverse: is driven off the outer most cog with the back clutch locked.

As 1st and reverse need the back clutch locked to work, that's why it would initially work in these 2 gears, but the car stood on its nose when it tried to change into 2nd gear (before it lost drive completely).
IMG_3210[1].JPG
Here are all the clutch packs, the input shafts, the oil pump & the brake band. The cog on the left also has a one way clutch in the front of it. It sits right behind the oil pump with the brake band around it. The input shafts (shown on the right with the clutch packs) go behind it & the oil pump goes at the front. The oil pump itself actually drives reverse when the clutch pack is engaged.

I didn't get any pictures of the other side of the gearbox or of the output shaft, but it only has 2 cogs on the back, & the output shaft just connects directly from one of these said cogs, through the regulator and onto the diff.

Interestingly, I was expecting lots of parts to be broken inside this gearbox, but there wasn't. The cogs were clean, there was no real wear on them; one shown on youtube was completely chewed up. The clutch packs are all in good condition & the brake band is unworn, which is surprising considering it's done 199250 miles. The only things that seem broken are that worn ring on the regulator, an apparently seized one way clutch in the back & the seized oil pump (which must have seized from standing, as it wasn't seized when the gearbox was removed).
1992 Citroën BX 1.9 Diesel Meteor 4x4 - The Project.

1992 Citroën BX 1.9 TXD (with GTI engine; Mulleys old car) - Parts car.

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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Slagtrooper »

Nice!

Can you take some pics on that area:

Top: PSA box
Bottom: I think it is from a Daewoo Nubira

Because i'm thinking if installing hoses on that parts pointed on bottom pic, in the PSA box, maybe the water cooler could be removed and instead, use an external radiator? For hot weather countries would be a good improvement if it could be done.

TIA
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Tim Leech »

Ive heard of the box failing in diesel models due to the diesel "shaking it to bits" plus they have more torque.

I have this box in my 19TZI, which has done 95k, but continues to perform as it should, except shifting up the box far too early when cold.
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by David »

Slagtrooper wrote: Wed Jul 15, 2020 3:25 am Nice!

Can you take some pics on that area:

Top: PSA box
Bottom: I think it is from a Daewoo Nubira

Because i'm thinking if installing hoses on that parts pointed on bottom pic, in the PSA box, maybe the water cooler could be removed and instead, use an external radiator? For hot weather countries would be a good improvement if it could be done.

TIA
Image
Image
The actual case of the gearbox is slightly different between the two pictures. Underneath the oil cooler there are two oil ports; one for letting the oil in & another for letting it back into the gearbox. The only way I could see of putting an external radiator in it would be to somehow modify the ports to pipe the oil up for the radiator or have the internals of the oil cooler removed and/ or modified so that the oil could get out of the (water) pipe ports, in which case you could then pipe it to an oil radiator that way, but I can't see it being very efficient, unless you had it engineered so that the oil could only get through one way. I did take the oil cooler off to have a look behind it, but I didn't get a picture. It just looks the same as behind the engine oil filter looks when it's removed. If I remember, I will pull it off again and get a picture of what's behind it.
Tim Leech wrote: Sat Jul 18, 2020 11:57 am Ive heard of the box failing in diesel models due to the diesel "shaking it to bits" plus they have more torque.

I have this box in my 19TZI, which has done 95k, but continues to perform as it should, except shifting up the box far too early when cold.
I've heard the same thing too, which is one reason why I was expecting to find serious damage inside, but it wasn't the case; Asides from the stuck planetary gear carrier, there was no real obvious damage inside. Bear in mind that this gearbox had over 100,000 more miles on it than yours has now when it was removed.
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1992 Citroën BX 1.9 TXD (with GTI engine; Mulleys old car) - Parts car.

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2016 Ford Focus Zetec - Daily Driver. (Absolute bone shaker).
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Re: ZF 4HP14 Automatic Gearbox - Information Wanted.

Post by Tim Leech »

All i do is when its cold is lock it in 2 or 3, ir if you keep your foot down its fine
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