Citroen XM Forum

No the manual boxes are a little more complex in terms of twirly coggy things so im not sure you could.
On the auto its a straight shaft from the crank, through the planetary gear set with an output shaft that comes to the gearbox end cover in the wheelarch, this has a cog on which drives a cog on a second shaft that runs parallel to the gear set back towards the diff (final drive) It would seam they used the same planetary gear set too.

This is the gear set which will be the same
4HP1813 by Deanxm, on Flickr

Here is the differential and final drive which will be the same, the two reduction gears are on the right laying face down.
4HP187 by Deanxm, on Flickr

And here are the reduction gears in place, they are both of equal size on the 2.0i and by the looks of the markings 144teeth in this case but if the left one was bigger and the right one smaller it would in effect give a longer geared final drive
CIMG2145 by Deanxm, on Flickr

In fact if you swapped the V6 you could make an even shorter final drive ratio and i wonder how this would work on the motorway, probably awefull but accelleration would be fantastic............
Not sure how the torque converter would react to this as i would guess the T/C stall is set to work nicely with a certain gear ratio, might try this once all the fiddly little bits are done like swapping the engine.

I would think they have altered the ratio's in this way on the Turbo engine too so before i take the 2.0i engine out i could have a go at messing about with the ratios and see what happens.........

D

Torque converter characteristics and stall are matched to the engine, not the transmission.

Have added 2.1 box info to my original post.
Also revised the petrol details as the boxes got changed.
As far as I can see all gear ratios were the same for all auto boxes.
They just used the reduction gears as a plug and play set up to suit function.
Will now search for post 1991 box changes and modifications.
Think this needs to be done before I collate a box change list.

John

The gear ratios are all the same, with the differential ratio being changed for diesels. The return shaft gears are the ones you have already deduced.

In essence, the petrol turbo Auto gearbox is the same as the V6.

In essence, the petrol turbo Auto gearbox is the same as the V6

Dean's car currently has the 2.0i non turbo box of course and it is still correct that the valve blocks and t/c are different?
With regards,
Matthew T.

MTXM wrote:

In essence, the petrol turbo Auto gearbox is the same as the V6

Dean's car currently has the 2.0i non turbo box of course and it is still correct that the valve blocks and t/c are different?
With regards,
Matthew T.

Hi Matthew. My reference was really for information if anyone was struggling to find a V6 gearbox. There are many more 2.0 CT in operation and scrapped.

I dont think it would be worth swapping boxes between nasp, Turbo and V engines, the V should just have different reduction gears, bellhousing and torque converter and thats it.

The turbo will have a boost detection in the valve block as well as throttle position to see engine power.

Everything else will be the same, as parts get hard to find its comforting to know any one of my (ok ive got seven) gearboxes could donate a diff, oil pump, planetary gear set or clutch housings.

Once this project is complete and running my fun V6 engine and box can come out of yog, could test this theory out.

For the record my 2.0i autobox is running some replacement turbo box parts including regulator body and valves and some valveblock springs.

Cant be bothered doing photos but the last head is sat on the engine, ported, valves re-seated, new valve seals, cam seal and the snapped manifold stud removed, just cleaning up the final rocker assembly and the head can go back on , another day should see the engine done. Having bad thoughts about painting the block Matte black again though............

D

Do you have any flow test info on the head porting?

I read of a great method of doing it. Use sandy water pumped through. It errodes the metaal where the flow is needed most.

How do you know the ports weren't large enough? I have previously reported about someone I know throttling some ports to improve performance.

Worth reading. http://mototuneusa.com/homework.htm" onclick="window.open(this.href);return false;

The ports are way big enough Will, huge in fact but there is a lot of casting chaff in there and markings that were filed out and sanded with course sandpaper to keep a bit of texture on the walls of the intake downstream of the injector.

The exhaust ports are very bad but all i did was take away the step behind the valve seat and smooth it out the same as the intake, im not removing material as i dont want the agro of having to make up templates to match all the ports, not only that but its not worth it for the intake and not possible on the exhausts due to the short heads creating a shallow roof in the exhaust and close proximity of the water jacket.

Will have a read through his site later, looks like he is restricting the intake and using a long intake to use the weight of the incoming air to accellerate the charge as it enters the cylinder, probably more use on low capacity engines at high revs but worth a read all the same, thanks

D

IMG_3070 by Deanxm, on Flickr
IMG_3064 by Deanxm, on Flickr
IMG_3079 by Deanxm, on Flickr

Getting on now, wont be long and i think i will crane the engine into the truck and take it to work, i have cleared a space in my office for it to stand because i really need the space in the shed for doing the gearbox, will still be a few weeks until the engine moves though.

Does anyone know why two injectors would be completely differnt, is this part of some passes bodgery or did cylinder 4 and 5 have a different injector for some reason, cant think what that reason would be but i need to make sure before it goes back together.

D