change of gearbox

[homer jw]

can u swap over an auto box for a manual if so whats involved hour wise ie how long does it take and what do u need car is 52 reg c5 diesel 2.0 hdi

[Gibbo2286]

It's a lot of work, not a job I'd recommend, gearbox out new flywheel and clutch, new mountings probably, gear linkage, possibly new centre console to accomodate the lever etc., new pedal box and pedal and associated switch and wiring. I wouldn't go there.

[addo]

I've just worked through a similar swap elsewhere on the 'net for a late D9 406.

Assuming you're fitting an ML5T it shouldn't be too bad. Subframe is likely to be OK, you will need new inner pairs for the driveshafts but keep the outer stubs, gaiter should clip into existing console, gearchange cable assembly uses same grommet in centre tunnel and same bolt holes. Can probably use a 406 Pug master and slave set, pedal box I am not sure of but quite possibly the auto one is adaptable with not much grief. Elapsed time, maybe twenty man hours for a competent mechanic.

Other than no dialogue with auto transmission I don't expect people would have any real problems. A Nigerian bloke reckoned they did it to all newer big Pugs there as the ZF autos cark readily in their environment (heat and high speed roads).

[CitroJim]

High-Speed roads in Nigeria? Really?

[Gibbo2286]

High-Speed roads in Nigeria? Really?

Well you're in the air most of the time.

[CitroJim]

Well you're in the air most of the time.

Unless you're flying Nigerian domestic airlines and then it seems you spend a lot of time crashing...

[Mandrake]

It's a lot of work, not a job I'd recommend, gearbox out new flywheel and clutch, new mountings probably, gear linkage, possibly new centre console to accomodate the lever etc., new pedal box and pedal and associated switch and wiring. I wouldn't go there.

Just to put some perspective on this, homer isn't asking out of idle curiosity its to save the car being scrapped as the car has a failed AL4 auto box, see the following thread if you haven't seen it already:

http://www.frenchcarforum.co.uk/forum/v ... =3&t=41417" onclick="window.open(this.href);return false;

I put my Lexia on the car and the gearbox has a loss of gearbox oil pressure rendering the car immobile, in other words a dead AL4.

A new auto box is out of the question due to price, reconditioning of the existing box is specialist work and could be a crap shoot depending on what the problem turns out to be, so a box swap is the only thing that will save the car. A 2nd hand AL4 from a scrappy might be ok but an auto box with no service history is still taking a chance, it might break down the same way (or a different way) in the future even if the oil is changed right away.

Conversion to manual is not something that occurred to me but could actually be a good way to save the car. Even if it means changing the inner drive shaft joints, fitting a clutch pedal and changing the gear change lever/facia, if the conversion was successful the gearbox would most likely outlast the life of the car and give better MPG to boot.

Addo: do you think the engine ECU failing to communicate with the gearbox is going to be a critical issue ? Is it likely to bring the engine management warning light on ? Does anyone know if the engine ECU can be reprogrammed with a Lexia to tell it that it has a manual box instead of an auto, or can that programming only be done once at the factory ?

If the lack of the gearbox ECU is likely to only throw up some non-critical fault codes in the engine ECU but not light the warning light its probably not an issue, but theres no way to know how it will respond until trying it. I assume the gearbox ECU (which is mounted separately to the gearbox) would need to be disconnected from the bus so its not still trying to talk to the engine ECU with the gearbox missing...

[Gibbo2286]

My recommendation stands, I wouldn't go there, better to either break it and sell the good bits or sell it to a breaker and spend the dosh on something else. It's not as though the cars a classic that's in short supply.

[addo]

High-Speed roads in Nigeria? Really?

Yes, apparently they do have some decently smooth longer highways.

I feel sorry for the (actually quite large) numbers of ordinary Nigerians who can't buy stuff off Fleabay because of the scammers.

RE the swap, I don't see much to fear. Knowing it's an AL4 is interesting; the inner shafts will definitely be wrong as they are "female" on an AL4 and "male" for an ML5. An HDI driveshaft set may swap right in. The engine-trans comm line is unlikely to be multiplexed; not enough data sharing to make it worthwhile.

[Mandrake]

The engine-trans comm line is unlikely to be multiplexed; not enough data sharing to make it worthwhile.

I don't think that's the case actually, even on my Xantia the engine ECU and gearbox ECU do communicate bidirectionally, the gearbox receives throttle opening percentage, RPM, calculated engine load and output torque from the engine ECU many times a second, and uses that data to help decide when to shift, lockup the torque converter etc.

In the other direction the gearbox ECU sends commands to the engine ECU to reduce the engine torque (by retarding timing on a petrol) when the gearbox is shifting to make the shifts smoother. I suspect it also commands the engine to reduce torque if any clutch slip is detected to help prevent damage.

On a diesel I assume it would vary the injector times to achieve a torque reduction. (homers C5 is a diesel)

If the gearbox ECU is missing the engine ECU may think the gearbox is in mechanical limp home mode. Whether the engine ECU will still allow full power output or will revert to a reduced torque mode is unknown. On the other hand if the engine ECU detects no communication to the gearbox ECU it might just assume its a manual box and go about its business normally. No way to tell really unless someone has already tried it...

So does anyone know if there is any difference in the factory programming of the engine ECU between auto and manual, or is it smart enough to adapt by itself ?

[CitroJim]

So does anyone know if there is any difference in the factory programming of the engine ECU between auto and manual, or is it smart enough to adapt by itself ?

Yes, there is a difference Simon. I know when people drop the ES9 into an Activa they prefer to get hold of the manual 'box engine ECU rather than use the auto one.

Even on something as prehistoric as my XM the engine ECU 'knows' that it has an autobox on the end of it as it has signal lines telling it what gear is selected. It does this simply (as far as I can tell) to drop the idle speed when in R or D to reduce creep. It idles at 840 rpm 'in gear' and 900 and something in P or N

My Activa, having the same engine and injection system makes no such distinction...

On a C5 it might be possible to 'tell' the ECU it is no longer speaking to an auto. It's amazing what can be done like this on a late car. The couple of times I've had a Lexia on a C5 it has boggled me just what can be done in that respect and that's only a casual look; given a serious look the possibilities may be endless...

I'm still wondering the economics of doing a manual conversion. How much is a n AL4 from a crashed scrapper going for? Crashed as opposed to scrapped as there's a good possibility the 'box is good from a crashed car...

[addo]

As mentioned, what the gearbox ECU tells the engine ECU to do, is pretty basic and relates more to the sensitivities of the auto box and a driveline in more constant mesh than a manual box. The engine ECU doesn't limit RPM in N like some autoboxes.

The bodgiest fix for the pressure reg issue, is to drain the oil into a tray, swap the upper two solenoids about, then reassemble and pour the old oil back in. An immediate improvement will usually show if the fault is a solenoid.