405 Gearbox Trouble

[evilally]

My 405 1.9TD has always crunched 3rd gear, which slows down progress a lot and is annoying. I would expect that the synchro is worn, or could it be anything else? I had a read in the Haynes about removing and refitting the gearbox, as my plan was to maybe source a recon box and swap it out. However it looks a bit too complicated for someone of my low level of skill So my question would be, where's a reputable place to source a recon box, and what sort of cost am I looking at to get it fitted?

[citroen7]

i have just swoped the engine in my 405td and in the process swoped the gearboxes as the donor engine box had the same fault as yours i am not saying it was easy but i used a xantia BOL to take the engines out! if you have a chain block to lift the engine at an angle then it should not really be a problem ,but an air con car will require a bit of jiggery pokery as space is limited it may sound ott but take the engine out and do a cambelt change water pump and clutch while you are at it just dont do what i have done and forget where everything goes back

[Pleiades]

I would say that it is not realy that difficult to fix.

You don't have to be a genius or a master mechanic to fit new synchro hubs to your box, crunching in 3rd is a common problem for the BX and Xantia.

I have done several of these and you can completley strip the geartrains out without even removing the box from the car, it's all done through the wheel arch.

If you look it up Citrojim has a good blog (I think it's called a blog) on the gearbox, as said you dont have to be a master mechanic but you do need to be methodical and lay the parts out clean and carefull.

Regards.
Martin.

[evilally]

Thanks guys, yes I did see Citojim's web page and it scared me somewhat. The most complicated thing I've ever done to a car is change a radiator. Is it realistic for someone like me to start taking gearboxes to bits? If I start this I want to be able to finish it, and not have a car sat in bits on my drive for several months

[CitroJim]

I'd concur that swapping out the gearbox is not hugely difficult and as long as you have a hoist, a jack and stands, it's doable quite easily in a day. If you look for my post on swapping a Xantia 1.9TD clutch, it'll tell you the basic steps in swapping gearboxes. Just bear in mind that a 405 will be simpler due to more space and no hydraulics but the basic procedure will be identical.

BE3 gearboxes suffer with third gear synchro problems a bit and the problem of getting a scrapyard replacement is that it may too have weak synchros

Against that, there are a whole plethora of 1.9TDs that used the same gearbox. Even a 'box from a 90bhp HDi will do quite nicely.

As Martin says, stripping a BE3, by gearbox standards, is quite easy but you do need a few special tools (I made them) and a hydraulic press is almost a necessity for dealing with the output shaft and ensuring bearings are not damaged nor teeth chipped. The downside to a DIY job is the cost of replacement synchro cones. They're over £100 apiece.

[evilally]

Thanks Jim, I shall ponder this carefully. I see that BE3 boxes are just about 10 a penny, but as you say it's a gamble that they don't have the same problem, or other problems. If I got a gearbox from a different car, would the ratios etc all be the same?

[Xaccers]

Cassy has the HDi 90BHP one fitted to her, and the ratios are slightly higher, but suit her (and me) well.

I'd get a gearbox from a scrappy, and strip it down to see how it works, and see if it needs any repair.
That way you can replace any synchromesh on the scrappy one and do the swap, rather than swap and find you've got one with the same or worse issues.
If it turns out the scrappy one is totally shot, at least you'll have it to practice on before you then work on your own gearbox too.

[CitroJim]

Xac, that's a good idea It's not hard to strip the 'box so far as to expose the gear clusters and synchro hubs and no special tools are needed, just beware of the detents on the 5th gear slector fork and the selector rods. Springs and balls can fly!

The synchro hubs can be reasonably inspected then to see if they're worn.

Here is a worn one:



You can just see the tapered faces of the light alloy cone clutch are shiny and a bit distorted. A good one will be dull and have radial lines on the faces. Also, you may also see the effets of intense heat on the steel parts of the clutch in the form of "blueing" on a well worn one. Another often seen problem is the breakage of the spring in the middle of the alloy cone. Another test is how far into the stell part the alloy cone will go. I should stay just a little proud. If it drops right in and the edge disappears it's well worn and will not exert any frictional force against the steel part.

All BE3 'boxes use exactly the same cones so any will act as a spares donor. generally all 1.9TDs used similar ratios and any minor differences can be lived with for the sake of a decent gearchange.

I'll try to take a picture of a good hub for comparison. I have one knocking around here somewhere.

[Downunder]

When I pulled my Xantia B3 gearbox apart after stuffing it through clip failure, I found second gear synchro and also strangely fifth gear synchro flogged out. Any clues about fifth gear synchro wear.

[CitroJim]

Any clues about fifth gear synchro wear.

Ummm, that's rather odd. 5th synchro normally has an exceedingly easy life having only to cope with up-changes

As the 5th synchro sits high in the 'box, I wonder if perhaps the oil level has been allowed to run low at some time in its life and starve it a little. The same could happen if the wrong grade of oil has ever been used. They really do only like 75W/80 and something like EP90 can be a killer.