As title I'm trying to establish the gear and FD ratios in a Xantia TD gearbox. I have searched high and low and although can find reference to the Xantia box cannot find the ratio information anywhere.

If anyone has or knows a source of this it would be very much appreciated.

Otherwise I'm simply going to have to pull the box to pieces and count the teeth therein.

Many Thanks chaps.

all the 1.9 TD's I've driven have had the same RPM/MPH ratio's. (405's 406's Xantias + 306's) I think the F/D would be different in the 406 and possibly later Xantia's due to the different tyre sizes used.

OK, so you think that there may be a difference between 306 and Xantia. Interesting, but I'm no closer to the ratios!!!

Anyone?

I just tried a google search fo these ratio's & found one site apparently hosting the xantia service & repair manual which might have this info but after downloading the first part it was corrupt & I'd used my credit so couldn't download the second part yet.

http://rapidshare.com/files/49693437/Citro...antia.part1.rar

http://rapidshare.com/files/49695517/Citro...antia.part2.rar

Found the ratio's for the 2.0 16v XU10J4 though.

Graham.

Part 2 (lower link) is the one to get as its the full Citroen Xantia Haynes service & repair manual but unfortunately it doesn't list any of the gear ratios.

Has the wiring diagrams in the back though.

Graham.

Thanks for your efforts Graham, much appreciated. I think I'm going to have to strip the box (or at very least take the diff out and establish what the CWP is).

We had a Xantia TD the other day that was 4.26 FDR, the gear ratios are more than likely 3.45, 1.87, 1.26, 0.97, 0.76 or 0.66. We didn't check them.

would it be easier/possible rather than stripping the whole box to put an old driveshaft in the diff and rotate it by hand until the input shaft had done a full rotation and see how many revolutions/part revolutions the driveshaft had done?

i guess assuming you knew the fdr

Sandy; thanks for that info

Matt; technically possible I guess but I don't know how accurate the results would be

any external I.d stickers or any markings? you can find the F/D info on Servicebox if you have the 4 digit/letter code.

most common figures for the Xantia XUD9TE; CP 19X79 - CT 22X18

You just posted one possible FD ratio there; 19 x 79= 4.16.

22 x 18 doesn't work though, unless its an amasingly low FD.

If its a mistype & should've read 22 x 81 the its a 3.68 FD.

Graham.

no its 22x18, but with the initials CT next to it so I don't know what it refers to what would CT refer to in transmission internals?

Second is always 1.85-1.87 in BE boxes, so if you select 2nd (after a head scratch), remove the speedo drive and mark a tooth on the plastic pinion inside the housing; put some mole grips on the input shaft and count the turns needed for one plastic pinion rev. That divided by 1.86 is the final drive. Now complete the process in reverse for the other gears!!

Well an update today. I had a fit of intregue so decided to start taking the Xantia TD box to bits. With the diff out and the teeth counted I found it was 19X77, which equals a 4.05:1 final drive, or exactly the same as a 1.6 GTI.

Bit of a bugger seeing as I was hoping to find something longer in there for use with my XU5T engine when it is done.

Next thing I guess is to strip the rest and see what is in there.

A further update, I got as far as removing the end cover to see what 5th gear was, found it to be 31/47, giving a 0.66 ratio, or far longer than most 5th gears.

A bit of maths shows that with the Xantia 4.05:1 FD as detailed above, top gear gives a shade over 25mph/1000rpm.

Works out about right I guess for a TD Xantia with a max revs of 4000rpm to be able to get to 100mph.

However with a 1600 engine capable of revving to 6500rpm, top speed is theoretically just over 160mph..........!!!

But 100mph would be 4000rpm. I can't decide if this will be far too long gearing, or make for a box thats long enough in the low gears to let the turbo torque do its stuff, whilst being able to cruise at speed at sensible rpm, or if its just too long full stop.

Next step will have to be to strip the box further and see what the other gear ratios are I think.

You want to be able to cruise in 5th at a reasonable 70 - 80 just under the boost kickin in for my opinion. It makes motorway driving a doddle as you don't have to drop a cog to overtake with zest.

Mine is 1.9 ratios 1,2 & 3 and then longer 4th and 5th. Have a go on Thursday at the meet and see what you reckon.

Tom, every TD I've driven had a top speed of 115mph give or take a few, though I'm unsure what the revs were, I was looking where I was going but the ratio from gearbox F/D to roadspeed would be different to a 205 as the Xantia uses larger tyres.

I don't see what your point is TBH?

the effective gearing will be lower in a 205 due to the different wheel sizes.

Ah, I see, but no, as I calculated my 25mph/1000rpm using the gearbox ratios I've established by counting teeth, and using 195/50/15 tyre rolling circumference as this is the tyre I'll use.

If anything the Xantia gearing would be longer than I have calculated.