Autobox Gearing

[Tim Leech]

I noticed when driving the TZi auto home on the motorway that it seems to be very low geared, at 80mph its pulling 4200rpm which is more than valver I checked that all 4 gears are working fine, the gearchange is smooth, I owned a 19TRS auto 2 years ago and it was much higher geared, ive checked the brochure which states 4th gear should be 25mph/1000rpm for an auto. Could the rev counter be reading over?

Also theres a small plastic tank attached to the drivers side recess where the wheelbrace sits with a couple of pipes coming out of it disappearing into the car. It looks to have been there from day one.

[docchevron]

That does seem a little on high side..

When you say all 4 gears work fine, does the lock up clutch engage?

[Tim Leech]

That does seem a little on high side..

When you say all 4 gears work fine, does the lock up clutch engage?

I dont know how I would test it to be honest Chris? Ive shifted through the gears manually and theres definatly 4 there, had another look in the brochure and its definatly states 25mph/1000rpm. But then again it says it wont have a oil or water temp gauge and and oil pressure gauge but it does! God knows!

[Tim Leech]

That does seem a little on high side..

When you say all 4 gears work fine, does the lock up clutch engage?

I dont know how I would test it to be honest Chris? Ive shifted through the gears manually and theres definatly 4 there the gearbox down changes fine and the kickdown works too, had another look in the brochure and its definatly states 25mph/1000rpm. But then again it says it wont have a oil or water temp gauge and and oil pressure gauge but it does! God knows!

I havent checked the ATF as yet.

[BX Bandit]

If you have access to the Citroen PR-Net, put your VIN in and see what gearbox it throws up. With the ratio's listed you can work out what you've got versus what you're supposed to have.

[jonathan_dyane]

That does seem a little on high side..

When you say all 4 gears work fine, does the lock up clutch engage?

I dont know how I would test it to be honest Chris?

As 4th should be lock up, there should be no slip from the torque converter present, which you should be able to detect by listening and also by monitoring the rev counter.

As well as ensuring that the level is correct, you should have the ATF changed asap, and make absolutely sure that Dexron II is used, anything else causes gearbox death.

[docchevron]

/\ what he said.

The lock up also works on third, but not fully.. 75% lock up is achievable on third, with full lock up (ie the planetary gear set is directly engaged to the crank, by passing the torque converter completly) on fourth gear.

So, when it's in top gear, if you open the throttle a lot, but not enough to effect a kick down, the engine speed should increase in line with road speed, just like a manual.
Equally, if you lift your foot off the throttle completly in top gear, the engine revs should NOT drop away immediatley, but decrease with road speed, also just like a manual car in gear.

If the result of that test reveals that the engine speeds up quicker than road speed, or falls away by 500 RPM or more when lifting off, then the lock up isn't working, which is fixable, but, er, well, it wont be cheap...

[Tim Leech]

Ok guys thanks for your help, she in for a full service and cambelt etc on Friday so will let you know how it goes. Im sure when I drove it there was no "drop off" in 4th gear as I was watching the revs like a hawk.

Ta!

[Vanny]

the canister is a charcoal fuel filter/condesner, its meant to take petrol vapour from the fuel injection system, compress them and feed them back into the tank. Exactly how it works i'm not sure. A lot of the later BX's had them supposedly but i have only seen them on CAT equipt models.

[Tim Leech]

Ahh thats what it is then, fair enough, as for the autobox there is NO slip in direct 4th so I guess thats just they way it is!

[Jaba]

Tim,
That ain't right. You are pulling 4200 revs at 80 mph. That is 19mph per 1000 revs, the same as a BX14 manual !
My tables show 22.3mph per 1000 for the GTi Auto - that means 3580 revs at a true 80mph.
I also have a spec for the TZi estate which is a bit higher geared at 22.8.

If your speedo and rev counter are accurate then the best way of looking at it is that you will have very good acceleration for an auto.

The 25mph per 1000 revs you are quoting shows up on my lists for the TZS carb model and not the TZi injection model you have.

[Tim Leech]

Ok jaba, it does indeed accelerate very well and can "light up" the front tyres in first and second if the roads are damp. Maybe the rev counter is out as it seems to tick over at 1000rpm and seems to indicate a higher readout than the engine sounds if you follow.

[docchevron]

Well, it's fairly common for the guages to be, er, for rough guidance only..

Although unusual to be THAT far out..

Can quite believe it if the speedo's out though, never driven one yet that is accurate in any way shape or form, although they usually seem to over read than under read..

[Dollywobbler]

Cor, I must have a rarity then - sat nav reckons mine is only a few mph out. Our Mini on the other hand...

[Tim Leech]

Well, it's fairly common for the guages to be, er, for rough guidance only..

Although unusual to be THAT far out..

Can quite believe it if the speedo's out though, never driven one yet that is accurate in any way shape or form, although they usually seem to over read than under read..

tested mine againt the speedo on the way home from southend, it was reading about 2/3 mph over.