Thread: Auto having issues

Originally Posted by SenatorKang

Hi all,

, just in time for the gearbox to start playing up.

Can you remind me on which model car we are talking about??

Originally Posted by SenatorKang

my first check is the fluid, but i can't yet as it says on the dipstick check when cold in N.

Just get up 15mins earlier in the morning .... Also cycle the gears ... then check

Originally Posted by SenatorKang

maybe i'll get a manual

NOOOOOooooooooo ..... Now we will have Blknight turning you into a "converted" all night


Don't drive it untill you have checked the fluid level properly .... or you will be replacing the box

Mike

Originally Posted by mike 90 RR

Can you remind me on which model car we are talking about??

Oops,'94 300tdi disco

Originally Posted by SenatorKang

Hi all,

My interwebs are back, just in time for the gearbox to start playing up. Symptoms:
when taking off, foot off brakes, creeps forward as normal then clunks (a clunk you can both hear and feel in the bum), i think into 2nd as it is then slooow. sometimes clunks back into 1st then changes to 2nd as normal. sometimes i think it takes off in 2nd and doesn't go into 1st at all. has no problems in any other gears (except that occasionally it doesn't want to engage the ddc and i have to put it back to '3' then back to 'd' and even then it sometimes won't engage only to decide to start working for no particular reason - it's been happening for a while)

my first check is the fluid, but i can't yet as it says on the dipstick check when cold in N. Rave says 1st-2nd problems are from a clutch brake? sounds expensive... maybe i'll get a manual

any ideas?

yep that makes sense...

if the fluid level is ok and in good condition and the box is hi miles without abuse (or low miles with abuse) then the bands/clutch packs can start to slip...

when you throw your boot into it the gearbox via electronic or mechanical means gets the "Go, right now" message so it grabs everything extra tight so the problem isnt normally evident till you try to creep then its getting the "no sweat, lets just dawdle along" message and the clutch/brakes start to slip, dispersing the oil interface between the friction agents letting them grip... and it continues till it hits a happy medium between the engine trying to overcome interia, as the inertia builds the reaction force on the gearbox relaxes so the limited grip available is enough to keep it together.


What your feeling may not actually be gear changes but a combination of the brakes binding and releasing in conjunction with the torque converter loading and unloading....

the basics of the TC thing is this... the more retardation effort you put on the output of a TC (IE slow the output down) the more torque multiplication it achieves from a given input RPM. If your engine RPM is held constant by a hand throttle idle control or whatever else when the brake in the gearbox grips the output speed slows down, the torque from the TC increases and the brake looses its grip, when it looses its grip the TC speeds up and the torque multiplication drops off which means the brake can now get a grip which means the TC slows down so it does more torque multiplying, when that happens.... and so on..... While this merry 2 step is going on some power is being pushed through the box and that will be making the car move. Eventually the inertia will be over come or the box will pick a different gear based on whatever is influencing it at the time and you start using a different set of brakes/clutches.

heres the short cut fixes...
WARNING, This may well be terminal to the boxes clutches and brakes I am only providing them for the absolute I have to get it moving and dont care if it kills the vehicle providing it gets me out of the immediate danger I am about to get into.

1. put it in sports mode, this forces the box to clamp harder and react more agressively so will mask the problem until it gets to the point where the parts are so worn that they have nothing left to give.

2. thin out the auto fluid. add some diesel as it doesnt have the lubricating properties or the filming properties of Most ATF's it will get out of the way of the friction surfaces more easily upping the friction co-effecient giving you drive again.

these fixes might get you 300m or they might last for a round australia trip. but one thing is certain, once you start doing these things you are killing your auto. and instead of a cheap, replace a couple of bearings and a clutch kit you will be up for a major rebuild.

well assuming the box is the original one (the engine isn't...) it's got about 250,000 on it... and nothing i would call abuse, that i know of. i'd really prefer the cheap replace a bearing and clutch kit option... i guess that means not driving it at

what's the cost compared to just putting in a manual? cost in hassle and money... as in, is it worth just pulling the auto out and putting a manual and associated paraphenalia in rather than pulling the auto out and then taking it apart?

thanks