Easy_Rider":w8mlbg7s said:
Any similarities to a '91 Porsche 968 Tiptronic gearbox, got a car with a mashed box (slips) that I need to look at but never managed to get round to.
Tiptronic will be a generation apart - not vacuum actuated, but ECU controlled.
Flushing the ATF may help, but if slippage has occurred, then friction material will have been compromised, which in turn may have compromised other parts of the 'box.
Flushing the ATF isn't a costly option, but outside of that, I wouldn't hold up too much hope. Some early 'boxes had software issues that were addressed by updates - and in some cases slippage in some ratios were addressed in some software updates (I don't know if the Porsche / ZF box suffered from this, though).
It may be possible for codes to be read, that give a hint as to what may be wrong. Is slippage in just one gear, or more than one?
First thing to do, check the condition and level of ATF (low ATF can cause slippage). If it looks pretty dark, and / or smells well used, get it changed. If there's any gearbox warning lights, get the codes read - that will (normally!) give a good insight as to what's wrong.