ZF Auto torque converter lockup inop.

[Craig]

I have a 1989 Range Rover Vogue SE with the 4 speed ZF auto box.
When I first got the vehicle a year ago in the UK the torque converter locked up perfectly at 54mph. I exported the vehicle to the British ****** Islands and the gearbox continued to work fine until one day the speedo started playing up (it only reads above 20mph occassionally) and the overdrive ceased to engage any more. I checked the fluid which was fine and the box works perfectly in all gears, except locking the torque converter. Strangely it also had an upshifting problem from 2nd gear but that cured itself after a short run and now is fine.
The gearbox is a reconditioned Ashcroft unit and is only 18 months to 2 years old.
Any ideas? It's not a major problem as I rarely get up to 54mph for any length of time, the island is only 13 miles long! It would be nice to have it working though.

Craig.

 

[discomike]

Craig,
One idea would be to drain off the fluid, put in one bottle of Lucas transmission fluid and fresh atf. This will clean out any of the sticking valves that may be causing the up **** problem and the lock up. Don't let it go, it will only get worse if left along.
Mike J.

 

[Craig]

Thanks Mike,
I'll do this when I get back to Tortola at the weekend. Thanks for your help.

Craig.