Hi all especially any gearbox gurus out there.
After having major shifting issues with my autobox I had the gearbox reconditioned by a top guy I've used before on my TD6 when that blew up some years ago. The box was removed, stripped new clutches fitted, valvebody mechatronic sent away for testing (all ok) torque convertor reconditioned, adaptions reset and refitted. After the rebuild it was much better but 1-2 and 2-3 changes were a little harsh. Told to leave it a couple of weeks to settle down but the changes were getting worse with some slippage and flaring being noticed. The car was then sent to another garage to have the new updated gearbox programme 'flashed' in.
This made no noticeable difference and a short time later the gears would slip in 2nd and 6th and the vehicle would flash up LIMITED GEARS AVAILABLE and lock in 3rd.
Car went back to be stripped out again, another new clutch pack fitted and a new valvebody installed. This was about 3 weeks ago and we are now experiencing the same harsh lumpy shift 1-2 and 2-3 and slipping of 2nd gear along with the Limited Gears warning. The garage I'm using is great and the guy who runs it is a lovely chap with decades of experience with autoboxes but we seem to be getting nowhere with this problem. I would be very grateful if anyone out there has any suggestions as to what to try next. Many Thanks

Problems with 2nd & 6th gears would seem to indicate an issue with the C-clutch although, as it’s a brake, there are no dynamic seals in its hydraulic feed path so it’s not one you would particularly expect to see leakage problems with. Presumably they’re testing the clutch circuits for leakage with air pressure before fitting the Mechatronic unit?





Phil

Bemble, many thanks for your reply. I know he has tested the box in situ with the pan and valveblock / mechatronic off and declared it good. Should I now be insisting the solenoids are replaced or the electrical part of the mechatronic, does the ecu give problems or is it a case of it works or it doesn't? Even after the gearbox rebuild the 1-2 shift was never smooth, it always felt like one of those electro mechanical boxes like the early Alfa Romeo Selespeed where there would be a distinct gap in the change as the mechanicals dipped the clutch and reapplied it. It's during this shift gap the revs will flare and if you are pressing on it will take several seconds for the box to eventually reign in the power, though often by then the vehicle has recognised a fault and put it into LIMITED GEARS. The rest of the changes are superb and kick down is seamless.

Certainly faulty solenoids are by far the most common cause of issues with the 6HP26 and as full set new costs £260 (ZF part no. 1068 298 044) it’s almost worth just trying it.



Didn’t you say though that the Mechatronic unit had been sent off for testing and came back with a clean bill of health? Do you know if it was properly tested on a Hydra-Test machine, or similar?



Why was a new valve body then installed? Was this a complete Mechatronic unit or just the valve body assembly without the electronic module (maybe so the new ECU didn’t have to be recoded to the vehicle)?





So the ECU that's in there now definitely has the latest firmware from Land Rover?

Phil