Gearbox lurch

[Richard Boraston]

Hi I’ve got a 2007 s type 2.7 diesel only done 39,000 miles in excellent condition love the car but have a problem when slowing down at a junction the gearbox gives a slight jolt as it goes from 2 into 1st gear I no these gearboxes have a fault I’ve changed the automatic transmission fluid but no change otherwise it changes up and down perfect apart from this any help would be appreciated thanks richard 

[JOE-DOT-COM]

hi

I assume you have checked the propshaft rubber couplings, as they can have similar effects

also when you changed the Oil, did you use genuine zf parts and oils, zf lifeguard 6, cheaper oils can cause all sorts of problems when they mix with the old Oil, about 6 litres stays in and cant be drained,

can sometimes be caused by gearbox software, can be fixed with a update, also it will need adaptations reset and gear shifts need to be relearnt after a Oil change because it can be a lot thicker if its not been replaced for some time, the two man relearn procedure, as used by jaguar, can get the shifts really smooth

if none of that fixes it, then its the mechatronics valve body, usually worn seals, o-ring and lots of little check valves, this is cured by fitting a sonnax kit, which replaces all the moving parts and cures low oil pressures in the valve body

these gearboxes are pretty tough, used in 1000's and 1000's of cars, like jaguar, land rover, citroen, ford, vw, bmw, maseratis, bentleys and lots more.

cheers

Joe

[Richard Boraston]

Hi thanks for your advice much appreciated