J Type Overdrive.

[tony]

Over the last 18 months I had my gearbox and overdrive overhauled by an "expert" who lives a distance from me. Gearbox good but o/d has never worked since.
Have acquired a manual from Ebay, taken o/d off gearbox and took it apart.
Think I've found the problem, One O ring on the operating piston was in two pieces. Obviously not replaced last time it was apart.
Fitting the bridge pieces that locate the pistons I find that mine are slightly curved. Can anyone tell me if this is correct or are they meant to be flat?
Thanks.
Tony.

[Alec]

Hello Tony,

they should be flat but I don't think that slight bend will affect the operation of the overdrive.

Alec

[tony]

Thanks Alec,
Both mine were bent, must be hydraulic pressure over the years. Found slivers of O ring on top of the piston. Seems like excessive travel may have pushed the piston out a bit allowing the O ring to exit the bore. Can't see any other reason. Mates got a large press so he's getting a visit this morning.
Tony.

[tony]

Success
Recently had a cortisone injection in my knee which makes it a bit more user friendly. Decided to get beneath the 2500 and attempt the removal of the overdrive which a previous 'expert' had a go at. He did fix the gearbox (new bearings etc) but seemed to fail with the o/d. He did the bearings and clutch etc but didn't appear to touch the hydraulics.
As stated previously I acquired a Vauxhall J type overdrive training manual from Ebay. Stripped the hydraulics and replaced all the O rings. One of the big ones (operating piston) was in two pieces. Thought this was the main problem. This proved correct. Took it for a drive this afternoon and it worked, for the first time in 15 months.
Marginably easier to remove the o/d than the whole gearbox but still a lot of hard to get at bolts and nuts. grrr. First time in 20 odd years I've had anything but electrical problems with Mr Laycock's product. Overall a Happy Easter.