A type overdrive relucatnce to engage

[Sheepdip]

I recently fitted an auto to manuak conversion with A type overdrive. In a nutshell, the overdrive is reluctant to engage, when it does so its positive. Seems to get better when warmed, also seems to need high mainshaft revs to work as very reluctant to engage in 3rd. With lots of auto experience I suspect valves. I cleaned the operating valve on top of unit and reseated as per manual, with no affect. That leaves the accumulator valve operated by the solenoid. Its not easy to get at so before embarking, does anyone have experience of this fault and suggestions or confirmation of net step?

Many thanks and for this forum which is great at tackling those issues techy issues you don't want to bore everyone with at a meeting!

Paul

[Sheepdip]

imported post

Oh dear - I've managed to botch this one! I removed the cover on side of overdrive, cleaned relief valve with difficulty, reassembled and overdrive didn't work :X. Did this several times, worried I might have damaged the valve seatby reseating so yesterdaydropped back of gearbox, took a lot of time reseating relief valve, all clean but still didn't work.

I thenran it on a jack and noticed at low speed the overdrive kicked in. On road test withgear selector switches bypassed, the O/D gently kicked in at 20mph and stayed in, but it won't switch in at speed. The solenoid current (at standstill) indicates the solenoid is fine, my only guess and next test is that the solenoid is not able to move the operating valve at higher pressure, but why?

I'm reluctant to buy a new solenoid as the gearbox is not good and I'd rather source a later type J type and rebuild.

Sorry for the nurdy questions but I'm flumoxed by all this wasted time - any ideas on getting this O/D working?

[Sheepdip]

imported post

Haven't had any replies on this but resolved it myself last night and thought I'd share it with you in case of similar problems.

Read quite a bit on the internet so could fully understand operation, although operating valve doesn't look under pressure, wondered if cleaning pump valve had increased pressure in system and faulty solenoid unable to cope. The solenoid has 2 windings with contacts breaking the circuit of the pull in winding when fully engaged. If only the holding coil is working then will be unable to pull in against pressure.

I cleaned the contacts and bench tested, noting the pull in current started at 10A and finally increased to 16.25A after a few tries (points bedding in?), with standby at 1.0A. Refitted, fine tuned actuator settings and it worked - much better than before, engaging in 3rd/top promptly and releasing nicely so I'm a happy bunny again.

[DJT]

imported post

Thanks for the update.

How satisfying to get a satisfactory solution by perseverence. Even better when it costs next to nothing too.

Dave

[Sheepdip]

imported post

Hi Dave, thanks for your comments. I'm pleased my perseverance has paid off as I was seriously about to reintstall the auto, before the wife sent me and the Stag to the breakers. Just annoyed about the wasted time!