Alanzjones Posted July 11, 2022 Report Share Posted July 11, 2022 I have a TR3A with a J type gearbox and overdrive which have both worked fine for the 7 years I have had the car. Last week at the middle of a 150 mile drive back to the UK the overdrive started to dis-engage. The overdrive would dis-engage, the revs would soar. the overdrive would re-engage. This continued until I switched off the overdrive Any clues? I thought it could be the solenoid or worn accumulator piston rings and bore ( I read the last bit). Does anyone know a reliable repairer of overdrive Thanks Alan Quote Link to post Share on other sites
ianc Posted July 11, 2022 Report Share Posted July 11, 2022 (edited) Pete & Tom Cox in Redditch - see page 17 in latest TR Action Pete Cox & Son Sports Cars). Pete has been fettling gearboxes, overdrives and axles for well over 50 years, and his son, Tom, has been working alongside him for some years now. Ian Cornish Edited July 11, 2022 by ianc Corrected my surname! Quote Link to post Share on other sites
BlueTR3A-5EKT Posted July 11, 2022 Report Share Posted July 11, 2022 Do you have overdrive in 2nd and 3rd? If so did it slip in those gears too? Start off by checking the oil level, which is easy to do if your gearbox has a dipstick. Otherwise you have to crawl in from the LH side and undo the side filler plug in the gearbox. Fill till oil comes out, leave for a few minutes and recheck. Overdrive and gearbox share the same oil and are filled through one fill point only. Asking which oil to use may cause a s###t storm on here! One designed for overdrives and old gearboxes with brassy bits in them. Something like this https://www.moss-europe.co.uk/dynolite-oils/dynolite-gear-oils/dynolite-gear-oil.html Then check the wiring continuity to the solenoid in every gear while waggling wires and gearstick and all switches. As it is J type it will probably not have a relay fitted. If it dies check that too. Peter W Quote Link to post Share on other sites
John McCormack Posted July 12, 2022 Report Share Posted July 12, 2022 I have a J type in my TR6. It was doing this a few years ago. The solenoid is also the valve for the high pressure oil that operates the overdrive. The o rings on the solenoid wear and when the oil gets hot and thin the oil bypasses the o rings and the pressure to the od drops causing it to drop out. I have heard of people replacing the solenoid o rings, rarely successfully. I put a new solenoid in and all is perfect for the past 5,000 miles. Quote Link to post Share on other sites
petertrs Posted July 15, 2022 Report Share Posted July 15, 2022 Another thing worth checking is the overdrive switch on the selector housing. I have experienced one of these creating a similar sporadic fault. Quote Link to post Share on other sites
Alanzjones Posted August 7, 2022 Author Report Share Posted August 7, 2022 Thanks for your help gentlemen. At first I thought it was just low oil level as the overdrive worked ok fpr a while but them started dropping out again. I have now replaced the servo ( what a god awful job) and the overdrive seems to be working ok, Thanks for your help Quote Link to post Share on other sites
BlueTR3A-5EKT Posted August 7, 2022 Report Share Posted August 7, 2022 Good outcome. Yes replacing the solenoid from underneath is a pig. Easier to remove the tunnel, then you can check the integrity of the other electrical bits on the remote. Peter W Quote Link to post Share on other sites
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