Neale1969 Posted August 3, 2023 Report Share Posted August 3, 2023 Hello All! A year since my last post! This time I am trying to get my ‘A’ type overdrive to function. It doesn’t work. My car is now just about ready to be tested for the road*. The last thing on my list was to wire up and test the overdrive. I completed the wiring last night with a brand new Lucas relay. I have tested the isolator switch and it only allows Overdrive to be selected on 4th and not on 3rd.? I only have one isolator switch on the gearbox case. The solenoid works fine. It clicks the mechanism and actuates it so that the hole lines up in the cranked fitting on the other side of the box so I am sure it is not out of adjustment. To initially test the overdrive I chocked the front wheels and put rear of the car on stands and carried out my checks running in 3rd and 4th. Before testing I drained the SAE 30 mineral oil and swapped it for SAE 90. I noticed that the gearbox had been loosing oil into the box section of the chassis around the exhaust, so I decided the SAE 30 was too thin. I took 1.5 litres of oil out and replenished it with 1.5 of new. The oil out was clean as I have only used the car for several road tests over the past few summers. The mesh gauze looked very clean inside and I haven’t removed it for cleaning. The manual states 2 litres capacity. I have filled it to the top line on the dip stick at the filler. After road testing the car and allowing it to settle the oil level remains the same at 1.5 litre. I have checked for air in the pump at the valve nut, slackened it and only had oil bleed out, no air. So to summarise, electrics and solenoid fine. Adjustment on actuating lever fine. Oil replaced with SAE 90. The gearbox otherwise works great. Smooth and not noisy, no rattles or dry bearing sounds. I have driven the car up to 50 mph on the road and attempted to engage overdrive several times to no effect. Should I chuck the extra 500ml in the gearbox and ignore the level on the dip stick? *Please note, I live in a very rural district of Northern Sweden with several private roads before reaching the main highway or ‘A’ road - so I’m not breaking any laws provided I stay of the private ones :) Any help and suggestions very welcome! Neale1969. -Sweden. Tr3A 1960. LHD, BRG. ‘A’ Type overdrive. Quote Link to post Share on other sites
Lebro Posted August 3, 2023 Report Share Posted August 3, 2023 Hello Neale. "Overdrive selected in 4th , but not 3rd" this could be the switch not being screwed into the gearbox far enough, maybe try removing any washers which are under the switch. As for the unit not engaging, The adjustment of the actuating lever sometimes requires the holes to be set to a bit beyond when they line up. this is often the case with older (used ) overdrives. Hope this is of some help Bob Quote Link to post Share on other sites
mike ellis Posted August 4, 2023 Report Share Posted August 4, 2023 Hi Neale, For overdrive to operate on 2/3/4 you need two isolator switches. If there is no boss for a second one you may have an early 2 top cover, or even gearbox. Check the gearbox number on the raised oval section on the left hand side of the box. Even better post a couple of pictures. Mike Quote Link to post Share on other sites
Neale1969 Posted August 4, 2023 Author Report Share Posted August 4, 2023 Hello Bob and Mike, Brilliant I will try these suggestions out tomorrow. From memory I think there may have been a slight gap between the isolator switch and the gearbox top. The gearbox is definitely older than the car…it has a bomb style short starter motor. I bought the gearbox and overdrive as an extra when I sourced the car so wasn’t on the car when I purchased it. I will free the pinch bolt on the actuator solenoid side and set the car running again on stands and see if I can manually push the mechanism to engage past the whole. If I’m successful then I will know where to back it off to in order to tighten up the pinch bolt again. will report back with my findings! many thanks, Neale. Quote Link to post Share on other sites
Neale1969 Posted August 6, 2023 Author Report Share Posted August 6, 2023 Hello Bob and Mike, Works! Thank you so much for the tips. I am attaching some photos here as I think the gearbox can be dated from the numbers and its appearance. After I loosened the pinch bolt I was able to manually engage the overdrive with the car on stands running in 4th by pushing the actuating lever. I have locked it in and the solenoid does the job perfectly. The OD kicks in straight away now. Very pleased! I tried to loosen up the isolator switch as there is a gap. The biggest open ended spanner I have is 1&1/8 inch and was a very good snug fit. However I could feel that it was more likely to round off the flats than turn the bolt so I gave up on that. I am fine with OD just on 4th. Is the switch copper? It feels very soft. Gearbox number 301039 Top cover number 301329 Brilliant to have had your help with this, thanks again! Quote Link to post Share on other sites
mike ellis Posted August 6, 2023 Report Share Posted August 6, 2023 Good that it is working. Those numbers are casting or part numbers. There should be a TS number stamped on the left hand side. Mike Quote Link to post Share on other sites
rcreweread Posted August 6, 2023 Report Share Posted August 6, 2023 Neale = those are casting numbers you have provided - in your last photo, you can just see the top ledge of an oval boss on the side of the gearbox - there should be 2 letters (TS) and some numbers after it stamped into the top ledge - that is the gearbox number. Re the OD, there is a brass plate rivetted to the top of the cylindrical bit of the OD casing under the remote- you can just see a bit of it on show in your first picture - the serial number should read 22/******/******, with the first two digits denoting the OD ratio, the next 5 or 6 the model the OD was originally supplied to and the last usually 6 digits, the number of units in that series It is clearly an early gearbox with a dip stick and screw on terminals on the inhibitor switch, so definitely a 3 synchro unit Cheers Rich Quote Link to post Share on other sites
Lebro Posted August 7, 2023 Report Share Posted August 7, 2023 The switch body is aluminium I think, which is why it feels soft. Bob Quote Link to post Share on other sites
ianc Posted August 7, 2023 Report Share Posted August 7, 2023 It's 53 years since I parted with my early TR2, but I seem to recall that it had overdrive on top gear only. However, the single switch, if used with the selector with humps in the correct positions, will permit overdrive in 3rd and 4th gears. Ian Cornish Quote Link to post Share on other sites
Neale1969 Posted August 7, 2023 Author Report Share Posted August 7, 2023 Hello All, gearbox number is TS12997. I can’t identify the number on the riveted plate under the gear top cover/ gear stick as there just isn’t enough room to see…but the copper/bronze and black riveted plate is there. Waiting for the rain to stop for further test runs with the car. Torrential wash out up here with nightly thunderstorms… good to know about the ‘humps’ if I ever get the courage to twist the isolator switch but I’m really tempted to leave well alone. At least with the correct number found the matter is settled regards it’s age. thsnks again! Quote Link to post Share on other sites
mike ellis Posted August 9, 2023 Report Share Posted August 9, 2023 That number suggests it is from a TR3 and would be expected to have o/d on 2/3/4 and two isolator switches. Perhaps someone has fitted a top cover/selector rods from an early car. If you are happy with it as it is I would be inclined to leave it. Mike Quote Link to post Share on other sites
Neale1969 Posted August 9, 2023 Author Report Share Posted August 9, 2023 Hello Mike, more than happy to leave it. So now I have a fuller picture of the history of my gearbox. Appears to work nicely so far. Maybe someone rebuilt it with spare parts years ago. I’ve had it sitting doing nothing since 2007….just kept it with fresh oil inside, now drained out and swapped. Quote Link to post Share on other sites
ianc Posted August 9, 2023 Report Share Posted August 9, 2023 I dug out my Laycock manuals, obtained in the 1960s, and I find (as I thought) that the early TR2 used overdrive unit 22/1275, which had 1.125" piston and was for top gear only. For this early type. the selector shaft in the gearbox would operate the isolator switch in top gear only - hence my mention of humps on the selector shaft in my earlier post. The 22/1374 was fitted to later TR2, TR3 and TR4, and used 1.375" piston. Both types use 1.75" accumulator piston and are 0.82 ratio, more familiarly known as 22%. - hence the 22 in the type number. I cannot find any indication in my Parts Manual as to when the change from /1275 to /1374 occurred. I suggest that Neale should check the identity of his overdrive unit - it should be stamped on one side The overdrive in 4VC is stamped 22/3109/000007, which is an identity unknown to Pete Cox and Overdrive Repair Services - how about that! Ian Cornish Quote Link to post Share on other sites
Neale1969 Posted August 14, 2023 Author Report Share Posted August 14, 2023 Thanks for the info Ian! I will take a look tomorrow if I can. It means taking the carpet and tunnel out but I want to check the solenoid again. Great news for me at least today, my car passed the Swedish MOT for the first time since I registered the car donkeys years ago. I’m including a photo of it here at 7am this morning outside the ‘Bilprovningen’. A big day for me and it sailed through without any issues. Seeing as I did everything myself I feel quite proud…and hugely relieved. Sadly I have to put the car away this week as I can only keep the car were I get to spend time all too infrequently. missing the wing piping below the rear lights and the grab handle on the dash board fouls the glove box so that is waiting for next time… thank you once again for all the help… Quote Link to post Share on other sites
ianc Posted August 14, 2023 Report Share Posted August 14, 2023 Excellent result, Neale, particularly as you did all the work yourself. Indeed, you should feel very proud. Now go and enjoy your car as it should be used - TRs like to be driven! Ian Cornish Quote Link to post Share on other sites
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