TwinCamJohn Posted July 8, 2017 Report Share Posted July 8, 2017 My TR3A is 1960 so I assume has the A type overdrive. Anyway, today on the way to a wedding the overdrive dropped out a couple of times. Once when I was at I think about 40 mph and another time whilst accelerating lightly in 4th at about 55mph. I can't add anymore as I left the O/D off so as not to, perhaps, make the problem worse and I was needed at the wedding ! Will have a look tomorrow but wondered if anyone had some pointers. My first line of attack is to check the gearbox oil level. Quote Link to post Share on other sites
peejay4A Posted July 8, 2017 Report Share Posted July 8, 2017 Definitely check the oil level. Then work on the electrical connections. Quote Link to post Share on other sites
ijonsson Posted July 9, 2017 Report Share Posted July 9, 2017 (edited) ...and solenoid actuator arm position Edited July 9, 2017 by ijonsson Quote Link to post Share on other sites
TR 2100 Posted July 9, 2017 Report Share Posted July 9, 2017 (edited) Most likely an A type, although if your TR did not come fitted with overdrive from new, someone may have converted using a J type. Oil level then electrical connections (solenoid AND earth). The overdrive switch earths through the selectors fitted in the top cover. You can check if these are working by taking earthing wire directly to earth but DO NOT leave it like that as the overdrive will then operate on ALL gears, including reverse. If you forget, and reverse with overdrive engaged, say goodbye to your overdrive. AlanR Edited July 11, 2017 by TR 2100 Quote Link to post Share on other sites
TwinCamJohn Posted July 9, 2017 Author Report Share Posted July 9, 2017 Thanks for the replies. Today I topped up the oil, but the problem is still there. So, oil level now discounted. Had a run tonight and it dropped out several times and then wouldn't work at all. Then came back again. I noticed an electrical buzzing as I changed to O/D which was coming from under the car on the left side. Car is LHD so easy to hear. Car back in workshop. Will continue during the week. Not sure if the above gives any more pointers ? Quote Link to post Share on other sites
dingle Posted July 9, 2017 Report Share Posted July 9, 2017 Sounds like the noise you are hearing is coming from the solenoid. Check the bullet connection near the sol. for looseness or corrosion. If no joy, remove the rubber boot on the sol. and run a ign. point file or emery cloth across the contacts. Berry Quote Link to post Share on other sites
peejay4A Posted July 10, 2017 Report Share Posted July 10, 2017 If the connections and interlock switches are OK and the operating lever is correctly adjusted you might have a problem with the solenoid. It has two stages of engagement. A high current pull in phase then a lower current holding phase. If the pull in winding is faulty you could get your symptoms. Quote Link to post Share on other sites
ianc Posted July 10, 2017 Report Share Posted July 10, 2017 (edited) Buzzing suggests that the hold-in coil of the solenoid is not doing its job. It has a very fine wire and this can fracture, usually adjacent to the contact on the top of the solenoid (under the rubber gaiter). The wire can be re-soldered if you are careful. Pete (Post #7): if the pull-in (high current) coil is open-circuit, you won't get a buzzing, but the overdrive can take a very long time to engage as the poor little hold-in coil (low current) struggles to lift the armature. And it may not succeed, in which case, the overdrive won't engage. For a detailed explanation, see my article in Section D8, page D49, of the Technicalities CD (written in about 1973, at a guess!). Ian Cornish Edited July 10, 2017 by ianc Quote Link to post Share on other sites
Lebro Posted July 10, 2017 Report Share Posted July 10, 2017 +1 for Ian's explanation. Bob. Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 I'm in the workshop today. Report later. Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 Got sidetracked this morning, so haven't started. In case anyone is looking at this over lunchtime, another question. Is it better to take out the tunnel to start with rather than grovelling around underneath with the car on stands ? Quote Link to post Share on other sites
RogerH Posted July 11, 2017 Report Share Posted July 11, 2017 Hi John, it's a lot of work but it is often better to remove the tunnel - it's surprising what you find that needs TLC. Roger Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 Also I forgot to ask..................I couldn't find the O/D relay ! It is not on the rear of the battery box on the left of the heater. I can't see it anywher in the cabin or under the bonnet.. Any tips on getting the tunnel out. Is it just all the fixings to take out ? Car has been all apart and repâinted in the last 8 years so shouldn't be anything never moved since 1960 ! Quote Link to post Share on other sites
Fireman049 Posted July 11, 2017 Report Share Posted July 11, 2017 (edited) John ~ +1 with Roger. If you remove the tunnel modify it as I did with mine by providing inspection panels which will make it far easier in future to service the gearbox/overdrive without having to remove the cover. Tom. Edited July 11, 2017 by Fireman049 Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 (edited) OK, I can see that there is much less faffing about if the tunnel comes off ! Anyway with the car on the stands there was nothing obvious. However , I did the first tests that are in the overdrive workshop manual. That is testing the wires on the relay. The relay is not original and I at last found it hidden behind the heater support strut. A positive thing was that the terminals had been marked by hand. First test ignition on and W1 was live. OK Second C1 was NOT live all the time. Third C2 was live when O/D switched on and in neutral OK According to my diagram C1 should go to "Generator control box-A (or ammeter)". But C1 appears to go out of the cabin and back under to the top of the gearbox. That's all I can say for now. I don't know if that is enough for any conclusions ? I shall have the tunnel off next week after the weekend run. Thanks for your replies and patience. Edited July 11, 2017 by TwinCamJohn Quote Link to post Share on other sites
Fireman049 Posted July 11, 2017 Report Share Posted July 11, 2017 John ~ Here is a wiring diagram for the Overdrive. Hope it helps. Tom. Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 Thanks for that Tom. In advance of taking the tunnel out does the fact that C1 is not live all the time as it should be according to the manual, give any clues ? Quote Link to post Share on other sites
Fireman049 Posted July 11, 2017 Report Share Posted July 11, 2017 Sorry John I'm not sure about C1. My 3A is wired up as per my diagram and works perfectly. Tom. Quote Link to post Share on other sites
RogerH Posted July 11, 2017 Report Share Posted July 11, 2017 OK, I can see that there is much less faffing about if the tunnel comes off ! Anyway with the car on the stands there was nothing obvious. However , I did the first tests that are in the overdrive workshop manual. That is testing the wires on the relay. The relay is not original and I at last found it hidden behind the heater support strut. A positive thing was that the terminals had been marked by hand. First test ignition on and W1 was live. OK Second C1 was NOT live all the time. C1 and C2 may be swapped around. Ideally C1 should be live all the time and C2 only live when in 2/3/4th gear and OD switched on. Third C2 was live when O/D switched on and in neutral OK According to my diagram C1 should go to "Generator control box-A (or ammeter)". But C1 appears to go out of the cabin and back under to the top of the gearbox. That's all I can say for now. I don't know if that is enough for any conclusions ? I shall have the tunnel off next week after the weekend run. Thanks for your replies and patience. Roger Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 OK Roger Following your comment here are the latest tests ! W1 live with ignition C2 live all the time C1 live if in gear with O/D on (buzzing loudly for a moment and then stops) W2 live with ignition on and O/D selected and car in neutral W2 not live with ignition,O/D selected and in gear. Quote Link to post Share on other sites
RogerH Posted July 11, 2017 Report Share Posted July 11, 2017 OK Roger Following your comment here are the latest tests ! W1 live with ignition correct C2 live all the time Should be C1 but OK C1 live if in gear with O/D on (buzzing loudly for a moment and then stops) Correct but shouldn't really be buzzing. This suggests that the solenoid change over from pull in to hold in is sluggish W2 live with ignition on and O/D selected and car in neutral Correct. W2 is live because the volts have nowhere to go W2 not live with ignition,O/D selected and in gear. Correct if in 2/3/4th gear. The volts drain to earth through the inhibit switches. Hi John, have a look at this wiring diagram http://www.advanceautowire.com/tr24a.pdf Roger Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 I have that TR3A wiring diagram. But not too brilliant with electrics ! C1 So if the solenoid changeover from pull to hold in is sluggish where would that suggest the cause is ? And presumably that would be why it drops out ? Quote Link to post Share on other sites
ianc Posted July 11, 2017 Report Share Posted July 11, 2017 Not boasting, but please read my Post #8 and then look at the Technicalities CD. Ian Cornish Quote Link to post Share on other sites
RogerH Posted July 11, 2017 Report Share Posted July 11, 2017 (edited) Hi John, not sure if the solenoid relays (within the solenoid) can be got at and cleaned. It would probably be easier to just fit a new one. Before doing that you could run a 12V lead from the battery and try powering the solenoid direct. That would remove all the other components. If it is the same then it is the solenoid. If it improves then perhaps the wiring loom needs looking at. Dirty/ corroded electrical joints can cause volts to disappear. Clean or replace. Roger Edited July 11, 2017 by RogerH Quote Link to post Share on other sites
TwinCamJohn Posted July 11, 2017 Author Report Share Posted July 11, 2017 Not boasting, but please read my Post #8 and then look at the Technicalities CD. Ian Cornish hello Ian, I haven't ignored your post (very grateful for all help) but I didn't know what the " Technicalities CD" was. Presumably a CD that one could have bought ? Quote Link to post Share on other sites
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