Graham Carr Posted September 29, 2019 Report Share Posted September 29, 2019 I have an overdrive not engaging on 1966 tr4A. Can hear the relay operating but no drop in revs. it appears I have a slightly unusual gearbox in that it has a dip stick and filler accessible from inside the drivers side trans tunnel, any ideas Quote Link to post Share on other sites
John Morrison Posted September 29, 2019 Report Share Posted September 29, 2019 Hi Graham, welcome to our forum. Dipstick says it is an early sidescreen box, if it is Tr, you need to look at the boss on the gearbox where the clutch slave cylinder cross shaft exits, for a number for confirmation here. Re overdrive not operating, first check the gearbox oil level. John. Quote Link to post Share on other sites
Graham Carr Posted September 29, 2019 Author Report Share Posted September 29, 2019 Hello thanks for the identification check have checked the oil level and it appears to be topped up. Quote Link to post Share on other sites
RogerH Posted September 29, 2019 Report Share Posted September 29, 2019 Hi Graham, you say you can hear the relay coming with a click (in front of your knees). But, can you hear the solenoid coming in with CLICK by your left hip. If you can't hear the solenoid then you either have a duff solenoid or dodgy wiring You may be luck and have an inspection/access hole in the tunnel to see the solenoid (you may still need to remove the 'H' dash support) You can power the solenoid direct from the battery with a fly lead to test it. If the solenoid is coming in then you may need to adjust the travel. Have you got a Workshop Manual? this explains all. Roger Quote Link to post Share on other sites
Bobble Posted September 29, 2019 Report Share Posted September 29, 2019 Graham This may be a long shot but I experienced the same problem earlier this year. Having tried all the usual "fixes" I had it looked at by an auto electrician. To cut a long story short the problem turned out to be dirty connections at the back of the ammeter. If I remember correctly power was reduced as a result and despite occasionally working the usual result was a click but no engagement. The ammeter was removed, terminals cleaned and reconnected resulting in no further problems. As stated this may not be a "normal" problem but it would be a cheap and simple option before embarking on a more expensive solution. Worth a try? Bob Quote Link to post Share on other sites
rcreweread Posted September 29, 2019 Report Share Posted September 29, 2019 (edited) Graham All the above advice is excellent. If oil levels are correct, most overdrive problems are electrical. As Roger says, check if the solenoid is operating when you switch the OD on - there should be a lighter less obvious click which is the relay operating, followed immediately by a more obvious click as the solenoid operates - it is sometimes not easy to distinguish between the two. You really need to visually see the solenoid plunger working on the side of the OD to be certain its working - this assumes your OD is a TR spec one - just to be clear, it is an A type OD I presume? If you can see the plunger moving and operating the lever which connects to a shaft going into the OD casing, make sure the clamp which holds all this together is tight and the shaft isn't slipping. If you can see all this happening, then you need to adjust the clearances as per the manual but be aware that over time the clearances can change so the easiest thing to do is to take tunnel off, jack up the car level and securely, run it in overdrive and move the lever manually to see if you can get the OD to engage - if none of this works then it's probably a gearbox out job and strip down. If the solenoid isn't responding to engagement, do as Roger says and try a direct supply to it to see if it works - if it doesn't, then hopefully that's your problem and new solenoids are readily available. If it does work, and work well with a clear and good operation ( use a decent sized cable direct off the battery as the solenoid can take quite a lot of current ), then you know you have an electrical issue somewhere along the line - just because a relay clicks, it doesn't mean to say it will always work in providing sufficient current to the solenoid. Given the fact that it sounds like you have a TR3, maybe an even earlier gearbox in your car ( the gearbox filler is your clue), then I do wonder what the rest of your set up is, as earlier boxes to your 4A would have had a spring clutch whereas your 4A would have started life with a diaphragm clutch - all of these bits are interchangeable if you use the correct compatible parts, which I assume is the case as your car has presumably been working OK up to this point . But it does point to the fact that have a mixture of bits and pieces which is why I wanted to check that it is an A type - I'm sure it probably is. If you can get the gearbox number which is normally stamped on the ridge above the raised rectangular bit on the LH vertical side of the gearbox and likewise the OD number which normally on a plate riveted to the OD it may help. Any chance of any photos? Sorry for such a long response, but if want more info, feel free to send me a personal message and I can send you my contact details and we can have a chat about it all Cheers Rich Edited September 29, 2019 by rcreweread spelling mistake Quote Link to post Share on other sites
ChrisR-4A Posted September 29, 2019 Report Share Posted September 29, 2019 (edited) Missed quote Edited September 29, 2019 by ChrisR-4A No quote Quote Link to post Share on other sites
ChrisR-4A Posted September 29, 2019 Report Share Posted September 29, 2019 3 hours ago, Bobble said: Graham This may be a long shot but I experienced the same problem earlier this year. Having tried all the usual "fixes" I had it looked at by an auto electrician. To cut a long story short the problem turned out to be dirty connections at the back of the ammeter. If I remember correctly power was reduced as a result and despite occasionally working the usual result was a click but no engagement. The ammeter was removed, terminals cleaned and reconnected resulting in no further problems. As stated this may not be a "normal" problem but it would be a cheap and simple option before embarking on a more expensive solution. Worth a try? Bob I had the same problem a few years ago, would engage initially but drop out when headlights or electric fan was on. Ammeter not passing enough current. Chris Quote Link to post Share on other sites
TorontoTim Posted September 29, 2019 Report Share Posted September 29, 2019 Graham, I've edited the title of the thread to include the topic covered as I think it's more helpful. If you'd like it changed further (or back) please let me know. Tim Quote Link to post Share on other sites
Graham Carr Posted September 30, 2019 Author Report Share Posted September 30, 2019 Thanks guys will follow up the help and advice Quote Link to post Share on other sites
Alfie14 Posted October 1, 2019 Report Share Posted October 1, 2019 Hi Graham I had this problem some time ago, the O/D suddenly stop working. l trailed through the forum for advice after trying several checks including including taking the gear box tunnel out to check the solenoid and wiring etc someone suggested checking the 2 bullet connector located near the main beam switch, bingo one side had come apart, l must have dislodge it with my shoe, reconnecting solved the problem l wish l had seen this feed earlier. Worth a check. Andy Quote Link to post Share on other sites
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