overdrive not working

[len]

my overdrive has stopped working, electrics are fine, have changed solenoid for a known working one all to no avail. my next move is to remove the sump off the overdrive and clean the filter. is there anything else i can check whilst sump off ?
thanks
Len

[JJF]

Hi
I'm no mechanic but I was talking to a guy the other week and he said he had the same problem. Turned out for him, it was the cable from the solenoid that went up through/beside (can't remember) the gear stick to the overdrive switch on top of the gear stick, apparently it had frayed and was shorting, he said he thought it had happened over time with all the gear changes. He said he removed the gear stick gater to check and the wire was frayed at the bottom of the gear stick.
I hope that makes sense and helps.
Cheers

[LAMBRETTLAD]

Hi
I'm no mechanic but I was talking to a guy the other week and he said he had the same problem. Turned out for him, it was the cable from the solenoid that went up through/beside (can't remember) the gear stick to the overdrive switch on top of the gear stick, apparently it had frayed and was shorting, he said he thought it had happened over time with all the gear changes. He said he removed the gear stick gater to check and the wire was frayed at the bottom of the gear stick.
I hope that makes sense and helps.
Cheers

well know problem and fingers crossed ,an easy fix

[richardthestag]

what overdrive? am guessing j type because solenoid easy change

gearbox fluid level first

then run 12v to solenoid from battery.

the circuit runs to fuse, then gearstick via connectors then to solenoid via connector above starter motor.

All known to be a ballsachem re high resistance and poor connectivity

"Wires through gearstick to switch issue" blows the fuse constantly. if electrics are fine then I would not think that is the issue. You could always lift the wood section of the centre console and join the two terminals that go to the switch to prove the case.

I fitted a brand new solenoid J-type to replace one that was sticky. Now the overdrive will not engage until the gearbox is hot. Suspect poor quality o-rings

[JJF]

Be interesting to know the outcome, lots of excellent advice, super stuff

[len]

Hopefully I will have a look at all the above tomorrow evening (again !)
cheers
Len

[sujitroy]

I built an J type. yet to be fitted. u say electrics are ok. does the solenoid work when fitted. I'm assuming u have to have the car in 3rd or 4th and then flick the switch. if Ok. when was the OD o rings last changed. Maybe they are old and u are not getting sufficient pressure. u can't see much other than seeing if the filter is dirty or seeing clutch material from the OD by removing the bottom cover

[len]

I built an J type. yet to be fitted. u say electrics are ok. does the solenoid work when fitted. I'm assuming u have to have the car in 3rd or 4th and then flick the switch. if Ok. when was the OD o rings last changed. Maybe they are old and u are not getting sufficient pressure. u can't see much other than seeing if the filter is dirty or seeing clutch material from the OD by removing the bottom cover

o rings have not been changed in my ownership (20 years) i did use the car tonight and the overdrive stayed engaged for about 10 secs and then jumped out and would not engage again. the filter is clean. the o rings you refer to ,,where are they ? are you referring to the solenoid o rings ?
thanks
Len

[sujitroy]

There a few O rings you can get to with the filter cover off. However, there are 2 larger o rings internal which are on some pistions. These can only be got too from opening up the OD. See screen shot

[sujitroy]

The solenoid O rings are easy to change. Are you sure you dont have an intermittent electrical problem? I would go down that route before tackling the OD.

[DJT]

The wires inside the gear-lever won’t necessarily blow any fuses if one of them is broken. Every time the gear-lever is moved it puts strain on these wires and an internal break is common. Had this several times with my old A-type Mk1 until I ran the wires inside a length of washer tubing stuffed into the gear-lever hole. New wires are available from many of the usual suppliers: the switch connectors are very small Lucar type connectors and not generally available separately.

https://www.angclassiccarparts.co.uk/products/triumph-5981/stag/electrical/gearlever-overdrive-wiring-loom-stag-mki-ii

[richardthestag]

Good point Dave

The failure I had in the gearstick loom was that the loom chaffed through insulation where it exits half way down, hence my cars intermittent thirst for fuses I hope that I have slowed the next occurrence by binding the loom tight to the gearstick with insulating tape around the hole where it exits.

your link ^^ not seen these chaps before, saved to my favorites now, thank you for that.

I am helping a friend out with an engine rebuild that kind of started with a non functioning a-type overdrive (the two issues are unrelated ) Circuit may help OP understand the electrics side.

overdrive wiring.PNG

• Gearbox fluid level first
• Then ignition on, gearstick in 3rd/4th and flick the switch, no click from the solenoid.
• After checking that the fuse was intact and did not have loose end caps, I took a look at the relay panel - above the parcel shelf inside the car. The relay is the rhs of the image above square with 4 circles in it.
• Interestingly the electric windows were very slow to operate. the earth wire to the relay was loose, cleaned it and the three other wires and the windows were quicker to wind up and down.
• then joined the two bullets on the loom that go to the gearstick switch - bypassing the gearstick switch and associated wiring - and again no click from the solenoid
• then from the multiconnector above the starter motor, pulled it apart and found the purple yellow wire on the gearbox side of the connector and ran 12v to it from the battery +ive. Yay got a click!!
• cleaned up connector above the starter motor with electric contact cleaner, ignition on 4th gear and flicked the switch and click from the solenoid. yay
• Test drive of victory failed though because overdrive was not engaging, difficult to hear the click of the solenoid when the engine is running.
• next along the line is the inhibit switch that will only allow you to engage in 3rd and 4th. It is a nice mechanical affair that fixed onto the gearstick extension on top of the gearbox (marked g/box sw in graphic above). It is just about possible to access the switch and two wires by removing the wood surround and rubber gaiter under it. Our one was very very grubby, cleaned it up removed the two wires, test drive and was able to join the two wires together and get a click. test drive was less fruitful.
• removed the switch, cleaned it up and tested continuity which was good. Refitted the wires - caused a lot of swearing - one person under the car feeding the wire from the solenoid up to a second person inside the car grabbing it and fitting it to the switch. not fun.
• In the end we kind of gave up/ran out of time. Thinking that the solenoid needed adjusting/replacing, and with a trip to Le Mans imminent and the car running we delayed next steps.

Alas the trip was not a great success with the engine using more oil than petrol - almost - on his return the engine came out because 4 bores were completely glazed very low compression. Figured that we could couple this work with gearbox overdrive.

Findings with the gearbox out of the car was that 12v to the solenoid feed and earth to the gearbox using jump leads, the solenoid operated with a solid clunk. did not need adjustment. puzzled I looked at the loom from the multiconnector to the g/box sw and found the wires to be in very poor condition. the insulation was no longer flexible and when stripped back the copper core had gone black - classic signs of overheating and high resistance in the circuit. the wiring would carry enough current to light a bulb - my standard test for high resistance - but not enough to push the solenoid against the oil pressure inside the overdrive unit when it was running. DOH! why did I not think of that before

Faced with the above debacle again I would remove feed wire from gearbox switch and run a fresh 12v feed straight to it for the mechanical test of the overdrive.

I cannot recall the exact supplier for the micro spade connectors to the switch I used when I remade the gearstick loom for my stag but would something like this work or is it still too fat?

http://www.vehicle-wiring-products.eu/product.php/617/female-terminal-for-2-8mm-mini-connector

[len]

thanks for all the advice.
i am heading back to the electrics, as from memory of last year the overdrive did blow some fuses,( i dont use the car much ) but has stopped doing that now. Last night i took the car out and the overdrive engaged for about 10 secs and then disengaged itself. its does sound like an electrical issue.it would not engage again.
cheers
Len

[len]

overdrive is now fixed. Electrical problem. Connector block down by fusebox, slightly loose connector, as simple as that !
i do believe the switch was also faulty, i have renewed the wiring for peace of mind , but i think the switch wiring may have shorted out every so often,hence the occasional fuse going. The wiring was not pretty .
thanks for all help
Len

[maverick]

The wires inside the gear-lever won’t necessarily blow any fuses if one of them is broken. Every time the gear-lever is moved it puts strain on these wires and an internal break is common. Had this several times with my old A-type Mk1 until I ran the wires inside a length of washer tubing stuffed into the gear-lever hole. New wires are available from many of the usual suppliers: the switch connectors are very small Lucar type connectors and not generally available separately.

https://www.angclassiccarparts.co.uk/products/triumph-5981/stag/electrical/gearlever-overdrive-wiring-loom-stag-mki-ii

Hi Dave,
I tried your suggestion a few years back and can see why it would work but any windscreen washer tubing I could get from scrappy int diameter was too small to get the wire junction inside and think the O/D was to fat to go up the gearlever.
Can you remember if it was off any car in particular,or any tips.
Thank you
Mark