Another Overdrive question........

[Ridgetone Triumph]

While driving through town and in 3rd gear I flicked the switch to select O/D and it went straight in, a few minutes later and at the traffic lights alls well. I get a mile further and finally got into top gear than selected O/D again, nothing happened 🤔
I flicked the switch in and out but still nothing. It last worked in 3rd so I changed down into 3rd and switched into O/D, it went straight in. I changed into 4th and engaged O/D again and nothing happened 🙁 So I changed down again to 3rd and the O/D worked, it wont engage while in 4th gear only 3rd. However if I am in 3rd O/D and change into 4th it stays in 4th O/D.....Confused, I am. Any thoughts????

[Pete Lewis]

Yes the inhibitor switch needs some adjustment  so its live in 3rd and 4th
bit of wear and tear and it doenst always make contact ,

Often giving the gear stick a pull to one side will make the switch work which just proves a little
de shimming of the switch is needed

pete

[RobPearce]

On what car? I'm guessing big saloon, so the same box as my old Stag, which had the same problem when warm. It turned out a previous owner had fitted two shim washers under the inhibitor switch. Lose one of them and it was spot on. Of course, access to the inhibitor switch on the Stag is a major pig - not sure the saloons are much better.

[Ridgetone Triumph]

Quoted from RobPearce

On what car? I'm guessing big saloon, so the same box as my old Stag, which had the same problem when warm. It turned out a previous owner had fitted two shim washers under the inhibitor switch. Lose one of them and it was spot on. Of course, access to the inhibitor switch on the Stag is a major pig - not sure the saloons are much better.

Quoted from Pete Lewis

Yes the inhibitor switch needs some adjustment  so its live in 3rd and 4th
bit of wear and tear and it doenst always make contact ,

Often giving the gear stick a pull to one side will make the switch work which just proves a little
de shimming of the switch is needed

pete

Thanks for the replies chaps, that is a good start. When I put in another box on the 2.5 estate the overdrive didn't work at all, when we removed the inhibitor switch the small ball end was rusted solid (the swapped box had laid dormant for 20 odd years) So swapper the switch with the old one and all was well. As you say Pete it most likely the switch needs some adjustment.......Hmmm I think we had to drop the rear of the box to gain access too 🤔

[Pete Lewis]

Makes you wonder if a hole saw through the tunnel would give easier access  

Unless you have very long thin fingers   its not the best designed location.

ive a few jobs on mine like check quill shaft, prop uj and gearbox jumps out of 1st so must remember to check mine when its off.
anytime now  
pete

[thescrapman]

There are some grommets in the tunnel suitably placed above the gearbox, you have to remove the plastic surround to access them.

[Pete Lewis]

Colin ,   thats useful  

   pete

  

[Ridgetone Triumph]

Cheers Colin,  now I know what those grommets are for 🙂

[Dale]

I'm 95% sure that it is the inhibit switch/adjustment which is, as already stated, the problem here but would suggest you check the wires around the base of the gear lever carefully as I have had a few fray (sometimes internally which is tricky to spot except by feeling for a partial break/weak bendy bit and looking to see if the colour of the insulation looks faded) where they flex and cause similar issues. If nothing else you may as well check and if necessary renew while it's all 'open'.

[Ridgetone Triumph]

Quoted from Dale

I'm 95% sure that it is the inhibit switch/adjustment which is, as already stated, the problem here but would suggest you check the wires around the base of the gear lever carefully as I have had a few fray (sometimes internally which is tricky to spot except by feeling for a partial break/weak bendy bit and looking to see if the colour of the insulation looks faded) where they flex and cause similar issues. If nothing else you may as well check and if necessary renew while it's all 'open'.

Thanks Dale,  I  can see some work heading' Poo's' way soon,  he has been neglected of late so is getting its own back 🤔

[Ridgetone Triumph]

I collected 'Poo' and drove him back 🙂
As he has been parked up for a while I haven't done any inhibitor switch adjustments but when I was driving him home I engaged the switch and nothing happened.....There's a surprise  (dizzy) I dropped down to 3rd engaged and still nothing 🤔
Don't know what made me do it but I placed my thumb heavily on the switch and slid it in and out about a hundred times........It engaged at one point (scared) I then experimented with the switch and found it engages and disengages overdrive if you press the switch hard, if I lightly push the switch it doesn't do anything. I am now thinking the switch on top of the gear lever is the problem. After a good few miles of driving and constant heavy pressure use of the switch things have been restored as now lightly engaging the switch works every time 😎
The wiring down the gear stick was replaced a little while ago so I think maybe the actual overdrive switch is wearing out  

[Raider]

I flipping hate those overdrive switches in the gearknob >

See my blog !

[thescrapman]

Pete

the grease has gone hard.

cheers

[Ridgetone Triumph]

Quoted from Raider

I flipping hate those overdrive switches in the gearknob >

See my blog !

That's a good idea Martin, did that with the race car, totally trouble free 😉

Quoted from thescrapman

Pete

the grease has gone hard.

cheers

I can pull it apart and inject some fresh, or give it to my Auto Electrician to do, he's a dab hand at old Lucas equipment 😉

[Ridgetone Triumph]

Oh forgot to say....Lovely Cherry fragrance wafting around inside 'Poo' driving back to my place 😀

[StagNL]

Stcik mounted OD switches can go duff after a few weeks.  All sorts of issues can happen.  Mine generally failed to make electrical contact internally.

Julian

[Nick Jones]

Those switches can be dismantled with a bit of care, cleaned up and reassembled with fresh grease.  Did this with our Spitfire one recently as it was as knackered as everything else.......  Also had to do the inhibitor switch and reversing light switch.

Failed on the light switch as someone had already had it apart and lost the moving contact 🙁

Nick

[Radders]

Quoted from Raider

I flipping hate those overdrive switches in the gearknob >

See my blog !

I have a similar performance overdrive gearknob to Martin, but mine is an Austin Healey one. Fit and forget! 🙂

[iggy]

Quoted from Raider

I flipping hate those overdrive switches in the gearknob >

See my blog !

hi i like the look of the black overdrive gearknob in your blog where did you buy it?

[Radders]

Quoted from iggy

hi i like the look of the black overdrive gearknob in your blog where did you buy it?

https://www.ukmgparts.com/product/brr-brr18-gearbox/gear-knob-with-o-drive-switch-black-stn1051b

[iggy]

thanks for the link Radders

[Ridgetone Triumph]

I took my toggle switch of the race car and reverted back to the standard switch as at the most inappropriate times when in close proximity with fellow competitors one has been known to knock this darn toggle switch while changing down into second and ended up in overdrive 2nd instead of 2nd or even worse 4th overdrive  >  

[Raider]

Quoted from iggy

thanks for the link Radders

They come with a different thread size though so you need to think about this. I got hold of a non overdrive gearlever which are not as easy to find as you might think. This has a 5/16ths UNC  thread but the overdrive gearknob I ordered is a 5/16ths UNF.

[piman]

Hello Radders,

if you look at the works rally 2000s, that was the type of knob and switch combination they used. Probably judged too 'agricultural' for a production car.

Alec

[Radders]

Quoted from piman

Hello Radders,

if you look at the works rally 2000s, that was the type of knob and switch combination they used. Probably judged too 'agricultural' for a production car.

Alec

Hi Alec, yes, I've seen them on the works cars.

I have to say I much prefer the feel of them to the Mk2 'slide' type, plus the overdrive stalk on the column can then be used for something else. (Wipers, full beam etc. Handy on night rallies.)