Amazon: New (to me) 1963 Volvo 122

[Othen]

Originally Posted by Laird Scooby

I can't remember if there's a limit/inhibit switch so OD only works in the 3rd/4th gear plane of movement on the gearshift or 4th only, if that has been bypassed then OD will remain until switched off. Hard acceleration in 1st or 2nd might damage it and certainly using it in reverse will. I'm guessing the repurposed HRW switch is to switch OD in and out, rather than act as an inhibitor?

It is a long story Dave; David (PO) and I know all the ins and outs. In essence GAM started life as a 4 speeder (and so has the higher ratio back axle - a good thing). David fitted a Type D OD from a P1800, but didn't finish fitting the inhibitor switch to the M41 gearbox (I've skipped a bit of the story here). I have all the bits and tools to fix it, I just need to find a day to drop off the gearbox, tap the right size hole, fit the mechanical switch, wire it in series and put the gearbox back.

It had almost got to the top of my 'to do' list before I sold the RB and bought the Barge. The Barge's OD switch (which I fixed) reminded me of it. I must get round to it soon.

The old HRW switch is just an on/off switch - powers up the solenoid or not, that is all. It would work in any gear (including reverse).

Alan

[Othen]

Originally Posted by 142 Guy

A proper OD interlock switch fitted on an M41 is a normally open contact switch which only closes to energize the OD solenoid when the transmission is in 4th. At least on later M41 equipped cars the interlock only operates when in 4th gear. I seem to recall that some may allow operation in 3rd; but, I can't remember whether that was a Volvo or non Volvo application. On vintage Volvos, if the steering column / dash OD switch contacts are closed the OD will engage when you shift from 3rd into 4th. A not necessarily desirable feature if you are shifting up after you downshifted to pass a slow moving vehicle.

The later Volvos with OD use an electronically controlled relay configured as a latch to control the OD solenoid. The switch to operate the relay is a momentary contact switch and the relay uses the OD interlock switch on the the transmission cover as a permissive. When in 4th gear, operating the momentary contact switch will cause the relay to energize and stay energized putting the OD into operation. Hitting the button again or shifting out of 4th will cause the relay to de energize and the OD to drop out. Shifting back into 4th will give you 4th gear, not OD. To re engage the OD you need to operate the OD switch again.

All the details here including relay numbers and wiring diagrams

https://www.swedespeed.com/threads/a....408489/page-2

The latching relays are not particularly expensive. If you want to find a nice period correct momentary contact wand type switch to mount on the opposite side of the steering column - that is the expensive part. If you are OK mounting a pushbutton in the dashboard that will be cheap.

Thank you for that erudite explanation.

David (the PO) or I should have probably explained that were were aware of the issue (exactly as you described) - but have a sort of shorthand because we both know the motor car well.

For this year I'll be happy just to get the mechanical inhibitor fitted so that I cannot inadvertently leave the OD switched on whilst changing down through the gears (or even worse into reverse). So far this has not been a problem, GAM has the higher rear axle ratio which helps.

The OD switch is just an off on switch (previously for the HRW) which I quite like - a bit of mechanical patina that reminds me this 60 year old motor car has a history. Now I've seen the very slick OD control on the Barge (1983 240 GLE) I'm minded to perhaps do something similar for GAM next year. I'd be very happy with a pushbutton momentary switch mounted where the ex-HRW one is now (on the far left of this photo):



... with a relay system similar to that on the Barge so it would only operate after permitted by changing unto fourth gear, and would then disengage otherwise.

... but that is a job for next year's list.

Alan :-)

[142 Guy]

If you are already aware of this, then you are set. If not ....

The M40 and M41 3rd and 4th gear shift rails are identical. However, the M41 has an additional part (#380648) which fits on the shift rail referred to as a dog in the parts manual. The dog is held in place on the shift rail by a lock screw. The dog is just a tab and I believe its function is to operate the OD inhibitor switch.

If you started out with an M40 you will need to source a dog (probably impossible unless you find a salvage M41). I believe the common solution is to have a small tab welded on the shift rail to serve the same function. You will need a photo of the rail or an open M41 to get the tab properly located. A machine shop could probably fabricate a dog if you don't want to go the welding route.

[Othen]

Originally Posted by 142 Guy

If you are already aware of this, then you are set. If not ....

The M40 and M41 3rd and 4th gear shift rails are identical. However, the M41 has an additional part (#380648) which fits on the shift rail referred to as a dog in the parts manual. The dog is held in place on the shift rail by a lock screw. The dog is just a tab and I believe its function is to operate the OD inhibitor switch.

If you started out with an M40 you will need to source a dog (probably impossible unless you find a salvage M41). I believe the common solution is to have a small tab welded on the shift rail to serve the same function. You will need a photo of the rail or an open M41 to get the tab properly located. A machine shop could probably fabricate a dog if you don't want to go the welding route.

Thank you,

I did not know any of that. I have some more checking to do before I start this job.

Alan

[Othen]

Originally Posted by 142 Guy

If you are already aware of this, then you are set. If not ....

The M40 and M41 3rd and 4th gear shift rails are identical. However, the M41 has an additional part (#380648) which fits on the shift rail referred to as a dog in the parts manual. The dog is held in place on the shift rail by a lock screw. The dog is just a tab and I believe its function is to operate the OD inhibitor switch.

If you started out with an M40 you will need to source a dog (probably impossible unless you find a salvage M41). I believe the common solution is to have a small tab welded on the shift rail to serve the same function. You will need a photo of the rail or an open M41 to get the tab properly located. A machine shop could probably fabricate a dog if you don't want to go the welding route.

Thank you, this needs some investigating before I start pulling GAM apart.

Are we saying then, that the M40 gearbox was never offered with an overdrive (Volvo would not have supplied it without an inhibitor)? If that is the case, and if I do have a M40 gearbox (that is what the build plate says, but I understand that isn't always right) then I'd need to get it modified before I could fit the inhibitor switch? Both these things need investigating.

If it is indeed impossible to fit the inhibitor I have to a M40 gearbox, then I might start thinking about some other solution - something like a microswitch tripped by the position of the gear lever in series with the OD switch. Perhaps even incorporating a relay and momentary switch similar to my 240.

I need to do some research :-)

[Othen]

Originally Posted by Othen

The intermittent non-starting problem returned again a few days ago - only this time it was less intermittent and more persistent (hence much easier to find). I started out eliminating things it couldn't be - the starter and solenoid were fine (I just ran a temporary wire from the exciter terminal direct to the battery - it started every time I made a connection), I swapped the battery with the RB and showed it also to be fine. The problem had to be with the control circuit, so I swapped out the momentary switch for another from my spares box - the issue persisted so it wasn't the momentary switch. I'd narrowed the problem down to either the ignition switch of a few feet of cable either side of it. I pulled out the switch (hard work with that armoured cable) and a bit of old fashioned domestic electricians' inspection of the lives found this:



... a fracture in the Ron Kwas starter loom close to the ignition switch, I must have trapped it or done it up too tight when I installed it. The cable was trimmed and a new connector installed in a few minutes - everything is back together and GAM is starting properly again.

All is well again in paradise.

:-)

I thought I'd solved the intermittent starter problem for good back in July when I last reported on this subject. GAM started straight away this eve (having not been used for a week or so whilst I have been working on the Barge), but after a short drive to Morrisons for some groceries the dead man's click returned as I tried to drive home. It did eventually start after a bit of fiddling with the key and the Ron Kwas starter button. I've tried it a few times since getting home and been unable to replicate the intermittent fault.

I've eliminated almost everything: taken apart and cleaned the starter, changed the solenoid, checked (and repaired) all the wiring. The only thing I have not been able to check has been the switch - which would be difficult as it is attached to that thick armoured cable.

The switch is prime suspect #1. The key is very sloppy and the gorilla spring doesn't work (hence the Ron Kwas starter button). My theory is that the contact is poor in position 3 (accessories being position 1, off is 2, normal running 3 and starter energised 4 - except I don't use position 4 due to the Ron Kwas starter button). Perhaps in position 3 the connection isn't always good enough to operate the starter?

I don't recall this issue ever happening before me fitting the Ron Kwas kit (there is nothing wrong with the Ron Kwas kit, I like it and it protects the starter without the gorilla spring's help). I'm thinking that perhaps in position 4 the contact in the switch may be good enough to operate the starter, whereas sometimes it is not in position 3 (just due to normal wear and tear).

I have a few options:

a. One would be to look for a replacement original switch - but that would be a difficult thing to find due to the armoured cable.

b. I could saw off the armoured cable to access the +ve wire to the coil and fit a replacement switch. I don't like changing from the original unless there is no other option.

c. I could try reverting back to using position 4 to start the motor (it just requires a wire moving one pole), but have the Ron Kwas kit wired in series such that the momentary switch protects the starter should the driver forget to return the switch to position 3 after starting.

d. I could fit a starter relay so the switch doesn't need to provide so much current in position 3 (and leave the momentary switch wired as it is now.

Intermittent issues are hard to track down, this may not occur again for another 2 months, but of the options I'm most tempted by 'c'. It is a fiddly, but not difficult job to move the starter circuit wire to pole 4, but otherwise it is free.

Any ideas or comments?

Alan

[142 Guy]

Originally Posted by Othen

Thank you, this needs some investigating before I start pulling GAM apart.

Are we saying then, that the M40 gearbox was never offered with an overdrive (Volvo would not have supplied it without an inhibitor)? If that is the case, and if I do have a M40 gearbox (that is what the build plate says, but I understand that isn't always right) then I'd need to get it modified before I could fit the inhibitor switch? Both these things need investigating.

If it is indeed impossible to fit the inhibitor I have to a M40 gearbox, then I might start thinking about some other solution - something like a microswitch tripped by the position of the gear lever in series with the OD switch. Perhaps even incorporating a relay and momentary switch similar to my 240.

I need to do some research :-)

The M40 fitted with the OD was the M41 .

To my limited knowledge, the modification to the M40 to make it an M41 was adding that little dog on to the 3-4 shift rail, fitting the inhibitor switch in the cover and deleting the tail piece with the speedo drive. I think everything else is pretty much the same.

If the boss for the inhibitor switch is present on the transmission cover then drilling and tapping to accept the OEM inhibitor switch is the way to go. Welding a tab onto the 3-4 rail to activate the inhibitor switch will work; but, you need to know the exact positioning of the tab when you do the weld. Having a machinist fabricate a tab like fitting retained by a set screw would allow you to test fit the tab to get actuation of the switch in 4th gear. If you want, I can post a screen capture of the parts manual showing the little 'dog' that Volvo added to the shift rail to operate the inhibitor switch. It really is quite a simple affair.

The OD relay and momentary contact switch is not a substitute for the inhibitor switch. If you look at those OD relay wiring diagrams they all include the inhibitor switch as a permissive to block operation in anything but 4th gear. Given the amount of 'free movement' that exists in the M40 / M41 long shift lever, I would not attempt to use a microswitch to sense shift lever position.

[Moomoo]

Something and nothing, my ‘83 240 DL had a five speed box, so did my ‘84 245 GL, yet my’91 945 tdi had the OD?

[Othen]

Originally Posted by 142 Guy

The M40 fitted with the OD was the M41 .

To my limited knowledge, the modification to the M40 to make it an M41 was adding that little dog on to the 3-4 shift rail, fitting the inhibitor switch in the cover and deleting the tail piece with the speedo drive. I think everything else is pretty much the same.

If the boss for the inhibitor switch is present on the transmission cover then drilling and tapping to accept the OEM inhibitor switch is the way to go. Welding a tab onto the 3-4 rail to activate the inhibitor switch will work; but, you need to know the exact positioning of the tab when you do the weld. Having a machinist fabricate a tab like fitting retained by a set screw would allow you to test fit the tab to get actuation of the switch in 4th gear. If you want, I can post a screen capture of the parts manual showing the little 'dog' that Volvo added to the shift rail to operate the inhibitor switch. It really is quite a simple affair.

The OD relay and momentary contact switch is not a substitute for the inhibitor switch. If you look at those OD relay wiring diagrams they all include the inhibitor switch as a permissive to block operation in anything but 4th gear. Given the amount of 'free movement' that exists in the M40 / M41 long shift lever, I would not attempt to use a microswitch to sense shift lever position.

Thank you again,

There is a lot of history to this issue in these pages (you have contributed previously). I have found this post from the PO saying the current gearbox is a M41 which came from a P1800 with the fitted type D OD:

https://www.volvoforums.org.uk/showp...&postcount=827

... David (the PO) is a very reputable chap who still drops in to this thread, so it would appear I'm in the clear :-).

Alan

[Moomoo]

Originally Posted by Moomoo

Something and nothing, my ‘83 240 DL had a five speed box, so did my ‘84 245 GL, yet my’91 945 tdi had the OD?

Sorry, wrong thread!🫢