Amazon: New (to me) 1963 Volvo 122

[Othen]

Originally Posted by Moomoo

I would say the reading on the phone in the picture is 100% accurate.

... near enough for government work :-)

[Othen]

Originally Posted by Othen

... The reason the speedometer reads a bit slow is that the motor car has a M41 gearbox and Type D O/D, for which the speedometer drive is wrongly geared for the Amazon rear axle...

... a chart!

M40/4.10 in B18 120/130 16 teeth/yellow pt#380164
M40/4.56 in B18 220 17 teeth/Green? pt#380166
M41/D OD/4.56 in B18 Amazon 18 teeth/Blue? pt#380168
M41/D OD/4.56 in B18 1800 18 teeth(fine)/Black pt# ?



... and the one thing Volvo never built as far as I'm aware is a 120 with overdrive and a 4.1:1 axle, cars that left the factory so equipped were all fitted with the 4.56:1 diff.

Apologies for plagiarising the above... so, thinking about this:

I will have a 4.10:1 rear axle, but with a M41+Type D O/D and the standard Amazon speedometer. The O/D will have a 18 tooth (fine) pinion, but with a 4.10: rear axle (rather than 4.56:1) it should have a 16 tooth pinion like the M40 (as 16/18=0.88 this results in 12% under-gearing of the speedometer compared with the rear wheels).

I think I could use a 16 tooth pinion from a M40 gearbox, but it would appear I'd have to also fit the metal speedometer gear from the rear shaft of the M40 gearbox, and have that gear machined to match the height of the equivalent one in the M41.

I don't have the 16 tooth pinion or the metal speedometer gear from a M40 gearbox, and I'm not inclined to take the O/D apart, get parts machined to fit, replace the O/D, fix all the resulting leaks and so on, so (unless someone knows better) my advice to myself is to leave the everything as it is, enjoy the benefits of the O/D, do a little mental arithmetic and stop worrying about trivia.

:-)

[c1800]

Originally Posted by Othen

I have tracked down a little oil leak on GAM: it is the gearbox - a M41 + type D overdrive unit (from a P1800 I think). It is very slow and ends up at the speedometer drive (although that may just be the lowest point of the gearbox. I jacked up the motor car yesterday and made sure the gearbox was full - but I couldn't find a fill plug for the O/D unit (unfortunately I don't have a green book for the that item), would I be right in thinking the M41 and type D O/D share the same oil?

Alan

Hi, yes, the Trans and OD share the same oil. When filling it’s wise to allow a minute it two for the oil to flow into the OD. As to the leak, it may be a small seal on the Speedo drive which can be changed with the trans/od in situ.

Is there a brass plate on your trans indicating whether it’s and M41 or M40? Often when adding overdrive an M40 could be modified by changing the lay shaft to add the OD. If it’s an M40, the oil fill plug may be in the wrong place. You’ll see a figure 8 shaped boss on the trans with the filler plug in either the lower or higher spot , if it’s in the lower spot you’ll have some difficulty completely filling. One method to overcome this is to Jack up the front of the vehicle while filling. Another is to drain the trans and OD and then fill the exact quantity of oil as per spec for the M41 through the shifter hole, after removing the shifter.

Yes there should be a drain plug for the OD.

https://www.skandix.de/en/spare-part...ype-d/1057761/

If you don’t know the age of the oil in there, it might make sense to replace it.

[john.wigley]

Originally Posted by Othen

Apologies for plagiarising the above... so, thinking about this:

I will have a 4.10:1 rear axle, but with a M41+Type D O/D and the standard Amazon speedometer. The O/D will have a 18 tooth (fine) pinion, but with a 4.10: rear axle (rather than 4.56:1) it should have a 16 tooth pinion like the M40 (as 16/18=0.88 this results in 12% under-gearing of the speedometer compared with the rear wheels).

I think I could use a 16 tooth pinion from a M40 gearbox, but it would appear I'd have to also fit the metal speedometer gear from the rear shaft of the M40 gearbox, and have that gear machined to match the height of the equivalent one in the M41.

I don't have the 16 tooth pinion or the metal speedometer gear from a M40 gearbox, and I'm not inclined to take the O/D apart, get parts machined to fit, replace the O/D, fix all the resulting leaks and so on, so (unless someone knows better) my advice to myself is to leave the everything as it is, enjoy the benefits of the O/D, do a little mental arithmetic and stop worrying about trivia.

:-)

Very sensible advice it is too, Alan.

I had a look in my 140 Haynes workshop manual to see if there was anything in there which might help you. It seems that the overdrives fitted to the B18 and B20 while the same in principle, differ slightly in construction and operation.

Whilst instructions are included for removing, stripping, repairing, reassembling and refitting the unit, the general advice given is that this work should not be undertaken lightly by the home mechanic, due to lack of facilities rather than of skill, but entrusted instead to a professional engineering workshop. The most important thing is that the oil is maintained at the correct level - which you are doing anyway.

Again, I think your approach to GAM is absolutely spot on!

Regards, John.

[Othen]

Originally Posted by c1800

Hi, yes, the Trans and OD share the same oil. When filling it’s wise to allow a minute it two for the oil to flow into the OD. As to the leak, it may be a small seal on the Speedo drive which can be changed with the trans/od in situ.

Is there a brass plate on your trans indicating whether it’s and M41 or M40? Often when adding overdrive an M40 could be modified by changing the lay shaft to add the OD. If it’s an M40, the oil fill plug may be in the wrong place. You’ll see a figure 8 shaped boss on the trans with the filler plug in either the lower or higher spot , if it’s in the lower spot you’ll have some difficulty completely filling. One method to overcome this is to Jack up the front of the vehicle while filling. Another is to drain the trans and OD and then fill the exact quantity of oil as per spec for the M41 through the shifter hole, after removing the shifter.

Yes there should be a drain plug for the OD.

https://www.skandix.de/en/spare-part...ype-d/1057761/

If you don’t know the age of the oil in there, it might make sense to replace it.

Originally Posted by john.wigley

Very sensible advice it is too, Alan.

I had a look in my 140 Haynes workshop manual to see if there was anything in there which might help you. It seems that the overdrives fitted to the B18 and B20 while the same in principle, differ slightly in construction and operation.

Whilst instructions are included for removing, stripping, repairing, reassembling and refitting the unit, the general advice given is that this work should not be undertaken lightly by the home mechanic, due to lack of facilities rather than of skill, but entrusted instead to a professional engineering workshop. The most important thing is that the oil is maintained at the correct level - which you are doing anyway.

Again, I think your approach to GAM is absolutely spot on!

Regards, John.

Many thanks chaps,

I thought the two transmission boxes might share the same oil. I’m pretty sure the gearbox is a M41, but I’ll check later this week. I’ll give it a good clean up to see if I can locate that little oil leak. If it turns out to be a seal for the speedometer drive that will be very convenient. The leak is just a little bit irritating, that is all (and oil leaks are a pet hate of mine). The rate of loss is tiny - maybe a teaspoon full per week.

Thank you for your comments John. Unless there turns out to be some easy aftermarket modification to turn the 18t pinion into a 16t one that can be done with the O/D in situ then I’ll take my own advice and leave it all as it is. It is unlikely that anyone has bothered to solve this one though.

I enjoy finding out about GAM’s little foibles. I started the last major improvement I’m planning on the motor car the other day: I dropped the two rear doors off at a local body shop that does a lot of work on classic cars for painting. The two will cost me £400, but in the context of the project I think that is okay. It will be nice to get the smart doors swapped over, once that is done I’ll repair the rusty ones and see if anyone needs them on this forum.

:-)

Alan

PS. There is a simple way I could correct the speedometer of course, I could change the 165/80R15 tyres for 60% ratio ones, that would give a rolling diameter of 22.9" instead of 25.6" - or lower the gearing to 90% of its current value. There are two problems with that though:

a. There would be no effective overdrive ratio, which is the whole point of having it fitted.

b. GAM would look like Noddy and Big Ears' car with tiny wheels and little ground clearance.

:-)

[142 Guy]

It is not uncommon for the speedometer drive to develop an oil leak. There is an O ring on the drive that can be fairly easily replaced (once all the oil is drained out).

The OD may or may not have a drain plug depending on its vintage. The later J version of the OD which has the access plate on the bottom does not have a drain plug. The earlier D version with the access plate on the side has a drain plug. On the J OD you complete the drain by removing the cover plate. If the cover plate gasket is original / old, have a new gasket on hand because they rarely survive removal. Once the cover plate is off you can clean the suction screen and the internal filter if you have a pin wrench to remove the screw in filter access cover.

[Othen]

Originally Posted by 142 Guy

It is not uncommon for the speedometer drive to develop an oil leak. There is an O ring on the drive that can be fairly easily replaced (once all the oil is drained out).

The OD may or may not have a drain plug depending on its vintage. The later J version of the OD which has the access plate on the bottom does not have a drain plug. The earlier D version with the access plate on the side has a drain plug. On the J OD you complete the drain by removing the cover plate. If the cover plate gasket is original / old, have a new gasket on hand because they rarely survive removal. Once the cover plate is off you can clean the suction screen and the internal filter if you have a pin wrench to remove the screw in filter access cover.

Super duper. The O/D has a drain plug (which is why I thought it odd there was nowhere to fill it, and so concluded it must share its lubricant with the M41), so it is a Type D.

When you say there is an O ring in the drive do you mean the speedometer drive? If so that will be an easy fix.

Many thanks,

Alan

[142 Guy]

Yes, the speedo drive. My parts manual shows the following for the D type OD. The seals are part #26 and #28. Part numbers are 380192 and 191117 respectively. Check with your parts vendor to confirm that is correct for the D type OD. I think #26 is the leaky one; but, do both to be sure.

[Othen]

Originally Posted by 142 Guy

Yes, the speedo drive. My parts manual shows the following for the D type OD. The seals are part #26 and #28. Part numbers are 380192 and 191117 respectively. Check with your parts vendor to confirm that is correct for the D type OD. I think #26 is the leaky one; but, do both to be sure.

Excellent - that is really helpful.

I've just realised that I topped up the M41 gearbox with the wrong grade the other day, I used 80W (as per the M40) rather than 20W40 (because I didn't have a green book for the M41). It won't make much difference as it only took a cupful (maybe 0.2 litre) out of 1.6 litres (it might even help a bit), but I'll take the opportunity to change the oil and swap out those two little seals in the next couple of weeks.

Alan

PS. I may be fortunate and get away with just changing the speedo drive seals to fix the leak - I've just had a quick look at that area and it would seem it is dry above the right angle drive :-).

[Derek UK]

The 2 seals are an O ring and what is know as the top hat seal. If you do have an 1800 box it has the fine toothed gear and black gear. There are no other gears that can be used with this fine toothed gear. 1800 used Smiths instruments whereas the Amazon used VDO.
Talk to OD Spares in Rugby to see if they can swap over an Amazon gear. That will at least give you a choice of the Amazon gears. They will probably say that D type gears are hard to find. Certainly some are easier than others. They might be able to do it while you wait if you take the box to them. Not too far away. I think you just have to take the flange off and then remove the tail casting. The gear then just slides off. I'm interested in this as I have an 1800 OD box in the garage. I can check in the parts book but I want to know if the same gear is used in both the M40 and M41.
http://www.odspares.com/
01788 540666