Thread: Amazon: - New (to me) 1963 Volvo 122
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Old Apr 7th, 2022, 13:20   #641
Othen
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Default Gearbox and OD

Today was a bit wet and windy for fitting doors and spray painting the sills, so I did some oily bits.

Readers may recall there was a very slow leak at the gearbox, and a correspondent suggested it might be the speedometer drive from the Type D OD. I had ordered an O ring and a top hat seal with the door seals and window scrapers, so I had them ready to fit today.

With GAM's front wheels up on some ramps access way pretty good. The old oil looked a bit gloopy, not much like 20W50, although that may be partly my fault because I'd topped it up with a cupful of 80W a week or two ago.

Getting the drive out was easy enough:



... eagle eyed readers may have spotted the problem already:



... that's right, there was no sign of a top hat seal whatsoever - which I rather suspect was the reason for the leak. Fortunately I had one, and changed that and the O ring:



I'm guessing I put it in the right place! So, I'm hoping that solves the gearbox leak problem.

I've also confirmed I have the black 19 tooth drive pinion for the speedometer, which is why the instrument reads 12% slow (see the discussion above, it isn't worth trying to fix).



I also noted that I would appear to have a M40 gearbox, rather than a M41 as I had thought:



I'm not sure how much difference there is between a M40 and M41 unit, but here is a question. The recommended lubricant for the M40 is 80W, whereas the M41 plus type D is 20W50 motor oil (because of the OD more than the gearbox I suspect). I'm pretty sure I've done the right thing in filling the combo with 20W50, but I'd welcome any comments from those much more knowledgeable than myself.

All seems well. I took GAM for a test drive, first to Morrison's gas station (about a mile away). The sender I had adjusted a few weeks was making the gauge read a little over half full, and the motor car had covered 102 miles on the odometer (which equates to 115 real miles). Filling up with Morrison's very cheapest E10 took 25 litres, so 5 1/2 gallons. GAM continues to return 20 MPG on exclusively local runs. Importantly: just over half on the gauge now equates to just under half a tank. Whilst this is much more accurate than previously, I'd rather it read a little low than a little high, so there may be a need for a little more adjustment yet.

GAM and I continued for another 5 or 6 miles to try out the gearbox and the OD - all is silky smooth. When we got home I looked underneath and couldn't see any evidence of oil leaking from the speedometer drive. I'm hoping the top hat seal has done the trick.

Fixing oily bits is so much easier than bodywork, but I'll get on with that NSR door soon :-).

Alan
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Last edited by Othen; Apr 7th, 2022 at 13:26.
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