When the car is warmed up it doesn't seem to have any issues.

But three times this past week while on a hill facing upwards it felt like the clutch didn't want to engage. Eventually I just pop it as it were and it does engage and go. Have never run into this on a manual tranny in my 40 years of driving.

Any suggestions?

Also recommendations on where to get a new top cap for the shifter? Mine has a crack in it and I would like to replace it.

Thanks in advance folks,
Scott

 

You probably have a worn out one way clutch in the overdrive. Page 15 of the attachment shows a picture of it. That is the only thing that will allow the car to not move when the clutch is released, BUT - when that happens the cone clutch in the overdrive has to slip also - and that's a bad thing, as far as wear on the cone clutch. Cone clutch is shown on page 14 item C. The little thin asbestos ring has to transfer all the power when the one way clutch slips - and that friction surface is certainly much smaller than your foot clutch touching the flywheel. Changing to a thicker or thinner oil might help (with a sticky one way clutch)- Some Volvo overdrives came filled with ford atf - (don't use GM dexron - it's too slippery) I've used straight 30 and 90wt (used in british trans with that overdrive unit) to try to extend the life (when orings stop holding pressure with atf) I've rebuilt many (years ago) so not sure if parts will still be available. Still have a list of the parts and their prices from years ago commonly used if you are curious. If I remember correctly it was a $1100 job back in the early 90's to overhaul.
It might be more economical to put a used m47 5 speed in than finding someone who knows enough about an overdrive unit to fix it right the first time. I certainly would not touch one - don't have the special tools needed anymore.
https://volvo1800pictures.com/docume...ck/laycook.pdf




Voluparts.com in Atlanta 404-352-3402 might have your shift cap.

 

Thanks for the info.

Now to decide to get the existing m46 repaired/rebuilt or located a good condition second hand one and swap it in. I have access to Chapman Automotive here on the island so used parts are pretty plentiful.

 

I would imagine finding a good electric overdrive might not be easy - and there's no way to tell if it's going to work until you bolt in onto the trans. (they come off the back of the trans with the trans still in the car)

The m47 pure 5 speed has it's problems - but it looks like you already own one of those so you should be aware of them. Might source one of those used -
Edit -

But from your other post - it seem you already have a parts car with a m47 just waiting to get transplanted.

 

I have thought about the m47 conversion but that presents it's own issues (driveshaft, speedo, etc).

And the '91 is more of a project and not a donor car although time will tell...