Okay, so to start, it's really cold outside. Negative forty yesterday. I don't like it, my car doesn't like it, nobody likes it. I really dislike working on it when it's this cold. Gotta do what you gotta do.

So last night I was on my way to work and had the car in forth traveling about forty-five. A light ahead of me turned red and I held the clutch in until I had stopped. I shifted into what I thought was first. I discovered that regardless of the shifter position, the transmission left it in forth gear. Barely got it moving from a stop and brought it back home.

Looking under the car, I don't know exactly what the linkage mechanism looks like. I'm not sure how to tell if it has been disconnected or misaligned. I don't know if the problem is in the transmission itself either. The shifter moves to other positions freely, but in actuality it stays locked in forth gear. Any ideas?

 

is this a 740 or 240 ?

doens't really matter, they are pretty much the same. the shifter pivots in a socket on a frame thats mounted on the back end of the transmission. below this pivot, the shift lever connects to a pushrod that goes forward into the back of the tranny. just above the drive axle, this rod rotates and push/pulls to activate the various gears.

you can see this pushrod below the frame in this picture




here's a blowup of the shifter assembly from a 740 w/ a M47 5-speed (the 240 and the m46 4-speed are all pretty similar)



my guess is pin and stuff 5/6/7 or parts 8/9/10/11 came apart

 

Okay, I found the linkage rod and had someone play with the shifter while I watched. It looks like everything is functioning correctly. There doesn't appear to be any missing piece and the linkage rod moves in and out of the transmission housing smoothly. You can hear the shifter move into the different gear positions and seat itself as if the car were changing gears. BUT the car stays in forth like a champ. :/

 

And it is a 240.

 

then its broken in the gearbox. your best bet will likely be finding another M46 (4-speed w/ overdrive) or M47 (5 speed) gearbox at a junkyard or whatever, and transplanting it, as the cost of a transmission overhaul may well exceed the value of your car, unless you have a particularly nice car you want to keep for a long time, and/or unless you know someone experienced in overhauling manual gearboxes who's willing to do this for cheap.

 

I know next to nothing about trannys... Is there a chance that this is a relatively simple solution that could be fixed quickly and easily with some light transmission work done by a professional? Or is it likely that it will need a complete overhaul?

You are correct about the price of an overhaul exceeding the price of the car. Ha! That's too bad.

 

here's the innards of a M47 just so you know whats involved.



the shift lever connects to the selector rail 67, which shifts 1-4 and is linked to the selector rail 75 which shifts R and 5 (at least I think I got that right, it might be a different combination). those forks 68 and 76 are what do the actual shifting of the synchros.

 

you'd have to talk to the tranny expert to find that out. I suspect that once you've taken it apart(*), you're more than halfway towards along a full rebuild and it would be crazy to reassemble it without replacing /all/ worn parts inside. this all has to be done in very clean conditions. you'll definitely save money if you remove and reinstall the tranny yourself.



(*) ok, taking it apart is easy. its the reassembly that will getcha!

 

Mmm, I see your logic regarding the rebuild. So how much work is it to swap a tranny? I don't suppose there's a nice step by step guide for this old beast?

 

I've never swapped one, but AFAIK, you unbolt the drive shaft, unbolt the tranny from the linkage and the clutch housing from the engine, unbolt the crossbar support, and lower the tranny out of the car with a transmission jack. the car has to be up on jack stands high enough so the tranny and jack can clear its way out.

there's probably sufficient details in the Bentley 240 Service Manual, thats pretty comprehensive. certainly, reinstalling it, all those fasteners need to be tightened with the correct torque.

 

do you happen to have the link for these diagrams, or ones with the names of the parts?
thanks

 

I don't. that was 6 years ago, and I don't even remember where I got them from, but I have a copy of the old VADIS parts catalog CD that covers all volvos up to around 2013. its a pain to use, only works under XP, so I have an XP VM under VirtualBox that I have to run to browse it. those may have been screen captures from my VADIS, or they may have been images I found online.