I've not been able to find any links on this forum addressing this subject, so I apologize in advance if this is repetitive. In my 1985 240 wagon, I want to replace my defective (bad overdrive) M46 tranny with a manual 5-speed M47. The mechanic doing the job reports that everything seems to fit, except my original speedometer (cable-driven) won't be usable. He also said that newer '87+ gauge clusters with electronic speedometers wont work in this car. He says that if I convert, I will have to drive the car without a speedometer. Unfortunately, that is not acceptable. First, is this true? Is there any way around this problem? I'm willing to purchase the correct part(s) if someone has a fix available.

 

Well for starters, the drive shaft on the m47 is longer than the m46 drive shaft, because of the overdrive box, so you'll have to swap the drive shaft out too. Theoretically, you could wire in the speedometer, although it probably wouldn't be fun. What is wrong with your m46 overdrive? There isn't too much to trouble shooting them if it's not working.

 

There are work arounds for the speedo issue but if you're paying someone to do the tranny swap you sure don't need to go through the hassle of the speedo deal. As mentioned, as the M47 is considerably shorter, the front piece d/s is longer. In addition, it uses a rubberized connector rather than the traditional u-joint. You're car is already wired for the M46...I'd really go back w/ one. And, I'd disagree w/ the previous poster as to the complexity of the Laycock o.d. unit. Back in the day, Volvo techs would pull and replace 'em...but they very seldom went into them.

 

I would replace the tranny with a good 4spd + overdrive unit, if I could find one. Where I am (Long island) the manual 5-speed unit is all I could locate. The shop where I found the tranny insisted on doing the installation in order to offer me some kind of guarantee. Since, it's cold and the car has a heavy sentimental value, they had the driveshaft, etc. I didn't mind paying for the labor. However, with the speedo issues, it sounded like mission creep (a.k.a. price of job increase) that might get out of hand.

 

Where I am, I've been able to find only the M46, and they seem to be pretty plentiful. I'm looking to swap out my '91's 240 AW70 transmission with an M46 from either an '83 or a '84 240

 

Good Luck with that. Remember you will have to address the difference between the '91 driveshaft's rubber connector and the older '83 or '84 u-joint. You will also have to deal with my speedometer problem in reverse - e.g. converting from electronic speedo to cable-driven speedo.

I also have a '92 245 with the automatic+overdrive tranny, and I've found it to be a solid performer. Wouldn't consider converting that car to manual.

 

Wow you are blessed to find an m47 ! The hassle of swapping would not be worth it. Last year my m47 pilot bushing seized up, trashing the input shaft. A call to Volu parts in Georgia revealed these are extreamly rare transmissions and parts are difficult to find.They did however sell me a used input shaft, and shims and I was able to repair the car. However the fellas at Volu,and a local Volvo guru, said the m46 would be easier to obtain and swap in than trying to locate an m47. To change requires everything from the bell housing to the drive shaft from a donor car.

 

Swapping an M46 into a 91 is child's play re: speedo issues. One merely leaves the speedo input from the rear end alone. Only the M47 driveshaft uses the gubo rubber connectors. The AW70 driveshaft is identical to the M46, all you swap is the fron short shaft as the lengths are different. I'm sitting on an M47 right now but have no desire to use it. It is lighter than a M46 but that's about it. It handles a bit less torque than an M46 so it's not ideal for turbo applications. Fine for n/a cars and nationwide still plentifull. All n/a cars got the M47 beginning in 1987. Turbo 7's still got the M46 right on to 92.