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M47 question

Jim Perry

New member
Joined
Jan 13, 2012
Location
Larsen, WI
New to forum, but not to Volvos! Is there documentation available on this site that shows parts diagram(s) for the M47 transmission?
 
Probably not. There are exploded diagrams in the volvo green manual or Bentley manual. Looking for anything specific? Not many people tear them down to rebuild/refresh, so there's not a lot of common knowledge out there.
 
I've had a few M47's apart. Read this thread thoroughly, as the Bently procedure is wrong for the later M47, but applies to the earlier M47 that has straight roller bearings, not taperd bearings.
http://forums.turbobricks.com/showthread.php?t=172817
If you plan on a complete rebuild, there is a lot of special drifts needed, so you may want to take it to a shop unless you have a lathe and can make them. If all you want is to replace seals and gaskets like I did, the Bentley is going to be your best resource, but beware of the above mentioned procedure.
 
GR-46427.jpg
 
I took the transmission to a transmission shop owend by a guy who probably knows what he is doing. I was invited to be there, and they took it completely apart, even though I think that was unnecessay. The techniques caused me to cringe a bit. I am not all that happy about that, but it's done now.

This transmission came out of my race car, and was modified by Sellholm, but a lot of what is shown for the stock applies for this Sellholm. As it turns out all I need a gasket set (of course) and the "slippers" (part #68 in the posted diagram), and because of damage during the disassembly, the bearings for the countershaft. Volvowebstore.com shows them as available, but the listed is for a later (740? 960?) - their year selection does not go back to the 240 series. I think the parts I need are the same regardless of year. I hope so.

Thanks for the diagram.
 
Volvowebstore.com shows them as available, but the listed is for a later (740? 960?) - their year selection does not go back to the 240 series. I think the parts I need are the same regardless of year. I hope so.


Just go get Timkens from the local bearing house!!! You?ll be way better off with today?s bearings, instead of something that?s been made 20 years ago.


Goatman
 
The techniques caused me to cringe a bit. I am not all that happy about that, but it's done now........ and because of damage during the disassembly, the bearings for the countershaft.

It is the incorrect procedure in Bently's that I refer to that can cause one to damage the counter shaft bearing, as it says to press against the bearing race which works for an early straight bearing box, but pushing against the taperd bearing race which is one integrated bearing and race, and will separate it, and destroy it. As shown by Goatman the press needs to be against the shaft itself. Luckilly I figured it our before I damaged the bearing and all went back together fine.
One other note is the bolt #59 that holds the 5th gear hub, I re-used the old one with loctite and has been fine, but reccommend a new one. The thrust washer #47 should also be replaced during this procedure
Also highly reccommend replacing the shift selector plate #81 and detent spring #73 as well as the two dowel pins #9 in the shift arm to shift selector ball socket to restore the original snap precision to the shifter.
M47ShifterAssembly.jpg
 
Thanks again for more information. The shop was not able to get the countershaft out without FIRST removing the bearing. There is a "cowboy" hat-like piece (#49 I believe) that they had to remove. That was quite the process to say the least. Probably not an item with the stock, but I also need to replace the 6 adapter plate screws. These are recessed into the plate and have a hex head for removal. They had to head them up to remove them, and there did not even seem to be Locktite on them.

We have a good bearing supplier locally. The gasket set is avialble from FCP Premium Autoparts for about $43 (http://auto-parts.fcpgroton.com/tra...-1977--product_type-Manual-Transmission-Parts). The gaskets that were on the tranny were labeled as non-asbestos and seemed to be almost like a type of vinyl-like material.

My shift lever came from Sellholm. This is a straight dog setup, no synchronizers. Intended to be shifted (at least on upshift) without clutch. The clutch is a Tilton.
 
This is a common problem with an M45/6/7, if you have a decent amount of HP:
IMG_6410.JPG


You could replace 3rd gear and the layshaft cluster, but replacing the whole thing with a T5 works better.
 
so it's just the 3rd gear that busts? and theres nothing from another transmission that can replace it?
 
It's what most commonly breaks in them from too much torque. It's simply the gear that is furthest from the ends of the case, and thus furthest from bearing support on the shaft. Under power, the gears try to move away from each other, with too much torque the shaft can bend a little, the gears run on the tips of the teeth, and violent destruction ensues. I think some people have tried $$$$ special straight cut and/or cryo treated gearsets, with little appreciable benefit.

I think the first gen M47's suffered from premature 5th gear failure because the oil level (as set by the side drain plug) was too low. later M47's moved the drain plug up an inch or so. On the early ones, you have to creatively think of ways to 'overfill' them.
 
later would fall into the 90's 740's correct? i'm n/a currently but going +t with a 15g soon id have to be really careful?
 
I'm not sure what years the M47-I was around, but I think that got fixed pretty quickly.

It seems like the thrid gear destructions seem to happen somewhere around the 225-ish HP level. Some people cna break them with less, some manage to ahve them survive with more, it's probably dependent on how much wear the trans has - more wear - more slack - lower torque handling capacity.

I broke mine with some browntops, 16T, and an NPR intercooler. It wasn't hard shifting, or dropping the clutch, just a cool fall day, shifted into third, put the foot down, boost climbed to about 17 psi, *KABOOM*.

It's one of those growing pains, some parts on a Volvo are really tough and way overbuilt, some aren't.
 
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