Transmission Swap

On a good (or rather, a bad) day, I found myself with both my daily use cars out of service due to them having eaten their automatic transmissions. Some of the history can be found here for the 164 or here for the 145. Automatics being quite expensive to repair, quite noisy, and with gas hovering around US$1.20/litre (yes, that's $4.30/gal) their additional fuel consumption of about 20 percent was beginning to annoy me as well. Both breaking down on the same day settled it, I was going to replace them with manuals.

In the below text, "transmission" can refer to either an automatic or a manual. Usually you can infer from type numbers mentioned which I mean. I've occasionally used "gearbox" for manual if I thought there might be confusion between the two.

At the bottom I'll include a short discussion on doing this swap if you're already starting out with a manual.

For starters, let's list the various pieces of kit we could dealing with.
The transmissions used by Volvo over the past 3 decades:

• BW35: 3-speed automatic. Mated to anything from B18 to B21 and B30.
• BW55: 3-speed automatic. Mated to B21 and later. Successor to the BW35
• AW70/AW70L: 4-speed automatic. Mated to B21 and later. L designates lock-up torque convertor
• AW71/AW71L: 4-speed automatic. Mated to B21 and later. L designates lock-up torque convertor
• M40: 4-speed manual. Mated to B16/B18/B20
• M41: 4+OD manual. Mated to B16/B18/B20. Essentially an M40 with D or J type OD.
• M400: 4-speed manual. Usually found mated to the B30, sometimes to B18/B20 in the P1800. Differs from the M40 by having different (supposedly stronger) bearings and a different attachment to the bellhousing.
• M410: 4+OD manual. Usually found mated to the B30, sometimes to B18/B20 in the P1800. Essentially an M400 with D or J type OD.
• M45: 4-speed manual. Successor to the M40. Mated to B21 and later, (europe only) also to B20 in early 240.
• M46: 4+OD manual. Successor to the M41. Mated to B21 and later.
• M47: 5-sp manual. Mated to B21 and later.

• B18: 1.8l 4cyl. Upright. Found in 544, amazon, 140
• B20: 2.0l 4cyl. Upright. Found in 544, amazon, 140 and (europe only) early 240
• B30: 3.0l 6cyl. Upright. Found in 164
• B21: 2.1l 4cyl. Slanted. Found in 240 and later. Later evolved into the B23, B230, B200, B19, B234.

I had already started to collect parts for the 164, as I was going for the more elaborate swap to a 240-series M46 transmission (4+OD). As the M45 (and higher) series transmissions have a different mounting to the bellhousing, as well as a different input shaft length, this requires a modified bellhousing. In the Netherlands you can get these modified bellhousings from Huke Basart (mail me for contact details). He has them in stock for the B18/B20 engines as found in the 544, amazon and 140 series. Unfortunately B30 bellhousings are much harder to find, so I had to bring him one and wait some weeks.

Unfortunately, this project was quickly draining the Volvo hobby budget, so for the 145 I decided to go for a stock M40 (4sp) transmission. A mate had just parted out another 140, so I could pick up all the parts from him.

The basic parts list is as follows:

• Transmission with gearlever
• Bellhousing with cluth lever
• Clutch cable
• Clutch pressure plate (which to me is the entire pressure plate/diaphragm/ housing assembly).
• Clutch driven plate
• Pilot bearing
• Throwout bearing
• Driveshaft
• Pedal box w/ pedals
• Some electrical cable and cable shoes to rewire the reverse light/lockout. Overdrive relay if you put in an OD transmission and want to use an original-style switch. You can also opt for a bigger switch, which is what I did.

More discussion of the individual parts will follow.

If you're going for a straight swap just get it ALL from the same car of a similar year (otherwise look below to the discussion of the transmission tunnel). Always use a new pilot bearing, and take a good look at the rest of the clutch components. Much easier to change them while they're still off the car.

The tool list is pretty standard for work on these vehicles. A good quality set of spanners, sockets and screwdrivers is essential, as is a nice big trolley jack. Those transmissions are heavy (a BW35 and an M46 are about 45 kilo (100 pounds) each). Having a mate over to help you certainly does no harm and speeds up the work fourfold.

First, disconnect the battery. You'll be working under the dash and around the starter motor, and we don't want an accidental electrical fire. Next, take a good look at your engine mounts. If they're collapsed, it's easier to change them while the old transmission is still in place, and you'll have a much easier time getting the tranny crossmember back in.

In the following instructions I'm assuming you don't care too deeply about the old tranny. If you do, take appropriate care not to get dirt into it.

Remove the shifter linkage. Undo the 4 upper bellhousing bolts, the kickdown cable, the transmission cooler pipework, and pull out the filler tube. Now jack up the vehicle as high as it'll go and put it securely on stands. You'll be working under the vehicle for hours so make sure it's secure and can't sink into the ground. If you can arrange to work somewhere with a proper lift, go for it. Get under the car and drain the transmission, undo the driveshaft, wiring to the lockout/reverse switch, the rest of the shifter linkage, make sure the cooler pipework is free, put the jack under the tranny to support it, remove the transmission crossmember, undo the rest of the bellhousing bolts and with the help of a big lever or tire iron move the transmission backwards, thereby seperating it from the torque convertor. Put a tray under the torque convertor housing, for once you seperate the tranny from the convertor some ATF will come out. Remove the transmission from under the car. Now undo the bracket under the rear of the engine that the two lower bellhousing bolts went into. Now you can undo from the frontside the 4 bolts holding the torque convertor to the adapter plate. Once the torque convertor is out of the way you can undo the 6 or 8 bolts holding the adapter plate to the crankshaft. On the 140 it's then simply a case of lifting it clear, on the 164 you may have to improvise with pullers to break up the intense relationship the adapter plate, hub adapter and crankshaft have formed over the past 25 to 30 years.

Congratulations, you've just removed one of the scourges inflicted upon the motoring public, the automatic transmission. You're almost halfway. Or try to keep yourself believing that, anyway.

Straight swaps would be anything you take off the same car with the same engine, like an M40 into a 140 or amazon, an M410 from a 164 into a 164, or M46 from a 240 into a 240.

If you're going for a type-original transmission (M40/M41 on the 544, amazon, 140 and some P1800, M400/M410 on 164 and some P1800) it's now a simple case of putting it all back together. Drive in the pilot bearing into the crankshaft, bolt on the flywheel, bolt on and align the clutch, followed by the "new" gearbox, "new" driveshaft, transmission crossmember (after cleaning out the holes in the chassis runners). For the M46/M47 conversion it's essentially the same, except for the fact that you'll have great fun mixing and matching parts to make it all work. After that it's time to move topside.

If you're going for an M45/M46/M47 style transmission now is when the fun starts. Of course you measured both the length of the transmission+bellhousing that came out, and the length of the gearbox+modified bellhousing that you're going to put in. You'll need this information to have the driveshaft modified to fit in the new situation. Find a competent driveshaft place to do this for you, as it needs rebalancing afterwards. This is not something you can do yourself, unless you're an extremely proficient weldor and have the equipment to balance driveshafts. Also make sure to express to the driveshaft place what you need to have done as clearly as possible, and perhaps get it in writing. Even then, they may make a mistake. I told them I needed it shortened by X centimetres, and the front UJ yoke replaced by a smaller one from a different driveshaft (the late 164 uses the large UJs everywhere, while the 240 tranny uses the smaller ones at the tranny side), restating that after that operation the driveshaft needed to be X centimetres shorter. Of course, came time to put it in, it turned out they had sawed off X centimetres and welded on the other UJ yoke, making it quite a bit longer than intended. A nuisance, but at least, since I had expressed myself clearly, they didn't give me any hassle over it and rectified it at no cost to me. Oh, one last thing, as the wheelbases changed between years, make bloody sure that both the front and rear half of the driveshaft will fit into the car if you're not going to use the original driveshaft but for example a driveshaft that came with the transmission. The rear part should have the same length, the front part is what you modify to accomodate the different tranny length, and check the size of the UJ flanges.

The next fun is the clutch. The 140, 164 and 240 bellhousings not only have different faces but also different wall thickness at any given point. Thus, some parts of the 240 bellhousing may intrude into the bellhousing, especially when mating it to the 164 bellhousing. I had an original pressure plate, and it got stuck quite firmly against the bellhousing. It's in the picture on the left, and at the bottom of the plate you can still see the scuff marks where it contacted the bellhousing. Procurement of an aftermarket driven plate that happened to be about 6 mm lower and about 1 cm smaller across the top (pictured on the left) solved that problem. Thanks to Jos from Wilpac for taking the trouble of measuring the driven plate he had in stock. For the 4-cylinder engines this should not be a problem, as they use the same driven plate anyway (at least the early 240)

As for throwout bearings, the modified bellhousing will have a 240 clutch lever and height, so an early 240 (equal to 140) item should work on an earlier 4 cylinder engine. For the 6 cylinder B30, it turned out to be a matter of searching for an item that fitted. In the end, we found one made by LUK. See this list for part numbers.

For clutch cable, use a 140 series item. The 240 has a too large mounting/ adjustment assembly, the 164 series item is too short and has the wrong attachment at the clutch end. Of course, if you're doing this on a 164, you'll experience significant wear of the clutch cable, as the clutch is bigger and a lot heavier. This, BTW, is also a problem on original 164 clutch cables.

The original 164 clutch operating lever is fundamentally different from the 140/240 setup. Unfortunately, that also means the B30 bellhousing lacks the lug to which you attach the sleeve of the clutch cable (or at least has it in a completely wrong place for our purpose). Fortunately there are two bolt holes for attachment of the hydraulic clutch cylinder found on some 164. Build a good strong bracket that bolts up to this to which to attach the clutch cable. An example can be seen in the picture. Of course you won't have this problem when converting a 4 cylinder car. Huke can also supply bellhousings suitable for hydraulically operated clutches.

Flywheels can also be a pain. The Volvo parts manual doesn't make it too clear what engines have the 6-bolt flywheel and what engines have the 8-bolt flywheel. Generally, 8-bolt flywheels were used from 1974, but I've seen many late engines with 6-bolt flywheels. Unfortunately, even the 4 digit engine type designation stamped on the side isn't completely helpful, as I've seen the same type of engine have different flywheels. 6-bolt B20 flywheels are widely available, as are 8-bolt B20 which are shared with the later B21/B23 engines. 6-bolt B30 flywheels are a bit harder to find but still not too much of a problem. 8-bolt B30 flywheels are rare, hard to find and often relatively expensive. The flywheels are not interchangable, although I have seen 6-bolt flywheels modified to 8-bolt. Considering the force on that little hub in the center of the flywheel and the need to have it perfectly flat and balanced, it's not something I would recommend, but I understand the occasional necessity for it.

The pedal boxes are not interchangable between the types of car, so you will need a manual transmission pedal box (brake/clutch) for the type of car you'll be putting it into, even if the rest of the parts came from another car with the same engine (for example, pedalboxen will not interchange between amazon and 140, or between 140 and 164, although almost every other part in this swap will). Quite a lot of wiring runs through the pedal box. The proper way of changing pedalboxes is to carefully unplug all the wiring, replace the pedalbox, and reconnect all the wiring. The quick&dirty way is to hacksaw or grind through the lower beams of both the old and new pedalbox, bend them open slightly, unscrew the old pedalbox, rotate it out of the way while pulling the cabling free, and put the new one in the same way. Weld up the cuts you just made if you feel like it. Due to the very heavy clutch action on the B30, reinforcement of the clutch pedal box is a good idea. See picture on the left.

As the M46 is different in length from any of the transmissions put on the 140/164 and earlier cars, you'll have to improvise with the transmission crossmember. The one pictured here was made by welding part of a spare crossmember to the existing one. Of course, there are many other options, including drilling additional mounting holes in the body, and creating an entirely new crossmember out of bar stock or angle iron.

Oh, and one last thing. The transmission tunnel. If you start out with an automatic with the shifter on the floor, there should be a nice big "hump" on the transmission tunnel, into which will fit the extended shifter of the M46. If you're starting with a manual with a short stick (like a modern car), the same hump should be present, although with a slightly smaller hole for the stick. This is no problem. Use the 240 stick, with a 240 rubber "sleeve" (the ribbed floppy rubber thing at the bottom) to nicely cover the big squarish hole left by the automatic shifter mechanism, or use a 164 sleeve to fit in the smaller round hole left by an M400/M410 short stick.
However, if you start out with an automatic that has a shifter "on the tree" (behind the steering wheel) or with an M40/M41 with the long gooseneck stick, you have a problem. The transmission tunnel in this case tapers between the seats, and no space is available for the long shifter mechanism. I have it from a reliable source that on the 444/544 the transmission tunnel is in fact so narrow that the OD of an M46 (or M41 for that matter) won't fit, a problem you won't have on the amazon, 140 or 164. This leaves you 2 choices:

1. cut out the "hump" from a 240 (your donor car or a junkyard), cut up the transmission tunnel on your car, and weld the "hump" on.
2. Modify the shifter mechanism to allow the use of a gooseneck stick.

The first option is in my opinion the most desirable from an engineering point of view. The modified shifter mechanism makes for rather sloppy shifting. You'll also have this problem when trying to use a short-stick (late) M40/M41 transmission in a car with gooseneck stick, although then you can at least swap the transmission covers, possibly having to drill and tap a hole for the 4th gear sensor.

In the end, I'm building up the 164 using the following items:

• Flywheel: 8-bolt B30 (new old stock, only one I could find at short notice)
• Transmission: M46 (from 240)
• Bellhousing: Modified by Huke, B30 front to M46 end.
• Clutch pressure plate: B30, aftermarket (measured to fit)
• Clutch driven plate: late 240 (to fit splines on tranny input shaft, which exists in both fine and coarse splined versions).
• Pilot bearing: standard B18/B20/B30/?? item, type 6202 (SKF, FAG, ...)
• Throuwout bearing: LUK CL-9768.
• Clutch cable: 140
• Pedal box: 164
• Overdrive relay: aftermarket.
• Driveshaft: shortened 164 with small UJ yoke (140/240) on tranny side. I've later seen a complete 240 driveshaft which had the right combination of UJs and could have been shortened instead.
• Clutch cable bracket on bellhousing: homemade
• Stick and rubber sleeve: 240

The 140 was done with parts that came from a similar 140, so no surprises here.

Still here? Good. You're now probably totally fed up with the rather long-winded discussion of what problems you can have finding the right parts in the Volvo parts bin, so let's get back to finishing the car.

Replace the pedal box (see above). Remember what I said about the illusion of being halfway? Hook up the clutch cable. Put in the shifter and shifter sleeve to finish off the mechanical work. Now take a good look at the electrical diagram for your car. The automatic transmissions have a switch that serves both the starter lockout and reverse lights. A manual has no starter lockout, and the reverse light switch switches to ground rather than being an isolated on/off switch on the M40/M41 box. The M46 has an isolated reverse switch like the automatics.. Locate the round, 3-terminal relay that on an automatic serves the lockout, and on a manual 140/amazon serves the reverse lights. You'll probably find it on the engine side of the firewall, next to the headlight relay. Terminal 87 goes to the starter, terminal 30/51 is the feed from the ignition switch, and 85 used to go to the transmission. Take off 87 and 30/51 and permanently connect them to each other. With an M40/M41/M400/M410, put the transmission side of 85 on the new tranny reverse light switch, then pull back the two wires that used to go to the tranny reverse light contacts and hook up the live one (brown on the 140 series) to 30/51, and the one going to the lights (white on the 140 series) to 87. On the M46, put connector shoes of the appropriate type on the right wires and it'll hook straight up to the original harness. Now you can at least start your car again and you have working reverse lights. If you have put in an OD transmission, get a suitable relay (another one of those round relays, or something aftermarket. Should be able to take several amps and endure being switched on for extended periods of time) or switch. Pull a wire from the OD fuse, run a wire to the OD solenoid, another wire to the OD switch in the car, and wire it all up. If you have another one of those round relays (which after all say "overdrive" on them and are the original OD relays), that would be switch to 85, other side of switch to ground, feed from fuse to 30/51, solenoid to 87. For other relays refer to the relay diagram. Anyway, always refer to the electrical diagram for your car and ask for help if you're unsure. Last but not least, go over everything once more and reconnect the battery. I sure hope all of the above made sense.

Congratulations. If all went well, you should now be finished doing this swap. Have fun, and drive safely.

Converting a manual: When you're doing this swap on a car that's already a manual, things become much easier. You will already have a clutch pedal, flywheel, clutch pack, etc, so you can skip those parts. It then becomes basically a case of remove old transmission, change clutch, put on new transmission.

If you're converting a 240 or later to manual, it's also much easier. You'll be using "late" parts anyway, so it's just a matter of finding a similar donor car and doing a straight swap.

Update 04JAN2001 I've now used this modification for about 10 months, and put a bit over 25000 miles on it. When it works, it works great. However, in stop and go traffic you really develop some leg muscles in your left leg. That clutch is heavy! It lso engages a bit roughly unless you are really gentle in engaging it. Due to the clutch being this heavy it also tends to go through clutch cables in about 6 to 8 months; the previous one (original volvo part, brand new) lasted about 8 months, and I can feel its replacement stretching already... All in all it's a great mod when your main use is highway miles. 75 mph at 3000 rpm really does make a significant difference from 3600 rpm on a 4sp or auto. If you do a lot of city or stop and go (eg traffic jams) driving, it'll probably start to irritate you. The above applies to the 164, the 140 has a much lighter clutch

Thanks to: Huke Basart, Veldhoven, NL; Ishmael at Temur garage, Soest, NL; Jos at Wilpac, Zundert, NL; Ronald Kerkhof at Terberg Techniek, Nieuwegein, NL; Brezan car parts, Leusden and Barneveld, NL; Wim Bottinga, Barneveld, NL; and the regulars at the Brickboard.com RWD forum.