MVS Forums contributor polskamafia mjl just wrote what may be the best Volvo Auto-to-Manual swap DIY on the Web.
M56 Swap Overview
This is a write up for replacing the AW50-40 slush box in an 850 with an M56 manual transmission. Most of the necessary information is already out there on various Volvo forums but another addition won’t hurt. I won’t go into detail on every step but I’ll try to add useful tips for what I found to be the tricky bits. I would recommend having the AC system evacuated by a qualified service shop before starting. This will allow you to keep the compressor attached to the engine. Trying to reinstall it is a major PITA.
I broke these up into ‘new’ and ‘used’ categories as some parts are better new while others are just fine being used. I also listed the vendors I used along with the part numbers and prices I paid at the time.
The items in the ‘Other’ category I recommend having on hand. Hopefully they will come with your transmission kit but having extras won’t hurt. My kit was missing a few of those pieces and it made life miserable for me. The EPDM hose that runs from the brake fluid reservoir down to the clutch master cylinder is extremely hard to find. Before you even start the swap make sure the one you got with your kit is long enough to reach between those two points or buy a new one. Volvo no longer produces them as far as I can tell and they are a huge pain to find. If anyone finds a source let me know as I would like to replace mine because it is way too short and just barely hanging onto the brake fluid reservoir.
Pressure Plate & R Clutch $203 272218
Flywheel Bolts (12) $5 9454743
Pressure Plate Bolts (6) $2 959220
Shift Cable Retaining Clips (4) $1.92 3502507
Clutch Hose $45 A544008
Throw Out Bearing $52 SB60120
M56 Axle Seal (2) $10 6843481
Intake Manifold Gasket $7 9146266
Rear Main Seal $34
-Transmission… M56H or M56L. You can do your own research on the gear ratio/final drive differences, but most prefer the H. This is what I used.
The transmission should include the bracket for the shifter cables. Clips may not be included, though.
These are the part numbers for clips that you may need:
-3502507 “clip”. 4 required, these are used at both the shifter assembly and at the transmission.
-989037 “lock brace” 2 red’d, these are the clips that hold the shifter cables where they attach to the shifter mechanisms on the transmission.
-986417 “washer” 2 req’d, these are used with the above clips.
–Flywheel… you can buy this new if you wanted to (I’m pretty sure it’s still available), but you’re better off just getting a used one resurfaced. This applies to the single mass, the dual mass is not typically resurfaced.
Dual mass and single mass flywheels are 100% compatible, so it’s literally as simple as swapping from one to the other (this statement assuming your car is already manual, therefore with a manual swap you can use whichever you have/can find). Both work with either the internal or external slave cylinder configuration. SMFs are known to chatter, so keep this in mind if that may bother you. There is some info floating around on this topic already, so I won’t get into that. However, the SMF is better for power, being much lighter. I used a SMF on both swaps that I’ve done.
–Pedals… two options here. If you have an 850, you need 850 pedals. If you have an S/V/C70, you need S/V/C70 pedals. The brackets are totally different. Now, you CAN in fact remove the brake and clutch pedals from the 850 bracket to use on the X70 bracket, but you lose the ability to have a return spring. The return spring design is totally different between the 850 and X70.
On X70 cars, the automatic and manual pedal brackets are exactly the same, so all you realistically need for these cars are the clutch pedal and the manual brake pedal. I cannot confirm this for the 850, so it’s safe to just get the whole assembly.
Additional part you may need:
-983479 “lock brace” clip that holds the master cylinder ram rod to the clutch pedal. Same as the clip on the brake master cylinder rod to the brake pedal.
–Shifter assembly… again, different between the 850 and X70. They are 100% compatible except for the shift knob, but that depends how picky you are. ‘98 and older cars use a different style, which is a royal pain to remove. ‘99+ shifters are slightly different, so the new style knob attaches. The boot is also different, but I’ll get to that!
–Shifter cables… nothing specific you need to know about these, at least I haven’t come into any issues with them yet!
–Reverse light switch… should be attached to the transmission
–Shift knob and boot… this is up to you, but if you want the correct knob for your car, you have a couple options.
The following are compatible with the 1993-1998 shifter assemblies:
-850 shift knob, black rubber/vinyl, 1993-1997. PN 6814305.
-1998 X70 shift knob, gray hard rubber. PN 9176166.
Then, the 1999 and 2000 shift knobs are different. They mount slightly differently, and are not compatible with the shifter rod on the -1998 style shifter.
-1999 X70 shift knob, gray plastic/hard rubber, PN 9445851.
The boots are different as well. For 850s, you may want to get a manual center console. The area around the shifter is slightly different, and there is no cutout for the automatic transmission mode selector button. 850 shifter boots are all the same.
1998 X70 boots have a plastic collar like the 850 boots, but are made for the X70 center console and are gray in color to match. There is no need to replace the automatic center console for the manual swap in these cars, as they are exactly the same. The boot clips right into place.
1999+ boots are the same on the bottom, but have a different neck to attach with a twisting action onto the newer style knob. These do not have the plastic collar like 850 and 1998 X70 boots.
There are some other shift knob options from Volvo out there, but I that topic deserves its own thread!
-850R clutch… clutch is your choice (although we have relatively limited options), but I always use the 850R clutch, part number 272218. Still available from Volvo. I am not 100% certain that this is compatible with the DMF, as it is designed for use with the SMF.
–Rear crankshaft seal/rear main seal… trust me, JUST CHANGE THIS while you’re in there. The flywheel has to come off anyway, so it would be stupid to leave it alone. Just because it isn’t leaking now doesn’t mean it will stay that way! Part number 9458178.
–Axle seals… you need two, PN 6843481.
–Clutch master cylinder… take my advice, USE A NEW ONE! I have been alright with a used one for now, but I am going to replace it soon so I can use a clutch pedal position sensor (old 850 master doesn’t have provisions for the clutch sensor). I’ll get into this later on in this post. PN 9163880. Absolute bear to install, but it’s a straightforward process. Just no space to work.
–Flywheel bolts… you need to replace these, as they are different between the auto flex plate and manual flywheel. PN 9454743, 10 required. Not a bad idea to order a couple extra just in case you lose one!
–Pressure plate bolts… PN 959219, 6 required, just like the flywheel bolts, extra isn’t a bad thing!
–Clutch master cylinder fluid feed hose… PN 9157190. Just a simple rubber hose connecting the brake master cylinder reservoir to the clutch master cylinder. You don’t necessarily need to use the genuine Volvo part here.
–Transmission input shaft seal… there are two different diameter input shaft seals offered for the M56 transmission. Your best bet will be to measure the one you have before ordering. The part numbers are as follows;
-1381798 41mm OD
-8675580 44mm OD
–Transmission fluid… you can either use Volvo 1161645 or a generic gear oil if you’re in a pinch. Otherwise, you can use your choice of a better quality transmission fluid like Redline MTL. I used Mobil 1 75w90 and I have no complaints. Best to get 3 quarts, the capacity is 2.2 qt., IIRC.
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