How to convert from automatic gearbox to manual on Volvo 850, S70, V70 or C70

by: dooby


I think this has been done a lot in the USA but not so much here in Uk. Anyway, foolishly my brother-in-law said we should swap my 850R auto to a manual over the Easter weekend – and I decided to take him up on it.

We decided it would be a better idea to get a donor car, rather than find out halfway through we were missing a crucial bit – so I sourced a ’96 850 2.5l 20v which was fitted with a M56H manual box. I also ordered some bits from forum member Rufe – 850R clutch, release bearing, flywheel bolts, rear main oil seal, and slave cylinder circlip. Tim Williams helpfully sorted me some clutch bolts (and a bunch of tips for the job).

We basically followed the Haynes procedure for removing an auto, then for refitting a manual. After that the extra bits (clutch hydraulics, pedals, gear lever) had to be done. Finally a bit of fettling with the electrics and cruise control. This was all made much easier by my 850R being a late model which gets its speed from the ABS system, rather than a speed sensor on the gearbox as earlier models did.

So here’s how the donor car started out:

Working on the naturally aspirated cars seems weird after a turbo car ๐Ÿ™‚

Here I’ve removed the air box so we can see the gear selector cables (rubber bellows) and the reverse switch (blue wires).

Here’s a shot down the front of the engine bay showing the clutch slave cylinder and release bearing fork.

Here I’ve removed the air box and piping, and the battery tray.

With the inlet manifold and starter motor removed, it’s a lot easier to see the clutch slave cylinder, it’s bleed nipple and the route the hydraulic pipe takes round the engine bay. I’ve removed the circlip to start to withdraw the cylinder – the bit with the bellows comes away, the rubber-booted metal lever stays put.

Here I’ve removed the slave cylinder, and you can see the clutch pipe is annoyingly threaded through parts of the air box support mount so I had to unbolt it.

Up under the ABS unit area, the pipe has a joint which can be disconnected by releasing this clip it’s slightly easier to get it all out of the engine bay in 2 parts than one…

I removed the centre console, the gear lever is only bolted down with 4 bolts and rubber bushes. Prying the gear selector ball sockets wasn’t that easy, I believe Volvo use a tool not disimilar to a balljoint separator, where a turning screw slowly forces the ball away from the socket.

Here you can make out the gear lever assembly and 4 fixing bolts.

Here’s some more bits removed from the donor car, the clutch and brake pedals, the clutch master cylinder and the gear selector cables.

And the centre console, gear lever and hydraulic pipe and slave cylinder.

Here you can just make out the hanging vacuum hose from the clutch cruise cancel switch, and the vacuum and electrical connections and switch for the brake pedal.

Here’s a shot of the gearbox as I’ve removed the gear selector cables, reverse sensor connector. I also removed the vertical gear selector lever by hammering out the retaining pin, as I think it adds to the height clearance required to withdraw the gearbox.

Here’s the engine support beam installed in the wing channels. I decided to cut out the old rubber mount to allow me to get the chain through.

Here’s the rear engine mount also disconnected, all ready for lowering the subframe.

Here you can see that with the suspension strut and wheel arch liner removed, and the subframe dropped on the driver’s side you can lower the engine enough for the gearbox to come out through the gap.

I couldn’t lever the driveshaft out as Haynes suggested, so I decided to withdraw it with the gearbox and then take a look. Bottom line, give it a sharp tug to overcome the spring clip. It’s easier to determine that won’t do any damage with the box on the ground…

Sadly, whilst trying to separate the gearbox from the block, my favourite prying screwdriver finally met its demise. RIP, old friend.

The gearbox weighs about 48KG, so have a way of taking most of the weight as it comes off the engine’s locating dowels – it’s hard to hold 48KG with your arms outstretched…

I don’t know why I thought it’d be fine to drop the gearbox without having drained the transmission fluid – I was intending to replace it anyway. If you do decide to follow my foolish lead on this one, I recommend cat litter or dry sand to try and get the oil off the driveway…

Here we can see the steering rack and anti-roll bar I’d already disconnected from the subframe (supported by the small chain), and the flywheel and clutch are exposed.

Here’s the bare box, removed.

Here’s the flywheel bolts coming out, a little at a time each time.

We took a shot of what looked like an alignment aid on the flywheel (the toothless region) but it turned out the flywheel and crank have a locating dowel which means they only go on in one orientation anyway…

We removed the flywheel by gently tapping it away from the block in the starter motor opening, and turning it by rotating the crank from the timing belt end.

Note the round metal locating hole within the crank – more on that later.

Here you can see the diff area, and release bearing throwout fork. You might be able to make out the semi-spherical part of the fork which rests on the ball behind.

There’s lot of room in the engine bay with no gearbox ๐Ÿ™‚

Here’s the 850R clutch (OEM Sachs) next to the naturally aspirated one – you can see the friction area is larger.

Here I’ve swapped the friction plates over, you can see the inner diameter is the same, but the 850R driven plate outer edge extends further.

Time to start on my car. It would be a while till it looked like this again…

After a while removing bits…

Even the rain showers didn’t deter us…

An ‘arty’ shot through the auto’s diff:

The driveshafts are only slightly different. The manual is thicker (top) but the donor car’s CV joint boots were in worse nick so I stuck to my auto driveshafts for now. I’ll probably rebuild the manual ones and swap later.

From top to bottom, my auto, donor manual, spare auto. Only the outer half of the shaft appears to differ.

My top engine mount is fitted with a polybush, but fortunately the donor car’s bracket bolts right up so I borrowed it to support my engine. The naturally aspirated brackets seem to have one less bolt point.

There aren’t as many shots of the autobox removal, as I was too busy filling the swear jar. For my car, we didn’t need to follow the Haynes advice and unbolt the torque convertor bolts through the access hole – it seems the bolts moved for my ’97 model year car at least.

The auto box weighs about 65KG, so is even harder to remove carefully and in a controlled manner than the manual. Again, do drain the oil first and you should have considerably less mess than me to clear up.

The support lug holes are quite small on the auto box, we ended up going to Homebase for some 3mm wire and wire clamps.

Here’s how to remove the bolts holding the torque convertor to the flex plate on my car. Again, rotating the crank with the timing-end nut to bring each of the 6 bolts into view.

Cat litter and sand – great tools to have handy if you’re a messy bugger like me.

With the torque convertor removed, we could undo the flex plate bolts. On my car they were 12-sided not 6-sided as on the donor.

With the flex plate bolts removed we could get at the rear main seal. The Haynes tip of using a bradawl is a good one here to remove the hardened old seal.

We also used their tip of cutting 2 grooves in one of the old flex plate bolts and using it as a tap to clear out any leftover thread locking compound.

You can see here the metal ‘bearing’ circular hole in the centre of my auto’s crank is bigger. Turns out this supports a protrusion from the torque convertor (presumably because of its additional weight). This is probably only important if you try to offer an auto box up to a crank from a manual as it won’t fit! Going the other way is fortunately OK as nothing protrudes from the clutch through to this crank ‘bearing’.

Yay, my car has a flywheel! The new bolts were M12 spline bolts, so make sure you’ve got a suitable socket ๐Ÿ™‚

850R clutch does bolt up to the naturally aspirated flywheel – this is quite a relief.

Some comparison shots of the auto and manual. Even without the additional fluid, you can see there’s more to the auto.

I used a Laser generic clutch alignment tool from Halfords, but if you’ve done a clutch before (I hadn’t) you might not need one of these if you centre it by eye.

Finally, we have a manual box. Again, not too many photos as this bit was tricky. It was getting late on the Saturday and eventually, although you shouldn’t *need* one for this job we chose to use the engine crane to help support the weight as we tried to mate the box onto the block.

I think we could have helped things by gently sanding the dowels (which are chamfered anyway) and locating holes. Also, there was an element of inexperience at play – we were worried about supporting the box (having located the gearbox shaft through the clutch) too long without the block to box bolts holding it snug.

In the end we prevailed and slowly tightened the bolts a little at a time to pull the box onto the block. Then, it was clearly as supported as intended.

With the box in place, it was time to try and install some of the other bits like the hydraulic pipe.

Here I’ve installed the slave cylinder and its new circlip against the release fork.

With the box in neutral, I wanted to try cranking the engine. As expected, on the first try there was absolutely nothing. I suspected this was due to the PNP switch, which will inhibit the starter motor from firing on auto cars unless the auto box senses it’s in Park or Neutral.

I wouldn’t advise this, but I swiped some wiring from the auto box (involved some snipping) to test it cranking. It did crank (I’d removed the fuel relay) and no nasty noises – good stuff.

Inside the car I started removing the centre console. Be careful, I managed to scuff the leather handbrake cover by accident.

Here I’m removing the auto selector cable – 2x 10mm nuts hold the bulkhead ‘grommet’.

This is the damage running big tyres and low suspension can cause ๐Ÿ™ I swapped the wheel arch liner over but I’ll probably have to roll my arches a little eventually.

Here’s the manual gear selector cables ready to go in:

And just poking through the bulkhead into the engine bay:

And now routed to under the centre console:

I reattached the gear selector cables, but we’ll come back to them…

Here she is all buttoned up again. Be extra careful tightening up coolant jubilee clips if you try this, I missed one and had to take a fair bit apart again to fix the coolant leak :-/

Here’s the consoles side by side. I think with a little fabricating, I can get that inner ‘lip’ and have my walnut back…

Gear lever installed:

Hmm, something not quite right ๐Ÿ™‚ Gear stick yet only 2 pedals?

Remove the nuts and push the blanking plate into the engine bay so you can fit the clutch master cylinder.

The brake pedals just swap over. Despite the long bolt, you don’t have to move all the wires and relays to remove and refit.

Here’s where I discovered a problem. There’s nowhere for the clutch assistance spring to push against:

Turns out the left side of the pedal ‘box’ is different, so a nut and bolt each later and I can swap them over. This is also where the clutch cruise control cancel switch goes (the round hole, bottom left).

That’s better, all the right pedals now.

At this point I decided to uprate the rubber gear selector bushes to brass. Thanks to Tony for the tip – these are the same as found on the Toyota MR2 and you can find kits on eBay, shipped from America.

Remove the clip, washer and bush – the new bush will be held in by the new ‘circlip’ (bottom left). Then, replace top washer and clip!

One of the old bushes was knackered anyway. I replaced both with brass.

To finish off the electrics, I stole the reverse switch connector from the donor car and spliced it into the appropriate auto box connector pins. I also jumpered it so it would always think it was in Park or Neutral thus allowing the starter motor to fire. More on this later… I used glue and cable ties to secure these wires in place – et voila, no auto box ECU required any more, and no gearbox warning light.

Next I drained the transmission fluid. The plug had a copper washer but it was the same measurements as the aluminium ones Volvo use on the engine oil sump plug so I replaced it with a new one of those.

At first I tried filling through here but it didn’t work (kept overflowing):

So instead I pulled the reverse switch and filled it (slowly) through there with new fluid.

So, you remember the starter inhibit wire? Turns out the inverse of the signal is used to tell the cruise control it’s in a gear and thus safe to engage. D’oh!

So, since the wire isn’t present on manual systems, the easiest way seemed to cut the relevant pin on the cruise control relay – 3T:

Here’s the clutch pedal cruise cancel switch and electrical and vacuum connections I took from the donor car:

Here it is all connected. You need to connect the electrical switches in *series* not in parallel, as they rely on pushing the pedal away to break the connection. I cut into the return wire of my brake switch and spliced in the wires which ran off to the clutch switch.

One gotcha here, it turned out the metal bracket holding the clutch pedal switch was just too far from the pedal to register as ‘up’ so my cruise wouldn’t engage. Took me a few days to find this – the fix was simple, gently bend the bracket nearer and test for continuity with a multimeter.

So there you have it, my 850R auto is now a manual. I’ve put 600 miles on it and so far nothing’s fallen off!

The DVLA were a little surprised I didn’t have a garage receipt for the work to include with the covering letter, but I have my re-issued V5 nevertheless. My insurance company (Greenlight) didn’t charge me either.

Despite Haynes giving the gearbox removal sections 4 spanners it’s clearly possible by mere DIY mortals ๐Ÿ™‚

Have fun, Pete


The instructions in this tutorial will work in the following models / years:

– 1991,1992, 1993, 1994, 1995, 1996 and 1997 Volvo 850
– 1997, 1998, 1999 and 2000 Volvo S70
– 1997, 1998, 1999 and 2000 Volvo V70
– 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 and 2005 Volvo C70 Coupe and Convertible / Cabrio