Rigging up an M410 hydraulic clutch

I've tracked down an M410 with the B20 bell housing for use on my 122. It is already a wider tunnel as the car was originally an automatic so clearance shouldn't be a problem. It seems like a pretty straight forward swap. Almost the same as the M41 with the exception of the clutch. The M410 only came with a cable clutch and my 122 has a hydraulic setup.

I know that I could possibly re-engineer the clutch pedal (using P1800 parts) and pedal box to use a cable but I though I would try looking at hooking up a hydraulic clutch. There are two options I've narrowed it down to. Both involve some level of fabrication but should be reversible should I ever decide to do so versus a more permanent swap in the form of a cable clutch.

The first is using the stock cylinder and putting a small hole into the bell housing and affixing the stock hydraulic clutch fork. I am thinking I could either drill and tap a hole and thread in a stud or mimic the stock arrangement and attach it with a hex bolt. The downside here is that I would be drilling into a very rare part. The upside is that I wouldn't have to touch the clutch system at all and fabricate a small bracket to hold the slave cylinder in the right spot.



The second option is to mount a pull type cylinder with a bracket to the bell housing brace bolts on the underside of the engine. This would be cleaner without really any modifications to the parts other than making a bracket. The downside is that I'll likely have to replace the master cylinder with a larger bore and the only slave I can find with a longer travel is the wilwood one, which is both a bit pricey and has lackluster reviews. I am also worried about putting constant strain on the rubber hose each time I engage/disengage the clutch.



Any thoughts on which would be the better option?

Hydraulic release bearing?

Is that Crank Position Sensor hole at the top of the bellhousing?

OttoB said:

Hydraulic release bearing?

Is that Crank Position Sensor hole at the top of the bellhousing?

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Do you mean the sort of release bearing without an arm? I guess the problem there would be finding one that would fit.

It is a CPS hole, the person who modified that bell housing had the transmission bolted up to a B230FT.

I like the second version. That makes it easy to make a bracket that bolts to the bell housing with the engine bolts. Just need longer bolts. You will still have to fab how the cylinder attaches to the clutch swing arm on the M410. To get good clutch leverage you'll need to move it at the end of the arm where the cable attaches.

dl242gt said:

I like the second version. That makes it easy to make a bracket that bolts to the bell housing with the engine bolts. Just need longer bolts. You will still have to fab how the cylinder attaches to the clutch swing arm on the M410. To get good clutch leverage you'll need to move it at the end of the arm where the cable attaches.

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It seems like they just used a piece of angle iron to mount it. Pretty easy to fabricate.

One thing that may get in the way is the little ring for holding the clutch cable. It seems that both individuals chopped it off. You can sort of see it in this photo from someone's restoration. Maybe it isn't always present. I guess I'll just have to see when the gearbox arrives.

Cable pull, hydraulic push, that is the question. When I built a V8 242 {1996} for a friend of mine years ago we used the Chevy bell housing the stock Volvo clutch release arm {tigged up the bell housing where the pivot should be for the stock Volvo arm, drilled, and tapped for the Volvo pivot}. Made a bracket the bolted to the bell housing and used the stock cable. I think that that car is still around as he sold it a few years ago

spock345 said:

Do you mean the sort of release bearing without an arm? I guess the problem there would be finding one that would fit.

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Not as hard as you would think, Tilton has a kit which has a machinable sleeve.

carver said:

Not as hard as you would think, Tilton has a kit which has a machinable sleeve.

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To work around the clutch cable stop on the bell housing I am thinking either the pull type cylinder or a release bearing.

For the pull type cylinder I could perhaps have the fixed rod (seems like it has some level of adjustment) go through the cable stop hole with some sort or delrin/nylon bushing and connect to the clutch fork. The bushing would either have to be greased or otherwise allow the rod to slide. Here I would worry about having the right length of fixed rod and any swing from the center line on the clutch fork putting strain on it. Something sort of like this.

For the release bearing it seems like there are ones that fit on a stud that replaces one of the bearing retainer bolts (looks kind of like the locator pin on 240 brake disc) and have the bearing ride on that. It seems that I need to get four measurements right, diameter of the sleeve around the input shaft, diameter of the bearing surface to engage with the fingers, bearing travel, and distance from the transmission bearing retainer (shims for clutch adjustment). It seems like there is more that I need to get right with this approach. Also a leak or future adjustment would be a pain.

The easy solution is just to hack the thing off, but given the rarity of the bell housing I'd rather not do that.

I'm in the middle of doing the same conversion that you are planning to do. Not meaning to throw cold water on your plans, but you might want to wait until you get your transmission disassembled and inspected to see what kind of shape the internals are in.

These units were and are problematic unless updated Volvo fixes (tapered countershaft roller bearing) are installed and parts for them are VERY hard to find. 2nd gear, the slider, the dog rings, syncros, and the countershaft bearings are where the other weaknesses lie. New dog ring springs and the dogs are finally available again (VP). Used parts or NOS Volvo pieces need to be sourced for everything else you may need.

Your best source of parts will be to pick up any other 400/410's you can find, but some of the later 164 pieces are not interchangeable with the 1800E boxes.

You might consider using a internal hydraulic release bearing http://forums.turbobricks.com/showthread.php?t=357178 as less fabrication is needed if you go that way.

Hi-Performance Auto Service in Torrance CA probably has the largest stock of parts in the US when it comes time to rebuild the internals.

Sort of unrelated but what’s the reason for choosing an M410 over an M41?

AndrewNance said:

Sort of unrelated but what?s the reason for choosing an M410 over an M41?

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It was really a matter of whichever one I got my hands on first.

vintagewrench said:

I'm in the middle of doing the same conversion that you are planning to do. Not meaning to throw cold water on your plans, but you might want to wait until you get your transmission disassembled and inspected to see what kind of shape the internals are in.

These units were and are problematic unless updated Volvo fixes (tapered countershaft roller bearing) are installed and parts for them are VERY hard to find. 2nd gear, the slider, the dog rings, syncros, and the countershaft bearings are where the other weaknesses lie. New dog ring springs and the dogs are finally available again (VP). Used parts or NOS Volvo pieces need to be sourced for everything else you may need.

Your best source of parts will be to pick up any other 400/410's you can find, but some of the later 164 pieces are not interchangeable with the 1800E boxes.

You might consider using a internal hydraulic release bearing http://forums.turbobricks.com/showthread.php?t=357178 as less fabrication is needed if you go that way.

Hi-Performance Auto Service in Torrance CA probably has the largest stock of parts in the US when it comes time to rebuild the internals.

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I talked to hiperfauto about it a bit and he recommended updating it to the tapered roller bearings if it doesn't already have them. I guess the challenge would be to figure out a bearing puller. I was told by the seller that it is a 164 transmission modified with the correct bell housing and input shaft. Which makes me interested in popping the top cover and bell housing off to take a look inside. I'll have to do so anyway to get the 122s shift lever on it.

When did Volvo switch over to the tapered roller bearings? I see M400s pop up ever so often on ebay. I'll definitely grab them when I can.

AndrewNance said:

Sort of unrelated but what’s the reason for choosing an M410 over an M41?

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Hey Andrew! They are perfect for racing and hi-performance applications. M40/41boxes can handle up to about 160 hp but are not strong enough for more. A 410 is not needed for normal everyday driving. One online source if it is correct rates them as being able to handle up to 400 ft pounds of torque.

spock345 said:

I talked to hiperfauto about it a bit and he recommended updating it to the tapered roller bearings if it doesn't already have them. I guess the challenge would be to figure out a bearing puller. I was told by the seller that it is a 164 transmission modified with the correct bell housing and input shaft. Which makes me interested in popping the top cover and bell housing off to take a look inside. I'll have to do so anyway to get the 122s shift lever on it.

When did Volvo switch over to the tapered roller bearings? I see M400s pop up ever so often on ebay. I'll definitely grab them when I can.

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Yes, tapered counter shaft roller bearing are necessary. According to Planetman they are a retro fix introduced fairly late in production for the 164. The bearings initially fitted are ball bearings which cannot handle the load and deteriorate and cause gear noise as the shafts are forced apart.

It is difficult to get the countershaft bearings out. Volvo made a number special service tools for these boxes and a special puller is needed to get the output shaft bearing and shaft out. The countershaft bearings are pressed into the case and without the special tools it is difficult to get them out. You can make your own pullers and there is an online article about rebuilding a 1800E box that will give you some ideas.

The 164 1st and 2nd gear ratios are lower than in the 1800E boxes and really too low for lighter 122 or 1800 cars.

You can use a 164 input shaft but the spline is SAE 1 1/8" in diameter, and the smaller 1800E shaft is SAE 1". You have to have a special clutch plate made up w/a the bigger spline to use the 1 1/8" shaft it or buy an expensive clutch plate from KG Trimming.

vintagewrench said:

Yes, tapered counter shaft roller bearing are necessary. According to Planetman they are a retro fix introduced fairly late in production for the 164. The bearings initially fitted are ball bearings which cannot handle the load and deteriorate and cause gear noise as the shafts are forced apart.

It is difficult to get the countershaft bearings out. Volvo made a number special service tools for these boxes and a special puller is needed to get the output shaft bearing and shaft out. The countershaft bearings are pressed into the case and without the special tools it is difficult to get them out. You can make your own pullers and there is an online article about rebuilding a 1800E box that will give you some ideas.

The 164 1st and 2nd gear ratios are lower than in the 1800E boxes and really too low for lighter 122 or 1800 cars.

You can use a 164 input shaft but the spline is SAE 1 1/8" in diameter, and the smaller 1800E shaft is SAE 1". You have to have a special clutch plate made up w/a the bigger spline to use the 1 1/8" shaft it or buy an expensive clutch plate from KG Trimming.

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I wonder if IRoll motors in Morgan Hill has the bearing pullers should it still have the ball bearings. I found the article you speak of and that will be my backup plan if I can't find someone with suitable puller.

From my reading it seems like the earlier production gearboxes had the same gear ratios as the 1800E box. Then later production cars got a more aggressive 1st and 2nd.

Early M410
1st: 3.13:1
2nd: 1.97:1

Late M410
1st: 3.54:1
2nd: 2.12:1

My car currently has 4.10 rear gearing that was standard on automatic and non-overdrive models. For comparison here are the final drive ratios for each transmission/rear end ratio. I am assuming an OD ratio of 0.79 which as far as I know is stock for the J type. I've seen some forums talk about late production 164's getting ~0.7:1 but nothing I can corroborate.

M40/41 with 4.10:1 (My car as it sits)
1st: 12.87:1
2nd: 8.16:1
3rd: 5.57:1
4th: 4.10:1

M41 with 4.56:1 (Factory OD 122 and earlier 1800, maybe also the 220)
1st: 14.32:1
2nd: 9.67:1
3rd: 6.20:1
4th: 4.56:1

Early M410 with 3.73:1 (early 164, although I am not sure if the M410 came in early 164s)
1st: 11.68:1
2nd: 7.42:1
3rd: 5.00:1
4th: 3.73:1

Early M410 with 4.30:1 (1970 1800E)
1st: 13.46:1
2nd: 8.47:1
3rd: 5.76:1
4th: 4.10:1

Late M410 with 3.73:1 (later 164)
1st: 13.20:1
2nd: 7.91:1
3rd: 5.00:1
4th: 3.73:1

These are the two possibilities then for what I would end up with in my car with an M410 assuming I don't change the rear end. The later M410 seems rather similar to the gear ratios from the early P1800 and 122 overdrive cars, although with a shorter OD as the D type had a steeper reduction.

Late M410 with 4.10:1
1st: 14.51:1
2nd: 8.69:1
3rd: 5.49:1
4th: 4.10:1

Early M410 with 4.10:1
1st: 12.83:1
2nd: 8.08:1
3rd: 5.49:1
4th: 4.10:1

If all else fails it probably wouldn't be hard to trade the gearbox for an M41.

I have the special tools to pull the rear main shaft and early countershaft bearings.

This is how I handled the problem on my race car because I didn't have room for a clutch fork or slave cylinder. It's not the cheapest option but it works well. I was using a .7" bore Wilwood master but a standard ?" bore master cylinder should work as well.

hiperfauto said:

I have the special tools to pull the rear main shaft and early countershaft bearings.

This is how I handled the problem on my race car because I didn't have room for a clutch fork or slave cylinder. It's not the cheapest option but it works well. I was using a .7" bore Wilwood master but a standard ?" bore master cylinder should work as well.

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I like how you routed the bleeder to the pivot bolt hole. Right now I am leaning towards the pull type cylinder because I have the clearance for the fork and I could fiddle with it without pulling the gearbox but this is my backup plan.

Which release bearing did you end up using? I am guessing you ended up drilling into the housing to mount it?

The line from the master comes through the pivot bolt hole. The bleed line is at the high point because air rises.

If you have room to make it work a pull type cylinder seems like the best solution. Hopefully you won't have to cut the ear off the bell housing.

I don't recall which bearing I used other than I got it from Tilton to go with the 7" clutch and aluminum flywheel that I also bought from them. It was over 20 years ago and there wasn't anywhere near as many choices as there are today. I do remember that it was a new product for them at the time and the first one I got was defective.

It does require drilling 4 holes in the bell housing. I used flat head screws, countersunk them and sealed them with a little silicone.

The photo of the pull-type slave is of my car. It has been working well for about 15,000 miles now. I too was concerned about the flexing of the hose and just turned the slave cyl. around so the body is now stable and only the rod moves.
I am using a stock size (3/4?) Wilwood master cylinder which matches up just fine. Light and smooth clutch pedal.
My set up is on a B230 / T5 trans in an Amazon, so your bracket would probably be quite different.
If you don't have to modify the bellhousing it could be returned to stock very easily.

TR Conn said:

The photo of the pull-type slave is of my car. It has been working well for about 15,000 miles now. I too was concerned about the flexing of the hose and just turned the slave cyl. around so the body is now stable and only the rod moves.
I am using a stock size (3/4”) Wilwood master cylinder which matches up just fine. Light and smooth clutch pedal.
My set up is on a B230 / T5 trans in an Amazon, so your bracket would probably be quite different.
If you don't have to modify the bellhousing it could be returned to stock very easily.

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I really like how clean it is. Did you just use some angle iron for the bracket?