Hello everyone, yesterday I started to replace the clucth on my father's 940 B200FT with M90 gearbox.
Car was bought on this February and it has a problem since the to disengage the clutch the drivers has to press the pedal very down to the floor.
Apart from that the clust was not slipping and if you shift slowly the drivability was fine.
As you know the 940 turbo with M90 manual gearbox is provided witha double mass flywheel that is no more available as a spare replacement since different years and from what I know this kind of flywheel cannot be resurfaced.
Many of you have an automatic gearbox but not all and I believe someone of you could have more exprerience with old RWD flywheels, abused and not.
Please, what do you think about the status of this flywheel? Can be reused or must be replaced?
Which could be the worst scenario if I replace only clutch disc, pressure plate and release bearing leaving this old flywheel?
Here were I indicate with my finger ther is a little groove but generally the surface is smooth at the touch and there is no gap exiting from the contact area with the clutch disc.
You might be able to find someone who will machine a dual mass flywheel. (It at least looks possible to chuck it up, looking at the photos) Googling around, seems like people have mixed results and you probably won't get a warranty on its performance or longevity.
ClassicSwede also has a less expensive kit. But I think the cheapest option will be getting a dog-dish flywheel from someone and then ordering the appropriate clutch.
If you are really on a budget you can try to remove the glazing and toss is back in. It could end up slipping.
With "removing the glazing" do you mean to give a little polish with sand paper by hand?
If not sticly mandatory I would prefer to not replace the flywheel and buy a new clutch kit since I've already bought a Volvo clutch kit.
I add one thing that I didn't tell you before, this is a stock car and it will never be driven heavily, my dad is 73 years old, he don't plan to tow anything and he isn't a driver who wants to see smoke exit from the tyres. Furthermore we live in plain and the most frequent hill that we rise is the exit of the garage.
P.S. A friend of mine suggested me to try searching for an used one in better condition, I'm not an expert with clutches (and that's why I asked help to you) but all these ones doesn't seem to my eye in much better conditions than mine: https://www.autoparts-24.com/volvo-940/flywheel/1/
P.S.S. I know the classicsweed conversion kit, but a person I know has some problems buying spare parts from that site and I had to remount the car quickly (I cannot wait for weeks)
You could try your luck with a die grinder and a little red "cookie" disc. I know some guys love to do this on brake rotors.
You already have the clutch for this flywheel, I would just clean it up the best you can and get the car back on the road. Almost every Volvo flywheel I have pulled has cracks and glazing and was still holding normal driving conditions.
May be you are talking about something like this: https://www.youtube.com/shorts/XbLmyC8P1p8 ?
Honestly my clutch tech knowledge is too basic to say if it's a good idea or not, I red the comments at the video and there are both people who say that is a good job and othe that is absolutely wrong.
In the while I tried to learn why hot spots are so bad and I thisnk to have found the answer into this video: https://www.youtube.com/watch?v=KeqzZniVmrM
I think that hot spots bring to slip the disc since the hotspots are harder and with a lower coefficient of friction but yesterday evening I've made this test: I cleaned up the contact surface of my dad's flywheel with break cleaner and I compared the friction of the old disc to the new one and in the opposite of what I believe the new one has a better grip than the old.
And since the old was never slipping, I cannot image a reason why the new one it should (at least for a while).
Any correction to this reasoning is appreciated.
Hello, at the end I've reinstalled the flywheel as-is without any DIY resurfacing.
The clutch seems to work fine but the most beautiful thing is that now the pedal has become a piece of butter. It's incredible!!!!
The first time I believed to have forgotten to reconnect the slave cylinder
To drive a car with a so soft clutch is a really a pleasure
Thanks very much to everybody for your opinions and feedback!
P.S. In the next months I will have to do the same job to my 940 (same engine, same gearbox), I hope to find a better flywheel than the one of my dad's car
Good to hear. How did you hold the crank still to torque the flywheel bolts? Or did you just slam em in with a strong gun?
I've loosed the bolts by using an impact gun but for tighten them with a torque wrench I built a clone of the Volvo flywheel locking tool.
I tighten the bolts to 70Nm as reported into the Haynes workshop manual and I've applied also medium thread locking compound.
I believe that as alternative solution you could hold the crankshaft from the front but I preferred doing this way.
Since I had to replace the main rear oil seal I've built also an inserting tool.
I share you some pictures in the case it may be usefull to someone to copy the idea.
NOTE: this was my first attempt doing this job, but next time I will improve it by replacing my old MTB sprocket with a solid plate and I will add 4 screws on the outside to better register the insertion depth (in my case it was 3mm inside)
It may be for an M46, but may not be for a 9 inch flywheel as used on later 240 and 740 and non USA 940. The smaller clutch and flywheel are probably fine for all the power most people are likely to make, but if you have really serious power goals, you may have to pay Centerforce to make up a custom clutch for you or shop elsewhere. I communicated with CF about a high performance 9 inch clutch and they did not have anything in stock that could handle 400 hp/400 lbs torque. They said they might be able to make one, but it would be custom and expensive. Rick Mard was the person I communicated with there. I am working with SPEC on a clutch that should be able to take that sort of power while being completely streetable. This will be for the Getrag 265 conversion, though they could also make a pure Volvo one if there was a point to doing so. They can also make aluminum flywheels or lighten stock ones. I may do an aluminum one or I may lighten a stock one. I am sending them one to look at. David Norton is the person I am dealing with at SPEC.
Philip Bradley
pbonsalb said:
It may be for an M46, but may not be for a 9 inch flywheel as used on later 240 and 740 and non USA 940. The smaller clutch and flywheel are probably fine for all the power most people are likely to make, but if you have really serious power goals, you may have to pay Centerforce to make up a custom clutch for you or shop elsewhere. I communicated with CF about a high performance 9 inch clutch and they did not have anything in stock that could handle 400 hp/400 lbs torque. They said they might be able to make one, but it would be custom and expensive. Rick Mard was the person I communicated with there. I am working with SPEC on a clutch that should be able to take that sort of power while being completely streetable. This will be for the Getrag 265 conversion, though they could also make a pure Volvo one if there was a point to doing so. They can also make aluminum flywheels or lighten stock ones. I may do an aluminum one or I may lighten a stock one. I am sending them one to look at. David Norton is the person I am dealing with at SPEC.
Philip Bradley
The m46 won't handle the power the centerforce dual friction will take, so it hardly pmatters. Remember, the clutch strength doesn't matter if the tranny behind it can't take as much....
After having talked with SPEC and McLeod about various disc size options, it appears that the 1/2" difference in diamter doesn't make for diddly-squat in extra power handling. Yes, a little bit more is obvious, but not enough to really worry about having to sitck to the 9". Convert to the 8.5", and your options will open up tremendously, since Ford also has the 8.5" as a stock size.
The power holding capability generally is determined by the clutch material, and pressure plate clamping force. Diamter is negligible in effect. I think I was told that most of the clamping force occurs toward the center of the disc anyway.
If you're really worried about a clutch not handling what you're going to throw at it, use a multiple-disc setup. My Class-8 has a three-disc. Indy cars use something along the lines of 6 discs. Top-fuel dragsters use about the same, IIRC. And I think the Indy cars have a 6" diameter disc pack. Of course, if you're needing a multi-disc clutch system, what are you doing attaching an M46 to it??!?? The M46 will be in a billion pieces, but the clutch will still be there.....
If you don't want to use a multiple-disc clutch system, but still need to handle more torque than the transmission can hold, use a sintered iron clutch disc. This will positively not slip. But it will also be extremely hard to drive, what with instantaneous engagement.