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Discussion Starter · #1 ·
installed spec/viva flywheel with stock clutch. never had any noise from trans before, but right after install and also rear diff reseal the trans rattles like its going to fall apart when its hot but noise goes away pressing the clutch or if i put pressure on the shifter. i am thinking the shift fork is rattling???? anyone else have this issue and any resolution??
 

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ABSOLUTELY normal. That noise is why they put DMF's in. Volvo and the others would not use DMF's and spend the extra bucks w/o a reason. You had to spend the extra dough on the DMF kit to get that noise to stay away. If you use lighter oil to lower drag, and especially when you have a trans with 3 countershafts, you have loads of gears to go drive and coast lash alternately when each cylinder fires to speed up crank and then the next compression stroke slows it down. Same reason that gets us a one way clutch on the alternator.
It is a noise but is harmless.
When you push on gear lever you are creating a load with the synchronizer, not a good idea by the way.

The noise will be reduced when weather gets hot again and the ECM kicks up idle speed if that is any consolation.

Or you can always sit with clutch depressed with it in gear.
 

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Discussion Starter · #3 ·
thanks for the reply, if i would have known it was going to be this noisy i would have just spend the extra 200 to get the dmf. now its going to cost a lot more because its is annoying as helllll.......
 

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Maybe somebody will chime in. I'm not sure if there is any worthwhile relief to be had by changing the trans oil.
You can't go thick 90 weight gear oil as the synchronizers are not compatible with thick oil but if Redline MTL has been tried and quiets it it might be enough to keep you sane.

I know it is grinding and growling and knocking noticeably and anyone telling it is ok is not really making it feel better.
 

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thanks for the reply, if i would have known it was going to be this noisy i would have just spend the extra 200 to get the dmf. now its going to cost a lot more because its is annoying as helllll.......
it will die down eventually, and you'll start to get used to it, from what i've heard after about a month you don't even notice the noise anymore because it's died down a bit and it just seems normal to you.
 

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it will die down eventually, and you'll start to get used to it, from what i've heard after about a month you don't even notice the noise anymore because it's died down a bit and it just seems normal to you.
I agree.

When I first installed my strut bar conversion kit you could feel major vibrations transmitted into the seats. Only a month later I stopped noticing it. I get reminded when a friend rides in the car and ask why their seat is vibrating. Lol. You'll get use to it.
 

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Discussion Starter · #7 ·
ya i might get used to it but the noise is going to be there right it will not be reduced. when i am parked in a parking garage it rattles worse than a old diesel truck. i know i should have researched it before i put it in but too late now. vendors that sell there items should have a disclaimer that says YOUR TRANSMISSION WILL RATTLE LIKE A METAL BOX OF MARBLES...
 

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Mine still hasn't. It's at it's worst when it's hot out too.

Perhaps different fluid would help? I'm not keen on trying.
 

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The noise is not going to reduce over time, or "wear in". As has been explained it is a result of the power pulses from the engine causing gear rattle. There is a reason that even performance cars like Porsche use a DMF. There would be too many complaints of gear rattle. Yes the the GT3 Cup cars use SMF, they also use plex and have no sound insulation because they are track cars.

I would not suggest depressing the clutch when in neutral, not only is it tiring, it is just that much more wear on the throw out bearing. It will eliminate the rattle however, since the engine is decoupled from the gearox.
 

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The clutch release bearing turns every rev the crank turns anyway. I will say the load is greater when pedal is depressed but the release bearing can take it and have long life.
 

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Dual mass flywheels what they are for and how they work

One of the major issues all the manufacturers have is the dual mass flywheel (DMF) which seems to need to be replaced every time that you need a clutch and that puts the price of clutch replacement up to around £1000 which on a car that has probably done in excess of 100,000 miles will probably make it uneconomical to repair. So the first thing to understand is what a dual mass flywheel is designed to do. The dual mass flywheel is an aid to making the gear change on your car lighter and more positive while also making the engine and gearbox smoother and quieter. So how does it work, in order to make an engine smoother you need to increase the mass of the flywheel but as you do this the mass of the gear train effectively becomes less as a proportion of the total mass that is in motion and you will get noise, rattles and vibration from the gear train, in order to get round this you would traditionally have increased the mass of the gear train which in turn would mean that the syncro’s (the brake that matches the speed of the gears that are about to be engaged) also had to become stronger and there fore the gear change becomes heavier and more agricultural. To get round this you have to increase the mass of the gear train without increasing the mass of the gears, this is done by splitting the flywheel into two separate masses (hence the name “dual mass flywheel”), one mass that is attached directly to the engine and one mass that is attached directly to the input shaft of the gearbox, these two halves are then separated from each other by a damper which stops the natural vibration of a large high capacity, high compression engine being transferred to the gearbox.

So how much trouble are dual mass flywheels and when are they worn? Well if you own a Peugeot 407 2.0l diesel you may well find that you need a new one every 20000 miles or less while on Alfa Romeo’s they seem to last well part 100,000 miles without trouble, I can almost feel the engineers amongst you bristle at this next comment but bare with me, and even with this sort on mileage on them they can often go again (not best practice) as long as there is only slight tangential rotation in the secondary mass relative to the primary mass, however if there is any free play axially it should be replaced, however on later cars they have a fully floating dual mass flywheel with internal clutch adjustment and that is almost impossible to asses the wear on it. These late flywheels also need special tools to stop them from adjusting up while you are doing gear box repairs so beware!
 

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I have a SM flywheel waiting to go in with the rebuilt engine. I do track the car, but it is also a daily driver. Seems like this might be an annoyance in the city - perhaps more to others than to me.
If I have to pick up clients at the airport, I guess I might want to send a limo, eh?
 

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" however on later cars they have a fully floating dual mass flywheel with internal clutch adjustment and that is almost impossible to asses the wear on it. These late flywheels also need special tools to stop them from adjusting up while you are doing gear box repairs so beware! "

I am aware of self adjusting clutch covers, like the R also uses, that require clutch compressor and a SAC reset ring be fitted to avoid the SAC adjusting during installation.
I have not seen a DMF with any compensation or adjustability.

SAC is a great development. Clutch clamping force always decreased continually during the life of clutch disc as it got thinner. The ramp ring behind the diaphragm spring keeps the clutch disc clamping force within a narrow range by adjusting the fulcrum point.

The synchronizers are changing the speed of the clutch disc and the input shaft and any other meshed shafts. With the clutch depressed the flywheel is not part of the mass the synchros control. All the technical information I have ever seen explaining reasons for choosing DMF was to avoid even heavier flywheels and/or higher idle speeds while also meeting demands for reduced emissions and satisfying owner's expectations as regards undesirable noise.
 

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Discussion Starter · #16 ·
i guess as long as its not damaging anything ill just keep it in until next clutch replacement as it will not be cost effective to change it out, then again i just did my clutch at 250k miles..
 

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Mine seems to be a little better after a month or two but I have a spec clutch if that makes a difference.
 

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The noise is less when the fluid is thicker. Usually the worst noise would be after long drive in hot weather.
In hot weather the ECM does bump up the idle speed, at 86F as I recall, and higher isle speed gets the momentum of flywheel up enough to reduce some rattling.
 

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Discussion Starter · #19 ·
i just changed out the volvo fluid which is a 75w gl4 for redline mt-90 fluid which is 75w-90 and noise is the same..
 

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i have heard of people using redline shock proof oil and it dampens the noise a little,I'm on the fence with a smf
 
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