so, is the main advantage to a muti-plate clutch the weight for quicker shifting? i like a light pedal, but i don't hear may people talking about that. i don't drag race, so maybe that's why i'm so happy with my single?

 

Still seems more than coincidental to me that the oil grooves are on the load side.

No doubt that there have been plenty of crankwalk events on the 95-99 7 bolt motors using pull clutches, but I have not heard of it being more prevalent for pull clutches, at least in relation to the number of builds using pull vs push. Any links or data to substantiate that for either DSM or Evo?

 

It is either coincidental or mitsi considered the specific design and side of the grooving more suited for better lubrication in ralation to the rest of the rotating assembly. I have not anything gathered in regards to links or data right now in front of me to post, as what I have said it is based on my personal friction with the dsm and evo world, either up close or through forums and the internet in general, I am sure if you search a bit you will find enough data. Also the crankwalk issue might be a lot more common with earlier evos, and I have seen and heard about it many times on evo 3 up to evo 6, but I have also seen it happen on a gallant vr4 and on an evo 7 or 8 if I recollect correctly, and in all these instances all the applications were using the pull type clutch system.







Marios

 

A twin/triple shifts better IF its lighter than what you're replacing. Its all about weight. The less the clutch disc(s) weigh (rotational mass is key here, not just the weight a scale tells you it is, so diameter plays a key role), the less work the syncros have to do to slow down the input shaft, which means a faster/better/cleaner shift.

 

Correct, the less the mass of the rotational assembly the less work the synchros have to do, the faster the shift. It is not only down to the diameter of the flywheel, disks, pressure plate, but also down to the materials and design of them, factors which determine the weight and mass of any rotating part including the clutch system. The weight of the whole rotating assembly- crank, pistons, rods, clutch system, pulley- plays a very important role in not just the gearbox shifting but in enough other aspects of the engine including intented performance.






Marios

 

this is not correct. weight of fly, crank and rotating assembly has very little to no effect on shifting. its pretty much the weight of clutch discs only and how well the pressure plate releases. when clutch disc is free wheeling between pressure plate and fly it is only directly connected to input shaft of tranny, its not directly connected to engine rotating parts. the syncro has to stop the rotating mass of the clutch disc/or discs, input shaft, and the gears the gears connected to input shaft.. of the three the clutch disc is by far the heaviest rotating mass. so reducing that mass has the most notable effect of stopping all three for a clean shift.

 

and you guys discussing grooved bearings are off as well. there are no grooves on the thrust bearings. the left and right thrust bearings are identical. that whole article about length of main bearing groove is irrelevant when discussing how a thrust bearing works. thrust bearing do not get 1/4 the oil pressure a main bearing would get.

 

It is correct, and I disagree it has more an effect to shifting than you think you know it does. It is not just the weight of the clutch disk/s but the whole rotating assembly and I am not talking about just the effect a heavier rotating assembly has on condition after disengagement but also on the condition before the disengagement, and the condition during disengagement-(from the time you put your foot on the clutch until the disk/s disengage). As these 3 conditions are interrelated by sharing the same rotating parts, so is their effect on each other, and by effect I mean stored energy that passes from the crank-pistons-rods, to flywheel to disk/s and finally to the input shaft of the gearbox. The heavier a part the more angular momentum (the tendency of a rotating object to keep on spinning) it has, thus the more energy it has/can store. So even when the third condition is in progress, the one where the gearbox carries only the weight of the disk/s as you said, it is not the case as it also carries all that stored energy that was passed on to it by the rest of the parts during the previous conditions. If you shave weight only from the disk/s you will only be doing just a part of the job as you will only manage to get less transfered/stored energy saved on the disk/s but the previous amount of that stored energy will be intact. The point is to be able to reduce to the minimum the whole amount of transfered/stored energy before it reaches the clutch disk/s and in turn the gearbox. Hence why lighter gearbox parts create better shifting conditions and not just of course, other advantages are in action too.

I agree on the part of "how well the pressure plate releases".







Marios

 

The article is just a short reference on main grooved bearings, and why bearings are grooved, I never said it has anything to do with thrust bearings. If you re-read my post on the matter you will see that I write and refer to crank bearings not thrust ones. Yes the thrust ones get much less oil pressure than the mains.


Thrust bearings do not have a groove, main ones do, I was discussing/explaining the fact of why mitsi designed the main bearing and groove the way they did and that the specific design has nothing to do with the clutch system either of the pull or push type as this was the point I wanted to stress.






Marios

 

show us some tech to what you are saying. I have tried some 50 different clutches personally. and have built over 100 4g3 engines and transmissions. I am quite certain from my experience what i say it true. in short the clutch disc is not connect to the engine during the shifting process. the only way it would be connected if the pressure plate, flywheel, or disc was warped and dragging. in that case the revs of the engine would have an effect. but with a properly working clutch the revs of engine has no effect.

FOR INSTANCE lightening the clutch disc by 25% improves high RPM shifting by about 500RPM. lightening the flywheel by 50% has ZERO effect on high RPM shifting. these are direct back to back test no other changes that I have tried in my own cars.

what You are saying is simply not true.

 

We will agree to disagree then, if you are conveinced that what I am saying it is not true then I have no way to make you believe the opposite. I have seen and done what I have described above enough times to know that it is as I say it is, and my experience does not include only evos or jdm cars. My last experiment of this was on my personal evo, which I have had it 12 years and in those years I have changed enough different clutch setups. The applied of what I said previously in action gave me as I expected and was aware off the results I was after. I was using a certain clutch system and revving to 9.8K rpm, which gave me troubles, I could not shift as fast as I wanted to at that rpm point of shifting, where in lower rpm points shifting was fine, also pressure plate was not the problem. Then I chose to use different parts, which I modified accordingly in order to be able to alleviate the issue, in fact the friction disks I kept the same just replaced them with new ones but the flywheel was one of the major changes, to a lighter one. Those issues not only disappeared from the first time I shifted but never had an issue since then. I use a twin disk push style clutch system.





If you wish to see in applied form and/or study in more depth and detail of what I said as simply as I could, you can check technology related to F1, or as I am greek-cypriot and know these guys and what they do, you can check out extreme tuners they have some posted photos I believe of lighter and specifically designed 4g63 rotating assembly including the clutch system which they have put in use with very good results.


I have no other way of showing you what I mean, unless you were in my car before and after the changes to see the difference.







Marios

 

you description of changes you made are vague at best. the resulting change to better shifting could have been for any number of reasons not related to changing the engine parts. yeah, no point in a discussing farther.

 

And such was my intention. I did specify that one of the major changes was the a lighter flywheel along with a modified lighter clutch system while the disks were kept the same as the previous set I was using on a previous setup which gave me troubles with shifting at 9,8K rpm. Since you wish to know a bit more, I changed engine internals with lighter modified parts, knowledge does not come easy, and although in general I choose to share a lot from what I have learned and still learning there are some things which I choose to keep for myself. The reason the shifting issue went away at 9,8K was gone was due to the lighter rotating assembly no other reason was there.








Marios

 

definitely best to keep that stuff to yourself. I prefer to lead readers in the correct direction with good repeatable data.

 

The weight of the flywheel and crank has nothing to do with how the car shifts. IF it does, your clutch is dragging and that issue needs to be addressed as the synchronizers are only designed to slow the input assembly, and the clutch disk. The only thing attached to and/or affecting the input shaft with the clutch disengaged is the clutch disc and its weight/MOI , and the weight of the input shaft itself, nothing else.