that is possibly your problem....it lets the space between the clutches shrink, acting like a long belt or short c2c......might just be your hang up.
CPC weights vs. Cat weights
- Thread starter pj8556
- Start date
hence my statement about rotating mass (the idea that weight distribution and specific placement over a surface area under rotation could produce more energy?)... I still believe that staying with a 68g weight moving 1 gram from heel to tip is moot. especially in a 4" circle at 8000 RPMs. Once the weight is out into max position at max RPMs the weight is the same regardless of where it initially weighed more (heel or tip) How could you measure the difference in a real world test? "feel" is about all you could say because i doubt you would get 1 foot higher on the hill... i dunno know for sure and i am open to math to prove me wrongWould be kind of fun to test one day, try cutler, factory, MTX 68g weights on three seperate pulls.
but weight for weight on a scale 68g will still be 68g no matter if you redistrubute weight to the heel or tip, thats all i was really trying to say. Good discussion though!
Ok, I gotta comment on this. Im not looking for a fight here but the further a rotating object moves out from the center in generates more force. (spin a yo-yo on a six inch string and then again with a two foot string and tell me which generates more force) Moving the weight changes the shift rate.
Second once the weight is shifted out, more weight in the tip would keep it there longer vs a heavy heel.
Third you can measure this in the field with a speed sensor and playback ability and shift force can be measured using a dyno and has been extensively by Dale Cutler and others.
So, ok 68k is 68g but you can absolutely influence the shift by moving the weight around.
I left it alone too, but you ae correct.
if you are getting mark only halfway around the clutch you have one of two problems:
1. you loaded one weight differently than the other two
2. More likely - your clutch is dying. VERY common on M7s. Stock clutch seems to only last 1500 miles or so. If you've ever had the clutch part to shim the belt to sheeve clearnace or broke the spider free or any reason, they die EVEN FASTER.
I like to butt two weights together, screw in the first weight to desired depth then screw in another short weight and lock it against the longer one...will not move that way. Even without it I've found they still stay put with the preapplied loctite.
hence my statement about rotating mass (the idea that weight distribution and specific placement over a surface area under rotation could produce more energy?)... I still believe that staying with a 68g weight moving 1 gram from heel to tip is moot. especially in a 4" circle at 8000 RPMs. Once the weight is out into max position at max RPMs the weight is the same regardless of where it initially weighed more (heel or tip) How could you measure the difference in a real world test? "feel" is about all you could say because i doubt you would get 1 foot higher on the hill... i dunno know for sure and i am open to math to prove me wrong
but weight for weight on a scale 68g will still be 68g no matter if you redistrubute weight to the heel or tip, thats all i was really trying to say. Good discussion though!
It does make a difference, I've done this exact test with the same total weight but loaded in different spots and it made a surprisingly big difference. I loaded the heal only and left the tip empty and was unable to get past 80MPH in 6inches of fluffy snow, I loaded the tip very heavy and I gained several MPH on top getting past the 80MPH mark but the launch suffered. I found the best to screw the first long weight in 1/2 way and the second shorter weight butt up against it. Gave me a good launch and upshift and retained the full top speed. I rarely mess with it now unless I go really high alt then I'll loose the shorter weight.
another thing I'd suggest is if you plan to use 74 grams then get the 70-80 gram weights, this way you'll not have to use so much of the weights and can have more places to put it.
If you get the 65-75 grammers then you'll have to load it up so much there won't be much adjustment on weither you load the tip or heal.
If you get the 65-75 grammers then you'll have to load it up so much there won't be much adjustment on weither you load the tip or heal.
Great thread, learned lots! So my question is this. CPC 65-75 wts, I have the 3/4" screw (3.17g) loaded in the heel such that it is flush with the heel of the weight- should be ~68g. Is that an OK spot for the weight to be, or "should" it be more towards the middle? Sled is a stock 06 M7 153... Can you guys elaborate on what I should be looking for and feeling on the hill?
Yes - I too left it alone (as Phatty seemed set in his ways) but you are right. But in addition to moving the weight around if you change the curve of the weight (the part that contacts the rollers) you will also influence how the weight will shift. A flatter curve (less curve) will shift more aggressivly, more curve will have a slower upshift. Today most of this is determined by the weight manufacturer but in the "old" days we used to grind flat spots and notches to change how a weight performed. This was also before the days of custom helixes, dozens of spring choices and weights in gram increments - today it is alot easier.
I also second getting the base weight as close to what you probably will need. This will allow a lot of options on placing the additional weight just where you need it.
Good discussion - the CPC weights are great but you must take the time to tune them. Once you have them dialed in you have a weight that is the best for your sled in the conditions you are in. The good news is that if conditions change, you can change the weights to match that and you are good to go.
Good Luck. Paul
i'll have ta see if i can round one up, probably wouldnt hurt to have it in there anyways.
sounds like this could be the issue as i believe i have just over 2000 miles on it and ive reshimmed it. i guess i might have to look into a new clutch sometime.
thanks for the help guys
So the theory is then that you can get different speed, force ON A SHIFT by weight distribution within a certain plane. I guess I can buy that a quicker/long shift is possible over weight distribution.
For the record, no one is fighting and im not stuck in my ways. Its been a good discussion and I am sure a lot of people besides myself are learning.
I guess the real answer would be then to take my weights out, and try arranging them in a bit different pattern and see what it tachs out at... easy enough to do!
Phatty - good stuff. Basically what you are looking for is a sled that when "pinned" it get's right to the RPM's you are shooting for and holds it on a long run (through the entire shift). If you are too heavy in the heal (but okay on the mid/tip) - sled will under rev in the beginning and climb to the correct RPM's in the end. If weight is too heavy in the mid / tip (but okay in the heal) - sled will race to the right RPM's but you will not be able to hold them on a long run. The nice thing about the cutlers is you can adjust the weight distribution whenever you want. You will find that small weight changes (and position changes) will impact your RPMs. A really nice tuning tool is a playback tachometer that shows you the RPM's on a run - that way you can concentrate on driving and look at your RPM's after the run. Keep in mind that if you really want to be picky - on any given day you may need / want to change your weights to keep your sled running at its best. Hope this helps and I did not mean to be so basic - I just don't know from what experience you are coming from. Also, this assumes secondary is set-up in the ball park and remains constant throughout your tuning of the weights. Good luck. Paul
Nice post Paul
Well said! I really do love these weights.
Well said! I really do love these weights.Your weight placement is fine. On the hill you should be looking for steady RPM within the max power range, and if you let off the throttle, they back on the throttle your RPM should jump right back up to desired power range.
If you load the tips of the weight, the sled will pull much harder, however your motor will rev slower, and your backshift will be slower.
On my 800 RMK, 58g polaris weights spin at the same rpm as TCP 62.5 lighting weights. The difference is the TCP weights have alot more curve.
hence my statement about rotating mass (the idea that weight distribution and specific placement over a surface area under rotation could produce more energy?)... I still believe that staying with a 68g weight moving 1 gram from heel to tip is moot. especially in a 4" circle at 8000 RPMs. Once the weight is out into max position at max RPMs the weight is the same regardless of where it initially weighed more (heel or tip) How could you measure the difference in a real world test? "feel" is about all you could say because i doubt you would get 1 foot higher on the hill... i dunno know for sure and i am open to math to prove me wrong
but weight for weight on a scale 68g will still be 68g no matter if you redistrubute weight to the heel or tip, thats all i was really trying to say. Good discussion though!
Just because the weights weigh the same does not mean they behave the same. For instance 73g MTX weights turn the same RPM as a 69g cat weight. Profile and where the weight is loaded makes as big of a difference as anything.
