Loading added weight on MDS clutch weights... where?

[Frostbite]

I got my MDS weights to work well at the end of last season on my M8. When I finally got the sled pulling the kind of RPM (8,200) I was looking for, it was in spring snow with a foot or so of powder on top.

This fall I swapped my 2.25' Powerclaw for a 2.6" Powerclaw and figured I would lose some RPM up top while climbing but, I sure didn't figure I would lose 6-700 RPM. So, I went to a higher total force primary spring and I am lightening up the weight in the tips of the clutch weights to reach the RPM I need.

However, back in my days of using Heavy Hitter clutch weights. Loading the heel affected the bottom end grunt of the sled, loading the middle hole regulated your mid range pull and the weight in the tips, of course affected the shift speed.

My question is: The inner holes on the (there are only two) MDS weights are empty. As I lighten my tips, my RPMs are increasing but, it sure feels like the amount of pull in the mid range is decreasing. I am almost thinking I should leave the outer (tips) empty and load the inner hole to reach my RPM target. I spoke with Steve about this idea on the phone on the day before Christmas Eve (what a great guy to return a call on a Sunday afternoon) and he said some guys had played with this idea. Have any of you tried this on the MDS weights? What were the results?

 

[WyoBoy1000]

So far I like the tip loaded as much as possible, but if you can reduce the springs in the primary and secondary there may be an advantage, I had mine working well with no shims in secondary.
But like always check your secondary bushings, I can't imagine loosing that much rpm. I think it might be wise to drop the helix angle.

 

[Frostbite]

Thank as always WyomingBoy, that's the scary part, I am using a 36 degree helix. I hadn't cleaned my clutches before the season started (too busy hunting) and my secondary bushing is a bit sloppy as well so, it could be a big part of the problem.

Yes, seemingly there would be more centrifugal force generated on the belt by having the weight further from the fulcrum. I'm just thinking back to my four stroke days and the middle hole was the key to the sled pulling or just making RPM. If I lightened the middle hole up I could hit my shift speed target but, the sled just seemed to rev and not pull nearly as hard. I really try to make the motor work to pull the weight/RPM. If the engine is clutched so it can easily make RPM, it doesn't seem to pull as hard, if that makes any sense?

 

[forreboy]

rpm

You shouldn't loose any rpm at all if you have a clutches in good condition and a good setup. I switched my PC 2.25" to a CE 2.5". I didn't loose any rpm at all. Make sure your secondary clutch is in good condition. Start with loading up the tip with as much as you can until you reach 8200rpm, when you feel that it reaches 8200 you can also try to add lightest bolt to middle hole. Then you should get lot of trackspeed even from middle. What are your elevation?

 

[Frostbite]

Forreboy, thank you for the info. My secondary is in good shape except maybe my bushings. I'm not exactly sure how to tell if they are worn beyond limits. The bushings look good but, the helix is a bit sloppy as it slides through the bushing. I guess I need the measurements to know when it's bad and and an inside caliper that goes up to at least 4".

I am riding Friday so I will be able to tell if what i have done has helped.

 

[WyoBoy1000]

If your all the sudden missing the shift feel, I would be looking at the clutching binding.
No way should you loose that much with just a track, something is wrong.
did you ever change the DD bearing.

On the PC mine feels like it raps up so fast it can't be shifting yet its pulling insane track speed. I'm really impressed with how its working. You better than ever on the M.

What spring are you running.

 

[Frostbite]

I had a Speedwerx H5 Blue/White 120-310 in the primary. In the MDS weights I had the middleweight bolts and one thin washer in each tip. After pulling only 7,500-7,600 RPM I went to the (solid) shortest bolts.

In the secondary I had a Fett Brother's secondary spring with a 36 degree helix.

Now, after my trip, I have swapped to a Red/White Speedwerx H5 125/340 spring in the primary. I have one of the short (hollow) bolts in each tip.

In the secondary, I went from using a primary that had stock rollers to one with Rock Rolelrs, a 36 degree helix and the very long Skidoo secondary spring.

Hopefully, I should be pulling plenty of RPM now.

 

[WyoBoy1000]

I wont run more than about a 295 finish and like it a little lower. I would run a spring where you can run nothing in the mid, and a solid bolt in the tip with a washer or 2. Then setup the rest to hit target.

 

[Frostbite]

That's exactly what I had installed last year. A solid bolt and two washers in the tip. I removed one washer on each weight the last ride to hit 8,200 RPM and it worked, so that's why I started at the beginning of this season.

What primary spring do you recommend?

 

[WyoBoy1000]

I'm liking the polaris green/black, its got just a tad more start with same finish.

If i could find a h5 with same rate I would like to try it.

 

[Hardass]

Green black or black green?

 

[Frostbite]

If I remember correctly, the only Polaris spring I have is the 120/340. I think it is a black spring but it's shorter than a Cat spring so it feels like an even lower engagement RPM. Also, the total force feels lower as well since it's shorter. I believe it's more in your suggested 290 range. I may have another Polaris spring as well but, I would have to do an archaeological dig to find out for sure.

I added an Arctic Cat gold to the M5 when I added the Cutler secondary because the engagement was so harsh. I think it was a 75/275. That spring may give a nice engagement and with a spring shim or two, the total force needed to pull a good shift speed. I ordered another one to try in my M8 at some point.

 

[forreboy]

spring

I use purple spring 121/240
My spider is reshimmed, engage soft about 3700rpm but with instant throttle response.
Purple seems to work great on many sleds with mds

 

[kidrman]

If I remember correctly, the only Polaris spring I have is the 120/340. I think it is a black spring but it's shorter than a Cat spring so it feels like an even lower engagement RPM. Also, the total force feels lower as well since it's shorter. I believe it's more in your suggested 290 range. I may have another Polaris spring as well but, I would have to do an archaeological dig to find out for sure.

I added an Arctic Cat gold to the M5 when I added the Cutler secondary because the engagement was so harsh. I think it was a 75/275. That spring may give a nice engagement and with a spring shim or two, the total force needed to pull a good shift speed. I ordered another one to try in my M8 at some point.

Lee - I still think you should try the Speedwerx 130/300. They only make it in the steel version so I just throw it away and buy a new one each year.

See you tomorrow!!!

 

[Frostbite]

If you still have one, bring one please. I will give it a try.

However, I have high hopes for more RPM tomorrow. Maybe too many....

 

[kidrman]

I only have the one in my clutch but we could put it in yours for a couple hours.

 

[INDEEP]

How'd it go Frostbite? Good thread.

 

[Frostbite]

The engagement bog is gone with the 120/310 Speedwerx spring.

The sled just seems to like this spring for some reason.

 

[Polarisrocks]

can anyone post a pic of the difference in the profile? a side by side pic??

Thanks

 

[armey37]

The engagement bog is gone with the 120/310 Speedwerx spring.

The sled just seems to like this spring for some reason.

How much weight did you run in your MDS with your h5 120/310 spring? I ride the same elevation as you. 3,000 to 6,500ft