Well, my original RS Nytro clutch finally hit 40K KM or about 24K miles. Basically, everything needs to be replaced and the shives are wearing so I decided to go with a new Power Bloc PB-80 model 1100-0222 primary clutch after reading Redbeard’s report on his Vec and Apex (thanks for that). The first thing that I noticed when ordering is that CV Tech has the same calibration for all 973 carbed motors regardless of the year or model of sled while Yamaha lists 3 or 4 different calibrations. However, the new clutch came with 9 extra weights to aid in fine tuning which was good to see. Price was $500 CDN plus $15 shipping. I also ordered the clutch holding tool which set me back another $29 and picked up a new OEM belt.
To remove the old clutch, I used the famed “water trick”. Essentially an M18 X 1.5 bolt with a few wraps of Teflon tape on the threads. After removing the primary bolt, I put the sled on its side and filled the bolt hole to within 1” of the clutch face with water, threaded in the M18 bolt and started cranking and POP, it came right off! It was a lot easier than what I was expecting. I used a cloth wrapped bar through the clutch openings to keep it from turning.
Installing the new clutch was dead simple using a 1/2" torque wrench and the CV Tech holding tool. Torque specs are Step 1: Tighten the CV Tech supplied bolt using the supplied crown washer to 85 ft-lb. Step 2: loosen the bolt and retighten to 43 ft-lb. It’s worth noting that the supplied bolt is not a metric bolt but is a standard ½” fine thread grade 8 bolt. I read some threads on here where people were concerned about this but personally I don’t think it’s an issue given how close these threads actually are over the length of thread that are actually used.
Testing the clutches on the stand looked good. Shifting was very smooth, back-shift was quick it seemed to shift out nicely. I left the new primary with the stock calibration and the secondary stock at 3-3 wrap and stock spring. Bushings, slides and spring were all changed last year. I’ll be testing this setup over the weekend and will report back with the results and any calibration change considerations.
A couple of things worth noting: I swapped out the skid to a 136 Mono 2 and stretched it to 144". The track is a 1.22 Ice Attack and the gearing was changed from 21/40 to 22/40. I do a lot of big trails which is why I geared up a bit.
Something that I forgot to mention. The clutch "clack clack clack" has been reduced by about 90%! Having said that, any clutch with 40K KM is going to clack more than normal.
Clutch installed with new belt:
Clutch holding tool, extra weights and the M18 X 1.5 bolt for removing the old clutch:
To remove the old clutch, I used the famed “water trick”. Essentially an M18 X 1.5 bolt with a few wraps of Teflon tape on the threads. After removing the primary bolt, I put the sled on its side and filled the bolt hole to within 1” of the clutch face with water, threaded in the M18 bolt and started cranking and POP, it came right off! It was a lot easier than what I was expecting. I used a cloth wrapped bar through the clutch openings to keep it from turning.
Installing the new clutch was dead simple using a 1/2" torque wrench and the CV Tech holding tool. Torque specs are Step 1: Tighten the CV Tech supplied bolt using the supplied crown washer to 85 ft-lb. Step 2: loosen the bolt and retighten to 43 ft-lb. It’s worth noting that the supplied bolt is not a metric bolt but is a standard ½” fine thread grade 8 bolt. I read some threads on here where people were concerned about this but personally I don’t think it’s an issue given how close these threads actually are over the length of thread that are actually used.
Testing the clutches on the stand looked good. Shifting was very smooth, back-shift was quick it seemed to shift out nicely. I left the new primary with the stock calibration and the secondary stock at 3-3 wrap and stock spring. Bushings, slides and spring were all changed last year. I’ll be testing this setup over the weekend and will report back with the results and any calibration change considerations.
A couple of things worth noting: I swapped out the skid to a 136 Mono 2 and stretched it to 144". The track is a 1.22 Ice Attack and the gearing was changed from 21/40 to 22/40. I do a lot of big trails which is why I geared up a bit.
Something that I forgot to mention. The clutch "clack clack clack" has been reduced by about 90%! Having said that, any clutch with 40K KM is going to clack more than normal.
Clutch installed with new belt:
Clutch holding tool, extra weights and the M18 X 1.5 bolt for removing the old clutch:
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