Soft Start Clutching Primary Spring Review

[stingray719]

I had some doubts about the new primary spring from Barn Of Parts as we had such good results from the GWG Yamaha spring. But I was pleasantly surprised after testing. On our test machine I removed the GWG and left in the 7mm shim and it lowered the engagement rate about 1k rpm (3800 to 2700). Ok, that's great but what about mid and top rpm change? I didn't do a scientific test but I could not tell any difference by seat of the pants, and racing it against our other Viper the difference was small enough it could have been conditions.

So the question then is how will this spring do on trail sleds that do not use as many shims as I do? Not sure as our Vipers running high country we put a lot more shim in, but at $26.00 for the spring it looks like a safe bet.

I just ordered another spring to put in our blue Viper.

http://www.barnofparts.com/Soft-Start-Clutching-NEW-.html

 

[tapex_07]

So what's the rate? The preload must be way lower to drop that much!

 

[STAIN]

I have emailed twice with parts request with no answer......?????

 

[titanrcr]

So what's the rate? The preload must be way lower to drop that much!

The rate needs to be very high if it still gets to a respectable shift speed.

 

[stingray719]

So what's the rate? The preload must be way lower to drop that much!

It is not listed, but my best guess would be very near the GWG judging by the performance.

 

[tapex_07]

Gotcha.
Overall are you pretty happy with it Sting?

 

[aquaticlaker]

Here is a list of springs and rates from Yamaha. You guys most likely can figure out which one of these is it.

http://www.totallyamaha.com/snowmobiles/aaTECH/Clutchparts/stdclutchcomponents.htm

 

[stingray719]

Gotcha.
Overall are you pretty happy with it Sting?

I ordered another soft touch spring for our second Viper, I think this spring is awesome.

 

[rebmo]

Thanks for the reviews. I ordered a soft start spring for my 2015 viper r-tx-dx. I was very disappointed with the jerky starts on my sled and surprised Yamaha would think anyone would like that. So, looking forward to a fix on this awkward jerky clutch issue. I'm just one of those folks that likes a smooth take off and not a jolt that will eventually amount to unnecessary wear on me and my sled drive components.

Is install just removing the primary clutch cover (6 screws), swapping the spring, and replacing the cover (6 screws)?

Thanks

 

[hibshman25]

Thanks for the reviews. I ordered a soft start spring for my 2015 viper r-tx-dx. I was very disappointed with the jerky starts on my sled and surprised Yamaha would think anyone would like that. So, looking forward to a fix on this awkward jerky clutch issue. I'm just one of those folks that likes a smooth take off and not a jolt that will eventually amount to unnecessary wear on me and my sled drive components.

Is install just removing the primary clutch cover (6 screws), swapping the spring, and replacing the cover (6 screws)?

Thanks

Before you remove the cover take a marker and mark the cover and sliding sheave with an x on one of the lobes which contain the sets of two bolts. There are internal marks cast into each piece but its easier to just mark outside if you are not familiar with where the "x" marks are cast into the two pieces.

It is as simple as just removing the 6 screws, swapping the spring, and then re installing the cover.

 

[rebmo]

Thanks for the install info and reminder on the alignment X.

 

[titanrcr]

Thanks for the reviews. I ordered a soft start spring for my 2015 viper r-tx-dx. I was very disappointed with the jerky starts on my sled and surprised Yamaha would think anyone would like that. So, looking forward to a fix on this awkward jerky clutch issue. I'm just one of those folks that likes a smooth take off and not a jolt that will eventually amount to unnecessary wear on me and my sled drive components.

Is install just removing the primary clutch cover (6 screws), swapping the spring, and replacing the cover (6 screws)?

Thanks

If the sled is jerky on take off you should be looking at your belt deflection as well.

 

[rebmo]

My "dislike" is that the engagement is at higher rpms and not gradual acceleration from lower rpms like most sleds I've driven. Engagement at the higher rpms (mid 3k range) results in a jerky start from a standing stop. I drove a 4-stroke turbocat this winter and it was butter smooth from start to 10mph and actually to 103mph when I let off on a lake. When I got back on mine it felt like it launched into a start rather than transition. If there is an issue with belt deflection (not exactly sure what you are suggesting please explain) I'd be glad to check it out. I'm not sure what to check.

Thanks, I'd like the sled a lot more if I could get that resolved.

 

[stingray719]

My "dislike" is that the engagement is at higher rpms and not gradual acceleration from lower rpms like most sleds I've driven. Engagement at the higher rpms (mid 3k range) results in a jerky start from a standing stop. I drove a 4-stroke turbocat this winter and it was butter smooth from start to 10mph and actually to 103mph when I let off on a lake. When I got back on mine it felt like it launched into a start rather than transition. If there is an issue with belt deflection (not exactly sure what you are suggesting please explain) I'd be glad to check it out. I'm not sure what to check.

Thanks, I'd like the sled a lot more if I could get that resolved.

Most of bad take off is caused by the clutch weights ramp, it has a bump made for 2 strokes and causes a high rev/jerk when taking off. If you buy 8fp weights from Barn of Parts (he has them used) and primary shims from Thunder products and 3.6 rivets from your favorite vendor you then have flat profile weights and a very low very smooth take off like you mentioned on your friends sled. COTC you have seen mentioned are the above described parts. You can still get a much smoother take off with just the spring, but the rest of the kit is really the best fix.

Soft touch spring
primary clutch shims (4mm for mid range 6mm for top speed)
8fp weights
3.6 rivets for 8fp weights


This is described in the "Frequently Asked Questions at the top of this forum list under http://www.ty4stroke.com/threads/clutching-on-the-cheap.129971/



By the way, my Viper engages at 2800 and takes off smooth as glass.

 

[titanrcr]

The lower engagement rpm will certainly help but even still, the belt deflection needs to set correctly to have a smooth start. If you are unsure of how to set the belt deflection you could refer to the owners manual.