SB Comfort Clutch VS BOP Soft Start Spring

[Seavey82]

I am interested in rather or not the smaller rollers in the SB clutch kit are worth the 170.00 price tag compared to the BOP soft start spring for 35.00. I understand rollers are expensive but what is the advantage besides lowering engagement a bit more than just the spring would do by itself. I have also read that smaller rollers may affect back-shift somewhat and would lower RPM of the shift range.

I emailed BOP asking this and he instantly got back to me with a quick response stating he was able to get the engagement down enough and did not see the need for smaller rollers. (Thanks for the quick response!!!)

I also contacted SB via phone and he stated his kit is better, never really had time to explain exactly why "he sounded busy and had phone connection problems" he stated that there is more grip force with the rollers at low RPM and I would get more power throughout and more top end. As for the quite kit SB offers with the kit I really don't see the need as its not the clutch making the noise its the stub shaft.

Bone stock on the XTX 1.75 I see 102 on the speedo consistently on the rail bed. I do not want to lose any speed or grunt the nytro has but would be nice to have smoother engagement. I did see that Yamaha made some primary spring changes starting in 2011 and now use BL-P-BL, in the 2010 -2009 Y-GR-Y. So maybe engagement did get smoother over the years.

I have read great reviews on both. I have read some mixed reviews on the SB kit where people lost RPM and top end and removed the kit and got there speed back. What are your experiences and thoughts on the smaller rollers.

Decided to go with BOP but just curious.

 

[jimbur]

I've got 3 machines with Travis' softer spring. We really like it, no ill side effects. I'm sure the SB kit is nice too but like you all i wanted was some smooth response.

 

[Hooray!]

I went with the SB quiet clutch (rollers, primary spring, anti-knock washers), the SB front steering "pins", the SB steering washer, the SB air box breathers, the SB rear transfer rod shaft spacers and the SB tunnel block off. Every product is well thought out and has performed as expected and better. I like the SB story and he did all the trial and error so a few extra dollars for the parts I am ok with and yes agree you can buy several of the items by raw part for less but I like the idea of supporting those that support our Nytros. Many of the SB parts are custom as well and not off the shelf. I bought my WRP seat and clutch weights from Travis, he also does a great job, thinking about his dual fan kit this year. Related to the SB quiet clutch, his rollers, spring and roller washers quieted all the rattles down, makes for a lower RPM smooth engagement with little effect on the top end. Might be my imagination but I think I lost 2mph off my top end when I did the quiet clutch and then gained back 3-4mph with the air box breathers. I also polished the sheaves, put on a new belt and changed my skis... Can't go wrong with SB kits or BOP kits, thanks to both for all your Nytro enthusiasm as well as all the other guys here that still support improving these great sleds.

 

[Seavey82]

I've got 3 machines with Travis' softer spring. We really like it, no ill side effects. I'm sure the SB kit is nice too but like you all i wanted was some smooth response.

Great to hear!! No ill side effects that was my concern!!

 

[Teamblue4]

I went with the SB kit also, for the quality and the time Chris spent talking to me about it. I installed the bop spring did nothing for me and never got a response back from them.

 

[Seavey82]

Teamblue4 could you give me some insight on the purpose of the smaller rollers since you spoke to Chris about it ?

 

[Hooray!]

Teamblue4 could you give me some insight on the purpose of the smaller rollers since you spoke to Chris about it ?

On page 7 of my front end plus rebuild thread I documented my SB clutch update, smaller rollers reduce start up RPM from 4200 to 2900. My post:

"Primary clutch assembly night... Longer explanation as lots of details. First, I want to thank Chris Schmidt at Schmidt Brothers (http://www.schmidtbrosmotorsports.com/) for being there EVERY time I call... he may be on the other line or wrenching but damn he answers every call... thanks. I was in the garage about to install the SB quiet clutch and SB comfort clutch kits and wanted to be clear on where each shim on the flyweights and rollers go. Pics show below how they install but all important to get right. The SB instructions note turn the primary clutch counter-clockwise ONLY (direction of engine travel - as you may or may not know, NEVER turn the primary clockwise as you will detension the chain on the other side of the engine potentially skipping a tooth in the process and introducing your piston to a friendly valve encounter... resulting in a top end rebuild and maybe some pistons to add fun to the party) so you rotate the primary only CCW to bring the bolt holding the rollers and the bolt holding the flyweights to a vertical orientation (between the two clutches), nuts pointing up so it is easier to stack his shims / washers on the bolt - pin - roller / flyweight stack. On the rollers, the SB comfort clutch kit includes new smaller diameter rollers so the launch RPM drops from 4200 to 2900. The SB rollers are provided complete, outer roller, inner bushing and if you price out the Yamaha standard size rollers and bushings they are more expensive than the SB substitute. This combined with a softer spring engages the clutch at less RPM yet still inside the engine's torque curve thanks to our RX1 triple motors and their low end grunt. The SB quiet clutch shim kit provides one slightly wider (white) shim replacing the right side flyweight washer (see pics). This takes up any play in the flyweights between the casting mount points of the primary clutch. My original flyweights (8000+ miles) had nice grooves worn in them (see earlier thread pics) so I sourced some new pulls from Barn of Parts (great deal, saved 40%, thanks there), interesting the new ones had virtually the same profile as the old except for a noticeable depression in the mid section. Worth going new with the balance of my rebuild IMO; after installation with the SB shims two of the three flyweights still moved freely but with tension (my old ones and yours likely flip around if you push them up and down with your finger). Thee third was actually "snug" as Chris notes but not "tight". You can see in the pics I ran some 240 sandpaper over the flyweight faces to clean them up perfectly of any mfg blemishes as there is no lubricant on the rollers / weights. I wondered about spraying some of the Thurst adhesive grease on the rollers and weight faces as that is super thin synthetic barrier, not sure if that is a good idea or not. The SB Quiet Clutch kit includes seven thin black washer / shims that you put around the roller pin, between the casting and the bolt head and casting and nut (see pic). Make sure the pin butts against the bolt head or nut face and the washer / shim is compressed between them and the casting, yet still around the pin. If it it between the pin and the bolt/nut face it will be squeezed between them and deform out as you tighten things. If the bolt head end does not take up play, you can add a second one behind the nut. I had enough play to put the one under the nut too and this one requires careful placement to make sure the pin buts the nut face (metal to metal) and does not pinch the washer / shim as there is only a few hundredths (maybe thousands) to work with as the nut compresses down against the pin. Hard to explain in words... Final product, hydraulic tight, no play, no noise... great job Chris. Final comment on this, I noticed the fiberglass looking liner / bushing for the primary clutch shaft on mine had some wear through the first layer (see pic). I suppose this can be replaced but wonder if this is normal, seems like an unlubricated spinning shaft in a fabric like bushing... anyone else seen this?"

 

[Seavey82]

Wow Hooray lots of details thanks. Guess my question was: what is the need for the smaller diameter rollers? What do they do? what are the advantages and disadvantages? I know you can lower RPM engagement with just the spring so why the rollers. I would think rollers may benefit a RT X more than an XTX as it reduces back-shift. That may be what he is trying to accomplish is get rid of the engine breaking. I actually like the engine breaking on the trail so I'm not on the break constantly I can see where engine breaking would suck in Powder.

 

[Hooray!]

Wow Hooray lots of details thanks. Guess my question was: what is the need for the smaller diameter rollers? What do they do? what are the advantages and disadvantages? I know you can lower RPM engagement with just the spring so why the rollers. I would think rollers may benefit a RT X more than an XTX as it reduces back-shift. That may be what he is trying to accomplish is get rid of the engine breaking. I actually like the engine breaking on the trail so I'm not on the break constantly I can see where engine breaking would suck in Powder.

My understanding is the smaller roller in conjunction with the right spring and fly weights makes things work well at low rpm and not give up,anything at higher rpm. Some here can confirm but smaller rollers is for top end I believe. I can call Chris at SB, he told me originally. Also that all smaller rollers are not equal. His system is rolling strong after 3000 miles for me.