| Author | Message | ||
     Ericz |
I have been researching clutch upgrade options and have looked at every aftermarket kit specifically marketed toward XB models. I have only found clutch friction plate kits and various stiffer clutch diaphragm springs that will drop into the stock XB clutch basket and hub. I have run Barnett's carbon fiber plate kit, which held up to ~140hp and ~120 ft-lbs, and then added the "competition" Rivera diaphragm spring (the stiffest available), which has held up to the recent ~190hp and ~150 ft-lbs. I was not able to run with the latest power for too long, so I can't say for sure how long the Barnett plate/Rivera spring combo would have lasted. My current motor build will be putting out significantly more power and I don't want to rely on the current clutch setup to hold up, so I have been looking into other options. If you have a 2004-2011 Sportster, you have several appealing options that "don't fit" XB models, which is true....to a point. I bought a clutch assembly from a 2007 Sportster to compare with my XB clutch. After a visual inspection, they are significantly different, but I still saw a light at the end of the tunnel. I'll begin with the clutch baskets. The XB basket is a "sprung" assembly, which has 6 coil springs that help to absorb drivetrain shock between the primary chain and the transmission gears. The Sportster basket is solid or "unsprung." While both work well in their respective motorcycles, the XB basket is a bit heavier due to the added weight of the springs. Another difference between the two is the type of bearing used to support the basket. The XB basket uses a slim roller bearing that allows the hub to be removed from the basket by hand. The Sportster basket uses a ball bearing, which requires that the hub be pressed in and out of the basket. The XB and Sportster basket share the same 57 tooth 3-row primary sprocket and 78 tooth starter ring gear. The clutch hubs and packs are a bit different too. The XB hub is designed to use a conical spring that sits inside a unique(thinner) inner-most friction plate. The Sportster has a uniform friction plate size and incorporates a riveted dampening plate in the middle of the stack. It is common for Sportster clutch upgrades to eliminate the damper plate and replace it with additional friction and steel plates. Now to the simplest of differences. With the sprung basket, the XB clutch assemblies use a spacing washer between the transmission mainshaft bearing and the clutch hub splines. This spacer is required for the roller bearing to properly support the basket, to "shim" the basket preventing it from shifting side to side on the hub, and to ensure proper clearance and alignment of the primary sprocket and ring gear. The Sportster basket relies on the press fit of the hub in the support bearing along with circlips on either side to prevent shifting, and does not use a spacing washer between the mainshaft bearing and clutch hub splines. What this means for an XB: A 2004-2011 Sportster clutch will work in an XB primary if you remove the spacing washer used with the XB clutch. Yay! This also means that ALL Sportster upgrade options become a reality for XB models! You just have to run a basket designed for a Sportster without the spacing washer. Baskets: Stock 2004-2011 Sportster http://evoindusa.com/mtrcycle/index.php?main_page= product_info&cPath=1_5_21&products_id=17&zenid=d81 ba8bb73c22d04e288c596d4488e71 Upgraded Clutch Hubs: http://evoindusa.com/mtrcycle/index.php?main_page= product_info&cPath=1_5_2&products_id=3 http://www.barnettclutches.com/products/scorpion_c lutch_components.aspx?cat_id=1&type=SP&prod_id=5 Here are some pics of the stock components:         | ||
| Teeps |
I have a question; does the throw out mechanism push or pull the pressure plate? Or, Can a hydraulic slave cylinder (Ducati style) be adapted to work on the Buell clutch? | ||
| Bike_pilot |
Awesome research! An internal, direct slave would be cool - a better setup than the external magura design. | ||
| Ericz |
The ball/ramp mechanism pulls the pressure plate out. | ||
| Blake |
Too cool Eric! Am really interested in your next turbo build. Scary big power you're chasing for the old V-Twin. I dig it! | ||
| Fast1075 |
Does anybody make a lockup clutch?? it would have easy lever pull at low rpm, and no slip at all at high rpm. | ||
| Wolfridgerider |
 clutch is slipping on my Uly... Thanks! | ||
| Ericz |
AIM makes a centrifugal weighted clutch for the Sportsters. It looks like it would be a tight fit in the XB primary cover though. Here is a link: http://www.aim-tamachi.com/home.php?cat=19 Just to be clear, the factory XB clutch holds plenty of power, and upgrading just the friction plates provides plenty of grip for most built motors. So, unless you like to spend money, the simple upgrades would be the best option. Swapping to a Sportster clutch basket would only be a good idea if you are trying to push 150+hp. | ||
| Sifo |
Nice info you've figured out. I wonder about using stronger diaphragm springs though. I know a number of folks have had failures of the primary case from the stress of the clutch mechanism. It seems to me that a stronger spring may be asking for trouble in this area. I'm not familiar enough with the problem to know how difficult it would be to possibly add material to beef up the area that fails. | ||
| Ericz |
The lip on my primary cover started to crack after upgrading to the stiffer diaphragm spring but I caught it before it broke completely. A good bead of weld around the back side of that edge has reinforced it enough to hold up to the increased force for quite a while. That's one solution I have experience with. | ||
| Teeps |
Ericz Posted on Friday, October 21, 2011 The ball/ramp mechanism pulls the pressure plate out. I thought so. Guess that eliminates a "proper" hydraulic clutch actuator. The Magura setup is no better, IMO, than a cable. As the same inherent weakness is still present with the case flange... | ||
| Bike_pilot |
I dunno about that - its better than a cable in that you eliminate the cable friction and cables don't work well for long in cold, wet weather. It would be entirely possible to make a hydro slave that pulls, i'm just not aware of any off-the-self slaves so configured. I'm a bit surprised that with as many sportsters are out there that no one makes a proper hydro clutch setup. Maybe sporty riders are more interested in shiny stuff than functional bits  | ||
| Greg_e |
There are dual action hydraulic cylinders in all sizes so I would assume there are also pull cylinders in all sizes if you start looking around a hydraulic actuators. You could always you a dual action and just have a bottle of fluid or extra hose full of fluid on the free side, might even get away with air on the free side. | ||
| Ducxl |
Back in the day when i built a Harley XL these people had interesting solutions to weak clutch assemblies>>Bandit Machine Works A Mr. McGee was in charge and very informative.He wanted to convert my Xl clutch to a big twin clutch.Just saying...while i do not think it can be done reliably.It CAN be done. | ||
| Cergun |
Ericz, Great info. I have a question about that compatibility findings in your post. Can I use a "XB" Clutch basket on a 2006 sportster with just adding the washer? |
