RSR BMW Clutches...Born in Racing

No that's not a BMW, it's a 139 cubic turbocharged 425 hp Harley that we race at Bonneville these days. 139 cubic inches is 2,277 cubic centimeters or about twice as big as your typical BMW. It requires a special multi-plate sintered iron clutch with a centrifugal lock up mechanism. More than 25 years ago we started turbocharging BMWs and ran into the same thing we encountered with Harleys, Kawasakis and Suzukis...double or triple the horsepower and zip goes the clutch.

Lock up mechanism, sintered iron plates with a high coefficient of friction, an outboard support bearing for the clutch, and an antiquated three part engine to primary to transmision assembly. This is what it takes to get the Bonneville Bullet down the long course at Bonneville.

What does this have to do with BMWs? Well, it shows we have the experience and the determination to take a bad design and get the job done. BMWs also have their bad points, even in stock form, and we aren't really happy unless BMWs have two to three times their rated horsepower. The science, materials and design are always interesting.

It takes experience to tackle problems and we have the experience, born out of necessity, to solve these problems.

Turbo History at RB Racing...1980's

In the early 1980's when we started turbocharging BMWs we quickly discovered three things. First, we found that the stock clutch held up well through about a 50% increase in power. Secondly, we weren't going to set any records with a stock clutch. Thirdly, we found that elevated power levels of 2x and 3x the rated horsepower required specialized clutch components.

Take a 50 horsepower Airhead and give it 90 horsepower and you were a hero on a flexi-frame, pogo fork wonder. At least you could spank a Kawasaki. Take a 70 horsepower K100 and give it 180 horsepower and you win dyno contests with your saddlebags along for the ride.

When we decided to bump the R engine up to 150 horsepower and go drag racing the clutch no longer worked. When we bumped the K100RS up to 312 horsepower the same thing happened. To run in the 10's with an airhead, or to run 206 mph with a K100RS, and 150 mph in the 1/4 mile, different clutches had to be developed. You couldn't change the basic design, or turn it into a multiplate or centrifugal lock-up, so new friction plates had to be made and stronger diaphragm springs had to be incorporated.

Customer turbo kits did not require clutch upgrades. The race bikes did. Now, all these years later, we need them again.

Dead Puppies

Destroyed male transmission splines and matching female splines on friction plate on "Oilhead" and K series clutches. No turbo, no 150 mph quarter miles, just "normal use". BMW tells you you have to pull the rear of your bike apart and lube these from time to time, maybe every 12,000 miles. Many destroy themselves at regular intervals. Major hassle and it costs well over $1,000.00 to do this because you get to replace all sorts of parts since you are already "there". In some cases in extreme use the clutch can shear apart.

There must be a better design. There is.

Slipping Clutches

Build a land yacht with a reverse, wheelbarrow handlebars, a marginal clutch, and you roll the dice. Slipping clutch in high gear. Thousands of dollars spent putting the same parts back in only to have them fail again. Maybe it's your riding style, maybe it's the design. All we know is we turbocharged ours and the clutch went south at 5 psi of boost. Seems a bit weak to us. Do we have an answer to this. Yes. But we need to see what the problem is before we engineer a solution.

You have twisted shafts. You have slipping clutches. You have seals that may fail and douse the clutch with oil. We'll deal with the first two.

Basic Design of BMW Clutches

Dry, single plate, diaphragm clutch as used on "airheads". These are low horsepower engines way, way, below 100 horsepower. It's capacity is defined by the pressure of the diaphragm spring, the surface area of the friction plates and the coefficient of friction of the assembly.

Your basic water buffalo clutch from a K100 and similar to all the later "Oilhead" R series. Same basic dry clutch with a single friction plate and a diaphragm spring. Spline problems on the R series and slippage issues on the land yacht LT's.

RSR BMW Clutches.. Street 360, Turbo Six Paw, Bonneville Four Paw

We offer three basic designs that address the limitations of the stock, unsprung, organic clutch. Sprung hubs lessen the shock to transmission splines. Kevlar and Cera-mettalic linings provide increased bite to prevent clutch slippage on bikes like the K1200LT and the R1100/1150/1200 GS series.

Finally, special solid hub racing designs for all out racing activities. Clutches have always been the weak link. Our racing heritage has forced us to address these issues. RSR BMW Clutches are available in both 17 and 24 spline variations as well as 165mm and 180mm diamters. Ceramic friction material (Cera-Metallic) and Kevlar friction material.

RSR Street 360

RSR Street 360: Six springs absorb the shock of engagement between the transmision and clutch splines. No more spline damage. Kevlar linings provide smooth clutch action and an increase in holding power of 15% above organic linings. Friction plates 60% thicker than stock. 300,000 PSI Dry Film Lubed splines. A superior clutch recommended for stock horsepower bikes. Outwears organic oem linings.

165mm and 180mm applications.

RSR Turbo Six Paw

RSR Turbo Six Paw: Six springs absorb the shock of engagement between the transmision and clutch splines. No more spline damage. Organic linings simply do not have the coefficient of friction that Cera-metallic linings have. If you need a clutch that won't slip this is your clutch.

Smooth engagement for street use. Cera-metallic linings. Six friction surfaces provide more bite than full circle organic designs. More solid engagement than organic materials but more suited for street use than three paw designs. No belleville spring (marcel) between the friction pucks. Friction plates 60% thicker than stock. A true high performance clutch recommended for applications where clutch slippage occurs in normal or heavy duty use. Turbo kit applications up to 240 hp. 180mm diameter.

Not available for 165mm applications.

RSR Turbo Four Paw

RSR Turbo Four Paw: Six springs absorb the shock of engagement between the transmision and clutch splines. No more spline damage. Organic linings simply do not have the coefficient of friction that cera-metallic linings have. If you need a clutch that won't slip this is your clutch.

Smooth engagement for street use. Cera-metallic linings. Four friction surfaces provide more bite than full circle organic designs. More solid engagement than organic materials but more suited for street use than three paw designs. No belleville spring (marcel) between the friction pucks. Friction plates 60% thicker than stock. A true high performance clutch recommended for applications where clutch slippage occurs in normal or heavy duty use. Turbo kit applications up to 240 hp. 165mm diameter.

If you want to spend $670.00 for a clutch without a sprung center you can buy one here.

RSR Bonneville Three Paw

RSR Bonneville Three Paw: Three friction plates provide more bite than the Turbo Six Paw with more abrupt engagement. Cera-metallic linings. Friction plates 60% thicker than stock. 300,000 PSI Dry Film Lubed splines. Used for race and turbo applications greater than 240 hp where more friction is required. More pressure per square inch than the six paw design. Solid, unsprung design.

For both 165mm and 180mm designs.

RSR"Dual Coat" 300,000 PSI Dry Film Spline Lube

As standard practice we apply dry film lubricant to all female RSR Clutch friction plate splines. In addition, each RSR Clutch comes with a mandatory dry film lubricant application kit to coat your male transmission splines. More than enough if you want to pull your bike apart half a dozen times in an obsessive, compulsive manner or, alternatively, if you choose to treat your special someone to a lube job.

Immune to heat and with a low coefficient of friction, the dry film lubricant, unlike traditional "spline grease", bonds to the metal and provides protection that grease alone cannot provide. The dry film lubricant is suspended in a liquid solution and will air dry. Simply clean and prepare the shaft per instructions provided and apply the dry film lubricant directly to the male transmission splines.

RSR High Temperature Grease Kit

We also provide a high temperature grease embedded with dry film media to coat the male and female splines. Same vial size as our dry film lubricant and plenty enough for multiple applications with your favorite toothbrush. The combination of the dry film bonding the clean parent metal of the male and female splines, plus the "reservoir" of the high temperature low friction grease, provides long term protection to the link between your engine and transmission.

We recommend a light coat on both your male and female splines. Remember, this is a dry clutch so you don't want blobs of grease flinging about. We simply use an old toothbrush to apply the RSR High Temperature Grease to the splines. The RSR Grease is incredibly sticky and you need a stiff brush to fully coat each groove.

We have provided a PDF Instruction on how to apply the two part system on your clutch and drive splines.

Choices

Two glass vials come with each RSR Clutch...one for the dry film lube and one for the high temperature grease. You may or may not choose to use these as old habits die hard. In fact, you can apply the 300,000 PSI dry film lubricant to your transmission splines and continue to use your favorite spline grease from BMW, Honda, or even Dupont Kratox. If you want to forgo the dry film application all together and apply your favorite "spline grease" that's your choice.

BMW's GL 261 grease is still being sold for your two wheeled masterpiece. In fact, BMW stopped using it in 1998 ago on their automotive transmission splines because it was "not suitable for prolonged exposure to high bell housing temperatures". We've got to move these refrigerators...We've got to move these colour TV's...Money for Nothing.

Clutch Alignment Tool

When you bolt down the clutch cover plate with the six special high strength bolts we provide, the clutch friction plate and the diaphragm spring must be perfectly aligned with the clutch housing and the centerline of the crankshaft. We machine this simple tool to keep things aligned so the transmission splines will slip into place. It is highly recommended that you buy the tool as it will save you endless frustration.

RSR Clutch Accessories

Part #
Description
Price
05-0200
RSR "Dual Coat" 300,000 PSI RSR Dry Film Spline Lube and RSR High Temperature Grease (Kit)
29.95
05-0201
RSR Clutch Alignment Tool 24 spline
19.95
05-0202
RSR Clutch Alignment Tool 17spline
19.95

Each RSR Clutch Kit comes with a "Dual Coat) Spline Lube (Kit). Alignment tool 05-0201 (optional) is suggested as, when you tighten down the clutch assembly, the clutch friction plate and the pressure plate has to be in perfect alignment.

"K" Bike RSR Clutch Kits

Model
Years
OEM Friction Plate
Diameter & Spline Count
RSR Street 360 Kevlar Sprung

All: $325.00

RSR Turbo Cera-Metallic 6 Paw Sprung

All: $395.00

RSR Turbo Cera-Metallic 4 Paw Sprung

All: $375.00

RSR Bonneville Cera-Metallic 3 Paw Solid

All: $375.00

K100
1989-1989
21 21 1 464 795
180mm
05-0100
05-0101
n/a
05-0102
K100LT
1986-1991
21 21 1 464 795
180mm
05-0103
05-0104
n/a
05-0105
K100RS
1983-1989
21 21 1 464 795
180mm
05-0106
05-0107
n/a
05-0108
K100RT
1989-1992
21 21 1 464 795
180mm
05-0109
05-0110
n/a
05-0111
K1
1989-1993
21 21 1 464 795
180mm
05-0112
05-0113
n/a
05-0114
K100RS 4 Valve
1989-1992
21 21 1 464 795
180mm
05-0115
05-0116
n/a
05-0117
K1100LT
21 21 1 464 795
180mm
05-0118
05-0119
n/a
05-0120
K1100RS
21 21 1 464 795
180mm
05-0121
05-0122
n/a
05-0123
K1200GT
21 21 7 670 455
165mm ; 17 Spline
05-0124
n/a
05-0125
05-0126
K1200LT
Up to 03/2004
21 21 7 670 456
180mm ; 17 Spline
05-0127
05-0128
n/a
05-0129
K1200LT
03/2004 and up
21 21 7 670 456
180mm ; 17 Spline
05-0130
05-0131
n/a
05-0132
K1200RS
1995 to 05/2001
21 21 7 670 455
165mm ; 17 Spline
05-0133
n/a
05-0134
05-0135
K1200RS
06/2001 and up
21 21 7 670 455
165mm ; 17 Spline
05-0136
n/a
05-0137
05-0138

Each RSR Clutch Kit comes with a "Dual Coat" Spline Lube (Kit). Kits also include special clutch cover bolts and hardware to mount the new clutch assembly. Alignment tool 05-0201 (optional) is suggested as, when you tighten down the clutch assembly, the clutch friction plate and the pressure plate has to be in perfect alignment.

"R" Bike (Oilhead, Hexhead) RSR Clutch Kits *

Model
Years
OEM Friction Plate #
Diameter & Spline Count
RSR Street 360 Kevlar Sprung

All $325.00

RSR Turbo Cera-Metallic 6 Paw Sprung

All $395.00

RSR Turbo Cera-Metallic 4 Paw Sprung

All $375.00

RSR Bonneville Cera-Metallic 3 Paw Solid

All $375.00

R850R
21 21 2 325 864
180mm ; 24 Spline
05-0301
05-0302
n/a
05-0303
R1100GS
21 21 2 325 864
180mm ; 24 Spline
05-0304
05-0305
n/a
05-0306
R1100R
21 21 2 325 864
180mm ; 24 Spline
05-0307
05-0308
n/a
05-0309
R1100RS
21 21 2 325 864
180mm ; 24 Spline
05-0310
05-0311
n/a
05-0312
R1100RT
21 21 2 325 864
180mm ; 24 Spline
05-0313
05-0314
n/a
05-0315
R1100S
21 21 7 670 454
165mm ; 17 Spline
05-0316
n/a
05-0317
05-0318
R1150GS/ADV
21 21 7 670 454
165mm ; 17 Spline
05-0319
n/a
05-0320
05-0321
R1150GS
21 21 7 670 454
165mm ; 17 Spline
05-0322
n/a
05-0323
05-0324
R1150R
21 21 7 670 454
165mm ; 17 Spline
05-0325
n/a
05-0326
05-0327
R1150R Rockster
21 21 7 670 454
165mm ; 17 Spline
05-0328
n/a
05-0329
05-0330
R1150RS
21 21 7 670 454
165mm ; 17 Spline
05-0331
n/a
05-0332
05-0333
R1150RT
21 21 7 670 454
165mm ; 17 Spline
05-0334
n/a
05-0335
05-0336
R1200C
1997-2003
21 21 7 670 822
165mm ; 17 Spline
05-0337
n/a
05-0338
05-0339
R1200C
2004 and up
21 21 7 670 822
165mm ; 17 Spline
05-0340
n/a
05-0341
05-0342
R1200C Independent
21 21 7 670 822
165mm ; 17 Spline
05-0343
n/a
05-0344
05-0345
R1200 Montauk
21 21 7 670 822
165mm ; 17 Spline
05-0346
n/a
05-0347
05-0348
R1200CL
21 21 7 670 822
165mm ; 17 Spline
05-0349
n/a
05-0350
05-0351
R1200GS
21 21 7 697 737
180mm ; 17 Spline
05-0352
05-0353
n/a
05-0354
R1200RS
21 21 7 697 737
180mm ; 17 Spline
05-0355
05-0356
n/a
05-0357
R1200RT
21 21 7 697 737
180mm ; 17 Spline
05-0358
05-0359
n/a
05-0360

Each RSR Clutch Kit comes with a "Dual Coat" Spline Lube (Kit). Kits also include special clutch cover bolts and hardware to mount the new clutch assembly. Alignment tool 05-0201 (optional) is suggested as, when you tighten down the clutch assembly, the clutch friction plate and the pressure plate has to be in perfect alignment.

Diaphragm Tricks

The earlier 180mm R1100 clutches have 1.75mm thick springs whereas the later model R1150GS models are 2.00mm thick. If you want a stronger clutch for the earlier models this is a good way to go. Think pressure times area. Lever pressure is about the same. Part Number 21 21 2 345 597. Study BMW part numbers long enough and you'll find enough variations to drive you crazy.

This is what we use on a R1100RT Turbo along with a 05-0034 Six Paw Turbo Clutch.

In general, you should stay with your stock diaphragm spring as this is what you feel at the lever. The way to a better clutch is through better friction materials and more aggressive designs proven in competition as well as sprung designs that insure smooth engagement and which lessen shock loads to the splines. Some people have used two diaphragm springs. We do not recommend this.

RSR BMW clutches. Born of necessity. No tricks, just logic.