riffer
14th September 2007, 22:06
The Suzuki RF900R was available in 4 model years: 1994 (RF900RR), 1995 (RF900RS), 1996 (RF900RT), and 1997 (RF900RV). Careful reading of either the factory service manual or the parts microfiche reveals that the design of the coupling between the engine and the alternator underwent a subtle change between the 1995 and 1996 model years. In the 1994 and 1995 years, the coupling was similar to that used on Suzuki GSX-R models of the time, a female splined receptacle built into the end of the starter-clutch shaft near a bearing held in place by a circlip. The male spline of the alternator simply mated directly with its female counterpart at the end of the starter-clutch shaft.
Suzuki Design Flaw #1: Due to the vicious tortional forces inherent to the direct coupling configuration, the 1994/5 RF900RR/S models, as well as several Suzuki GSX-R motorcycle models, would occasionally have their starter-clutch shafts break (shear). Since the shaft sits atop the transmission gearing, the mess that such a failure causes is potentially severe and expensive.
Suzuki Design Flaw #2: In an effort to remedy Design Flaw #1, a new coupling was introduced for the 1996/7 RF900RT/V models. The shaft design changed, the bearing design changed, no circlip was used, and, press fitted to the end of the shaft, a new hub was introduced into which was pressed a special generator damper with an interior female spline receptacle. Separating the inner metal splined piece of the damper from the outer metal piece is a mysterious section of black, rubber-like material. The purpose of this black damping material appears to be twofold: (a) it absorbs rotational accelerations, presumably to protect the shaft from failing à la Design Flaw #1; and (b) it acts as a weak point so that, when a failure must occur, it will occur in the damper, presumably a less expensive failure mode. In reading various accounts from many RF owners, the failure of the rubber coupling in the RF900RT/V models is far more prevalent than the more catastrophic consequence of Design Flaw #1.
Design Flaw #2 is undoubtedly the Achilles heel of all RF900RT/V motorcycles. It manifests itself typically before the bike has travelled 10,000 miles, sooner in some and later in others, depending on riding style. In cases where the failure occurs before or soon after the warranty period is over, some owners have not had to pay for the repair themselves. Others have been told by Suzuki representatives that the problem is only caused by aggressive riding; i.e., it is the rider's fault and not a Suzuki design issue!
Note: Several people on the various RF and Suzuki mailing lists have complained about a lack of information on the rubber damper/coupler in the RV and RT models in the Suzuki factory service manual. Some information does, however, exist. On pages 11-13, 11-14, and 11-15, there is specific service information on the RF900RT (1996) model's starter clutch. Given the way these manuals are written, this information naturally applies to the RF900RV (1997) model also.
If you're interested in seeing how the different parts look across the various model years, look here (first page) (http://andreas.warby.org/E3Alternator.gif) and here (second page) (http://andreas.warby.org/E4Alternator.gif) to view scans of two of the relevant microfiche slides.
Perhaps an implicit acknowledgment by Suzuki that Design Flaw #2 is really a flaw is that two of the relevant part numbers that need to be replaced due to Flaw #2 have been updated (see parts list below). Note, though, that some RF owners have reported a recurrence of the effect of Flaw #2 even after the parts have been replaced. It isn't clear, however, whether the replaced parts in those instances had updated part numbers. Also, some owners have experienced sloppy repair jobs by their mechanics, situations that could of course contribute to recurrences.
What follows isn't a How-To on this repair. This thread is simply a collection of facts, photos, and impressions intended to assist fellow RF owners in dealing with an unfortunate issue afflicting an otherwise superb piece of engineering. (Note that some owners also deem the "RF second gear problem" to be a design flaw. While it appears to occur less frequently than the alternator coupling weakness, it is another sore point in RF history.)
Parts List:
09262-25116: starter-clutch shaft bearing (alternator drive end)
22736-46E01: generator drive hub (updated from 22736-46E00)
22740-46E02: generator coupling (updated from 22740-46E01)
31156-17E00: alternator o-ring
Pics:
1. View looking down on the engine after the rear cowling, the fuel tank, the left fairing pieces, and the air box have been removed. Note that the carburetors have been separated from the engine, but the throttle and choke cables were left completely intact. Only the idle adjust screw had to be removed from its mount on the frame. Note that several breather hoses needed to be removed, and the main fuel line from the fuel pump needed to be unhooked from the fuel supply manifold on the aft side of the carb array. Also in this photo, note that the starter motor has been left in place, while the alternator was removed and placed on the frame cross-piece behind the engine (on the right of the photo). Finally, the starter-clutch cover has been removed, as well as the starter-clutch drive assembly. The little starter idle gear and its shaft, situated on the left side of the cavity under where the starter-clutch cover sits, were left in place during the work.
Important: The starter idle gear shaft has a circlip on it with two loose washers on either side. Ensure that these washers do not come off the shaft and drop down into the transmission! That would really suck.
2. An out-of-focus view of the drive end of the alternator. Note the need to clean little black pieces of rubber debris out from near the seal and under the drive splines.
3. The starter-clutch cover after removal from the engine and with most of the old liquid gasket material already removed. Note the nice little oil channel leading from the oil journal bolt hole in the top right corner to the shaft indentation at the top of the picture.
4. Holding the inner splined piece of the old damper/coupling.
Suzuki Design Flaw #1: Due to the vicious tortional forces inherent to the direct coupling configuration, the 1994/5 RF900RR/S models, as well as several Suzuki GSX-R motorcycle models, would occasionally have their starter-clutch shafts break (shear). Since the shaft sits atop the transmission gearing, the mess that such a failure causes is potentially severe and expensive.
Suzuki Design Flaw #2: In an effort to remedy Design Flaw #1, a new coupling was introduced for the 1996/7 RF900RT/V models. The shaft design changed, the bearing design changed, no circlip was used, and, press fitted to the end of the shaft, a new hub was introduced into which was pressed a special generator damper with an interior female spline receptacle. Separating the inner metal splined piece of the damper from the outer metal piece is a mysterious section of black, rubber-like material. The purpose of this black damping material appears to be twofold: (a) it absorbs rotational accelerations, presumably to protect the shaft from failing à la Design Flaw #1; and (b) it acts as a weak point so that, when a failure must occur, it will occur in the damper, presumably a less expensive failure mode. In reading various accounts from many RF owners, the failure of the rubber coupling in the RF900RT/V models is far more prevalent than the more catastrophic consequence of Design Flaw #1.
Design Flaw #2 is undoubtedly the Achilles heel of all RF900RT/V motorcycles. It manifests itself typically before the bike has travelled 10,000 miles, sooner in some and later in others, depending on riding style. In cases where the failure occurs before or soon after the warranty period is over, some owners have not had to pay for the repair themselves. Others have been told by Suzuki representatives that the problem is only caused by aggressive riding; i.e., it is the rider's fault and not a Suzuki design issue!
Note: Several people on the various RF and Suzuki mailing lists have complained about a lack of information on the rubber damper/coupler in the RV and RT models in the Suzuki factory service manual. Some information does, however, exist. On pages 11-13, 11-14, and 11-15, there is specific service information on the RF900RT (1996) model's starter clutch. Given the way these manuals are written, this information naturally applies to the RF900RV (1997) model also.
If you're interested in seeing how the different parts look across the various model years, look here (first page) (http://andreas.warby.org/E3Alternator.gif) and here (second page) (http://andreas.warby.org/E4Alternator.gif) to view scans of two of the relevant microfiche slides.
Perhaps an implicit acknowledgment by Suzuki that Design Flaw #2 is really a flaw is that two of the relevant part numbers that need to be replaced due to Flaw #2 have been updated (see parts list below). Note, though, that some RF owners have reported a recurrence of the effect of Flaw #2 even after the parts have been replaced. It isn't clear, however, whether the replaced parts in those instances had updated part numbers. Also, some owners have experienced sloppy repair jobs by their mechanics, situations that could of course contribute to recurrences.
What follows isn't a How-To on this repair. This thread is simply a collection of facts, photos, and impressions intended to assist fellow RF owners in dealing with an unfortunate issue afflicting an otherwise superb piece of engineering. (Note that some owners also deem the "RF second gear problem" to be a design flaw. While it appears to occur less frequently than the alternator coupling weakness, it is another sore point in RF history.)
Parts List:
09262-25116: starter-clutch shaft bearing (alternator drive end)
22736-46E01: generator drive hub (updated from 22736-46E00)
22740-46E02: generator coupling (updated from 22740-46E01)
31156-17E00: alternator o-ring
Pics:
1. View looking down on the engine after the rear cowling, the fuel tank, the left fairing pieces, and the air box have been removed. Note that the carburetors have been separated from the engine, but the throttle and choke cables were left completely intact. Only the idle adjust screw had to be removed from its mount on the frame. Note that several breather hoses needed to be removed, and the main fuel line from the fuel pump needed to be unhooked from the fuel supply manifold on the aft side of the carb array. Also in this photo, note that the starter motor has been left in place, while the alternator was removed and placed on the frame cross-piece behind the engine (on the right of the photo). Finally, the starter-clutch cover has been removed, as well as the starter-clutch drive assembly. The little starter idle gear and its shaft, situated on the left side of the cavity under where the starter-clutch cover sits, were left in place during the work.
Important: The starter idle gear shaft has a circlip on it with two loose washers on either side. Ensure that these washers do not come off the shaft and drop down into the transmission! That would really suck.
2. An out-of-focus view of the drive end of the alternator. Note the need to clean little black pieces of rubber debris out from near the seal and under the drive splines.
3. The starter-clutch cover after removal from the engine and with most of the old liquid gasket material already removed. Note the nice little oil channel leading from the oil journal bolt hole in the top right corner to the shaft indentation at the top of the picture.
4. Holding the inner splined piece of the old damper/coupling.