RC45 SUSPENSION TUNING
The RC45 as stock is very good for the road. As with everything though, it can be improved upon.
First thing's first though, always make sure both the front forks and rear shock absorber are in good condition, with fresh oil and no leaks.
The RC45 is very low at the rear, which makes the steering lazy but increases on-road stability. Improvements in handing can be made by either fitting a spacer under the top shock linkage mount or by fitting a HRC ride height adjuster.
If using the standard rear shock it is also required that the HRC “B” linkage is used to allow clearance between the shock and the linkage on full extension.
HRC and Öhlins offer a number of different spring for the standard front forks.
REAR SHOCKS
The most common shock to be fitted to the RC45 is the Öhlins. This comes equipped with ride height adjustment and does not need the HRC adjuster or linkage. This fits the standard linkage and swinging arm.
The second is the SBK Öhlins shock and linkage kit. This replaces the stock linkage with an Öhlins designed unit as well as using a different Öhlins shock. This is the better of the two Öhlins arrangements available but does have its drawbacks. First the SBK linkage can not be used with a HRC swinging arm unless both the linkage and swingarm are re-machined. This linkage also nearly always fouls both a HRC exhaust system and the Yoshimura exhaust systems.
The final option is the HRC Showa shock. This can only be installed when used with the HRC swinging arm and requires the use of the HRC “A” shock linkage, tie rods and ride hight adjuster.
SWINGING ARMS
Five types of swing arms were made for the RC45. Four of these being available to buy in the HRC kits.
- The stock arm.
In 1994 HRC produced a strengthening kit for this arm. It included a large alloy plate to be welded to the arm. In stock form this arm can be used with the stock shock and linkages as well as the SBK Öhlins shock and linkages. It can also retain the standard rear axel and rear brake set up. This swinging arm only has one rear hub pinch bolt.
- 1995 spec HRC
This can only be used with the standard shock and linkages or the HRC “A” kit shock and linkage. As stated above, to use the Öhlins SBK shock and linkage the arm and linkage must be re-machined. This arm also allows the use of the stock rear brake and comes with two rear hub pinch bolts
- 1996 spec HRC
This is identical to the ’95 item but had the rear brake torque arm boss relocated meaning it can not be used with the standard rear brake set up and must be used with either aftermarket parts or the HRC “A” kit rear axel, disk and calliper.
- 1997 spec HRC
Two ’97 spec arms were produced. The first being identical to the ’96 item the second only have the provision for the HRC “A” kit linkage rather than both the “A” kit and stock linkages.
- HRC Works dual sided arm.
Only ever a factory part, quite rare to find and must be used with the HRC factory shock and linkage.
FRONT FORKS
Both Öhlins and HRC make front fork springs for the standard forks. The most commonly fitted are the Öhlins.
Öhlins also make direct replacement Road and Track forks designed to use all the standard hardware such as mudguard (fender) and wheels. These can be fitted with the stock yokes and clipons
HRC front forks were made by Showa. These can not be fitted using the standard parts and require either the HRC yokes or the standard yokes to be re-machined. The standard yoke and HRC yoke also have a different offset. These forks also require the use of a HRC spindle and the 40mm pitch Brembo callipers.
HRC BASIC SETTINGS
| Standard Showa forks | |
| Fork projection through yokes | 10.0mm |
| Spring weight | 0.9kgf/mm |
| Spring preload adjuster height | 18mm |
| Oil level | 90.0mm (445cc) |
| Rebound damping | 1 click back from maximum |
| Compression damping | 5 clicks back from maximum |
| Standard Showa rear shock | |
| Ride height extension | 9.0mm |
| Spring weight | 17.0 kgf/mm |
| Rebound damping | ¼ turn back from maximum |
| Compression damping | 12 clicks back from maximum |
