DAMPING ROD GALLERY
Look for your style damping rod and follow the links for Emulator installation.

►How Emulators and Damping Rods Work

►Fitting Cartridge Emulators General Overview for Unlisted Models

►Emulator Tuning Guide

►Emulator Parts List Download (.xls)

Type 1 - Cupped-top

      Dirt and Street (most common type)
      Japanese KYB and Showa - early 70s to present

This is the most common type of damping rod on Japanese KYB and Showa forks from the early 70s to present.

The top of this damping rod is cupped. It may be round (top) or have a hex (middle) or a double hex (bottom). The hex is for a Damping Rod Holding Tool. A universal Damping Rod Holding Tool is available (TFDH 01).

Piston rings are standard.

Emulators are designed to sit in the cup on top of these damping rods. The fit does not have to be exact. The requirement is that the Emulator must cover the top opening of the damping rod completely. Move it over to the side to check for gaps.

The main fork spring holds the Emulator in place.

The only other requirement is the existing compression holes (on the bottom of the rod) must be enlarged and/or added to. The new holes should be located above the existing holes. The exact size of the holes is not important. It must have enough area to transfer control of the damping over to the Emulator.

Type 2 - Non-Cupped Top (i.e. Flat-Top, Protruding-Top).  

Japanese KYB, European Betor, Bultaco, Marzocchi, BMW, etc. from 1970s to early 80s Dirt and Street

Found  European dirt and street bikes wtih Marzocchi Forks, Ducati, Laverda, Can Am, etc. These are similar to Type 1 but at the top of the damping rod there is a boss protruding above the piston.

This style fork require adapters. Emulator Adapters may be included in the Emulator Kit , in some cases they must be purchased separately or you can fabricate your own if you have a lathe. See the Product Search for applications.

38mm Marzocchi shown. See Type 2-1 below for details.

Type 2-1 1972 Ducati 750GT

These forks have  check ball inside the rod top that must be removed. Emulator Adapter is required. Stock Piston Rings should be replaced by Race Tech Piston Rings. RT Hi-Performance Fork Springs are required as stock springs are too long and soft. 

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Type 2-2 1974 Kawasaki KX250 - 36mm KYB

This damping rod requires machining. This general style is found on many KYB 36mm Kawasaki, Suzuki, Yamaha early to late 70's

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Type 2-3 1970-79 BMW R50/75/90/100 Brembo 36mm

This fork has a check ball with spring inside the bottom that must be removed. Top portion of the protrusion of rod must be cut off at the chamfer below the outlet holes and top hex. The FEGV S3301 Emulator Kit requires custom made 35mm tall 3/4" PVC Adapter. 

The (8) existing compression holes should be drilled out to 6mm (1/4"). It is fine to maintain the existing hole pattern even though it is different than the Emulator Kit instructions in regard to orientation of the compression holes. Maintain stock hole pattern and simply enlarge the existing holes. 

MORE DETAILS...

 

Race Tech Product Applications are:

FRSP S2643xxx Fork Springs (required)

FEGV S3301 Gold Valve Emulators 

Type 2-4 1980-92 BMW R65/80/100
Flat-Top Brembo 36 & 38mm

This BMW fork has a flat top requiring an Emulator Adapter. The Piston Ring is thin and flat similar to a Shock Piston Ring.

- The 36mm Forks use FEGV S3301 Emulator Kit with FPEV AD3301 P Adapters.

- The 38mm Forks use FEGV S3501 Emulator Kit with FPEV AD3507 P Adapters. 

The Bottom-out Cone on the bottom of the Damping Rod is threaded on.

The rest of the installation is standard per the Emulator Kit instructions. A total of (6) Compression holes should be drilled, 6mm (1/4") for 36mm forks, 8mm (5/16") for 38mm forks. 

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Type 2-5 BSA & Triumph 34.5mm Forks, Early

Found on Triumph and BSA 500-650cc street as well as Scrambler models early to mid 1970s. The Hex shaped portion at the top of the rod must be removed and discarded. It un-screws from the main rod. The piston assembly should then be tightened and Loctited back onto the rod. The FEGV S3301 Emulator Kit used for these forks requires custom made 20-25mm tall 3/4" PVC Adapter to replace the top nut.

It is recommended to replace the stock o-ring with Race Tech Piston Rings FPPR xxxxx. At a minimum install a new o-ring as every one we've seen is worn.

There is typically a slot rather than compression holes at the base of these damping rods. The slot is maintained but supplemented by quantity 6 holes, 6mm (1/4") drilled 90 degrees from the stock slot.

Note that Fork Spring length is critical on these models! Stock springs cannot be used, Race Tech springs are a must! Check your stock spring length for comparison. RT springs are 425mm long. Room must be allowed for 30-40mm combined height of the Emulator and Adapter.

Custom FRSP 2550 series Fork Springs can be made if needed at the length and rate required.

 More Details...

Race Tech Product Applications are:

FRSP S2643xxx Fork Springs (required)

FEGV S3301 Gold Valve Emulators 

Type 2-6 BSA & Triumph 34.5mm Forks, Late

Alternate style found on Triumph & BSA 500-650cc street as well as Scrambler models mid to late 1970s. The Top Nut & Screw assembloy threaded onto the rod must be removed and discarded. It un-screws from the main rod. The piston assembly should then be tightened and Loctited back onto the rod. The FEGV S3301 Emulator Kit used for these forks requires custom made 20-25mm tall 3/4" PVC Adapter to replace the top nut. Thus the modification are basically the same as Type 2-5 early models.

It is recommended to replace the stock o-ring with Race Tech Piston Rings FPPR xxxxx. At a minimum install a new o-ring.

There are slots on each side of the rod, 1 upper & one lower rather than compression holes at the base of these damping rods. These slots are maintained but supplemented by quantity 6 holes, 6mm (1/4") drilled 90 degrees from the stock slots.

Note that Fork Spring length is critical on these models! Stock springs cannot be used, Race Tech springs are a must! Check your stock spring length for comparison. Race Tech springs are 425mm long. Clearance must be allowed for 30-40mm combined height of the Emulator and Adapter.

Custom FRSP 2550 series Fork Springs can be made if needed at the length and rate required.

 More Details...

Race Tech Product Applications are:

FRSP S2643xxx Fork Springs (required)

FEGV S3301 Gold Valve Emulators 

Type 2-7 Husqvarna 35 and 40mm, mid 1970s to mid 1980s

These forks are notorious for being really harsh. They have an interesting design that fills the rebound chamber around the damping rod head at the top. It is common for the Piston Rings to wear out and/or break. They require special adapters and slightly smaller Emulators than you might think.

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Type 2-8 1975 Yamaha MX250 - 34mm KYB

The Head of the Damping Rod is brazed on so there is no flat surface for the Emulator Adapter to sit. This one requires machining.

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Type 2-9 1983 KTM 125MX - 40mm Marzocchi

This is a common Marzocchi 40mm fork. Notice the holes on the right side of the rod. There is also a plastic floating ball inside the damping rod. 

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Type 2-10 Yamaha 38mm, YZ 250-400 1977-78

These forks require machining with a lathe.

The stock damping rod has a piston band but it doesn't seal well, even when new. Besides you can't buy original replacements at this point. Therefore this model falls into two categories. It is also a Type 3 (no piston ring) as our adapter has a piston ring built in.

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Type 3 - No Piston Ring

Common on Japanese and European dirt and street bikes in the 60s and early 70s. Similar to Type1 but the damping rod does not have a piston ring. This makes the damping inconsistent and it also decreases over time.

To remedy this, Emulator Adapters with built-in Piston Rings are available. They are included in some Emulator Kits or else they must be purchased separately. See the Product Search.

1972 CZ 250 shown

Type 3-1 Betor and Bultaco 35mm

Betor & Bultaco 35mm Damping rod top spring post protrusion is very tall & there is no piston ring.

FPEV AD3302 P Adapters with piston rings solve both of these issues. The Adapter with piston rings is included in Emulator Kits for Betor & Bultaco Forks, 35mm Betor forks are common on European Dirt & Street Models 1970-80.

Common applications are: Aermacchi, Bultaco, Ducati, many European applications.

FPEV AD3302 P Adapters with piston rings are also sold separately if needed.

More Details... 

Race Tech Product Applications are:

FRSP 2838xxx Fork Springs (required)

FEGV 3302 Gold Valve Emulators 

FCOS 35 P Fork Seals 

Type 3-2 Ceriani 35mm

Ceriani 35mm Damping Rods are flat top style with no piston rings. This application requires adapters with piston rings that are included in Emulator Kits FEGV 3303/FEGV S3303 for Ceriani 35mm Forks.

FPEV AD3303 P Adapters with piston rings included in Ceriani Fork Emulator Kit and also sold separately.

These forks are common on many European Dirt & Street Models 1970-80 as well as Ceriani & Paoli aftermarket forks from the 1970's on. This style fork is also stock on some European models.  

Race Tech Product Applications are:

FRSP S2838xxx Fork Springs (required)

FEGV S3303 Gold Valve Emulators 

FCOS 35 P Fork Seals 

Type 3-3 1949 - 1960s H-D FL - 41.25mm

These forks were the standard for Harley on 41.25mm forks from 1949 thru the 60s.

The Head of the Damping Rod has no piston ring and protrudes as well. This requires an adapter with a piston ring built in.

If you take the clip out of the bottom of the fork tube it will look like the image at the bottom.

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Type 4 - With Linear Valve - early to mid 80s

Found on some Japanese dirt bikes in the early to mid 80s. These are just like Type 1 but the bottom damping rod bolt has a valve built into it. This valve is called a Linear Valve.

Sometimes this valve is adjustable with a screw on the bottom, sometimes fixed. The Linear Valve must be disabled so it doesn't add to the damping created by the Emulator.

These can have Non-cupped (flat-top or protruding) as well as standard cupped-top. MORE DETAILS...

Suzuki DR350 and 84 RM250 Linear Valves shown

Type 5 - Anti-Dive Brakes - from the early 80s to current.

 

Found on some Japanese street bikes from the early 80s onward. These are  Type 1 Cupped-Top or Type 2 Flat-Top but there is an additional anti-dive valve near the bottom of the fork. 

The Anti-Dive valve is typically on the outside of the fork.  There will be a brake line or electric wiring attached attached to the Anti-Dive Mechanism bolted to the lower section of the fork slider.

Type 5-1 - KYB Cupped-Top with Anti-Dive Brakes 

Kawasaki, Suzuki, Yamaha 36, 37, 38, 40mm Forks 

These forks have an external Anti-Dive Valve Mechanism with a brake line or electric wiring attached. Found on KYB 36, 37, 38, and 40mm forks from the early to mid 80s.  Common models; Kawasaki ZX600/900/1000 Ninja, Suzuki GS750/1100E, RG500, Yamaha RZ500, XJ750R Seca, XJ900R Seca, XVZ12 & XVZ13 Venture .

These are just like Type 1 with standard cupped-top. However the bottom damping rod is stepped at the bottom for the Anti-Dive by-pass with the compression holes hidden inside the bottom stop cone. This system requires the fork oil to travel thru the Anti-Dive mechanism before it reaches the compression holes

The Anti-Dive Valve must be by-passed. This is done by adding the additional compression holes just above the step and bottoming cone so that fork oil can reach the compression holes without first having to move thru the Anti-Dive unit.

Compression hole modification locations are crucial. The additional compression holes required for Emulators must be drilled just above the step at bottom of the Rod.

 

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Type 5-2 - Showa Honda Flat-Top & Cup Top with TRAC Anti-Dive Brakes - early to mid 80s 

Found on some Honda street bikes from the 80s onward with TRAC noted on the fork slider. This style are just like Type 1 or Type 2 but the bottom damping rod on the TRAC fork has a check valve attached to it. 

These can have Non-cupped (flat-top or protruding) as well as standard cupped-top.

This is a mechanical actuated Anti-Dive valve unit. The actuator is on the outside of the fork; a plunger attached to the brake caliper. The Anti-Dive Valve must be disabled internally so it doesn't add to the damping created by the Emulator.

Honda Showa 37, 39, 41 & 45mm Honda forks require removing the Anti-Dive Check Valve from the Damping Rod. See details. 

These forks can have either non-cupped (flat-top on some Showa 41mm with rebound damping adjuster) or standard cupped-top on Showa Honda 37mm TRAC Forks .

Showa Damping Rod pictured from 41mm Honda V65/VF1100S Sabre & Magna with 41mm TRAC Forks. This style also found on Interceptor Models thru the late 80s as well as GL1200-1800 Gold Wing

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Gold Valve Emulator Kit Instructions for 80's Honda with TRAC Forks 

Type 5-3 - Showa Honda Flat-Top with Adjustable Rebound Damping - early to mid 80s 

Found on Honda street bikes in the early  80s onward typically along with TRAC  Anti-Dive Forks. These models will have one fork that has the TRAC unit, the other fork will have the Rebound Damping Adjuster in the Fork Cap.

These are just like Type 1 or Type 2 but the bottom damping rod has a flapper inside it attached to a D shaped rod running from the fork cap into the top of the damping rod. 

These can have Non-cupped (flat-top or protruding) as well as standard cupped-top.

This mechanism must be disabled  as the adjuster rod would interfere with the Emulator. Showa 37, 39, 41 & 45mm Honda forks require removing the rebound damping adjuster mechanism. See details. 

Showa Damping Rod pictured from 41mm Honda V65/VF1100S Sabre & Magna with 41mm TRAC Forks. This style also found on Interceptor Models thru the late 80s. 

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Gold Valve Emulator Kit Instructions for 80's Honda with Damping Adjustable Forks 

Type 6 - KYB Cupped-Top with Adjustable Rebound Damping Suzuki 37mm Forks 

These forks have an external Rebound Adjustment Mechanism. Found on KYB 37mm forks from the early to mid 80s.  Common models; Suzuki GS1100E

These are just like Type 1 with standard cupped-top. However the damping rod has internal mechanism allowing for 4 postion Rebound Damping Adjustment that can be maintained with the Gold Valve Emulator Installation.

These forks may also have a Preload Adjustable Fork cap.

Damping Rod assembly and clocking is critical to maintin proper operation and adjustment of the Rebound Damping Control.

Race Tech Product Applications are:

FRSP S2643xxx Fork Springs (required)

FEGV S3301 Gold Valve Emulators 

 

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