RFY Shocks – Model 2 Analysis

with 10 Comments
RFY damper with rebound adjuster.
RFY damper with rebound adjuster.

Having traveled the web over trying to find information on RFY shocks I have encountered several models of the damper unit. They appear to come in a wide variety, though I have yet to encounter many of those in the wild. Recently, I got my hands on a set with rebound adjustment and frankly it was tough to contain my excitement as I completed a thorough tear down.

For the purposes of this article as well as others I may write I have designated this RFY damper the “Model 2.” I have done this simply because RFY fails to offer any model names. From this point forward the RFY damper with rebound adjustment will be referred to as the “Model 2.”

The only version of the Model 2 I can find in the wild is the black and orange version pictured above. I dislike the color scheme, but I suppose some may like it. To get my hands on these rare birds all I had to do was plop down a lump of my hard earned cash. All in the name of science, that’s what I keep telling myself. The goals were three fold. Firstly, I wanted to look at the piston and shim stack to see how they compare to the Model 1. Secondly, I wanted to check out the rebound adjustment system and compare it to a known system. Finally, I wanted to check spring rate to better understand where the Model 2 falls on the spectrum of spring rate. Let’s get started.

Pricing and Competing Products

Coming in at $135 a pair with shipping included. Given the feature set, the price point for this damper package is incredible. In my opinion the Model 2 is an extremely attractive purchase. That said, rebound adjustment is an advanced feature that may not be for everyone. Keep in mind that the base market for these dampers is those with vintage model bikes that require twin shocks.

Twin shocks packages are not unique in the market place. Hagon currently produces a wide range of available units. Hagon produces a low cost damper that has rebound adjustment, the 2810 model. It features a similar shaft adjustable rebound clicker. However, it is not rebuildable and preload is only adjustable via a stepped cam ring. The Hagon 2810 starts at $299. Asides from the obvious price disadvantage, the RFY has the Hagon beat The Hagon Nitro is in fact significantly cheaper most other comparable dampers. Given that the price decadency becomes so large between the RFY and those other products I don’t feel they are comparable.

Build Assessment

This shows the spring rates of the two available RFY springs.
This shows the spring rates of the two available RFY springs.

The spring is a small departure from the spring that comes on the Model 1. The primary change to the spring is that it no longer uses a smaller diameter lower perch. Both the upper and lower perches are of the same size on the Model 2. The spring is comprised of 7mm wire and is wound in a progressive nature. That is to say, the coils are wound in closer proximity to each other at the top of the spring. This provides a spring rate that increases progressively as the spring is compressed. Overall spring rate changes towards the stiffer, coming in at around 100lbs/inch (depiced by the gray line).

The overall construction of the model is improved. Generally, the finish on the machine work is a little better. The threads on the preload collar are tighter and are more confidence inspiring. The machine work is more intricate on the canister itself. The upper eyelet and top of the shock are a different casting than the Model 1. This was likely done to accommodate the shaft mounted adjuster at the bottom of the shock. The canister size has also been reduced when compared to the Model 1. This gives the shock a slightly more proportional aesthetic in my opinion.

Intenernal breakdown of RFY rebound adjustable shock.
Intenernal breakdown of RFY rebound adjustable shock.

The relevant dimensions of the damper unit appears unchanged. Overall length is 320mm just as the previous model. The spring length remained unchanged. The threads that allow for clevis adjustment at the bottom are the same as well, meaning that existing pieces can be interchanged. The compressible travel remains at around 2.75 inches excluding the bump stop rubber.

Before disassembling the shocks I worked the shock through it’s range a few times. There was a large air pocket detected where almost no damping was provided. Further disassembly pointed out the iffy nature of RFY assembly. The fluid contained within was thin and watery. It contained little or no lubricating properties and was very mineral spirits like in consistency. This problem however is easily corrected through proper reassembly.

Disassembly of the unit is similar to the Model 1 with one exception. The spring can now be removed via sliding the lower perch off the damper shaft. This is accommodated by the slotted lower perch. I prefer this design, it makes spring removal quicker and easier.

Penske damper drawing showing shaft adjustment.
Penske damper drawing showing shaft adjustment.

Inside the shock the main difference is the shaft adjuster. The shaft is hollow and has a set of ports (holes). When the shaft extends in a rebound type event the piston tries to compress oil from below the piston. This oil typically is forced through the shim stack that is on the top of piston. The rebound adjuster ports change how this function works slightly.

In a low velocity rebound event, where piston speed is slow, the ports in the shaft allow oil to bleed through the shaft without opening the shim stack on the piston. The amount of fluid that is able to bleed through these ports is adjustable via the knob at the bottom of the shock shaft. This knob effectively opens and closes the ports incrementally via a needle type jet that is housed inside the shaft. As you slowly close the ports with the needle, you decrease the amount of fluid that is allowed to pass through. As flow is restricted a greater amount of low speed rebound dampening is added. High speed damping, where piston speeds are very high, remain unaffected. This is a because the rebound stacks will handle high velocity shaft movements. To the left there is a diagram from Penske literature the illustrates this.

Shim stack inside the rebound adjustable RFY shock.
Shim stack inside the rebound adjustable RFY shock.

The piston and shim stack are significantly more advanced than those in the Model 1. This stack has several shims assembled in a standard pyramidal shape. This is very similar to the shim stacks in Penske’s and Ohlins and is in line with industry standards. The porting on the piston is nice as well. By appearance the piston seems to be a digressive/digressive design, meaning that in both heave and rebound the damper should be less progressive than a standard piston. This however is speculation and testing via a shock dyno would better determine ┬áthe characteristic of the piston and shim stack.

Further analysis revealed that this damper, unlike the Model 1, is not a proper reservoir type shock. All of the parts are there to accommodate a functioning reservoir, though the manufacturer never machined the port that connects the reservoir to the shock body itself. This ultimately means that the shock will never function properly. As the shock rod is pushed into the damper body hydraulic lock will occur. This is not conducive to proper damper function. This is a complete and udder failure on the part of the manufacturer. Confusingly, the manufacturer still assembled the shocks with the bladder and complete reservoir assembly despite that it stands no chance of working sans the connecting port.

A final note. It appears as though the reservoir could be removed from the damper body. This would accommodate the machining of a port from the reservoir to the damper body. This would restore all function to the damper, and ultimately make it a superior unit to the Model 1. Also, further investigation into the use of the rod, shim stack, and rebound adjuster in the Model 1 damper body will be investigated. In the coming weeks I hope to contact the manufacturer and investigate further.

Final Conclusions

Despite what is an incredible damper package for the price point, I can not recommend these units. The omission of a properly functioning reservoir means that the damper will never work correctly. As a result, all of the advances that the Model 2 makes over the Model 1 are meaningless. If you are in the market for a low cost damper, go with the Model 1.

10 Responses

  1. Avatar
    Eric
    | Reply

    Chris – thanks for all the research and info – some “tuners” would rather die than share info – I’m like you – information is always a good thing!!!

    Just following up to see if you ever got a response from RFY on the non-existent reservoir port issue – I’m in the market for a new pair of shocks and times what they are every penny matters – but of course if performance/safety is a question any amount of savings just ain’t worth it.

    On a side note: any thoughts on RacingBros Bazookas??? They seem to be a good mid-cost alternative to Ohlins and from what I’ve seen the quality is way better than RFY/TEC.

    Thanks and have a great day.

    • Chris
      Chris
      | Reply

      Hi Eric,

      No word back yet from RFY on the lack of port. It’s proving tough to get in touch with anybody with meaningful information. The standard (cheaper) RFY shock does have the proper port though, so it should be “okay.” I think I am going to try to buy the rebound adjustable RFY inners and put them in the cheaper RFY bodies. That’s still a ways off though.

      The RacingBros Bazookas I’ve seen are for mountain bike applications, at least that I’ve seen. Perhaps I’m mistaken though. Link me?

      • Avatar
        Eric
        | Reply

        Hey Chris,

        Pologies for the delay – “life” happens – Racing Bros. info – http://www.racingbros.com/ – only US distributor I could find is here – http://www.racingplanetusa.com/xanario_search.php?language=en&query=racingbros&sessID=01e71fc2f568ae6bc09226be55ebaca1

        “Franken”shocks??? Kinda defeats the purpose of “low-cost” if you have to buy two shocks to make one good one:-(

        Received a reply NOT from RFY but a seller on ebay – becauseofstyle – that sells the rebound adjustable RFY shocks and they say RFY has addressed the port issue – it’s a different color scheme than the shock you have (even worse if possible) – http://www.ebay.com/itm/2pcs-320mm-Motorcycle-Adjusted-Thread-Rear-Suspension-Air-Shock-Absorber-Damper-/400672978390?pt=Motorcycles_Parts_Accessories&hash=item5d49f875d6&vxp=mtr – is it worth the $134.70 to find out???

        • Chris
          Chris
          | Reply

          The intent of the Franken shocks was more to source the rebound adjustable inners and put them in the low cost RFY bodies. Depending on the price of the innners, it might be a sweet upgrade.

          The shock body on the set you say are correct are externally identical to the ones I purchased, with the only difference being the spring. Ugly certainly describes them well. Is the seller a native English speaker? I keep running into the language barrier. I’d really like to find the actual source of these things, but nobody seems willing to divulge the information.

          • Avatar
            MNL
            |

            Chris, wonderful website, definitely enjoy reading your dissections of RFY shocks. Noticed this while looking at 320mm shocks for an open wheel racecar project:

            http://www.ebay.com/itm/12-5-320mm-Pair-Air-Rear-Shocks-Absorber-Adjustment-Motor-50-300cc-600lbs-Soft-/191075391478?pt=Motorcycles_Parts_Accessories&hash=item2c7cfb17f6&vxp=mtr

            http://imgur.com/ESN6uTl

            Could this be the solution to the lack of a connection port on the RFY model 2’s you reviewed?

          • Chris
            Chris
            |

            Hi!

            Thanks for reading!

            I have seen those shocks on eBay on various occasions. Several people have asked me about them in emails as well. I have never seen a set in person, though they do appear to be properly machined, I wonder what is under the cap on the reservoir. If it’s a Schrader valve, then great! If it’s an imitation reservoir than not so much. As much as I’d like to buy a set and look them over, I’m equally sure I don’t want to spend the money right now. If you purchase a set please let me know what you find!

            I considered machining the port on the model 2’s, as I have access to a mill, but to what end?

            What kind of open wheel car are you working on?

            Regards,
            Chris

  2. Avatar
    fabrizio bertollini
    | Reply

    Do you have the web site of RFY ?

    many thanks
    Best regards
    Fabrizio Bertollini

    • Chris
      Chris
      | Reply

      Hi Fabrizio,

      Sorry, I do not have their website. They used to be branded NTC, and that website can still be located. Though it hasn’t been updated in some time.

      Regards,
      Chris

  3. Avatar
    Nick
    | Reply

    Hi Chris,
    Great information and a good read as well.
    I was looking at similar shocks (or the same) as the model 2’s for a Triumph Rocket project I am thinking of starting but concerned about the spring weights given the bike is around 806lbs wet and I’m around 250lbs on top of that.
    Your thoughts and if I did buy them what sort of additional carriage would you charge for a rebuild to Australia ?
    Finally as a bit of additional information I just came across these on a website I deal with through work;
    http://www.dhgate.com/product/rear-shock-absorber-320mm-rear-shock-absorber/238592620.html#s1-15-1b|1782574870

    Thanks.
    Nick

    • Chris
      Chris
      | Reply

      Hi Nick,

      Thanks for commenting! Unfortunately, I don’t think any of the RFY units are quite stiff enough for a bike that heavy. Shipping to Australia is around $60 U.S.

      The shocks you link to I believe are similar to the Model 3 shock that I reviewed. The adjusters are fake. I have not seen this dual reservoir shock in person though, so I could be mistaken.

      Regards,
      Chris

Leave a Reply

Your email address will not be published. Required fields are marked *