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The Shop
BFRC 16mm shaft displaces 2.19mm with a 54mm reservior in 25mm stroke (1")
18mm shaft displaces 4.59mm with a 42mm reservoir in 25mm stroke (1")
With 160 psi of nitrogen pressure in both shocks, the BFRC exerts half the pressure the 2017 Showa shock does, effectively bringing down the BFRCs force against the shock shaft to 80 psi. This could explain the wallowy feel, lack of rebound, loose feel and cavitation.
Anyone care to check my calculations?
I'm coming off as 05 yz250.🤙
"This thread Delivers"!
Replaced the check sleeves with my 1mm longer ones which have a total length of 2.88mm
Assembled and bled the shock and felt the compression was MUCH STIFFER than the rebound, and this is backwards. The rebound should ALWAYS feel harder. I don't like changing too many things at once when testing, but made no sense to put the valve cartridge (Adjuster assembly with rebound & compression valves).
Since the shock has way too much low speed compression and way too little rebound across the board, I took 3 of the 34mm x .15 shims off the compression and moved it to the rebound side. This increased the rebound and reduced the compression noticeably. The check valves will no longer be a potential restriction as they were the smallest orifice for the oil to pass to get to the rebound side which I have stated (IIMHO) is starved during big hits.
First pic is the check valve open 2mm.
The HUGE reservior reduces the pressure against the shaft during compression. If it were to match the tension of the 18mm shaft on a 2017 Suzuki Showa shock, the pressure would need to be 320 psi which I wouldn't run. Way more surface area with a smaller 16 mm shaft means less force required to overwhelm or compress the bladder at 160 psi.
1) During compression, oil flows around the check valve, into the compression valve ports
2) Oil flow under pressure opens the compression valve stack and flows into the center chamber
3. Some oil flows through the compression adjuster needle into the center chamber to the reservior, most continues towards the rebound valve
4. Oil continues flowing through the ports in the rebound valve freely which will push the check valve open
5. The pressurized oil flow opens the check valve. If too small it cannot flow to the rebound side of the piston and there is where cavitation can occur, especially high speed hits. I added a longer check sleeve to reduce or eliminate this.
The check opens further so as not to be part of the restriction we want controlled by the valving stack and the needle adjuster. Rebound is upside down the same flow.
Pit Row
Seems that would be a no brainer, going back to 2012 through 2017. But if it were that simple people wouldn't be Frankensteining old Suzuki guts inside WP bodies. This BFRC has so many things dimensionally different than a standard shock it makes it challenging to apply what has worked to this shock.
WP body with 08-17 piston/shaft/clevis works great and is a good option if you don't mind getting your hands dirty.
If you choose to modify your own BFRC shock, all you need is a bike pump of some kind and a vise with soft jaws.
1) Clamp the shock rod end into your vise
2) Bleed the nitrogen out and push the valving cartridge (the BEST THING about the BFRC Shock) into the shock around 1/8".
3) Pull the circlip.
4) Put a bike pump on the schrader valve and pump slowly to push the valving cartridge out. Won't take much, have a rag and bucket ready below the shock.
5) Use a spray cleaner on the cartridge and/or compressed air
6) Remove the nut and lay out your parts in order on a paper towel or rag
7) Really look at the system and understand how it works.
Revalve: Frankly everything you'll need to make the shock work MUCH BETTER you already have on the valve stacks.As a starter I moved 3 of the 10 34mm shims on the compression valve to the rebound stack. This will slow the whole rebound circuit and really calm down the rear end, it should prove to be dramatic. I'm not exactly sure who sells shims should you want to create your own 2 stage valve stacks but they're out there.
!!!! NOTE !!!! The most DANGEROUS thing about this shock is the circlip for retaining the Valving cartridge. You MUST push the cartridge in beyond the groove for the circlip in the shock body. The cartridge has a groove at the very outer edge which will surround the circlip once you put a little air in the shock. When assembled, the circlip would be impossible to remove because the valve body where the adjuster screws are will be flush with the circlip. If you don't have this seated properly, when you charge the shock it will explode. Once you've bled the shock of all air, charge with 160 psi nitrogen.
This shock can be made awesome, it just needs a little tweaking. I have to ask myself where Suzuki tested this thing to send it with this horrible stock dampening, a sand Supercross track? Way too much compression, way too little rebound. It's a hot mess.
I have an 08 KYB I used for a little while for sale in the bazaar forum
3 screw adjusters are low speed, high, what's the 3rd?
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