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CRF 150R Forks Mid Valve Shim Stack

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I disassembled the mid valve on one of my CRF150R forks as I said I would. I was careful while disassembling the shims, but I still missed the orientation of the valve body. The attached picture shows the shims from bottom to top.IMG_0784.JPG

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Valve body has small ports to the rebound shim stack (nut end), large ports towards the compression check valve (piston rod). Easy way is put the small bleed hole towards the rod (opposite the nut).

Edited by Chuck.

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Thanks chuck, I was careful everywhere but got turned around while looking at the valve. Bleed hole on the top side, got it.

BTR, is this the info you were looking for? Do you guys have any guidance on adjusting the shim stack for a less harsh ride?

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Sorry I only use Cr85 forks. Chuck knows way more then me on 150 fork. Chuck maybe can post where to put spacer/washer for mid valve.

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Two days a go I redid my forks so still fresh in my mind. I measured the compression ports and the float on the check valve, and then calculated their areas. When the check valve is open it has the same area as the ports so I didn't find a smoking gun for harshness unless the areas are small enough to restrict suspension speed. The CR80s also use a check valve for compression on the mid and I could measure them for a comparison.   I didn't measure a base valve but it flows about 1/3 as much fluid as the mid and the Goldvalves appear to have larger ports.

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So Chuck what did you do to your forks in the way of mods. I sure would like to hear from other member on Cr85 fork with new mods. How they like or don't like it, so far its only me  2 bikes done. Also Mikes bike.

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I am going to remeasure the shims tomorrow, I found several that were stuck together. I will post the results.

BTR, I thought you wanted to see the shims in the mid valve on the 150R fork? It must not be the same as the 85R forks? Anyway, it was easy to get apart and I have never been inside one before so it was good training. Now, if I only new what the hell I was doing I could make some changes!

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Problem now that I see them nothing like Cr85 fork. If you like PM me  I think I know who you can send picture to  that will know what to do.

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My ride Weds showed I was getting near full travel on a couple of ditches, didn't feel anything hard but the wipers cleaned the dirt down to what would be full compression.  Forks felt a bit harsh on small sharp bumps but that may have been my frame of reference from not riding for 6 months. Found 2 miles of new gnarly ST and found 2nd gear using the clutch was better than 1st, made me wish I'd brought the Trials bike.

My revalve is not a big change just a little softer on the GV so low speed is now 4th from softest and the high speed is 2nd from softest. Also checked all of the shim stacks for correct order. I considered using your float shim mod but the clickers were close to those recommended in the CRF150R manual so I thought I'd limit things to only two changes. Fluid level is the same at 5" (very close to max recommended in the manuals) and I'm running .32kg springs, but consider that my XR is about 30lbs lighter than a CRF230.  I have .34 & .36 springs so I could go to a lower oil level and stiffer springs, just thought I'd work on the harshness via damping first and then deal with stiffer springs and lower oil levels. 

The mid valves are the CRF150R units shimmed as I listed in a another post.

Edited by Chuck.

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10 hours ago, Chuck. said:

My ride Weds showed I was getting near full travel on a couple of ditches, didn't feel anything hard but the wipers cleaned the dirt down to what would be full compression.  Forks felt a bit harsh on small sharp bumps but that may have been my frame of reference from not riding for 6 months. Found 2 miles of new gnarly ST and found 2nd gear using the clutch was better than 1st, made me wish I'd brought the Trials bike.

Not a big change just a little softer on the GV so low speed is now 4th from softest and the high speed is 2nd from softest. Also checked all of the shim stacks for correct order. I considered using your float shim mod but the clickers were close to those recommended in the CRF150R manual so I thought I'd limit things to only two changes. fluid level is the same at 5" (very close to max recommended in the manuals) and I'm running .32kg springs, but consider that my XR is about 30lbs lighter than a CRF230.  I have .34 & .36 springs so I could go to a lower oil level and stiffer springs, just thought I'd work on the harshness via damping first and then deal with stiffer springs and lower oil levels. 

The mid valves are the CRF150R units shimmed as I listed in a another post.

Increase fork spring rate but lower fork oil level?  Why would you change the oil level?  You don't think the fork is bottoming, at least it isn't bottoming hard if it is at all, why would you change the fork oil level? 

You have harshness on small bumps with 0.32kg/mm springs and still suspect spring rate is contributing to the harshness and not just the damping?  Fork oil level isn't in the equation yet since the fork is hitting these small bumps in the upper part of the stroke.

Sounds to me the logical approach would be to address high speed compression damping, no?  Maybe fork spring preload? 

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Ok Chuck I don't understand So your forks are Cr85 with 150 cartridge and MV?  You did not put washer spacer in MV. On GV you revalved it same as me Or?    I have not had my cut of Java yet. Wt oil and brand you used?    Just like to have info on 150 fork Thanks

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Ok Chuck I don't understand So your forks are Cr85 with 150 cartridge and MV?  You did not put washer spacer in MV. On GV you revalved it same as me Or?    I have not had my cut of Java yet. Wt oil and brand you used?    Just like to have info on 150 fork Thanks

Chuck runs 150r forks

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I startered with early Showa 37s from a 96 CR80 and began swapping in CRF150R (07) parts in 2012.

 

13 hours ago, MetricMuscle said:

Increase fork spring rate but lower fork oil level?  Why would you change the oil level?  You don't think the fork is bottoming, at least it isn't bottoming hard if it is at all, why would you change the fork oil level? 

You have harshness on small bumps with 0.32kg/mm springs and still suspect spring rate is contributing to the harshness and not just the damping?  Fork oil level isn't in the equation yet since the fork is hitting these small bumps in the upper part of the stroke.

Sounds to me the logical approach would be to address high speed compression damping, no?  Maybe fork spring preload? 

I changed the high speed stack to reduced high speed damping. The reason for the idea of less oil was because I'm within 1/4" of max recommended oil level and reducing the air spring for more stroke on bumps could be beneficial but then I would need to use a stiffer spring to maintain bottoming resistance. I have those stiffer springs on hand and I have used them in these forks.  One of my riding areas has sections of soft soils and grades that are hardened with concrete cinder blocks, some of which become dislodged. When riding you come blasting around a corner or down a switchback and there is cinder block or a large piece of one on your line, and dodging isn't always successful. The speeds are usually low but the bumps aren't.  As a side note the most compliant front suspension I have ridden is the Greeves leading link front end with rubber torsion springs and Girling shocks, only about 6-7" of travel but it sure sucked up the bumps.

12 hours ago, bajatrailrider said:

Ok Chuck I don't understand So your forks are Cr85 with 150 cartridge and MV?  You did not put washer spacer in MV. On GV you revalved it same as me Or?    I have not had my cut of Java yet. Wt oil and brand you used?    Just like to have info on 150 fork Thanks

All of the Showa 37 parts interchange, I started with 1996 CR80 forks and now I'm at mostly CRF150R.  I started with RT GVs in the CR80 forks but always had a bit of sting on bumps.  One cartridge had a bit of friction at mid stroke so I swapped it out with a 150R cartridge. Next I changed the sliders to 150R for the larger axle but kept everything else the same, including the fluid. I rode this last set up all of last summer and again last Thursday to refresh my memory. The forks still have a bit of sting that is noticeable on gravel roads and chuckholes, and whoops are not good, but other than that they work OK.  The revalve is not a big change for the next ride, but progress.  Since my mids have a check valve for compression I can't use your float shim, but I considered using the float shim in the GVs. I'm using RaceTech Light oil (15.2cSt) cartridge fork fluid. 

Both of my mid valves have a check valve for compression so their contribution to harshness will be via flow restriction thru the ports at high suspension speeds. My CR80 (96) mid uses a different type of valve that combines a check valve on compression and the shims (18x11x 0.11 x 5ea) deflect on their ID for rebound, picture is in another post. My CR150R forks (07) use a more conventional check valve for compression and a conventional shim stack for rebound, again picture is in another post. Our forks may be different because Honda used many different mid, and base, valves in these forks; seven different base valve part numbers and eleven different mid valve part numbers.   We should compare pictures. I don't know what valves were used on the RM80 versions.

Because the mid flows about 3 times as much fluid as the base I've always been suspicion, contrary to RT comments, that the mid's ports were the cause of high speed compression harshness.

Edited by Chuck.
grammer & spelling
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My current CRF150R mid valve:

Check valve for compression, on left
Piston/Valve body, then rebound stack
.10x17 (2)
.10x10
.10x17
.10x10
.10x15
.10x13
.10x11
.10x10
.32x16 (4)
17 plate
nut

591a0826a6ed9_CRF150RMidValve.jpg.a9db5904b1f87969606e146caac12fe2.jpg

Base valve is RT Goldvalve. Check valve for rebound then Compression stack.
.10x17 (4)
.10x11
.10x17
.10x15
.10x11
.10x10
.10x9

This will probably change after a ride next week.

There seem to be several labeling conventions for shim stacks, some obviously are short cuts that assume reader inside knowledge. Most usually contain the shim OD and thickness, and round the values to nominal.  So if there are any preferences post them up

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I do not know how to do the calculations yet but from my little valving experience i believe our problem with these usd forks is the flow rates of the base valve. The GV is supposed to assist but it seems that its still limited. Based on my observations, the area of the BV ports are no where close to area required for the volume of oil trying to pass through them without port flow resistance. (Hydrolock)

BTR's modification of the MV reduces the amount of fluid that is required to pass through the BV by allowing some to bypass the piston when the flow becomes to great for the BV ports at high speeds ( sharp edges)

Please correct me if i'm wrong!

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I think Chuck can answer this more then me. The little I know the old school type base valve Cr85 fork same as Xr250/400. Yes base valve problem does not pass enough oil. So we drilled it,we removed shims Right direction it helped. Then we bought gold valve yes it passes oil like a modern bike.Do bad I was still complaining.Spacer/washer in MV BINGO. Now drilled BV works and GV. Only the results matter.

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The base valve only deals with the displacement of the rod entering and exiting the cartridge and it is 10mm in diameter. The mid valve deals with the area displaced by the piston minus the area of the rod; the piston is 20mm in diameter.  The Showa 37 rod is 10mm diameter and has 79sq mm of area, a 20mm piston has 314sq mm area. Doing the arithmetic I find the piston will flow 3 times the fluid of the base valve. I haven't done any calculation on base valve port area so I don't know the flow areas. I did however calculate the port area of a mid valve and flow area of an open check valve and they were very close to the same.  At this point I think I need help from a program like Shim Restackor.   In the interim trail riding will need to suffice.

It seems that BTR and I are using forks with different mid valves but I think we are chasing the same goal.

Grayracer came up with an idea to reduce initial sting on his YZ459 forks; place a pivot shim behind the first face shim. Not as loose as a pivot shim between the face shim and mid valve as suggested by BTR, but  because I don't have a compression stack in the mid valve I may try this on a base valve. It is also on my list for the next revalve on my CRF250X. https://www.thumpertalk.com/forums/topic/914419-mod-to-dell-taco-fork-for-desertoffroad/

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8 hours ago, Chuck. said:

The base valve only deals with the displacement of the rod entering and exiting the cartridge and it is 10mm in diameter. The mid valve deals with the area displaced by the piston minus the area of the rod; the piston is 20mm in diameter.  The Showa 37 rod is 10mm diameter and has 79sq mm of area, a 20mm piston has 314sq mm area. Doing the arithmetic I find the piston will flow 3 times the fluid of the base valve. I haven't done any calculation on base valve port area so I don't know the flow areas. I did however calculate the port area of a mid valve and flow area of an open check valve and they were very close to the same.  At this point I think I need help from a program like Shim Restackor.   In the interim trail riding will need to suffice.

It seems that BTR and I are using forks with different mid valves but I think we are chasing the same goal.

Grayracer came up with an idea to reduce initial sting on his YZ459 forks; place a pivot shim behind the first face shim. Not as loose as a pivot shim between the face shim and mid valve as suggested by BTR, but  because I don't have a compression stack in the mid valve I may try this on a base valve. It is also on my list for the next revalve on my CRF250X. https://www.thumpertalk.com/forums/topic/914419-mod-to-dell-taco-fork-for-desertoffroad/

I was also thinking about using the shim for float as BTR did with the GV shim stack but wouldn't it still have the issue of the ports being too small.

What if we added Float to the check valve on the BV to allow flow through the rebound circuit on the BV during compression! Wouldn't that be similar but more effective when more flow area is required?

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Interesting ideas. And I had similar thoughts regarding port sizes but we don't yet know if port size is the issue. BTR's idea of a float shim on the compression stack is similar to Grayracers early crossover shim. My recollection is BTR added the float shim to the compression stack on the mid valve, my CR80 and CRF150R forks do not have a compression stack on the mid valves. I could add BTR's float shim to the mid valve rebound stack and that would allows some initial fluid flow on compression until the face shim flexed against the valve body; just might be enough to soften the initial compression harshness. 

I may ride this Friday if so I will have a ride report and can do some mods for a ride the following Wed.   

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