New 49mm fork modification
Former Sponsor
Joined: Feb 2009
Posts: 117
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From: Las Vegas
We posted a video on you tube to demonstrate how the valve works.
http://www.youtube.com/watch?v=TA0NHDMsKNc
The inertia valve is the gold part in the middle. You can see ports open when the valve opens. This is what allows us to have a fast wheel response and the chassis to have a slow response.
Just for fun I believe you can also click on some of the other videos by this user and see some of the offroad race cars we have set up.
http://www.youtube.com/watch?v=TA0NHDMsKNc
The inertia valve is the gold part in the middle. You can see ports open when the valve opens. This is what allows us to have a fast wheel response and the chassis to have a slow response.
Just for fun I believe you can also click on some of the other videos by this user and see some of the offroad race cars we have set up.
Last edited by Ricor Shocks; Feb 19, 2009 at 03:53 PM. Reason: typo
Thread Starter
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Banned
Joined: Oct 2007
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Here is a very good explanation on how these units work.
The inertia valve is held closed by a light spring. When you have an Intiminator in your hand, you can push the inertia valve down and see the oil ports open. That is the secondary oil circuit that bleeds off high speed compression dampeing and lets the wheel move up very quickly as it hits a bump. When the wheel hits a bump, the damper rod moves up, but the inertia valve remains in place due to its inertia (weight) and doesn't move. The damper rod moving up opens the oil ports. So if you hit a bump, the wheel moves so quickly, the chassis response is drastically reduced. The bump is not transmitted to the chassis.
The Intiminator also has a shim stack, which is the primary oil circuit. Fork compression moves oil though the shim stack just as in any other fork. If the wheel is on perfectly smooth pavement and not moving up, the inertia valve does not open because it is held closed by the small spring. So, if you are on a perfectly smooth road, which does not cause vertical wheel movement (fork compression), and then hit the front brake, the forks compressing (brake dive) can force oil through only the shim stack. The shim stack resists fork compression due to fork dive because it is most effective when the inertia valve is closed (wheel is not moving up to cause additonal fork compression).
If you are hard on the brakes, causing fork dive/compression, and then the wheel hits a bump, the inertia valve will open in response to the wheel moving up to blow off high speed compression dampening, HOWEVER, the compression dampening provided by the shim stack remains intact and resists fork dive. Both circuits work together. The inertia valve in the seconday oil circuit lets the wheel move up, and the shim stack in the primary oil circuit holds the chassis up.
The inertia valve is held closed by a light spring. When you have an Intiminator in your hand, you can push the inertia valve down and see the oil ports open. That is the secondary oil circuit that bleeds off high speed compression dampeing and lets the wheel move up very quickly as it hits a bump. When the wheel hits a bump, the damper rod moves up, but the inertia valve remains in place due to its inertia (weight) and doesn't move. The damper rod moving up opens the oil ports. So if you hit a bump, the wheel moves so quickly, the chassis response is drastically reduced. The bump is not transmitted to the chassis.
The Intiminator also has a shim stack, which is the primary oil circuit. Fork compression moves oil though the shim stack just as in any other fork. If the wheel is on perfectly smooth pavement and not moving up, the inertia valve does not open because it is held closed by the small spring. So, if you are on a perfectly smooth road, which does not cause vertical wheel movement (fork compression), and then hit the front brake, the forks compressing (brake dive) can force oil through only the shim stack. The shim stack resists fork compression due to fork dive because it is most effective when the inertia valve is closed (wheel is not moving up to cause additonal fork compression).
If you are hard on the brakes, causing fork dive/compression, and then the wheel hits a bump, the inertia valve will open in response to the wheel moving up to blow off high speed compression dampening, HOWEVER, the compression dampening provided by the shim stack remains intact and resists fork dive. Both circuits work together. The inertia valve in the seconday oil circuit lets the wheel move up, and the shim stack in the primary oil circuit holds the chassis up.
Ultimate HDF Member
Joined: Oct 2007
Posts: 7,562
Likes: 11
From: Palm Harbor fl.
i have 2" lowering kit from progressive up front. is there a recommended length to cut the spacer that goes on top the spring? Progressive has the spacers recommended up to 1/2" above the fork tube. 1/4" or even for a softer ride. Also, how much room does the intiminator take up? Will it require a spacer cut to still provide the same preload as before?
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Banned
Joined: Oct 2007
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From the posts I have read the intiminator would add 5/8". If you're measuring how much the spacer sticks up above the fork tube then I would follow that becuse the spacer will just be 5/8 thinner. If your using the stock spacer then I would assume you need to trim it 5/8" to maintain the preload you have prior to installing the intiminator. I would contact Ricor and ask to make sure of their recommendations.
The rule of thumb "I" follow is rider sag should be 1/4 of total fork travel and I set this with preload on the spring. My Street Bob has more than 1/4 of total travel form the factory so the aditional 5/8 may bring it into my spec.
These Ricor instructions are pretty generic and don't mention trimming the spacer, they might not be the final draft? Maybe Ricor can chime in.
CB
The rule of thumb "I" follow is rider sag should be 1/4 of total fork travel and I set this with preload on the spring. My Street Bob has more than 1/4 of total travel form the factory so the aditional 5/8 may bring it into my spec.
These Ricor instructions are pretty generic and don't mention trimming the spacer, they might not be the final draft? Maybe Ricor can chime in.
CB
Road Master
Joined: Apr 2007
Posts: 949
Likes: 1
From: Pacific Northwest
I just installed a pair of these along with changing out fork oil to 15W, all told a little over an hr(not counting trip to auto parts store to get 10mm 12 sided socket to get brake caliper off) to jack up bike,remove caliper, wheel, fender, fork brace, slide out forks, put in wood vise,removes cap and springs, empty into bucket, pump a few times to get it all out, fill w/ fork fluid(26 oz. approx, measured 100mm from top fully compressed), pump 8-10 times, reinstall on bike. The difference really is quite dramatic, as soon as I got on bike I thought wow I'm gonna like this change!
Road Master
Joined: Apr 2007
Posts: 949
Likes: 1
From: Pacific Northwest
Ok< I've now had another day on the bike since installing intiminators, no more front fork dive when braking, seems to glide over small irregularities much better. Front now seems much more solidly planted, steering response seems quicker too. I had already installed a works performance triple rate spring kit, and although better than stock, it still felt lacking. Ricor suggests either 10 wt or 15 weight, I went with 15 w for more damping. IMO this was money very well spent. I hated the stock Showa forks since day 1, very little damping, felt like a pogo stick, I put in progressive spring kit, didn't like it, swapped it out for works, changed the orientation of collars a couple of times to shorten spring duration on the works kit(to stiffen it up I'm a big guy 6'3' 235), and got something I could live with, now after adding the Intiminators I am completely happy with the front. The rear has been a similiar trial and error, progressive 440's, works, and now YSS Z 366TRL. I was going to spring for a pr of Ohlins but decided enough already. My bike already handles great compared to stock(also have sputhe positrac and an SE fork bace) I'm a big proponent of suspension first, then brakes, then motor work. Anyone want a pr of 440's HD 12" (chrome springs)and a set of progressive fork springs cheap(already sold the works rear shocks) they only have a couple k on them and look perfect, 270.00 plus shipping? cost new about 570.00 for the set(rear and front).
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Former Sponsor
Joined: Feb 2009
Posts: 117
Likes: 0
From: Las Vegas
i have 2" lowering kit from progressive up front. is there a recommended length to cut the spacer that goes on top the spring? Progressive has the spacers recommended up to 1/2" above the fork tube. 1/4" or even for a softer ride. Also, how much room does the intiminator take up? Will it require a spacer cut to still provide the same preload as before?
We have only ever had an issue on a sporty where it didn't have enough sag.
