Harsh damper - MVAgusta.net
 
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post #1 of 7 (permalink) Old 11-30-2010, 03:33 AM Thread Starter
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Harsh damper

Anybody here has some good advice about making the rear damper softer , or any advice to buy another softer damper.
That i lose some riding qualities is expected .I just had a talk with the Belgium service center for Wp and he said they could change the yellow spring for a softer one.
Including labour that would be around 175 euro,s.Any one here on this road before ?

Last edited by Greny; 11-30-2010 at 03:50 AM.
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post #2 of 7 (permalink) Old 11-30-2010, 06:41 AM
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I should get some advice from on here on adjustment before you start taking it apart..I don't know enough to advise you but there is alot of knowledge on the forum...I think possible preload adjustment could be relaxed a touch ?

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post #3 of 7 (permalink) Old 11-30-2010, 11:27 AM
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There are several factors that contribute to how a rear shock will feel under compression. 1. Spring rate (that's the inherent resistance to compression of different springs. Changing the spring rate by changing the spring is what WP are suggesting you do) 2. Leverage: Have a look at how your bikes swing arm is connected to the top of the rear shock. The MV Agusta F4 & B4 (Brutie) use a pivot, like a seesaw to to transfer the force of the swing arms movement into compressive force onto the shock. That linkage ratio and the spring rate is, unfortunately, compromised as it must be a Jack of all trades. It's got to control compression for, potentially, a 60 kilogram rider up to a 100 kilogram rider with a 100 kg pillion on board. 3. Compression damping: That's where you can tune the resistance to oil flow within the shock under compression using the screw adjuster. 4. Preload: That's the adjustment of the amount of pre-tension on the spring and is most useful in setting geometry of the bike for a given riders weight, it has less effect on compression damping than 1,2 or 3 above.
5. The shim stack. This is a set of thin metal washers inside the shock that deflect and allow more oil flow to reduce compression damping during rapid compression. The thinner the shims in the stack the earlier their effect on rapid damping will be felt.
The fact of the matter is that, initially, the shock tends to be designed to be relatively soft in the initial part of the compressive stroke and very much firmer in the latter part of the stroke. This is because the manufacturer must, again, design the suspension system for a wide range of potential rider weights, they don't want the shock to bottom out under the harshest of compressive forces.

Your solution may be as simple as reducing the compression damping adjuster (3. above). This will allow more oil to flow through the valve in the shock softening the compression stroke.
If you have the manual refer to the suggested settings.

Last edited by The_castle; 11-30-2010 at 11:10 PM. Reason: Wanted to clarify some points.
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post #4 of 7 (permalink) Old 11-30-2010, 12:41 PM
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Quote:
Originally Posted by The_castle View Post
There are several factors that contribute to how a rear shock will feel under compression. 1. Spring rate (that's the inherent resistance to compression of different springs and it what WP are suggesting you do) 2. Leverage: Have a look at how your bikes swing arm is connected to the top of the rear shock. The MV Agusta F4 & B4 (Brutie) use a pivot, like a seesaw to to transfer the force of the swing arms movement into compressive force on the shock. That linkage ratio and the spring rate is, unfortunately, compromised as it must be a Jack of all trades. It's got to control compression for, potentially, a 60 kilogram rider up to a 100 kilogram rider with a 100 kg pillion on board. 3. Compression damping: That's where you can tune the resistance to oil flow within the shock under compression using the screw adjuster. 4. Preload: That's the adjustment of the amount of tension on the spring and is most useful in setting geometry of the bike for a given riders weight, it has less effect on compression damping that compression 1,2 or 3 above.
The fact of the matter is that, initially, the shock tends to be designed to be relatively soft in the initial part of the compressive stroke and very much firmer in the latter part of the stroke. This is because the manufacturer must, again, design the suspension system for a wide range of potential rider weights, they don't want the shock to bottom out. 5. The shim stack. This is a set of thin metal washers inside the shock that deflect and allow more oil flow to reduce compression damping during rapid compression. The thinner the shims in the stack the earlier their effect on rapid damping will be felt.

Your solution may be as simple as reducing the compression damping adjuster (3. above). This will allow more oil to flow through the valve in the shock softening the compression stroke.
If you have the manual refer to the suggested settings.
Well put dave

Cheers, Simon


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post #5 of 7 (permalink) Old 11-30-2010, 05:20 PM
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Theres some good insight into how the shock works there guys.
I don't however find the brute rear overly harsh if set up correctly.
The spring rate is pretty spot on for my weight 85kg with gear.
Make sure you set the static sag correctly , but the biggest adjustment that controls the comfort for me is the high speed compression damping, because our roads here in Nth Qld are littered with short sharp fast bumps consisiting of potholes & shoddy patch repairs the high speed & not the low speed comp is of major importance, set up properly the sachs on the brute is as good as if not better than a high end shock on my other bike.
You only then have to fine tune the rebound to keep the rear in contact with the ground to minimise wheel spin.
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post #6 of 7 (permalink) Old 11-30-2010, 08:06 PM
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What's your setup now Greny?

Did you set the sag?

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post #7 of 7 (permalink) Old 11-30-2010, 10:53 PM Thread Starter
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Thx all already for the input especially @ The Castle.
I wanted to start getting out the tools but will have to wait till spring
They started 2 hours after my post with salting the roads , guess winter started early this year , which means for me that of my 4 bikes only the Vfr (cheap winter bike) will come out to daily commute .So i guess i let you people know in spring
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