Wilbers 641 competition with hydraulic preload

Two years ago I bought a rear shock from Germany, the Wilbers 641 competition, with three way and Hydraulic preload adjustments;
ordered for my bile / weight / driving style.



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The hydraulic preload adjustment ring failed three times.
The O-rings between the preload body and the shock tube destroyed and in one occasion both O-rings melted!

As I had already 25000 km on this shock, I asked for a replacement of the shock oil in a local store.
They told me that the shock oil was in a very bad condition due to extreme heat!!!
So Idecided to have a look a bit closer.

Comparing the 641 with the stock there is a difference of the location of the preload ring, in 641 it is located lower. Furthermore, 641 is wider.


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As a result the ring is less than a finger away from the exhaust tube of the left back cylinder.

The exhaust tube of the right back cylinder, located over the left one, has a stock protection that prevents heat to damage the stock shock.


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An emergency solution is to cover the exhaust tube with thermal wrap to reduce thermal transfer.



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Another solution is to use a Teflon ring in the bottom of the shock so the preload ring to be locked higher, as in the stock shock. I have done both.


http://www.vfrdiscussion.com/forum/uploads/1283786925/gallery_11350_5581_658927.jpg


The rear suspension now needs three to four clicks softer adjustment and in is not becoming so much softer after some minutes of riding as before.

To my opinion this problem is 100% Wilbers fault as they should have test the shock a absorber they offer for this specific motorcycle.

Have you contacted Wilbers about this?

[image: View Post]SEBSPEED, on 06 September 2010 - 11:50 AM, said:

Have you contacted Wilbers about this?


No. But I wonder if other aftermarket shocks have the same problem.

WP has it, as a friend of mine had the same problem and he used also thermal wrap.

It would be a good idea to send them your pics so that they know about the problem. If they know about it, they might be able to do something to correct it.

I have a Penske in my 5th gen. After awhile the shock locked up solid, the internal rubber stop had melted from the exhaust heat and fouled the valving. Their solution was to replace the rubber stop and all seals with a high temp material, Viton I believe. Been fine ever since.