VC Refurb Pitfalls

What about rebuilt Viscous Couplings?

There had been two companies in the USA selling rebuilt VCs. For more information on these units, search the archives for posts containing Oregon or ‘rebuilt VCs’ or ‘rebuilt viscous couplings.’

Generally, the price of these units is somewhere around $600 or $700 last I checked.

The issue with these units is that:

    1. In the past, they were leaving no air in the VCs, which the factory says will destroy them.
    2. They do not replace the plates. The factory says the plates must be replaced. More recently after I asked about these issues, they started advertising that they were replacing the plates as well. Not sure how they were doing that, since there is no supply of these.
    3. They are experimenting with the right fluid to put into the VCs so they are guessing at what to use.

The factory engineers who designed the viscous couplings sent me a slightly more emphatic email from Austria about these VCs and here is what they said:

‘Technical: What is being done by the company is in grave contradiction to our experience. Leaving no air in the unit, will cause the unit to disintegrate when going into the hump condition. Using a thinner fluid will result in less torque transfer to the front axle, reducing off road performance. If you can live with it, it’s o.k. The cause for a degraded performance of a VC unit lies in a change of the physical shape of the plates (microscopic wear of the burrs intentionally created when piercing the slots. Thus rebuilding the unit without changing the plates at the same time is an exercise in futility.’

Subsequent to receiving the above information from the factory, I received in September of 2001 information from a well known list member who purchased a rebuilt VC who experienced excessive binding with that unit. This list member returned his rebuild unit in favour of an OEM unit. One of the two companies who had been rebuilding the units now expresses a reluctance to even open them because the air % setting is quite sensitive.

What about used Viscous Couplings?

I have available some used viscous couplings for sale as well for $275. The used VCs that I have available are generally from vehicles which were taken off the road for other reasons, such as an accident or because the owner was breaking a vehicle into parts and selling the parts off one by one. Thus, they most likely are OK but have wear on them. Because the condition of the plates inside these VCs and degree of wear (cooking) of the internal fluid is unknown, it is unknown how long these will last. In addition, since I have not tested these VCs personally, it is unknown if they are working properly. However, none of the used VCs that I have for sale include any VCs which were rejected by the owners or which were reported to be too stiff or not function right. If you take delivery of one of these VCs and find that it is too stiff and or otherwise fails to function correctly according to the tests detailed in this document, you may return it and I will send you out another used VC to try. In this way, by buying a used VC from me, you can be assured of getting one that works correctly or receive a refund. The downside? The downside of a used VC is that it will likely fail at some point in the future sooner than a new one would, and its performance may seem to be OK but in fact be subpar and it is not certain that you would be able to determining or diagnosing that the VC was not working right unless you followed the instructions in this document very carefully. Used VCs may be returned to me for replacement or refund for a period of six months from the date you receive it so you will have some time to decide if you like yours.

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