uprated viscous cupplings

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Re: uprated viscous cupplings

Postby MWP » Sat Mar 16, 2019 3:19 pm

eric thompson wrote:You mean our existing fluid? I will ask and let you know... But I assume that's just to get a baseline as we would want more than an equivalent.


That would be great :)
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Re: uprated viscous cupplings

Postby CMS-GT4 » Sat Mar 16, 2019 3:44 pm

This paper on VCs is worth a read. Particularly section 4.3
https://pdfs.semanticscholar.org/1142/c ... e3e8e5.pdf
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Re: uprated viscous cupplings

Postby eric thompson » Sat Mar 16, 2019 4:18 pm

CMS-GT4 wrote:Just from what I read lately on whats involved in doing the VC right, I think it might be worth paying more to have a shop do it. I do not know for sure on our unit, but it seem other units are filled under pressure, and I have even read there is a bubble that is left in the system that serves a purpose.
Having looked at a lot of these cut open online I see the plates having holes in them. I wonder if there is a tunablity with the plates and holes like there is with a shock. And like a shock, I am wondering if this is not done right you can make it worse.

On the note of the location of the VC, I have wondered if there was a way to cram a clutch pack in there or something instead. The tooling may make this out of our realm as well.
I have not been able to find the link, but there used to be an imprezza blog where a person rebuilt their vc. They had shown how to test it with a torque wrench. Perhaps if anyone has a VC out of their car they can get their tq rating off it and the milage and we can do some data analysis.
I've wondered the same about a clutch pack instead... The KAAZ diffs I have, with its rearranged shaft designs, put the front diff where the VC is and a true center diff in the trans itself. So a clutch diff would fit but I assume design and engineering would make it super expensive. I've been told a spool can be made to fit but I'm pretty sure that would still lock everything 50/50 full time.

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Re: uprated viscous cupplings

Postby MWP » Mon Mar 18, 2019 2:02 am

CMS-GT4 wrote:Just from what I read lately on whats involved in doing the VC right, I think it might be worth paying more to have a shop do it. I do not know for sure on our unit, but it seem other units are filled under pressure, and I have even read there is a bubble that is left in the system that serves a purpose.
Having looked at a lot of these cut open online I see the plates having holes in them. I wonder if there is a tunablity with the plates and holes like there is with a shock. And like a shock, I am wondering if this is not done right you can make it worse.


They are not completely filled (air, or nitrogen left in the unit), so as the liquid & plates expand it has somewhere to go. Too much liquid and it'll push out the shaft seals.
The holes & slots are just there to allow the fluid to move around a little. They dont really change the VC's torque holding properties.
They are nowhere near as complicated as a dampers valve stack.
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