faster with bad viscous clutch?

J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: faster with bad viscous clutch?

I don't know that there's a simple test for the VC. It should be very stiff, but yield slowly at some point (probably with a bunch of torque applied, like 500 ft-lbs). I don't know that anybody has come up with a procedure for testing one.

'JustDreamin'
 
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Re: faster with bad viscous clutch?

I found this browsing around and it makes sense. Basically from the way I understand how the viscous works, if you do this test the truck should be able to spin the rear tires slightly at idle without the fronts moving the truck, but if you give it some gas it should make the front tires pull the truck. You can read more here http://syncro.org/VCTest.html

Using a heavy floor jack with wheels, put a block of wood on the jack and raise the rear of the van using the skid plate. Be careful, you can bend it. The wood block, if long enough, distributes the weight across enough of the skid plate to minimize that risk. Lift both back wheels off the ground 6" or so on a smooth level parking lot, with the jack's wheels parallel to the Syncro's. The rear of the van will be moving on the jack wheels, so you need to make sure there are no obstructions that could catch the jack wheels and cause the van to fall off the jack.
Now, put a 1x1 piece of wood in front of each front tire, 2x4 may work too. You need to block the front wheels like this to be able to test whether the VC is capable of absorbing the spinning of the rear wheels without locking up and causing the front wheels to engage and climb over the wood. If you can get the rear wheels to turn/spin in the air with the clutch fully disengaged, and without the van climbing over the wood blocking the front wheels (can't be too high...1-2"), then the VC is definitely good, or the fluid is not cooked. The van should climb over the blocks as soon as you increase the engine RPMs.

It may take several tries to get the van to do this. The VC is very sensitive, and it will want to engage as you let the clutch out. Some advise using the hand brake to help slow the spin of the rear wheels ... or to start them spinning slowly at first. It is really neat when you get it to work. Suddenly, the VC is working before your eyes in a very graphic way!

I am going to try this tonight once i get the other transfer case installed. I am curious to see what happens but after reading up I am fairly sure that my transfer case does have a locked up VC.
 
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Re: faster with bad viscous clutch?

Well i just finished putting it back together and I think the truck is actually faster than it was with the bad transfer case. And boy was mine bad, it has a ton of slop in it, and this is the first time i can remember that I can make turns without any binding, it feels so much smoother now. It also still launches just as hard as before. I am very pleased :)

Now im going to crack open my old one and see just how bad it was. Im curious to see how much it will need to rebuild it and what it costs to do one.
 
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Re: faster with bad viscous clutch?

Thanks that link is awesome, very nice breakdown it will def be useful when i pull mine apart. (which hopefully i have time to do this week)
 
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