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LBS

Limited Slip; Corn Starch in my Differential?

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LBS
My idea of limited slip is a little different than simplicity's. And I have a crazy idea! Have any of you ever played with cornstarch and a little water? It's cool stuff. It is very runny until you stir or move it, then it gets as hard as concrete, and as soon as you let the pressure off it's liquid again. I was thinking I could take the springs out of my diff and put washers in their place so it would slip easily, and fill it with something like cornstarch that would lock as soon as it moved. I tried using oil instead of water and it just made goo, and I’m a little leery of putting water based stuff in there. Maybe antifreeze would work? Would it keep it from rusting? do you know of anything else that does the same thing? Whats going on, how does it work? Any ideas? (You can tell I've been playing all day!):D Gearz & Goo!

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rjgoth
Dude are you on crack? .... kidding. You bring up a very interesting idea. If you could get a lubricant instead of water to have the same properties as the water and corn starch mixture...... hmmmmm. Keep messing with it and let us know what you find out. Ryan

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D-17_Dave
Farmers use an additive in thier chemical spray called adjavant. It allowes an oil molecule adhere to a water molecule. Maybe some of this would allow you to use some of both in your concoction.

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LBS
I could see the Subaru stuff working in a torque converter type situation. But I don't think our little diffs would make much heat, especially in the winter. You would need two plates real close with fluid between them so it could heat quick, gears don't do that. But I think this stuff would work! You should mix up some of this cornstarch stuff and see what I'm talking about, its easy, and you'll get addicted!

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HubbardRA
What is your problem with the limited slip? Is the limited slip too tight or too loose? From my experience they are usually too loose. I have one that I have modified to tighten it up. I have also locked the rears, which is also very easy. What is your ultimate objective? Even if you can come up with the material you are talking about, you would have to design a way to completely fill the diff cavity with no extra space so that it couldn't be pushed out of the gear teeth because that is the only surface such a material could act on. I suppose you could fill it magnetorheological fluid and mount an electro-magnet to the diff. This way you could lock and unlock the diff with a toggle switch.

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Leroy
See what happens when guys get to spend time in the kitchen? Hmmm, Quicksand it is, Cornstarch is fun to get a hand full of it and squeeze It acts like snow crunch without the cold. good fer diaper rash and why not differentials, commonly refeerred to as rear ends. I actually have more fun watching jello bounce, and homemade cookies rise and spread out, ah the smell of it.

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Leroy
See Rheology http://www.liquidsresearch.com/products/magnet.asp Magnetorheological fluids are stable suspensions of magnetically polarisable micron sized particles suspended in a low volatility carrier fluid, usually a synthetic hydrocarbon. Liquids Research Limited produce magneto-rheological fluids that are capable of giving high shear stresses at low applied magnetic fields. The unique nature of this class of magnetic fluid allows dramatic changes in rheology to occur within the bulk of the fluid on application of a relatively modest magnetic field. The material can change from being fluid to solid almost instantaneously, the rheology of the material reverting to its original state upon removal of the field. Magnetorheological fluids have existed for over fifty years. However, it is only now that fluids are available that are stable and give shear stresses that are adequate in demanding applications such as automotive damping. Liquids Research Limited produce thixotropic magneto-rheological fluids that are suitable for applications where high shear stresses are required, these applications include seat suspensions, vehicle suspension systems and exercise equipment.

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rokon2813
LOL Thanks Leroy :D Is that what all those big words were? The worst part is it actually made sense, I just had no clue just what material you were talking about.;) Might have to dig up my vial of mercury and a magnet tomorrow and play a little.:D:D Hmmm, a liquid electric clutch.......

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Leroy
quote:
Originally posted by rokon2813
LOL Thanks Leroy :D Is that what all those big words were? The worst part is it actually made sense, I just had no clue just what material you were talking about.;) Might have to dig up my vial of mercury and a magnet tomorrow and play a little.:D:D Hmmm, a liquid electric clutch.......
The Mercury comment was to lighten it up. It's not good to play with. It causes cancer in labratory rats. Rheology is about magnetically affected variable liquids. do a google search for it or click on the link i provided. http://www.liquidsresearch.com/products/magnet.asp

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Woodydel
The cornstarch mix is a colloidal suspension. A fun experiment is to fill a mortar tub with the cornstarch mixture. Place the tub next to a table. Stand on the table. Jump down into the tub containing the mixture with your feet first. The mixture will not splash. Info about colloidal suspensions and shear. [url]http://www.che.udel.edu/research_groups/wagner/website/papers_files/s00397-002-0290-7.pdf[/url]

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IronPony
I think VW called it a "viscus" coupling. Not sure of the spelling. The system worked to allow for two wheel drive except when your drive wheels lost traction then the other axle would kick in automaticly giving 4 wheel drive. Dan

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ka9bxg
Way back in the old days AMC used a viscus coupler in there 4 wheel drive cars it consisted of multiable disks with a silcone product.It was very slimy stuff.It did work OK but if it would have been any good other companys would have used it.Bob

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Kent
quote:
Originally posted by ka9bxg
Way back in the old days AMC used a viscus coupler in there 4 wheel drive cars it consisted of multiable disks with a silcone product.It was very slimy stuff.It did work OK but if it would have been any good other companys would have used it.Bob
I think this is very similar to, if not the same as the VW/Audi AWD setup....

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HubbardRA
The torque converters in automatic transmissions are also viscous couplings. They allow slippage at low flows through the vanes, but tend to lock (stall) as the input speed increases. The stall point of a viscous coupling depends both on the viscosity of the fluid and the pitch and number of the blades (vanes) in the coupling. Problem with a tractor diff is that there is so very little relative motion, even when spinning one wheel, that the viscosity of the fluid would have to be extremely high(nearly solid).

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LBS
According to woody's article ethelyne glycol (antifeeze) can be used. It also looks like there might be something better than cornstarch, I'll have to read (and play:D) some more. That was a great link woody, Thank you. I think we might have the best mod yet for our "toys"! I'm going to try it.

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