Clutch-based LSD for R180 from Russia.

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stascom
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Clutch-based LSD for R180 from Russia.

Postby stascom » Tue Jan 01, 2019 3:33 am



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palmerwmd
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Postby palmerwmd » Tue Jan 01, 2019 3:41 am

Hotness!!!
its not cheap but then again I paid $1500 for a Nismo clutch type LSD for a 350Z before (which possibly also might fit a R51 now that I think about it)

So for what it is,... even with shipping, it seems a good value..

I wish one of us on this board would try it out.... :P
Then a few of us might get it....

stascom
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Postby stascom » Tue Jan 01, 2019 4:03 am

I just got a 1.5 Tomei for my 350z :D

docwatson
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Postby docwatson » Fri Jan 04, 2019 12:53 pm

stascom wrote:I just got a 1.5 Tomei for my 350z :D
Please test fit it on your R51, if you have a V6. It would be great to know if these work.

kevinthefro
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Postby kevinthefro » Sat Jan 05, 2019 1:30 am

My thought is: the Pathy comes with an electronic Limited Slip function and a mechanical LSD will offer little or no improvement over that so no, I would not want a mechanical LSD, regardless of price.

I've watched the Nissan electronic LS engage numerous times when offroading, both on my car and my buddy's Xterra, and it's comparable to an LSD. It controls wheelspin and gets you through sand, gravel or snow.

Where LIMITED slip fails - electronic or mechanical - is low speed with one wheel off the ground - it will spin the free wheel helplessly. I've seen this with trucks, Jeeps, and my Pathy. Uneven ground requires ZERO slip and that requires a locker.

If you still don't believe me that's OK, just buy a 370Z LSD for the rear instead and try it out - at least it will be Japanese and not fall apart and leave you stranded like that Russian thing will. No offense to the Russians, but...seriously.
Last edited by kevinthefro on Sat Jan 05, 2019 1:39 am, edited 1 time in total.

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palmerwmd
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Postby palmerwmd » Sat Jan 05, 2019 1:36 am

Kevin I get you..
but this one is even supposed to be 0.8 lock.. so if a wheel is in the air the other wheel will spin at a rate of 0.8 of the free wheel.
So its not that much different from a full locker?

Or am I misunderstanding it?

kevinthefro
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Postby kevinthefro » Sat Jan 05, 2019 2:09 am

My understanding is that number .8 (80%) is not a gear ratio but the torque split ratio, meaning the maximum torque split is 80/20. A regular differential has a torque split of 50/50, so if one wheel is on a slippery surface and can only muster 100 ft/lbs of torque pushing against the ground, then the wheel with good traction only gets 100 ft/lbs of torque too and your car goes nowhere.

With an 80/20 split, if one wheel can push against the ground with 100 ft/lbs of torque, then the other wheel can push with up to 400 ft/lbs. Or 300 and 1200. That's really good for road racing so you can keep more power on in a turn even though the inside wheel has less weight on it.

With either type of differential, multiplying by zero equals zero, so if one wheel cannot push against the ground with any torque at all, it spins and the other wheel gets zero torque too.

Some people on the 4x4 forums have pointed out you can trick a helical or Torsen into sending torque to the wheel on the ground by riding the brake with your left foot, thus giving the floating wheel something to push against. So that's one thing a helical type (the Russian unit) can do that the electronic limited slip can't do.

One wheel off the ground requires a 100/0 torque split - 100% of the torque to the wheel with traction and zero torque to the wheel off the ground. The only thing that does that is a solid axle or a locker and that's why ARB can charge what they charge.

I learned all this last year when I got the idea of swapping in a 370Z VLSD rear end but after many hours of digging through off-roading forums and road-racing forums, they all said that viscous, helical/Quaife, Torsen and clutch LSDs will not send any torque to the wheel with traction if one wheel has zero traction. I didn't believe it until I looked up Quaife and Torsen's manufacturers' documentation online and they said the same thing. Both wheels have to have something to push against.

It would be interesting to know under what circumstances anyone here is experiencing traction loss, and then talk about whether a helical LSD will do anything for them above and beyond the stock electronic limited slip.

docwatson
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Postby docwatson » Sat Jan 05, 2019 6:52 pm

A wheel in the air with an LSD makes the LSD just about pointless. You can trick it a little with some left foot braking but for real traction you would need a locker.

I haven't had much success with the ABLS off road. From what I have read on the Frontier forum (maybe Xterra) the helical LSD reacts much quicker than the ABLS. There are even Frontier guys that dropping the locker in favor of the helical LSD. Additionally, I would think it would be more consistent in RWD hitting slippery patches.

I am speaking rear LSD though. I am not sure I would put a front LSD in the R51. I would drop the extra $200 on an ARB over the $750 for this LSD.

stascom
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Postby stascom » Sun Jan 06, 2019 2:12 am

docwatson wrote:
stascom wrote:I just got a 1.5 Tomei for my 350z :D
Please test fit it on your R51, if you have a V6. It would be great to know if these work.
I have an Xterra. Lokka in the front and working on the ARB in the rear.
kevinthefro wrote:My understanding is that number .8 (80%) is not a gear ratio but a torque split ratio meaning the maximum torque split is 80:20. If one wheel has less than 20% of the traction then it will take all the energy and spin like a one-legger.

One wheel off the ground requires a 100:0 torque split - 100% of the torque to the wheel with traction and zero torque to the wheel off the ground. The only thing that does that is a locker and that's why ARB can charge what they charge.

Last year I had the idea of improving traction by swapping in a 370Z rear but after many hours of digging through off-roading forums and road-racing forums, they all said that viscous, helical/Quaife, Torsen and clutch LSDs will not send any torque to the wheel with traction if one wheel has zero traction. I didn't believe it until I looked up Quaife and Torsen's manufacturers' documentation online and they said the same thing. Both wheels have to have something to push against.

Some people pointed out you could trick a helical or Torsen into sending torque to the wheel on the ground by riding the brake with your left foot. So that's one thing a helical can do that the electronic limited slip can't do.

It would be interesting to know under what circumstances you or anyone else is losing traction currently, and then talk about whether a helical LSD will do anything above and beyond the stock electronic limited slip.
Clutch-based LSD will transfer 100% of the torque to whatever wheel has traction. The harder the wheel resists spinning against the carrier (as in the more traction it has on the ground), the harder that side's clutch pack gets compressed. Under power a functional clutch-plate LSD is 100% locked. Period. Clutches wear out. But it doesn't happen overnight, and when it does, it still leaves you with an open diff. I think it's perfectly acceptable for the front end. I wouldn't wheel with one in the rear though.
docwatson wrote: I am not sure I would put a front LSD in the R51. I would drop the extra $200 on an ARB over the $750 for this LSD.
If you already have a compressor, and someone did the electrical and plumbing for you then $200 more for the ARB is a better deal.

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palmerwmd
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Postby palmerwmd » Sun Jan 06, 2019 2:14 am

Stascom, thank you for the input.. that is how I tought it worked also.. but i encourage the discussion going forward and am interested in counter arguments.

:)

kevinthefro
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Postby kevinthefro » Thu Jan 10, 2019 2:15 am

stascom wrote:Clutch-based LSD will transfer 100% of the torque to whatever wheel has traction.
Absolutely true, if, as you said, you are under POWER. If you are trying to crawl over rocks slowly, the lifted wheel will spin.

Amigo, I'm trying to save you money and aggravation, not trying to prove a point.
If you have the time and money, go ahead and add the Russian helical to the front and let us know how it goes.


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