How should an OBX act like after preload is set

[nash542001]

I set the preload on the OBX like RYbrant's website said with 1 to 1.5 turns till the cases are fully clamped, but then it acts like a solid diff when I try to put an axle in it and turn them. Is that how it should be or did I do something wrong?

[JMortensen]

You should be able to spin them in different directions with a lever, but your springs are now jamming all the gears together and that should make it difficult to spin.

[heavy85]

Mine was essentially a spool when I got it because one of the helical gears was machined too long. I would take the washers out and put it back together without just to make sure its made right. Once you confirm that then go back and add the washers.

[nash542001]

It spins freely with all the washers out and with 0.5 turn preload it is a little harder to turn, but with 1.0-1.5 preload the whole thing is lock up solid neither side will spin just the whole diff.

[nash542001]

Define what type/size of lever. I do not have any special setup nor have it where I can put on a wheel for more leverage. It is just me turning by hand with axles in the sides. I at least thought they would turn in both directions, but not none at all.

[JMortensen]

So the diff is out of the car? I tested my clutch LSD breakaway with 280Z side stubs. Just stuck one in a vise with the splines up. Set the LSD on that one. Stuck the other one on top. Took a piece of metal 3' long and drilled a couple holes in it, and bolted it to the stub, then put a torque wrench on the metal to measure the resistance. Basically copied Gordon Glasgow's idea, but using the short stub axles from a 280Z instead of the long axles from a roadster's solid rear axle. If you don't want to actually measure the resistance, just make yourself a lever and pull and skip the torque wrench.

 

http://www.gordon-glasgow.org/lsd4.asp

Edited November 28, 2013 by JMortensen

[nash542001]

Ok, so I can test the breakaway away on this type of LSD like the clutch type. I thought the helical was different and would not be able to test that way. If it acts the same as a clutch type in operation I will be fine and check it the way JMortensen describe. I just wasn't sure on exactly how it could be tested for correct operation before install. I will try that as soon as I get a chance.

[m1ghtymaxXx]

Have you given it a generous slathering of gear oil? Mine was quite hard to turn by hand dry as well. I assume you have stub axles in it? Try putting a screwdriver through the studs and turning it like that. 

 

As for measuring breakaway torque, I'm not sure how consistent a reading you get given the "torque sensing" nature of helical diffs. I thought the more differential action they see, the tighter they lock up. 

 

My experience sounds similar to yours and mine works fine.

Edited November 28, 2013 by m1ghtymaxXx

[JMortensen]

You'll just be testing the breakaway, not the correct operation of the unit. You can do some funky stuff hanging weights off of the tires to check the operation and figure out what the TBR is.