Anybody broke an OBX posi unit yet?

[Force Fed Mopar]

I think I may have at the track last night. Came off the line at 4k on 23.5 slicks, pulled good, then at the top of first right before the shift something in the diff let go. No noise, no warning, just suddenly there was nothing there. Axles are good, or at least appear so. I can put it in any gear still, clutch still sounds like it's working properly. But I can put it in any gear and let the clutch out and it doesn't even try to move. No grinding, no squealing, doesn't bog the engine, everything sounds fine just doesn't move. It rolls fine.

DodgeZ says ring gear, but seems like I'd hear something.

[Vigo]

I'd think you'd have to break every single tooth off the ring gear for it to just not move at all.

I think what could happen with an obx is if you shear one axle between the splines and the axle seal area, it will just freewheel that little chunk of axle and not spin the other one. So i would not rule out a broken axle until you can verify that one of them isnt broken where you cant see it.

I think a simple way to test this is to leave the car off, in gear, jack up the front and try to turn a wheel. I think even with an obx if you move one wheel the other one is supposed to do something (if the car is in gear), so if one moves without moving the other, it may support my idea..

[turbovanman²]

I've come close but never broken it. The teeth are worn but that's it. I seriously doubt you broke it but if you did, you beat me to it,

[zin]

I'm placing my bet on the axle being sheared at the end of the splines, I seem to recall this happening before, but I don't recall if it involved an OBX or not...

If I'm right, removal of the remaining bit can be tricky, and that best way to do so would be to remove both axles, and push/tap a long rod/extension from one side to the other.

Mike

[cordes]

I'd think you'd have to break every single tooth off the ring gear for it to just not move at all.

I think what could happen with an obx is if you shear one axle between the splines and the axle seal area, it will just freewheel that little chunk of axle and not spin the other one. So i would not rule out a broken axle until you can verify that one of them isnt broken where you cant see it.

I think a simple way to test this is to leave the car off, in gear, jack up the front and try to turn a wheel. I think even with an obx if you move one wheel the other one is supposed to do something (if the car is in gear), so if one moves without moving the other, it may support my idea..

I don't believe that test will work with a torque biasing diff. I too bet that you've snapped an axle just in front of the splines so you can't see that it's broken.

[turbovanman²]

When I jack up my van in the pits to put on the slicks, if I have it in park, one wheel on the ground the lifted up wheel doesn't rotate.

[cordes]

When I jack up my van in the pits to put on the slicks, if I have it in park, one wheel on the ground the lifted up wheel doesn't rotate.

Isn't that what it would do in park anyway?

[85boostbox]

My bet is on the flywheel side of the clutch. Just had it happen not to long ago on my sprint. Flywheel side gone, pressure plate side still in tact. Will take a pic. Would shift into gear perfectly just not move anywhere. Would bog the engine either.

My bet is on the clutch.

[Reaper1]

I don't think you can tap through the OBX can you?

[zin]

You may be right ... I seem to recall removing the axle was difficult, might have ended up welding a rod to the stub to remove it ... but that seemed extreme... I have one in the garage, if I can find it, I'll confirm it passes through.

Mike

- - - Updated - - -

You may be right ... I seem to recall removing the axle was difficult, might have ended up welding a rod to the stub to remove it ... but that seemed extreme... I have one in the garage, if I can find it, I'll confirm it passes through.

Mike

[Force Fed Mopar]

Yeah I haven't totally ruled out an axle yet. I may jack it up today and and pull the wheels and check.

[85boostbox]

As stated I have money on the flywheel side of the clutch gone. You would have heard the axle snap or something break. I just had this happen to the sprint. Literally.

[Force Fed Mopar]

As stated I have money on the flywheel side of the clutch gone. You would have heard the axle snap or something break. I just had this happen to the sprint. Literally.

Yeah the clutch or the OBX is what I originally suspected. The clutch is an FWD-P 4-puck sprung hub assy. The whole drivetrain has been in the car for about 1.5-2 years, probably has 30-40k miles on it, daily driven with many trips down the track, few mountain runs, several long out of state trips. I have broke an axle before, broke right at the tripod in the inner CV joint, and it did act just like this.

[Pat]

My money is on axle at the splines. I have damn near a shelf of them at this point.

[Reaper1]

More reason to get the black car running!

[Force Fed Mopar]

My money is on axle at the splines. I have damn near a shelf of them at this point.

That's what it was, driver side axle sheared at the splines. Swapped it out and all seems good. About to take it on a mountain run lol.

[chilort]

Like the fuse-link of the drive line.

[jonnymopar]

That's what it was, driver side axle sheared at the splines. Swapped it out and all seems good. About to take it on a mountain run lol.

I suppose that's a pretty neat and tidy way for an axle to break. It's better than having a stray piece of axle swinging around like some medieval weapon!

[turbovanman²]

Isn't that what it would do in park anyway?

Can't remember, lol.

[Vigo]

That's what it was, driver side axle sheared at the splines. Swapped it out and all seems good. About to take it on a mountain run lol.

Huzzah, my theory wins.