Play in rear differential 8.8

Joshs93four-oh · Feb 11, 2008

I hope someone in the know can give some info on this- I can grab the driveshaft of my truck and turn it about 30 degrees either way. I've had the rear cover off to do the axle seals and the play is in the small gears in the spool(I don't know anything about differentials). Is this normal? The wear patterns looked ok and the diff makes no noise at all. I thought it would of been pinion to ring gear play but it isn't. Why did my rear diff wear so quickly? I check all ford 8.8's that come in the shop for this and none have been as bad as mine. I dont tow anything and the truck is very light...I dont get it. It's a 5-speed and I have to shift around this problem to avoid jerking the driveline(happens mainly when letting out of the gas pedal quickly). Thanks in advance to anyone who replies!! Josh
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California dispensary

MAKG · Feb 11, 2008

There is always some play because gears are meshing. There is a spec for this, called "Backlash." You hold the flange stationary and measure how far the ring gear can rotate. This is quite different from putting the parking brake on and rotating the flange.

Now, if the flange is floppy, even a little, that's a big problem. But a cold gear has to be able to slop around some in the rotational direction, or it will bind when it heats up.

This play is between the ring and pinion gears. There is no spec for play within the differential gears (side gears and spider gears), as they don't see the vehicle weight directly, and aren't nearly as sensitive for that reason. If they clunk, I'd replace them. But that's it.

metalmacguyver · Feb 11, 2008

when i set my parking brake i have about the same amount of play. It does not cause me any concern. the "spool" you mentioned is actually call the carrier.

Evan · Feb 11, 2008

If your play is not caused from the backlash between the ring and pinion, it is most likely play from the spider gears in the carrier. If they are worn, this play can be quite a bit, but it's not necessarily a problem. It will cause an annoying clunk at times but that's about it.

Hahnsb2 · Feb 11, 2008

That play sounds excessive for a normal diff... I know about how much 30* of play is like compared to stock. Adding the locker gave it 25-30* of play according to the manual and will clunk if you dont shift around the problem as you described. The axle in stock form did not clunk.

Joshs93four-oh · Feb 11, 2008

Thank you all for your advise! I think I just drive it until it launches the carrier! lol Josh
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Evan · Feb 11, 2008

Joshs93four-oh said:
Thank you all for your advise! I think I just drive it until it launches the carrier! lol Josh

Good choice. I've never seen a failure associated with this. I think you'll be fine for years to come.

Joshs93four-oh · Feb 12, 2008

Thanks Evan. Ya know if it was a GM rear diff it would have broke by now. It just kills me...How can anyone design a Large Truck and then put a mickey mouse rear end in it? Makes me laugh everytime I see one! That tin-foil 7.5 GM read diff...Might make a good lawnmower axle!!
Josh
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YAMAHA GT80

Play in rear differential 8.8

Joshs93four-oh

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MAKG

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metalmacguyver

Yeah, I built that.

Evan

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Hahnsb2

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Joshs93four-oh

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Evan

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Joshs93four-oh

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