If someone here could explain to me how to set the lash in my 3rd member I would appreciate it. It is a 489 case with a posi. I've read the the "manual" but it's like reading german to me. Talk to me like I'm 10 yrs old. lol.
setting the lash in 8 3/4
- Thread starter supercuda
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805moparkid
Slant and AFX Guy
ok are you running new gears or used ones?
Coronet 500
Well-Known Member
Tighten cap bolts by hand then screw in adjuster to take out all lash in the gear. Torque one bolt on each cap and set backlash to 1/2-1 1/2 thou (basically none).
Now this is the part I didn't understand at first, your tightening only the one adjuster to "push" the ring away from the pinion to get backlash and tighten (preload) the side bearings in one operation. Torque the other two bolts and recheck backlash.
There is a bit more to it which the manual states ie rotating and checking in 4 spots etc..
Now this is the part I didn't understand at first, your tightening only the one adjuster to "push" the ring away from the pinion to get backlash and tighten (preload) the side bearings in one operation. Torque the other two bolts and recheck backlash.
There is a bit more to it which the manual states ie rotating and checking in 4 spots etc..
Get a factory service manual for your car. It explains the correct way in depth.
running used gears. replacing bearings on the posi.
Posi. So you're runnin a chevy rear end.
This is the way I've set them for 40 years and is the way Yukon Gear explains to do. Take almost all the play out of the ring and pinion. Then tighten the side that pushes the ring gear away form the pinion to get a backlash of .006-.010.
You need to have dial indicator and a magnetic base to set backlash.
sorry. in the words of the GREAT JOE DIRT...."Posi-trac"
I think I can get my hands on a magnetic dial indicator. So you're saying tighten one adjuster to push the ring gear to zero lash on the pinion. Then tighten the other to push ring gear away .006-.010 from the pinion, while not moving the the first adjuster at all. correct?
LOL, it's a Suregrip. One problem you may encounter is if you didn't check backlash before you took it apart.
Usually it's best to mark the bearing caps as to which side they came from and check the backlash prior to taking it apart when putting the same gears back in. Set them to .006-.010.
805moparkid
Slant and AFX Guy
you took a backlash spec measurement before pulling it apart right?
You need to indicate on the ring gear. The .006-.010 will be the distance the ring gear rocks back and forth rotationally against the pinion.
Keep in mind once you have it back together you might encounter some howl from the gears.
I did not take that measurement before disassembly. I did mark the caps. Also I took the suregrip and ring gear out without moving the adjuster that pushes the ring into the pinion. This is what the guy I bought it from told me to do.
I'm sure it will howl. by the looks of the grooves in the pinion, it wasn't set up right in the first place.
So you left the adjuster ring in the threads in the housing? If so that may have helped some.
I would still grab a dial indicator and check it if you can before buttoning it up.
Johnny Dart
Well-Known Member
So your running a rear out of a Trans Am ?
65-440
Well-Known Member
I've never took before measurements. whats the point, its all coming apart and will be setup once its all together. maybe someone explain this reason ??
805moparkid
Slant and AFX Guy
because as the gears break in (assuming it was done correctly and no abnormal wear) the clearance will grow, and continue to grow throughout its life. if you turn around and setup a set of gears that were running @ .012" back at .006" its not going to be happy.
If you are installing a new gear set, then you don't need to. If you are running the same gears, it's best to get a before measurement so you can get them back in as close as they were. Otherwise you will end up with howling gears.
Tighten them until you have about .001 clearance, or just until you can tell there is the smallest of backlash. Then tighten the other side to get the desired backlash. This does two things 1-set backlash and 2- prelode the bearings. I have never lost a carrier bearing by having them to tight.
ibleedmoparts
Well-Known Member
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