dvw
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Though there is a solid sleeve availible for the 489, it normally uses a crush sleeve .
Doug
Will 741 Case Gears Fit a 489 Case?
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Doug
MoparLeo
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I guess I was misinformed. Every thing I have ever read ( I read a lot ) over the many years has stated that the 489 requires a crush sleeve to set pinion depth/preload. And that they are not reusable . The 742 only uses shims?
beanhead
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The crush sleeve was a negative in the 489, so the gearheads came up with the solid spacer there instead which eliminated any issues. 489 with solid spacer upgrade=tuff stuff! The 489s pinion diameter is only 1/8" larger then the 742 though, they're both really good. You are correct 742 does use shims to set depth
MoparLeo
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Glad I am not losing it ....yet.
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Yup.....have used the solid spacer several times when setting up the 89 case rears. In fact, I will not set one up anymore using a crush sleeve (at least not for a customer) as I think they are nothing more than a negative as beanhead mentioned.
Preload and pinion depth are two different things. A shim or shims are used under the rear pinion bearing to set the depth of the gear, you need to then set front bearing preload. You can set that using a crush sleeve or shims depending on what case you are working with. If you set preload too tight, it will wear the bearings faster but it will not change pinion depth....at least not at first. As the bearings wear, the depth will change slightly over time. And I have reused crush sleeves before for my own junk when setting up used gears and have had good results however I do not recommend doing that.
Jack Shultz
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Now, the real answer may have been eluded. I am looking to change the gear case from a 741 to a 489. Not touching the pinion gear, and using the ring gear from the 489. Basically, The part that holds the spider gears is shot. That is the only part I want to transplant. So, is the main bearings on each side the same size from 741 to 489? AKA, remove the caps, pull it out, swap ring gears, put it in, and set back lash.
dvw
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The side bearing inner diameters are different, therefore the bearings are different. However they use the same diameter outer race. So as stated the carriers can be swapped. The 489 carrier will require the 489 side bearings. Measure the back lash before removal. Reset backlash to the same spec with the new carrier. No need to touch the pinion.
Doug
Doug
Jack Shultz
Member
Correct, Exactly what I did today. I measured the backlash (.011) removed both carriers from their cases, swapped the ring gears, dropped the 741 carrier into the 489 case and set the backlash to .011. It is ready to install in the housing. A friend is going to make a posi out of the 741 case with the 3.91 gears that was in it. Win win.
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.011 is a bit much....think I would have tightened them up a bit. After all, they did start out with less but who really knows lol. Did you check BL in at least 3 places? .011 ain't bad but that's my limit....dirt track guys usually run more but no one runs the 8 3/4 anymore that I know of.
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