What to check on differentials before I put it in

[jb1dsl]

I just got two complete pumpkins and was wondering what I need to look at before I put one in. I need to see if I need to replace anything. One is a 3.25 open that someone took apart and put springs and discs in to make it act like a posi. I have seen where the guy who had it laid down two tire marks on the highway, so it was acting like a posi. It feels really tight but when I turn it, it kind of feels like something is really tight. Is that the way a posi feels? The bearings all look good and the teeth on the ring and pinion are good. the other is a 3.55 richmond geared pumpkin, it turns very smooth and feels really good. I need to know what to look and check. Also has anyone heard of putting springs and discs in an open rearend and make it act like a posi. Can it be rebuilt?

thanks

 

[jb1dsl]

anyone?

 

[jb1dsl]

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[thehueypilot]

I don't know about adding spring and discs, but the rear end that has the Richmond gear will have the backlash and centerline (pinion depth) dimensions etched into the gears. The pinion will have the pinion depth etched on the back side. It will say for example (CD 1.036) and the ring gear will have the backlash etched onto it. The ring gear will say for example (.010"). You could check these two to make sure it was set up right. The pinion rotation effort should have no more than 20 in/lbs of preload on it. You should see a faint pattern on both sides of the ring gear teeth which should be centered or slightly towards the toe (inner end) of the tooth.

 

[jb1dsl]

should it turn real freely or should it have some resistance to a turn

 

[thehueypilot]

Smooth and Free.

 

[351carlo]

As smooth as 15 in/lbs of pre load will allow...

it's smooth, not exactly 'free'.

 

[rbohm]

As smooth as 15 in/lbs of pre load will allow...

it's smooth, not exactly 'free'.

exactly. put a dial type inch/lb torque wrench on the pinion nut and turn the pinion with it. you should read 15-20 in/lbs of resistance, and the pinion should turn smoothly.

next i would put some white grease on the ring gear teeth, and using an impact wrench, or large drill, spin the pinion gear and check the tooth contact pattern. there are plenty of charts available, notably in repair manuals, to see if you have a proper tooth contact pattern.