Found out the hard way what happens with too much pinion preload

alosix

Expedition Leader
Finished up the 4.88s a day or too ago. Was right on the edge of a D44 spec for preload on the pinion and put it together.

Well. It appears my electric impact isn't strong enough to properly use for preload measurement. After torquing down to 180 I'm guessing it was too much.

So, out on the test drive today. I got a whole 2 lights before it started acting up. Granted I did this during rush hour in silicon valley.

2 lights in on the 4 lane expressway between my place and costco for gas I know its time to stop. I pull up on the concrete median.

There's a little smoke around the pinion, nothing too bad. It didn't manage to fully lock up, just kinda slow things down. So that's not soo bad.

So now's the fun part. Getting home. Air Impact out, front tire off. 1/2" 12 point out. caliper and unit bearing bolts out.

Pulled the axle out, beat out the c-clip on the inner unjoint of the drivers size. Of all the tools I had with me I didn't have a flat head screwdriver. So yes, you can remove a D44 c-clip with a swiss army knife.

Next up, reassemble the mess.

I got it done before the first tow truck drove by, and first cop for that matter. First I was thinking about just turing off the other way from the median and driving home, then a cop pulled up behind me when I was leaving to let me out. Really nice gesture from the Sunnyvale PD. I really thought I was going to have to explain myself since the Jeep was back together and I'm up on a raised concrete median looking like I'm doing a u-turn, but they didn't pull me over.

Got it home in one piece with my pride hurt a bit. I knew I should have checked that again. This isn't the first diff I've done, but the first one I've screw up. Whoops :).

getting it back apart SUCKED. the yoke side race pretty much siezed to the pinion shaft. I pretty much had to drill a hole in the side of the race, bread the cage, and pull all of the rollers out to get the thing apart.

housing looks ok. I didn't make it far enough to really kill anything. Looks like I just need a new R&P (I really trashed the pinion getting it out) some bearings and a few misc bits.

Next up. I'll actually be using my yoke holder again and torqing close to spec before taking preload measurements again.

And this diff has such a pretty pattern that came very easy. Oh well :)
 
Last edited:

obscurotron

Adventurer
Oooff, suck.

You know, I was going to bail to Costco for gas today, too (I think I know where you were) and would have rolled up and lent a hand. Next time, I should go put cheap gas in the CJ and extend my good karma. :)

Most folks suck, but it's a rule that I always stop for fellow offroaders and busted up rigs to see if the owner needs a spare set of hands, a tool or a few spare curse words!

Finished up the 4.88s a day or too ago. Was right
on the edge of a D44 spec for preload on the pinion and put it together.

Well. It appears my electric impact isn't strong enough to properly use for preload measurement. After torquing down to 180 I'm guessing it was too much.

So, out on the test drive today. I got a whole 2 lights before it started acting up. Granted I did this during rush hour in silicon valley.

2 lights in on the 4 lane expressway between my place and costco for gas I know its time to stop. I pull up on the concrete median.

There's a little smoke around the pinion, nothing too bad. It didn't manage to fully lock up, just kinda slow things down. So that's not soo bad.

So now's the fun part. Getting home. Air Impact out, front tire off. 1/2" 12 point out. caliper and unit bearing bolts out.

Pulled the axle out, beat out the c-clip on the inner unjoint of the drivers size. Of all the tools I had with me I didn't have a flat head screwdriver. So yes, you can remove a D44 c-clip with a swiss army knife.

Next up, reassemble the mess.

I got it done before the first tow truck drove by, and first cop for that matter. First I was thinking about just turing off the other way from the median and driving home, then a cop pulled up behind me when I was leaving to let me out. Really nice gesture from the Sunnyvale PD. I really thought I was going to have to explain myself since the Jeep was back together and I'm up on a raised concrete median looking like I'm doing a u-turn, but they didn't pull me over.

Got it home in one piece with my pride hurt a bit. I knew I should have checked that again. This isn't the first diff I've done, but the first one I've screw up. Whoops :).

getting it back apart SUCKED. the yoke size race pretty much siezed to the pinion shaft. I pretty much had to drill a hole in the size of the race, bread the cage, and pull all of the rollers out to get the thing apart.

housing looks ok. I didn't make it far enough to really kill anything. Looks like I just need a new R&P (I really trashed the pinion getting it out) some bearings and a few misc bits.

Next up. I'll actually be using my yoke holder again and torqing close to spec before taking preload measurements again.

And this diff has such a pretty pattern that came very easy. Oh well :)
 

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