Vibration after swapping in replacement rear end

[Gibbs]

I understand about the solid spacer and shims vs the crush sleeve. My trail truck has Dana 60 front which uses solid spacer, and GM 14 bolt rear which uses a crush sleeve. And the crush sleeves on these AAM 11.5 axles are amazingly hard to crush, so I'm definitely not concerned about over tightening it. Today, I experimented with the "spare" 11.5 AAM, trying to increase bearing preload with my neighbor's (non-worn-out) 3/4" impact. I hammered the crap out of it, marking the nut and pinion and watching closely as I went. I only got the preload to go from 2 in/lb to about 4 in/lb. And this was using all 1/2" airline, high flow fittings, and straight tank pressure (140 psi) from my compressor. From my experience today, it's highly unlikely to overtighten the crush sleeve. If you were using a 1/2" gun, there's just no way. Thanks for your input.

 

[Gibbs]

Well, I got my truck back on the road tonight. I put the Anti-spin into my original axle housing with new carrier bearings/races, 20 in/lb of carrier preload, and .006" backlash. I went ahead and checked the pattern and it looked good as well. The only thing that wasn't as good as I liked was the ring gear runout. It was about .003" to .0035". But there's nothing I can do about that. The mounting surfaces were perfectly clean and degreased and the ring gear bolts were torqued in 4 stages up to 175 ft/lb. I guess it is what it is. But the main thing is that the vibration is gone and now a have a mediocre factory limed slip :-laf I'm not sure what was causing the vibration with the other axle--maybe the pinion flange had an imbalance? The pinion bearings feel perfectly smooth so I really don't think that's the problem. Maybe it just didn't like my truck I'll eventually put it back together and set the gears back up and try to sell it. Anybody need a 3.73 open diff AAM 11.5 for cheap?

 

[S.Morris]

With that much runout, you can sometimes improve it by rotation the ring gear 180 deg on the carrier and rechecking. .0035 on a .006 means you are closing up to .0025 on the backlash. I would open up the .006 to .008 and run that. Specs are specs in a perfect world but slightly too much is usually better than slightly too tight in this scenario.
Since you are running new carrier bearings they may give a touch at break in. JMO but I would recheck this runout after 500 miles of light breakin and if it is still tight, open it up a touch. When temps rise and you are pulling hard, that .0025 may close up to 0!

 

[Deleted member 995608]

I learned my lesson buying used axles axles a few years back when I did the DRW conversion for my 2500.

Only cost me a new DRW housing $900, a new ring R&P set and set up fee's. $1500 bucks later, my fancy dancy (supposedly rebuilt) $1000 DRW rear end cost me $2500 bucks. What a deal that was.

Along with the above experience and a few others, I'm just about finished trusting anyone's word anymore; too many people flat out lie without any remorse.

My motto now from here on out is - "If ya buy cheap", "Ya buy twice".

 

[Gibbs]

S. Morris, I will recheck the runout and backlash after its been run-in a while. I really don't tow very much so I'll let it ride for a bit before I mess with it. Do you think it would be worth removing the ring gear and rotating it to get better runout numbers? Or just recheck the backlash and open it up if needed?

JHawes, I don't think the guy that sold the axle was trying to dupe me, but there's no way of knowing for sure. I think it worked out in the end, but I had my truck down for far longer than I wanted; and by the time I drove to get the axle, swapped it in, tried different things to alleviate the vibration, swapped it out, then set up the gears, I could've just ordered a new anti-spin and installed it and then wouldn't have another axle to deal with. Buying used always has its risk...

Thanks for ya'lls help.

 

[S.Morris]

There is no guarantee that rotating the ring gear will get better numbers, but it is very possible to pick up .002. You could also just open up backlash the same amount and call it good if your setting does not change after run in.

 

[Gibbs]

I appreciate the advice. When I checked the runout I read off the tone ring and I now have my doubts as to how accurate it is. I will go back and measure backlash in four places, 90* apart, on the ring gear to recheck backlash and runout at the same time.

 

[K5IP]

Gibbs,
Sounds like you have it under control, but I remember changing the carrier unit on a Ford van to change the rear end ratio.
I too ended up with a large vibration. Upon further inspection (and dial indicator measurement) I found the replacement carrier/ yolk to be out of round. Changing the yolk to my original one fixed the problem.
Rog