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 ADD Wheel bearing torque specs
#884191
05/04/08 09:25 PM
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Joined: Mar 2006
Posts: 59
OP
Getting the Wheeling Fever
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Hey guys, I have a '91 truck and it's got the Automatic Disconnecting Differential System, and I can't seem to find any torque specs for the wheel bearing adjustment and lock nuts on this type of system.
I can find the specs for wheel bearings on manual hubs and automatic locking hubs, but not for ADD.
I put it back together with 45 ft/lbs on the adjusting nut and 60 ft/lbs on the lcok nut, but then realized I was reading the wrong thing. Even though the wheel spins fine by hand at these specs, and the bearings are tight.
Truck is apart right now, so if anybody can help me get it back together tonight with the right torque specs, it would help. Gotta go to work in it tomorrow.
Thanks.
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Re: ADD Wheel bearing torque specs
[Re: 4Crawler]
#884193
05/04/08 10:21 PM
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Joined: Mar 2006
Posts: 59
OP
Getting the Wheeling Fever
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Thanks 4Crawler! So it looks like the inner (adjustment) nut should be torqued to 21 ft/lbs, and the outer lock nut should just be snugged up.
Am I reading that right?
Thanks again!
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Re: ADD Wheel bearing torque specs
[Re: mmcpeck]
#884194
05/04/08 10:31 PM
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Joined: Jan 2000
Posts: 12,153
Web Wheeler
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As noted below, more than just going to 21, there is a procedure before that: Then proceed to assembling the wheel bearings:
* Drive in the new race(s) in the same manner as removing the old race.
* Pack new inner bearing, put in inner bearing
* Drive in new seal
* Pack outer bearing
* Either put outer bearing into it's race and slip whole unit onto spindle or slip unit on spindle then put outer bearing in. Be careful not to dump new/clean outer bearing on ground when putting it on spindle.
* Put washer with tab on it for the slot in spindle on.
* Put inner spindle nut on.
Now there are two schools of thought on properly tightening the wheel bearings. First is the method documented in the Toyota Factory Service Manual:
* Tighten the nuts finger tight, then using a spring scale, measure and record the seal drag while turning the hub with the scale attached to a wheel stud
* Then tighten the nut and re-measure the bearing drag until it reads about 3-8 lbs more than the seal drag alone.
The second method seems to produce similar results and is a bit more straight forward:
* Torque spindle nut to 43 ft. lbs.
o Spin hub right 4-5 rotations
o Spin hub left 4-5 rotations
* Loosen inner spindle nut
o Spin hub right 4-5 rotations
o Spin hub left 4-5 rotations
* Torque spindle nut to 43 ft. lbs.
o Spin hub right 4-5 rotations
o Spin hub left 4-5 rotations
* Loosen inner spindle nut
o Spin hub right 4-5 rotations
o Spin hub left 4-5 rotations
* Torque spindle nut to ~21 ft. lbs.
The idea behind the second method is to ensure the bearing is fully seated in the grease and then the final torquing sets the pre-load fairly accurately. I used the second technique on my first rebuild (I didn't have a spring scale then) and I found the bearings a bit tight. In fact they seemed to be getting a bit hot on a highway trip to go wheeling. However, after two days crawling rocks, they seemed to settle right in. When I got back, I picked up a scale and measured the bearing drag and both sides were about 8 lbs. total (don't know what the oil seal drag was and I wasn't about to find out :-), so I guess it worked OK.
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Re: ADD Wheel bearing torque specs
[Re: 4Crawler]
#884195
05/04/08 10:36 PM
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Joined: Mar 2006
Posts: 59
OP
Getting the Wheeling Fever
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Oh yeah I saw that part also, I will definitely be doing the whole procedure, but I just wanted to make sure I got the spec right, so I guess 21 is right.
Is there any spec for the outter lock nut, or it just really needs to be snugged down?
Sorry for the basic questions, but I haven't pulled these apart before, and I don't want to ruin my bearings driving to work this week. Just a bit nervous, sorry.
Thanks again for your help.
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Re: ADD Wheel bearing torque specs
[Re: mmcpeck]
#884196
05/04/08 10:54 PM
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Joined: Jan 2000
Posts: 12,153
Web Wheeler
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Yes, as noted ~21 ft.lbs. for the final torque or measure the bearing drag with a fish scale. Snug up the lock nut (no FSM torque spec for that), then bend a tab down from the lock washer to keep it from loosening up.
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Re: ADD Wheel bearing torque specs
[Re: 4Crawler]
#884197
05/04/08 11:41 PM
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Joined: Mar 2006
Posts: 59
OP
Getting the Wheeling Fever
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Thanks for the help 4Crawler, much appreciated!!
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