Question RE front wheel bearing installation and preload. (2 Viewers)

[sw00py]

I have a spring guage to test preload and everythings good until I go to torque the lock nut. I'll get the adjusting nut set and my preload will read 10 to 12lb on the spring scale, but when I go to torque the lock nut down to 57 ftlb or whaterver Hayes says, my preload increases to 15lb. If I loosen the lock net a bit I can get the preload back to the upper end of the spec of 12lb.

So my question is what's more important to have in spec, the preload or the torque on the lock nut? Hopefully that makes sense.

 

[gnob]

is your star washer good?
3in/lbs is pretty irrelevant.
ive literally NEVER used a scale for wheel bearing preload.
its really hard to overload the front bearings.

 

[aztoyman]

This is a subject you're going to get a LOT of opinions on. BASICALLY speaking, you want them tight enough to have no free play, but not so tight that you overload them enough to got hot and fail. There is room for SOME variance in how tight.

I know I didn't answer you specific question but you will probably get a bunch of forum member's methods and they probably all work fine.

 

[aztoyman]

I'm guessing that there is enough play in your washer that tightening your lock nut moves it a tiny bit. So what you did to compensate is going to give you both to spec. The preload is not going to be loose if tightening the lock nut to spec moves the preload to spec when you're done.

I've never used a scale either. But some people do.

 

[sw00py]

I'm guessing that there is enough play in your washer that tightening your lock nut moves it a tiny bit. So what you did to compensate is going to give you both to spec. The preload is not going to be loose if tightening the lock nut to spec moves the preload to spec when you're done.

I've never used a scale either. But some people do.

Thank you for the reply and advice. Can I ask you another question on this topic? So to preface I've never done any mechanical stuff before owning this truck aside from fluid changes but I got this 84 Toyota pickup that needs a good bit of work so I am learning to DIY stuff and am definately getting hung up on following specific instructions since I am still learning to understand how everything works together.

I have the Chilton and Hayes manuals and I've been following youtube tutorials by 6th gear garage and lowrange offroad on rebuilding the steering knuckles. I've found that both the videos diverge from the manual when it comes to tightening the adjusting nut (inner most spindle hex nut) for the wheel bearings. In both videos they say to torque it to 47 ftlb, then loosen and retighten just to hand tight or 4 ftlb. But the manuals say to torque the adjusting nut to like 50 ftlb (don't recall exact number but a lot more than hand tight).

How do you deal with the adjusting nut? Hand tight or torqued more? I found that if I torque it to the manuals spec my preload is pretty far above above the 12lb spec.

Thanks again!

 

[gnob]

follow the fsm. finger tight bs is for tiny vw type bearings.

 

[aztoyman]

The initial torque spec that is high is to make sure that the bearing cups (also called races) are fully seated in the bores they are installed in. They are a tight fit and sometimes they don't get installed completely down into the bore. If that happens you may "think" your bearing is properly adjusted but the load of the vehicle can actually seat the race down in the bore when you put you vehicle back on the road. Now you have a loose wheel bearing.

The bearing cone/rollers need to be tight enough to allow the wheel to spin freely but have no play. The engineers put a lot of work into what the bearing should be set to.

Realistically, there is an acceptable range and is why you get so many opinions on the "best" method to set them.

Like gnob said ,following the Factory Service Manual is probably best.

If I was out on the trail and had to replace a wheel bearing and didn't have a manual, I'd tighten the adjusting nut little by little while turning the hub to a tighter than normal amount to make sure the bearing seated. You can actually feel it if it moves. If it doesn't it just gets hard to turn.

Then I'd back it off loose and tighten enough to take out the play and maybe a tiny bit more. It should roll smoothly and not have any movement side to side or clunky feeling. I'd be confident it would get me home.

 

[ntsqd]

I always tighten the adjusting nut while turning the wheel hub until it's so tight that I can't turn the hub. Then back it off and set the pre-load. As AZ has said, likely we all have our own method for setting this and those come about by having done it a bunch. Following the FSM is a good idea until you have developed the experience needed to do it other ways. And like gnob said, these aren't tiny bearings and they can handle some pre-load.

I will suggest that one way to make the bearings less sensitive to the pre-load is to hand-pack them with a premium grease. I use a synthetic Constant Velocity Joint grease in all wheel bearings.

 

[sw00py]

I always tighten the adjusting nut while turning the wheel hub until it's so tight that I can't turn the hub. Then back it off and set the pre-load. As AZ has said, likely we all have our own method for setting this and those come about by having done it a bunch. Following the FSM is a good idea until you have developed the experience needed to do it other ways. And like gnob said, these aren't tiny bearings and they can handle some pre-load.

I will suggest that one way to make the bearings less sensitive to the pre-load is to hand-pack them with a premium grease. I use a synthetic Constant Velocity Joint grease in all wheel bearings.

Okay cool, thank you. I will err on the side of more torque, tighter hex nut as per FSM even if that means my preload is above spec while making sure the hub still rotates freely. Appreciate it!

 

[dfarr67]

There is a procedure that goes back and forth with stepped torque- that's what I did.

Toyota Front Axle Rebuild