HELP! Need help with wheel bearing preload

1973Guppie · 02-09-07, 11:23 PM

HI,

so I am finishing up my front disc brake minitruck conversion. vehicle is a 1970 FJ55 and I am swapping over minitruck knuckles. Everything went fine and I got to the point of having the spindle, backing plate, seals together. I then went and installed the hub/rotor assembly with the inner and outer hub bearings. I have read all the posts on bearing preload and I installed the outer bearing, washer and nut, then torqued to 45 lb, backed off, finger tight (5 lb), then checked preload by attaching fish scale to the wheel lug. Problem is that I get about 25 lbs?? I even loosened the whole hub asembly back off, and repeated the process, still get about 25 lbs and that was with the inner nut just finger tight.

What am I missing here? maybe too much grease in the knuckle? would it be ok to just go with it the way it is?? I am tempted to do so. From what I can see everything is sitting as it should and I was very careful to assemble everything exactly the same as it came off, all new seals and gaskets. I even took pics of how the minitruck axle came apart to make sure it went back together the same.

any help appreciated as I am hoping to button up the front axle this weekend!!

thanks,

Noah

peesalot · 02-10-07, 12:22 AM

does it spin smoothly ? run it....

ranger · 02-10-07, 12:35 AM

You tighten the inner nut to 43 ft lbs, then rotate the hub a few revolutions, loosen it then torque again to around 43 ft lbs. (this is what seats the bearings) Rotate the hub again to see if it spins freely, you will have some resistance. Put the lock tab washer on, then the outer nut and torque to 58 Ft Lbs. Bend tabs over the nuts. I usually get two on the inner and two on the outer.
I tried the fish scale to measure preload this weekend for shats and giggles and the result is even with the nut backed off the preload measurement is higher by 10 lbs than max the FSM calls for. I contribute these readings due to new grease and chilly garage.

1973Guppie · 02-10-07, 01:28 AM

pees, yes it rotates smoothly, just fine.

ranger, from my info there is knuckle bearing preload and wheel bearing preload. I measure the knuckle bearing preload and it is fine, I did this by using the fish scale and measuring the amount of pull it takes to turn the knuckle when attached to the steering arm, the issue I am having is with the wheel bearing preload so I don't think I am confused? as I mentioned I am attachinh the fish scale the the lug stud and rotating the rotor hub assembly and it takes about 25 pouns, the FSM calls for 12 pounds at the most. I am getting a reading of 25 pounds to get the rotor to turn.

should I just run it and not worry about it?

Noah

Cruiserdrew · 02-10-07, 06:39 AM

1973 is correct-there is a WB preload spec as well. I have found that in the winter, the cold grease prevents you from getting and accurate pre-load measurment. Over the last year, I have adopted Landtank's (giving credit where due) method. Torque to 48 or so, spin many times to distribute the grease. Then back off to 0. Then torque the inner nut to 10 foot-lbs. Add the star washer and torque the outer nut to 43 foot-lbs. Check for loosness and if none, bend the tabs and call it good. That pre-load is not reproducable enough, unlike the torque spec on the inner nut. In warm weather, the preload using this method comes out around 10 on the fish scale. All 3 of my trucks are now setup with this method with absolutely no issues.

Since this is a new build, I reccomend you drive for a few weeks, and then go back and do the wheel bearing preload again. New bearings can loosen up after some driving.

1973Guppie · 02-10-07, 09:21 AM

cruiserdrew, pees, thanks!, I know what you mean about it not being reproducable, it seems on some pulls it comes up about 15, then others 25, I will just torque the inside to 10 lb and call it a day. Will update my build thread here soon.....

Noah

mikesc · 03-06-07, 07:44 AM

I have the same proble that Guppie has with my wheel bearing preload. I did it the way that is recomended above and still comes in sometimes at 15 and others at 25 lbs. What else could be causing this?

tucker74 · 03-06-07, 07:52 AM

Quote:

Originally Posted by mikesc

I have the same proble that Guppie has with my wheel bearing preload. I did it the way that is recomended above and still comes in sometimes at 15 and others at 25 lbs. What else could be causing this?

Torque the inner nut to 48 ft/lbs - spin the rotor 10 revolutions forward, then 10 backwards. Back the nut off and tighten it finger tight (48 in/lbs), stake the inner nut (if you forget to do this the outer nut will over tighten the inner). Then torque the outer nut to 48 ft/lbs ... this is the point you want to measure preload. If it reads 8-12 lbs stake the outer nut -

Tucker

1973Guppie · 03-06-07, 10:00 AM

mikesc, toss the guage back in the tool box and follow the reccomended procedure they mention above, that's what I did as I could not accurately reproduce an accurate preload, my thinking is that it is difficult to have a pull guage truly test a load when pulling on a lug stud on a round wheel? It would make sense that at some points in the circle the pull would be harder or easier depending on what axis you are pulling at. OR, I am just an idiot. Could be either.

Noah

mikesc · 03-06-07, 10:12 AM

Guppie, I am with you I am going to set it like tucker said and move on. The knuckle bearings came out perfect so I am not going to sweat it either. Thanks

Mike

'74 UA FJ · 03-06-07, 11:36 AM

Run it. God forbid you actually put 100,000 miles on an fj40 or 55 and have to get new wheel bearings...

theo · 03-06-07, 06:09 PM

You can check the adjustment once in awhile to reassure yourself that the bearings are OK. Here's how I do it:
Grab the hubs after driving the freeway for half an hour. If they're hot the bearings are too tight. Warm is OK, cool is more gooder. If they're cool, jack it up and check for play. If there is play the bearings are loose.

Cruiserdrew · 03-06-07, 06:42 PM

Quote:

Originally Posted by theo

You can check the adjustment once in awhile to reassure yourself that the bearings are OK. Here's how I do it:
Grab the hubs after driving the freeway for half an hour. If they're hot the bearings are too tight. Warm is OK, cool is more gooder. If they're cool, jack it up and check for play. If there is play the bearings are loose.

The problem with the temp check method is that the hubs are a heat sink for the rotors. So any brake use at all and the rotors and thus the hubs will be very hot. I like the preload I get with around 10 foot pounds on the inner nut. Usually hits the high end of the fish scale spec.