Wheel Bearings - Preload Question

Truck: 1968 M35A2 - 16 Spline C240 Rockwell Axles.

So the TM says to tighten the locknut until the wheel binds then back off. Well I have tightened it until it doesn’t tighten anymore and the wheel doesn’t bind. I set them by feel... no play in the hub afterwards. Tightened the outer locknut to 150 ft lbs.

Curious if anyone has run into this and what they did? Bearings were in good shape... no pitting, rust or visible wear.

dbesade said:

Truck: 1968 M35A2 - 16 Spline C240 Rockwell Axles.

So the TM says to tighten the locknut until the wheel binds then back off. Well I have tightened it until it doesn’t tighten anymore and the wheel doesn’t bind. I set them by feel... no play in the hub afterwards. Tightened the outer locknut to 150 ft lbs.

Curious if anyone has run into this and what they did? Bearings were in good shape... no pitting, rust or visible wear.

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Actually, the TM says:Turn wheel, tighten inner adjusting nut (3) 50 lb-ft (68 N•m),
then back off nut (3) 1/16 to 1/4 turn.
3. Install new key washer (2) and outer adjusting nut (1). Tighten nut (1) 100–200 lb-ft
(136–272 N•m).

It's all about feel. You don't want the bearings too tight, because as they heat up, they'll be tighter, and run to hot.
Too lose, and they're going to run hot also.
Really it's just about hand snug. A few thousandth's of play, to just zero play.

In my experience, it's **** hard to feel any play by grabbing the drum itself, and it's **** hard to get consistent play by just backing the nut off a predetermined amount... I might get flamed for this, but what has worked for me is to tighten the inner nut to 50' lbs., put a lug nut on two opposing studs of the drum (across from each other), spin the drum if I can (if I can't, I back the nut off until I can) then grab the lug nuts and give the drum a hard shove inward, toward the backing plate, then yank it back out toward myself, in quick succesion. I keep backing the inner nut out one flat at a time, spin the drum, and yank/shove the lugs, just until I barely hear and/or feel the tiniest "thunk" as the bearings hit their limits in the cups when shoving the drum in and out. Install the washer, torque the outer nut, and spin/yank again. I want to hear/feel that tiny "thunk" when the washer and outer nut is installed. If I don't feel the tiny thunk, then I keep backing the inner nut out 1 flat, reinstall the washer and outer nut, and try again until I do. It's better to have a little extra play rather than too little. On long trips I check my hub temps with a temp gun, and since I started adjusting my bearings this way they consistently run cooooool.

Menaces Nemesis said:

... I might get flamed for this, but what has worked for me is ....... ........ and since I started adjusting my bearings this way they consistently run cooooool.

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No, you won't get flamed... In this case "the end justifies the means", no matter how exactly you proceeded.

Myself I go to 150 /200 foot pounds while spinning the tire. Back off then go to 50. Back off 1/8 and never had over heat or leaking outer wheel seal. Trucks without an outer oil seal I go 1/4.

Floridianson said:

Myself I go to 150 /200 foot pounds while spinning the tire. Back off then go to 50. Back off 1/8 and never had over heat or leaking outer wheel seal. Trucks without an outer oil seal I go 1/4.

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I'd venture to say that you have far more experience than I do, but like others, I have sheared the slot-tab off of the newer seals by torquing the inner nuts over 50, even when they're greased good on both sides;
https://www.steelsoldiers.com/showthread.php?132817-Newstar-hub-seals
Seems like the newer outer seals have some really soft metal plates!

Floridianson said:

Myself I go to 150 /200 foot pounds while spinning the tire. Back off then go to 50. Back off 1/8 and never had over heat or leaking outer wheel seal. Trucks without an outer oil seal I go 1/4.

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Floridianson's answer is the closest to what we do on big rigs all the time. We tighten the nut to about 200 to 250 Ft Ibs while spinning the wheel assembly, then back off about 30 degrees (or until there is no load on the bearing, also the brakes should be backed off during this while process) . Then retighten until the nut is just snug (you should be able to back off the nut by hand) . Then tighten the outer jam nut. This method seats the bearings and allows almost zero lash or clearance to prevent heat build-up during use. (You really need to be extra careful on front hubs. You need no extra clearance on them ! Not unless you like to steer all over the road) . I've used this technique for over 40 years on trucks and busses and off-road equipment and never had a problem. Now if for some reason your running a European truck like a M.A.N. then all reason goes out the door ! They are tightened to over 300 ft Ibs and left that way ! Really crazy bearing system. Takes a special puller to remove the wheel hubs and to reinstall them.

I edited this post for Gringletaube's benefit.

Well since the front axles don't have the outer grease seal we can do it to them. Myself when I do a axle job on a truck that has an oil seal inner not like some of our military stuff I am real care full with the install. Most of the time I use my correct wheel dolly as it helps so much. If I am using the wheel dolly or installing the hub buy hand I do this. I place the hub on and push it in till I can get the outer bearing in just enough to center the hub. I push the hub /bearing on farther till I can get the nut on. It's very important not to let go or let the drum/hub sag if I am not using the wheel dolly before I get the outer bearing on. As soon as I can get the nut on I run the hub up using the nut till I get the hub seated. So on a truck that does not have an outer seal we can go to the higher torque to seat the bearing. Now we can also do this to our military truck with outer seals just buy not putting on the outer seal on till you seat the hub and high torque it. Then back off the nut and hold the outer bearing in with you fingers and put on the outer grease seal and torque to lets say 75/100 foot pounds. Then back off and do the 50 . If your like me I use air tools so running the nut on or off is fast.
Yes I have seen where some people having trouble with the outer seal tab breaking off. Maybe they are made of the recycled beer cans we send to China.

I live on the Mexican border. I once had a 5th wheel RV trailer come in with extremely loose wheel bearings that couldn’t be tightened. Mismatched bearings and cones. Guy had just had them installed....in Alaska.

That proved to me that loose is better than tight...but like menaces you want them barely loose. I like to use a wheel and tire to yank on for leverage.

All,

Thank you so much for the assistance. I have 3 three hubs by Hand/Feel... and have no play with the tires installed, and I did the last rear with the 50 ft. Lbs. method... they all had the same feeling. For the front, I'm thinking either the 50 ft. Lbs. method or RustyStud's method.

If there is an issue, I'm going to be doing a shakedown ride and then taking the rears off again anyway for brake work... so I'll have an opportunity to adjust the preload.

Regards,


Dave

dbesade said:

All,

Thank you so much for the assistance. I have 3 three hubs by Hand/Feel... and have no play with the tires installed, and I did the last rear with the 50 ft. Lbs. method... they all had the same feeling. For the front, I'm thinking either the 50 ft. Lbs. method or RustyStud's method.

If there is an issue, I'm going to be doing a shakedown ride and then taking the rears off again anyway for brake work... so I'll have an opportunity to adjust the preload.

Regards,


Dave

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If you don't already have one, get one of those laser thermometers from harbor freight. They have coupons in their catalogs for them at $17.99. They're handy for all sorts of stuff... checking out hub and other mechanical device temps, checking to see if the wife is angrier than usual and about to strike, etc. (don't let her see you point it at her... that seems to just escalate things)

Bearing preload is one of those things that every manual seems to have a different way of doing it, each of us were taught a different way and have seen other people do it different ways. We are all looking for the same end result. A seated bearing and the adjuster nut right at but not over the too loose line and locked in place.

When I took over my class last century. There were some old manuals gathering dust on the shelves. One was a 1958 Oldsmobile factory service manual. It listed out a torque value for the nut, said to spin the hub 19 times one direction, re torque, spin 19 times the other direction and then a final torque setting. I have never attempted their exact procedure myself.

My personal method on the M35 trucks is to put the tire on after the adjuster nut is no longer able to be turned by hand. Then, while spinning the tire I tighten down the adjuster nut to seat the bearing. Once seated, I push/pull on the top of the tire while backing the nut out until I feel slop. I tighten/loosen the nut while push/pulling until I can barely feel any slop in the tire. Then torque down the lock nut. No slop, temperatures after hours on the road are never more than a few degrees above ambient and the steering is as good as these trucks can be.

I'm just glad these trucks have the two nut assembly. Light duty cars and trucks with the cotter pin and castle nut never seem to be close to what I consider correct. You have to choose too tight or too loose. I always choose too loose for bearing life unless weird steering issues develop later. Then I go too tight and live with it.

(Oops, did I just do nineteen turns, but only counted eighteen ...!?)

Still, I'm convinced that in order to get these tapered bearings correctly seated, it is much "healthier" for them to spin the whole assembly a dozen turns or so while (hand)tightening the adjuster nut - vs. simply applying brute force with everything stationary, by torquing that first nut down to as much as 200 ft-lb (!)

Yes, this may require to momentarily back-off the brake shoe adjusters. But that also allows for a much better "feel" during the whole process.

Menaces Nemesis said:

If you don't already have one, get one of those laser thermometers from harbor freight. They have coupons in their catalogs for them at $17.99. They're handy for all sorts of stuff... checking out hub and other mechanical device temps, checking to see if the wife is angrier than usual and about to strike, etc. (don't let her see you point it at her... that seems to just escalate things)

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Hah! Thats how this started . I saw my hubs running hot. Which brings me to my next question... what do you guys feel is "Hot"?

-Regards,

Dave

The last hub I shot that was grease hubs on a 939 series was 120*

Floridianson said:

The last hub I shot that was grease hubs on a 939 series was 120*

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Is that hot or good?

That's pretty cool if you ask me now that is with an empty bed.

gringeltaube said:

(Oops, did I just do nineteen turns, but only counted eighteen ...!?)

Still, I'm convinced that in order to get these tapered bearings correctly seated, it is much "healthier" for them to spin the whole assembly a dozen turns or so while (hand)tightening the adjuster nut - vs. simply applying brute force with everything stationary, by torquing that first nut down to as much as 200 ft-lb (!)

Yes, this may require to momentarily back-off the brake shoe adjusters. But that also allows for a much better "feel" during the whole process.

Click to expand...

In the process I mentioned your suppose to spin the wheel during the tightening sequence. The brakes are always suppose to be backed off. That is just common sense. The only way to get large wheel bearings to fully seat is to torque them down hard. That has been industry standard for over 8 decades now.

rustystud said:

In the process I mentioned your suppose to spin the wheel during the tightening sequence. ................

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Thanks for editing your post.

gringeltaube said:

Thanks for editing your post.

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I've mentioned this so many times in the past I figured most have seen what I've written and only needed a little reminder. I guess not.