How hot is too hot?

[JDToumanian]

I have finished replacing the rear axle seals and cleaning and repacking the bearings. I adjusted the bearings per the TM, tightening to 50 ft.lbs. and then backing off 1/16 - 1/4 turn (shooting for 1/8 turn) to get the keeper to line up with a flat on the nut. All seems well except for the hub temperatures...

After a 15 minute drive at 50 mph, I stopped to check the hub temps. One was barely warm, two others were warm and the last was fairly hot. This troubled me a bit, so I decided to pull the axle shaft of the hot hub and recheck the adjustment. As it turns out, this was the tightest of the lot, I only had loosened the nut a hair over 1/16 turn, so in order to get a different adjustment out of it I flipped the adjusting nut over. This time I got just over 1/8 turn out of it and was pleased - confident all would be well.

However I went for a drive today... It was in the low 80s and I drove Route 66 at 50+mph for 20 minutes and stopped to check the temps... 1 warm, 2 hot but not too hot to keep your hand on, and the same one was still quite hot... more than about 2 seconds would make you say ouch. This time I think I can rule out tightness as the cause.

So is this abnormal? I realize the hubs are connected to the brake drums, I plan to check brake adjustment, but the hubs came off and on with no interference from the brake shoes, and the wheel seems to turn freely jacked up with the axle shaft out... So I hadn't suspected dragging brakes as the cause. How slight a drag of the brakes can cause this? Do you think the bearing is bad? What did I do wrong? Is this normal?

All advice is greatly appreciated!

Regards,
Jon

 

[M35A2]

One way to see if the brakes are binding is to get an empty washing up bottle filled with water. Drive for 20mins at 50mph, pull over without using the brakes, get underneath and try and sqirt water on the brake drums. If it steams then your brakes might be binding.

Did you pack the bearing with enough grease?

Is the bearing seated correctly? As you tighten the bearing, keep rotating the wheel. I find using the book torque settings is a bit hit and miss. Tighten the bearing as much as you can, so that the wheel hardly moves, then slacken off until it moves freely by hand. If it is still doing this after you have done the job, then drive it for an hour or so, it may just need to bed in properly.

When I did my Land Rover bearings there are two nuts that screw onto the stub axle. The first tightens the bearing, the second is a lock nut. The first nut needs to be tightened as much as you can to seat the bearing, turning the wheel while doing so. Loosen off until the wheel moves freely, then just tighten the nut by hand, leaving it very slightly slack. When tightening the lock nut, it tightens the first nut slightly.

Hope this helps. I haven't done it on a M35, but the principle is the same.

 

[red devils dude]

this is a good topic what is the best way to adjust the wheel bearing nuts I'm planing on doing all mine
so I'd love to know.

 

[wallew]

According to RandyLBarnes, who is a diesel mechanic for a trucking company, the CORRECT method is to tighten the axle nut ALL the way down until the wheel does NOT move. That seats the bearing properly. Then loosen the axle nut. Tighten down to 'finger tight'. THEN one quarter turn after that. You have now properly tightened the axle nut onto the axle bearing.

A caveat here is that you have a clean race AND a clean bearing. Otherwise there will be scoring of the race at a minimum and a wiped out bearing AND a torn up race as the worst case.

 

[red devils dude]

when I did my pick ups front wheel bearings I used a dial gauge on the rotor then tightened untell no
play was readable at top edge of the rotor.

 

[Polverone]

Jon,

I am having the same difficulties. What did you ever resolve on the hot hub issue?

 

[OPCOM]

I had this and it was brakes which were adjusted too tight when the wheel was put back on. The temp was 167 degrees coming off the highway as measured witha DVM and thermocouple probe.

 

[JDToumanian]

Ya know, I never did anything. The temps eventually settled down all by themselves, and now all six hubs are pretty close to the same temperature after a fast freeway trip, and all are only warm to the touch.

On a related topic - wheel bearing grease - I had wondered how much to use. Did I use too little? Too much? After packing the bearings, do I add additional grease to the hub and spindle? When I disassembled the hubs, there was literally handfuls of grease. Probably almost a whole tube per hub.... I finally found a definitive answer in print in a TM. The lube order section in TM 9-8022 (Dec. 1954), Section 110 "General Lubrication Instructions" (page 199) states:

"After bearings are properly lubricated, pack hub with sufficient amount of lubricant to uniformly fill it to inside diameters of inner and outer bearing races. Coat spindles and hub with thin layer of lubricant (not over one-sixteenth of an inch) to prevent rusting. Do not fill hub caps to serve as grease cups under any circumstances. They should be lightly coated, however, to prevent rusting."

Basically, I drove very cautiously and stopped to check bearing temps frequently when driving "fast", and instead of getting hotter and burning up the bearings seemed to stay cooler as time went on.

Regards,
Jon

 

[jimk]

Then loosen the axle nut. Tighten down to 'finger tight'. THEN one quarter turn after that. You have now properly tightened the axle nut onto the axle bearing.

cut
Might want to check this(THEN one quarter turn after that). Usually the nut gets loosened 1/8-1/4turn after.Tightening the lock nut causes the adjustment to tighten again as the jam nuts push away from each other,causing the inner nut to take up the play from the loosened bearing.Also most spec that the wheel be rotated as it gets tightened to seat the bearings.Then only to a torque (~100ft/lbs) as it would have to be very tight to stop the well dead(and, what is bind(TM))?. Over tightening, or not rotating ,risks brinneling the bearing.JimK

 

[Barrman]

Here is a great site if you want to learn all about bearings. Timken says this:

http://www.timken.com/products/bearings/techtips.asp

 

[Polverone]

Thanks Jon and Jim,

I took it apart again and tightened the inner nut while turning the wheel until it did not rotate quite as easily. I couldn't tighten the nut any further and I was using the 19" 3/4 drive socket wrench with the proper axle socket so that was where it ended up. Loosened it between 1/8th and 1/4 turn. Tightened the outer nut until my veins popped outa my forehead. Inner nut didn't move. Have to make trip to Riverside to be in a parade (109 miles each way) in 3 weeks so want to get it all done now.
If you read this Big Mike and Will Wagner would love to have you guys come out. Goes for you too Jon.

On the hub grease, I also had about a wheelbarrow full of grease inside the hub so I glopped a whole bunch back in there, ( I did clean all old grease out first), not sure if it was even with the bearings but it was pretty darn close.

Thanks

 

[jimk]

Torque on that outer nut is important.Best set at spec. but better too tight than too loose. Deuce calls for 50ft/lbs while my trailer(Dexter axle)looks same but spec. is 225-250ft.lbs. That is a lot for the 2 or 3 threads the thin nut offers. I used a t-wrench. Felt fine. Must be a strong (stronger alloy) nut. Whomever was in there before had used a chisle. A sure failure waiting to happen with 10T on trailer. My dumper same(chisled), Always good to check these .

JimK

 

[gringeltaube]

.... Whomever was in there before had used a chisle.
JimK

To often this is the case! After a nut was treated that way it may increase its inner diameter and fit very loose on the spindle. The best thing to do is replace it!

 

[gringeltaube]

Normally a used (and abused), slightly worn nut shows some axial play compared to a new one that barely can be turned with the fingers.

So the whole bearing adjustment procedure depends a lot on the condition of the spindle nuts and the spindle itself!
After initial tightening of the first (inner) nut against the bearing like posted above, backing off 2 flats (1/4 turn!) before the second (outer) nut compresses everything, could be still insufficient to avoid excessive bearing preload!

I go back 3 flats, tighten the outer nut, rotate the tire/wheel/drum/hub assembly a few revs, rock it with a pry bar trying to feel any free play, if so go 1 flat back in of 1st nut, again the same, until free play just disappears. Final torque of outer nut: approx. 200ft.lb.
Don’t forget bending of one lock washer tab over the 2nd nut, just in case...!

Gerhard

 

[Recovry4x4]

Great explanation Gerhard.

 

[cranetruck]

The worn nut theory doesn't make sense to me at first glance, but I have too much respect for Gerhard to argue.

 

[jimk]

Overtightening is bad.it can create wear,cracks,even strech the metal.

It is unlikely my chisled trailer nut was damaged. It was perhaps 5ft/bs (instead of 225-250).

Lube on the threads effects torque. I don't remember exactly but for something like 20% for oil,30% for grease/90W, 40-50% for moly grease. A concideration if you grease wheel studs.JimK.