Bearing Failure

[RandyEarle]

Outside right front wheel bearing on our 1999 Newmar Dutch Star failed at 37,000 miles. Overheated and stuck to axle. Still had substantial oil in case and no damage to inside bearing. Mechanic suggested cause as either faulty bearing or improper installation. We purchased it in August 2009 with 29.000 miles and had unit "serviced". Have to replace axle since it was heated enough to change colors. Spartan had no spares. Have to have one manufactured. Plant closed for a month. Hope to get on the road again next month. Any ideas on defective bearings?

[a k]

Did the bearing spin on the axle? Change in color wouldn't be cause for replacement, would it? Did the plastic cup on the outside melt? If not, I'd just replace the bearing.

[RandyEarle]

Originally Posted by a k

Did the bearing spin on the axle? Change in color wouldn't be cause for replacement, would it? Did the plastic cup on the outside melt? If not, I'd just replace the bearing.

The bearing did not spin on the axle. The part that keeps the bearings aligned (the race?) distorted and the solid part next to the axle was "welded to the axle. It took a torch to get it off. Mechanic smoothed axle and put new bearings in place and I drove it 30 miles to garage. I checked their warning with my repair shop and they agreed it would be dangerous to drive very far.

The plastic inspection cover melted. It was still in place, but the red plug had come out and the hole for it was out of shape. Cover was white instead of clear.

[Ronnie Bledsoe 2006 Dutchstar 43']

Randy, how did you know? What were the symtoms?
Does anyone know if a TPMS would have given a warning of high temp?

[a k]

Just a question. Had the wheel been trowing oil before the bearing went out? I had that red rubber plug come out of mine for no reason and it did throw out the oil , but I caught it only 4 oz low. Bearing and everything else ok. Could have fell out and run low and overheated. Outer bearing will run out of lube before inner bearing due to diameter of inner brg larger.

That red rubber cap scares me. I put masking tape over after refilling and drove 500 miles no trouble. Thru the damn hubcap from taking on and off too many times.

[EngineerMike]

Randy- the cup had to spin to generate enough heat to "weld." If the tech is saying otherwise, the tech doesn't know his business.
Most likely failure cause is improper "axial or lateral runout" on the bearing installation, aka bearing "pre-load." There are various recommended preload practices you can find googling "bearing preload" or "bearing lateral runout" that talk about setting up dial indicators, etc. However, approximately nobody uses them. Instead truck shops use the TFAR method (That Feels About Right) of tightening down the nut, spin the tire, tighten a bit more, spin the tire, etc, then back off the nut & install the keeper. Failure is actually rare with this method, tho a neophyte first timer could mess you up pretty easily. For that reason, the training method consists of supervised bearing pre-load by a seasoned pre-loader, and that training method seems to achieve pretty good results.

Usually when pre-load is bad, it is bad enough to produce heat right off the bat. It may not be problematic tight away. I recommend using an infra-red temp probe to check hubs before repacking, then again within 20 miles after bearing repack. If its getting hot and you detect it right away, then you can get it fixed before trouble on the road.

Probability also is that replacement of your axle is an exercise in excess safety factor, but it is one that I would do when convenient, tho I wouldn't sweat driving it around for the time needed to get the new axle as long as the axle temp is good.

[AFChap]

That red rubber cap scares me. I put masking tape over after refilling

I've driven my Spartan chassis over 50k and never had any problem or concern with the red rubber cap. The only problem I have heard of is if the little breather hole in the red cap gets plugged. (the hole keeps pressure equal inside and outside so grease is less likely to be forced out due to temp differential, etc). I check it occasionally to ensure it is open (stick a tooth pick, straight paper clip, etc through the hole).

Actually, I wonder if when your cap came out "for no reason", it was actually because the breather hole was plugged ??? IF YOU HAVE COVERED THAT HOLE WITH TAPE, poke a hole through the tape over the breather hole so you don't cause more problems with your "fix".

[RandyEarle]

Originally Posted by Ronnie Bledsoe 2006 Dutchstar 43'

Randy, how did you know? What were the symtoms?
Does anyone know if a TPMS would have given a warning of high temp?

I am new to driving a MH. First symptom was a popping sound followed by something like the rumble strip on side of road. I stopped MH to inspect. All tires looked good. Felt tires and no excessive heat. I had just filled propane tank for first time. There was a smell like propane. I assumed pressure had built up in tank and relief valve had let off some gas and I had steered over rumble strip in response. Big mistake. I drove about 50 more miles and filled up with fuel using right fill and didn't notice anything. No unusual sounds while driving. No pulling, etc. No apparent oil leaks. BTW left fron seal failed and did leak oil so I was somewhat familiar with signs of leaking oil. Anyway, I went 10 miles before the sound started again. I pulled off on exit ramp and checked tires again. Wife followed smell and saw a little smoke from rt. front wheel. I pulled inspection plate and saw melted plastic cover. Camping world sent mechanic.

Randy
,

[RandyEarle]

Originally Posted by EngineerMike

Randy- the cup had to spin to generate enough heat to "weld." If the tech is saying otherwise, the tech doesn't know his business.
Most likely failure cause is improper "axial or lateral runout" on the bearing installation, aka bearing "pre-load." There are various recommended preload practices you can find googling "bearing preload" or "bearing lateral runout" that talk about setting up dial indicators, etc. However, approximately nobody uses them. Instead truck shops use the TFAR method (That Feels About Right) of tightening down the nut, spin the tire, tighten a bit more, spin the tire, etc, then back off the nut & install the keeper. Failure is actually rare with this method, tho a neophyte first timer could mess you up pretty easily. For that reason, the training method consists of supervised bearing pre-load by a seasoned pre-loader, and that training method seems to achieve pretty good results.

Usually when pre-load is bad, it is bad enough to produce heat right off the bat. It may not be problematic tight away. I recommend using an infra-red temp probe to check hubs before repacking, then again within 20 miles after bearing repack. If its getting hot and you detect it right away, then you can get it fixed before trouble on the road.

Probability also is that replacement of your axle is an exercise in excess safety factor, but it is one that I would do when convenient, tho I wouldn't sweat driving it around for the time needed to get the new axle as long as the axle temp is good.

Mike,

I wish I had had someone suggest going on. Left it in Shreveport on way to Dallas. Less than 200 miles. Oh well, in Florida now.

I will definitely check temp of hubs after short drive. I guess this has to be done regularly, since there was at least 8,000 miles on bearing since installation. Most likely it had never been removed and reinstalled.

Randy

[RandyEarle]

[QUOTE=EngineerMike;584345]Randy- the cup had to spin to generate enough heat to "weld." If the tech is saying otherwise, the tech doesn't know his business.
OTE]
Mike,
It was an assumption on my part that part next to axle did not spin. No one told me that.

Randy

[a k]

No vent hole in my red cap. I have oil filled hub, not grease. Just picked up 2 new red vent caps. Will try that. I have K2 chassis

[AFChap]

No vent hole in my red cap. I have oil filled hub, not grease

???? Mine also are oil filled, and definitely have a very small vent hole in the center of the red rubber cap. Mine is a Winnebago modified MountainMaster Gt chassis.

[a k]

Maybe I'm not looking at it that close. I hope your right. What a mess it makes. I'll worry about it at the end of March. 14 Degrees here in the midwest.

[RV Wizard]

a k, you might look at some salvage yards for an axle off a coach that was totaled from some other problems. Good luck and keep us posted.