Hub unitbearings

[Greg-100]

Sorry, never got back to you... never saw your post.

I was talking about the unit bearing.

NPPA has bearings and races you can install to replace the bearings and races in the unit bearing.

I rebuilt a unit bearing about 4 times, each time having to cut the race.

My belief is I had the wrong info for NPPA about the axles, as each time I put the unit bearing together, it wouldn't turn.

My YJ has had a long history of rebuilds before I got it, so I feel I don't have the hub NPPA thinks I have.

But in the end run it is cheaper to buy the unit bearing complete.

The bearings that go into the unit bearing are common, as the part's person looked them up in the book and pulled them off the self.

So it might be possible, to buy cheaper bearing and races from another source and rebuild the unit bearing for cheap.

It is the bearing in the unit bearing that fail, so all you need to do is replace the bearing. (cheaply)

My framer friend runs a John Deere bailer that burns out one of the bearing regularly.

It is a $80 bearing from JD, JD has someone else build them the bailer to sell with their paint, they sell the same bearing for $60, but his sis in-law got the crossover number and got the bearing from an industrial part depot for $40, then for $20 from an offshore company.

So if you dig enough, you can get parts for the right price.

Greg

[JackstandJohnny]

buy the cheap ones with a one year warranty from Autovalue. keep reciept. that'll be the last set of bearings you ever have to buy... if you drive it/wheel it/ it has large tires, you'll wear out the unit bearing enough that you can replace em under warranty every year........

[cLAY]

The problem comes with having them wear out on the trail or road. When I was running 31s I was going thru the cheap Parts Source ones every year. I checked them often but still broke down on the road with them twice. It can be REALLY hard to tell they are starting to go until its too late. I learned after awhile that a really faint grinding when cornering at speeds above 60kn/h meant one was starting to go. Jacking it up and spinning the tire I didn't feel anything, removing the tire and turning by hand didn't reveal anything(due to drag from axle shafts), only completely removing it and turning it my hands could I feel a roughness.

A few years ago I put a premium one on from Canadian Tire on my sister's ZJ, was around $200 I think and its actually held up fairly well. After buying lots of parts from PArts Source(I used to live really close to one) I've come to realize that they sell junk. I get all my parts from either NAPA or the dealer now, and usually the premium ones. It is expensive usually but I just HATE replacing something that I worked on less than a year ago. The fact that NAPA actually has people who know what they are doing helps out a lot too. Having pimple faced teenagers tell me that they can't look up a u-joint by part number, only application doesn't really work for me. Especially when I have to wait for him to stop bragging about the muffler he just put on his Honda that looked too big for my Dodge Cummins truck.


At an average of $200 per unit bearing and at 2 a year in about 3 years you can pay for a hub conversion kit. That was my motivation for going to a D44, was tired of replacing unit bearings and could spend $1200 on a bearing conversion kit. Of course in the end the D44 probably cost me 3 times that. 

[calltrex]

just go with the factory ones

they last years

i beat on my ruby for 2 years with 37 rubber and i never had to change them

[jpthing]

I run 35's and it gets used about 50/50 on and off road
I have chewed through a pile of the cheap "made in China" unit bearings from NAPA. My Friend got me 4 at staff discount pricing and I chewed through all of them in a couple of years.
Now I am running the SKS ones from NAPA. They have a red seal, the cheapies have a black seal. The new ones seem to hold up pretty well.
The other day I had one out and I thought about prying out the two rubber seals and repacking the unit bearing using one of those bearing repackers (of course the repacker would have to be stretched a little, it only fits about 2":of bearing).
I wonder what is the principle cause of failure. One or all of ther following?
1) grease working it's way out and being replaced by mud and dirt
2) increased offset and tire weight overloading bearing
3) Shock loading from wheeling, curbs etc

probably a combination of all three. Perhaps I will try repacking one and see how it lasts.

A VERY INTERESTING THING ABOUT CHEAP PARTS PRICING:
When my friend picked up those cheap wheel bearings for me we figured uot just how much of a rip they usually are. She got stuff very near cost, so you could see what the stores cost was by buying with the staff discount. The cheap ones were around $200 and the good ones around $250 (retail price.) With the staff discount the cheapies went for around $40 and the good ones for around $185...so in other words, the parts stores simply price the cheap chinese stuff to be a little cheaper than the regular stuff, regardless of how cheap it really is.

It is true that the factory (timken?) ones last a lot longe, in my experience.

Unlessyou are selling your Jeep I cannot reccomend the cheapies...I get around 3-6 months out of them.

I have never had a problem with them failing suddenly...They gave lots of hints first, and then became very slightly loose...I have never had any fail unexpectedly.

[calltrex]

or do the warn hub conversion then u dont have to use unit bearings anymore

[Mikes off road]

I just came across this thread. Now from what I understand the early year XJ did come with rebuildable unit bearings. It was some time in the late 80's or early 90's that they went to a non rebuildable type. As for the hub conversion kit I have run the mileMarker on my XJ with 35's and blew three hubs out and took out the spindle that came with it. The reason I choose Mile Marker is they don't show a tire size limit in any of there ad's but when I spoke with them about blowing all the stuff apart he asked what size tires I was running. It wasn't till then that he said they are not built for tires that size and ended up giving me my money back. (have three spare hubs for sale if anyone is looking for some) Next upgrade would need to be the hub conversion that changes the bolt pattern to a 5x5.5 or a HP44

[RckyMtnTJ]

I was doing some searching on helping a buddy out with getting his reverse lights working on his Ram and came across this brief writeup about making hub bearings greasable.  Not sure if this is feasible or not.





Its at the bottom of this page:

http://www.mark74.com/ram_modifications.htm

[cLAY]

All XJs stock from the factory came with unit bearings, first XJ came out in '85, before that Cherokees were a completly different vehicle, considered a Full Size Jeep, designated SJ, same basic chassis and drive train as a Grand Wagoner or J series truck.

In '85 XJ line came out also called the Cherokee or for clarification the "downsized Cherokee".  Pre '85 full size Cherokee(SJ) with a D44 front axle and serviceable bearings, after '85 downsized Cherokee(XJ) with a D30 front axle and unit bearings.

What was failing on the MM hubs? Bearings, hubs or spindles?

[cLAY]

I'm not really sure how much greasing would extend the life of the unit bearing. I personally think they just are over stressed with bigger tires. I try stay out of the mud and still had poor life span on my cheap bearings.

On a Ram with a heavy load I could see the grease overheating and breaking down and then being able to pump fresh grease in would help. Although I suppose this argument could work bigger tires as well. Bigger tires/more load/more heat/grease breaks down......

[Mikes off road]

With the MileMarker hubs I blew three hubs within 9 months. the final straw was when the spindle it self broke right where it flattened for the spindle bolts. The Mile Marker tech told me that a 35`tire was too big for the hub kit and they recommended only running a max of 32``. He also said that the only kit he was aware of that would handle 35`s was the warn 5x5.5 kit.