Micro stub bearing end play.

onanysunday

onanysunday

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I installed the Jamar pro x micro stub kit on my car 3 years ago. So after three seasons with the car jacked up there is a tiny bit of play on one side. At what point do you look at pulling them apart and replacing? Or how much play until they completely fail?

 
Have you checked the nut on the stub axle? The stub axle holds the bearing together, if the nut comes loose, the bearing will fail.

In my opinion, the bearing is toast and needs to be replaced. The question is no longer if it will fail but when. They are a sealed bearing assembly and if the nut is tight on the stub axle means the bearing has worn enough into the hardened surface to create play. After it wears past the hardened surface, the rate at which the bearing fails is rapidly increased. Buy another bearing and put this bearing in the tool box as a spare.

I would call Jamar and discuss this premature failure with them. I am assuming this is the larger 3.90" bearing that should easily handle the weight and power of your Funco. I would estimate a lifespan of 10-15+ years for that bearing on your car.

 
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Jamar sells two different 934 Micro-stub kits. One kit has the smaller bearing and the other kit comes with the larger bearing. Smaller bearing measures 3.60" and the larger bearing measures 3.90" If you have the smaller bearing, 2-4 years is the life expectancy. Larger bearing should last for many years. Let us know what bearing size you have and what Jamar says.

 
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You sure that was 3 years ago?  I thought you did that upgrade in the summer of 2020.

 
Check if the nut is loose first.  Sometimes they wear in a little and need re-torquing.  If it gets loose again, replace them.  JMHO...

 
It is the 3.90 bearing. There is a cotter pin for the nuts so not sure how it could be coming loose. Kartek says if it's starting to feel some end play it is starting to go bad. They do have them in stock at $300 per bearing. Hopefully this thing will survive another 3 days. I will keep an eye on it

 
onanysunday said:
It is the 3.90 bearing. There is a cotter pin for the nuts so not sure how it could be coming loose. Kartek says if it's starting to feel some end play it is starting to go bad. They do have them in stock at $300 per bearing. Hopefully this thing will survive another 3 days. I will keep an eye on it
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Nut didn't move to get loose, the bearing itself beds in and the nut is no longer tight.  5 minutes to get to it with the rattle gun will tell the tale.

 
Rockwood  you were right. Nut backed off and sheared the cotter pin into five pieces. 1.767 nut. I had ground the six sides to make an American socket fit it. Now I'm wondering if I can beat on it with a chisel and get it tight enough to go do a ride today and a ride tomorrow before I can get a socket here.

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I took a hammer and a punch to each little lip on that big nut. Got it tight enough. Held fine so far for a ride tonight.  I got a breaker bar and a socket coming tomorrow. Problem with the design on this is the washer is thick enough you can't get a full size cotter pin in the hole. If it had a full big size cotter pin or it would not have sheared off like that. Need to either make the hole bigger or put a thinner washer on it to accept the proper size cotter pin.

 
if it was tight enough it would not need a cotter pin, I would make sure it was torque properly, or maybe mag them to make sure they are not cracking 

 
Found this on Pacific customs website:

This micro stub bearing assembly must be torqued with an actual torque wrench before moving the vehicle. The axle nut must be torqued to 250 ft./lbs. After the first 5 miles of driving, you must RETORQUE the axle nut because the bearings will settle. If you do not torque your axle nut with a torque wrench and if you do not retorque after the bearings settle, the bearing assemly will fail. If you understand this, please click the bubble to the left. If not, then click your browsers back button.




 


 
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Wonder if THIS is the same part. 33 spline and 3.90 hole. Hmm. 

 
Every year you should check the torque on the Micro Studs,  Front Spindles and Suspension components, 

Lug Nuts should be checked multiple times a year,  

 
Called Bob at BRP today. Super nice guy. He was the first to do these microstubs in the 90s and he gave me the history. Then everyone copied. Wheel offset and load makes a big difference how long these last. Sounds like these have a limited life span when you have a lot of abuse and load on the car. Have to say I am very disappointed I now have a setup that will need bearings every 1.5 to 2 seasons. That will be $600 each time for a pair. Wishing now I would have bought Bobs kit since his bearings are a lot cheaper. Never thought they would need replaced this often. No other choice but to buy the Jamar. On the other side of the coin maintenance is much easier. Don't touch it for a couple of seasons. Although I would go a couple season on the Funco centerboard bearings before maintenance. Those bearings that were in the car for 15 years are still good and I just need to sell those parts. Other thing is I was able to make the car a little wider with the microstubs so it does work very well. Oh well my .02. 

 
onanysunday said:
Called Bob at BRP today. Super nice guy. He was the first to do these microstubs in the 90s and he gave me the history. Then everyone copied. Wheel offset and load makes a big difference how long these last. Sounds like these have a limited life span when you have a lot of abuse and load on the car. Have to say I am very disappointed I now have a setup that will need bearings every 1.5 to 2 seasons. That will be $600 each time for a pair. Wishing now I would have bought Bobs kit since his bearings are a lot cheaper. Never thought they would need replaced this often. No other choice but to buy the Jamar. On the other side of the coin maintenance is much easier. Don't touch it for a couple of seasons. Although I would go a couple season on the Funco centerboard bearings before maintenance. Those bearings that were in the car for 15 years are still good and I just need to sell those parts. Other thing is I was able to make the car a little wider with the microstubs so it does work very well. Oh well my .02. 
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Bob is good people and makes his stuff locally. He has even stayed late and made me axles on Friday night so I could head to the dunes for the weekend. 

 
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