Micro stub bearings

No idea how it failed but the bearings were cooked and failed.  Sent it back to Kartek for evaluation as they said that they wanted to see what happened.  After they got it back they contacted me and said they dont have a reason for the failure.  So as of now i have put another one of their bearings in and hope it lasts longer than 3 trips. I checked and retorqued as they had in the specs.  Pretty pissed that i have had to buy 3 now as 1 of the first 2 went out so fast.  Ill attach pics of what it looked like when i took it off.  You can see the heat transfer and the races.  When it failed it took out the rotor and caliper too.  

View attachment 96827

View attachment 96828
Damn, I hate to see this. I was going to buy these bearings. Not only do you have all of the work but those units are not cheap. Crap. 

 
Damn, I hate to see this. I was going to buy these bearings. Not only do you have all of the work but those units are not cheap. Crap. 
I will tell you i just took other side off as well and there is 1/2in of play in the bearing after torquing initially and retorquing per their instructions.  I dont trust these anymore so i will be finding another option.  I dont know if its an install error or what but i have never had an issue with the Pro Am set.  I replaced as they were just old and was told that Pro Am wasnt making replacements any longer.  So for now original ones are going back in until i can find a suitable replacement.

 
I will tell you i just took other side off as well and there is 1/2in of play in the bearing after torquing initially and retorquing per their instructions.  I dont trust these anymore so i will be finding another option.  I dont know if its an install error or what but i have never had an issue with the Pro Am set.  I replaced as they were just old and was told that Pro Am wasnt making replacements any longer.  So for now original ones are going back in until i can find a suitable replacement.
Pro Am told you they were discontinued? 

 
No idea how it failed but the bearings were cooked and failed.  Sent it back to Kartek for evaluation as they said that they wanted to see what happened.  After they got it back they contacted me and said they dont have a reason for the failure.  So as of now i have put another one of their bearings in and hope it lasts longer than 3 trips. I checked and retorqued as they had in the specs.  Pretty pissed that i have had to buy 3 now as 1 of the first 2 went out so fast.  Ill attach pics of what it looked like when i took it off.  You can see the heat transfer and the races.  When it failed it took out the rotor and caliper too.  

View attachment 96827

View attachment 96828
I wonder if the crush sleeve spacer between the taper bearings was not to width spec . Either too wide making bearings loose or too narrow making them too tight .

 
Pro Am told you they were discontinued? 
Originally when i called Roy said that he wasnt going to produce them anylonger.  Must have been a misunderstanding and spoke with him today and he still is making them and still has them.  I think he isnt producing the entire kit any longer but still making the replacement bearings.

 
No idea how it failed but the bearings were cooked and failed.  Sent it back to Kartek for evaluation as they said that they wanted to see what happened.  After they got it back they contacted me and said they dont have a reason for the failure.  So as of now i have put another one of their bearings in and hope it lasts longer than 3 trips. I checked and retorqued as they had in the specs.  Pretty pissed that i have had to buy 3 now as 1 of the first 2 went out so fast.  Ill attach pics of what it looked like when i took it off.  You can see the heat transfer and the races.  When it failed it took out the rotor and caliper too.  

View attachment 96827

View attachment 96828
What grease did you pack them with?

 
I installed the Kartek rebuildable bearings and had a failure after 3 trips.  Sent it back to them as they said that they havent had a failure on these yet.....  After getting it back they couldnt tell why it failed and that im out of luck.  So i have just installed another one of them and now i am nervous to drive the car as the last one just failed.  I followed their tighten instructions and retightened them after 5 miles or so.  So take that for what its worth but im not sold on their new rebuildable system as of now.
Was this recently? I also bought the rebuildable ones from Kartek.

 
I dont think it is a quality issue,  I think the issue is just like a midboard working or failing, or a Ring a and pinion issue, 

Personally I like getting my own bearings from Timken Direct Supplier,  On my S4D i get bearings with matching Races, 

The other issue i see is the Crush Washer, I think the issue is the Crush Washer is not working correctly, its to loose or to tight, sounds like it might be to tight on the bearings, and causing no lubrication on the fulcrums,  

I would want to feel the preload of a assembled bearings and compare that to a build your own kit,  

 
Always that option. I guess 6k or more upgrade would be much better than a 300$ bearing… I haven’t had a bad enough experience with stubs to warrant it. I have seen issues with midboards too. Plus those rebuilds get spendy. I have a spare set up in the trailer that if I break I can easily get back on 4 wheels and get back to camp. 
ive put 1 bearing in my midboards since 2006.... doing 9-13 trips a year, and an avg of 1200-1500 miles per season, and you get more wheel travel.. 

 
Sure hope these hold up. 
My issue was when I got everything installed I had a very very small amount of play when I jacked the car up only on one side. I was able to torque the 36mm nut more and it helped but I could still feel a small wobble. I wasn’t happy about that at all. Even also the machining was off on the back lip where the 10 (12 points) thread into and come out the back side it was rubbing. I went to Kartek and they said on the next batch they will cut another .10th of material off. I said cool thanks! I ran a washer and it helped the issue so I didn’t have to cut my bolts.

 
Last edited by a moderator:
The VW style bearing housing had a spacer in the center, they torqued to 250lbs,  

if this does not have a spacer or a crush washer,  then torquing them down more than the front 2'' hollow, is going to be a issue, 

is there a spacer between the bearings,  

ive put 1 bearing in my midboards since 2006.... doing 9-13 trips a year, and an avg of 1200-1500 miles per season, and you get more wheel travel.. 
Depends on the midboard we service so many of them over the years,  The Cons of some of them 

  • Tatums

  1. No True inner seal, just a Lip seal this is really only a dust ring,  so for the sand it will eat the bearing and leaks out grease if not maintained, 
  2. Hub pretty much bolts flat to the arm, so has a low shear load,  
  3. The 6 CV bolts push against the aluminum so they need to be tie wired to keep them together. 

  • Gray Area,

  1. same as a Tatum ( Was affiliated with Tatum for many years so same design)  but  use a steel plate that the cv bolt ride against, and notches for CV balls to be changed easier.  Little better design than the Tatum, but still no true inner seal, 

  •  Gear one,

  1. Stronger than a Tatum and Gray Area, do to the midboard goes into the mounting plate like a microstub, this increases shear load dramatically,  but Still no True inner Seal, 

  • Proam / Kartek / JMar, 

  1. Double the Price of the above Midboards, 

Pros, 

  • Tatum is the Cheapest of the Mids, just got to keep them greased up on the bearings and clean the sand out of them, 
  • Gray Area, More money than the Tatum, but has a chromoly Plate for the CV bolts to push against, and the ball tracks notched all the way to the front, easy to replace cv parts 
  • Gear one, has a great design on the mounting that the bearing housing goes into the arm
  • Kartek and Proam, Almost does not have to service in a sand car,  

  1. They mount inside the arm so it is hard to shear them off,  
  2. 15 bolts on the mounting, others use 12
  3. The Inner seal is a True seal, same as the outer seal, 
  4. Bolts are shoulder bolts made for a Midboard other use standard or cut hardware, 
  5. CV bolts go against a chromoly mounting plate, like a drive plate, 


 
Back
Top