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What causes hub drag?

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#1
obrut

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I pulled my hubs on my 96 and clean and repacked them like I have done several times before.  I installed and torqued to 75, spin them a bit, then 125 and spin them again and final torque of 180 ft lbs.  I noticed that the passenger side seems to have more resistance to turn then the drivers side.  Its smooth and no play but seems to not spin as free as the driver side.  No brakes installed at this point just the hub on the spindle. 

 

In the past I did not notice a difference when doing this maintenance.  Both hubs are OEM as far as I can tell, both have the white plastic bearing cages and neither had any signs of damage or made noise and I didn't bump anything on track... just doing maintenance like I always do.

 

I did some searching but could not find any discussion on what causes the hubs to drag. 

 

What can cause drag on the hubs?

Is this even an issue?



#2
Bench Racer

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Take the current passenger side hub and install on drivers side and install drivers side hub on passenger side. 


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#3
Steve Scheifler

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Good advice Bench, start by eliminating variables, in this case spindles.

Bearings eventually wear out. You may not see actual damage but the surface of the balls and races degrade and drag increases, so wear rate increases and so on. That may or may not be the case at this point with yours but it’s a possibility. If you are over-packing them (stuffing the void in the hub), don’t.
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#4
obrut

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Thanks for the replies, I don't think I'm over packing them, they are both packed the same.  I will try flipping them side to side and torque them down and see what happens tonight and post my findings.


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#5
obrut

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Swapped and it follows the hub. I had a extra set of spindles and hubs so I checked those hubs and they seem similar to my tight hub. Maybe the tight is ok and the other is worn out.

I pulled one of the extras apart and I installed it on both sides of the car and it's the same. I put my hubs on the extra spindle and one is tighter then the other.

My guess is one hub is worn and spins easier, is there a way to measure this?

Also what happens if there is too much grease? Wouldn't it just squeeze past into the dust cap?

 

BTW the loose one is the one that has been on the drivers front, I mostly run blackhawk.



#6
Tom Sager

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180 ft/lbs might be a bit much.  I think the upper end of the spec is 150.  I'd check that and if so re-torque.  


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#7
obrut

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I got the 180 ft/lbs from Dave's book. Tom do you use 150? Shop manual says 123-159 ft/lbs

#8
Tom Sager

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I got the 180 ft/lbs from Dave's book. Tom do you use 150? Shop manual says 123-159 ft/lbs

 

Yes, 150 - 160.  The other thing is all the variation we have in hubs now.  Ancient original Mazda, Parts store bought and the better hub that Mazdaspeed currently offers.  You might try a bit less torque.  More recently I'm using the Mazdaspeed units, torque to 150 and getting what I believe is good life from them in the Hoosier 7.5 era.  They spin freely.  


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#9
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Drag is also affected if you over pack the hub and the type of grease you use. I am assuming that is not the difference but it is a factor.


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#10
TylerQuance

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I have found hub bearing drag is a very small part of the front wheel drag equation.

Flat brake pads, square brake caliper brackets, and tight-fitting slide pins are substantially more important to keep your wheels rolling free.

#11
obrut

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I cleaned, repacked and added new longer studs to one of my extras.  I installed and torqued both hubs to 160 ft lbs and both are smooth and seem to spin the same.  I'm going to do the same to the other extra so I'll have spare if something happens.  Is there any reason I shouldn't press the longer studs out of the worn out hub and reuse them?  What about the hub itself, paper weight?

 

Thanks



#12
Tom Sager

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I cleaned, repacked and added new longer studs to one of my extras.  I installed and torqued both hubs to 160 ft lbs and both are smooth and seem to spin the same.  I'm going to do the same to the other extra so I'll have spare if something happens.  Is there any reason I shouldn't press the longer studs out of the worn out hub and reuse them?  What about the hub itself, paper weight?

 

Thanks

 

You should be able to re-use the studs.  The old hub you could keep as an emergency spare.  You now that if you take it with you to the track you'll never need it.   :lol:


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#13
Alberto

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If you're looking for some entertainment, you could probably source some new ball bearings and maybe cage and re-test


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#14
obrut

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Tom, I'll just keep the entire hub with studs as a spare then, ill bring it with me evertime I race so I don't need it!

Alberto I didn't know we could buy the bearing cages. The races look fine, do the bearings just wear out, not sure if that's the entertainment I'm looking for.

#15
Bench Racer

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Information for obrut. The front hubs are case hardened .015-.020 deep after hub machining in the area of the outer bearing groove. Not the entire hub. For my 2 cents the case hardening will peal away first causing bearing failure. I searched for a picture of the case hardening pealing away, couldn't find. I did run across the free wheeling hub which was from JD1.


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#16
obrut

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Thanks bench racer that's good to know. So if the case hardening is usually the first to go then the hub is junk. I'll have to do some research to see what that looks like.




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