1996 Bronco Front Wheel Hub

[majestek12]

Experiencing issue with 1996 Bronco full-size front wheel hub - I had converted from factory auto hubs to Warn Manual Premium several years ago (made sure to get the full conversion set - hub body, lock nuts, etc. ) and had no issues from 2005 to current. 

Lately I had been having a little bit of rolling vibration and upon inspection the inner lock nut key washer on the passenger side had spun on the spindle allowing the bearings/hub to loosen and tire to wobble.  I guess I didn't check to make sure it was installed correctly after I disassembled to replace the balljoints last summer.  Destroyed threads on spindle.  Due to needing a new spindle and with the known situation I ordered a new spindle, inner and outer bearings/races, bearing lock nut set (inner, key washer, outer lock) and necessary seals.  The BOM on the axle (3rd member 44/"IFS"/TTB, ABS) is 610447-10 - I made sure to cross reference the BOM against the spindle I was ordering.  Interestingly, the vehicle is a 1996 but the BOM matches that listed from 1994 - last-production-year leftover parts pick-a-thon?

Spindle bearing was greased and two-piece seal installed on shaft/spindle.  I torqued the spindle retaining nuts to 35 ft lbs as per ALLDATA specs.  Cleaned out the hub and drove out the old races, installed new races and packed bearings, seals, etc.  and made sure races were fully seated.  Put it all back together, making sure to spin the wheel while torquing the inner bearing lock nut to 50 ft lbs as per ALLDATA, then backed off 90*.  Installed key washer, and outer lock nut to 180 ft lbs (man, that was a . . . ).  I noticed that the wheel seemed to require too much force to turn but figured it was done to spec.   I reinstalled the hub body and installed the c-clip on the axle shaft.  I noticed that the hub-body outer snap ring didn't sit fully in the grove inside the wheel hub - the hub body was too far out to allow the ring to fall into the grove in the hub.  When I attempted to install the hub face/knob the lip didn't sit fully inside the wheel hub.  So, I took it all back apart and checked the races again, performed the bearing seating procedure several times, and reattempted the hub install with the same results.  It seemed that the wheel hub was sitting too far up on the spindle, which meant the manual hub body was sitting against the end of the spindle and not far enough out in the wheel hub. 

I disassembled, again, and this time tried backing off the inner lock nut 160-180* after seating and reassembled.  This time the wheel spun much more freely ("correct" by feel) and the hub body outer lock ring sits in the wheel hub grove correctly and the hub face/knob recesses into the wheel hub correctly.  Reinstalled the tire and noticed that there was a wobble when pushing/pulling the tire.  I double checked and the balljoints are stationary, the play is between the spindle/hub.

I figured that I had backed off the inner nut too far so I took it allllll apart, again, and checked that the spindle was sitting correctly in the knuckle and that it was torqued down correctly.  I tried several permutations of preload/"backing off" the inner nut after seating.  The situation is that if I tighten the inner locknut enough to keep the hub from wobbling it requires too much force to turn the tire and the manual hub body/face won't install correctly.  If I loosen the inner locknut enough to allow the proper turning force and installation of the manual hub body/face the hub/rotor wobbles when pushing/pulling on the tire.

I double checked the bearings/races and for 1996 the only bearings listed are Timken set 37 (outer) and 45 (inner), with no notation of difference for manual vs auto hubs.  I checked the part numbers of the bearings/races that I removed and they match set 37 and 45 that I put in.  I am sure the races are seated properly.

I noticed on a parts website that for 1994 axles there is the same inner bearing set 45 listed but two different outer bearing sets - set 37 for auto hubs and set 38 for manual hubs.  I verified this by researching the Timken Bearing Application Guide (BSAC).  Could this be the problem? I can see the bearing/race set fixing the issue with the "spacing" of the wheel hub and hub body, but cant' see it addressing the rotational-torque issue.  The rotor/hub assemblies are listed as different part numbers between 1994 and 1996, but some also list that they fit 1990-1994, some 1994-1995, and some 1994-1996.  I can't find the specs on them but I do know that 94/95 was the transition to ABS so it may just be the tone ring difference between the parts. 

The only other issue I can think of is the spindle - the original that I removed had the keyway/washer grove facing upwards.  The replacement spindle, when installed as required by the ABS sensor location/cutout in the spindle, has the keyway/washer grove facing down.  Could this be the problem? Although the keyway is facing down the pin on the inner lock nut aligns correctly with the washer holes and an eyeball comparison of the two spindles shows all dimensions the same, execpt for the cutout for the ABS sensor. 

Thanks for taking the time to read this ridiculously long post, and thanks in advance for any insight!!

[billr]

Yeah, a long post and I can't really help.  But, if nobody else can either, then I can pass on the web-site for a friend that has a specialty shop for off-road/4WD stuff.  I don't like to be promoting any products or vendors here, but will if you can't get any other help.  (He is in N. Calif.)  OK, Tony?

[majestek12]

Believe me, any help would be appreciated!! I called the vendor I got the spindle and bearings from (who I know to be very reputabale and accurate and so won't mention name, like you say don't want to cast +/- light. . . ) and after a lengthy phone discussion he had no ideas either.

He did say that the location of the keyway grove on the spindle doesn't matter, and that he had never seen Timken Set 38 on a 1/2 ton axle.

The only thing else I know to do is replace the rotor/hub assuming that the wobbling (heat?) may have damaged it. . .  but, pressing the races went as I expected, and it seems the races themselves take the rotor out of the equation in this instance as long as they are seated on their bosses. . .

 

[nickb2]

Are you sure you are not installing the three lock washer system in reverse, that would be the only cause which would allow the bearing to back off this way, they are designed to lock if they are installed with the 4 notch washer with the pin on it first, then the washer with the holes and the other 4 notch washer that has not pin. Maybe the pins have sheared, and when you are tightening these washers together, your actually applying pressure to the sheared pin stump, bring everything out a fraction of an inch casing your seating problems. Does this make sense to you, here is a picture of OEM manual lock system. Rotational force of 20 inch pnds is normal, not foot pnds. A needle torque wrench is good for checking this, I always have a cheap needle torque wrench just for this. The actual pin that sometimes shears off can be replaced, part number is in the description. There was also two different differentials for this model, both are not the same adjustment for bearings, the nut torque for the DANA 44 is 70ft/pnd back off 90° then re-tighten to 15ft/pnd

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[majestek12]

nickb2 - thanks for the info and diagram.  I paid attention to install the nuts and such in the correct order on the first go 'round and double checked them each time I reinstalled the hub to make double sure. . .  Unfortunately they're on correctly.  I'll dig into it again and use a micrometer to check the old and new spindles for measurements.  As well, I'll swap the rotors and wheel hub from side to side and see where the problem goes or stays. 

Thanks for all the info and insight guys!!

[CraigE]

I would check out the rear grease seal very carefully.  It may be holding the rotor out a mm.   Good Luck  CRAIG   

[majestek12]

I think I may have found the issue - and I'm a big fan of putting out fixes for public knowledge.  

1996 was the last production year of the bronco and vehicles manufactured after 05/95 had pick-a-part axles put in from remaining stock.    So, the BOM on the axles from these years may indicate they are older than the vehicle (for instance, my 96 had BOM 610447-10 which was a 1994 axle).    However, Ford swapped out the spindles to work with the ABS hubs/rotors and kept the axle the same.    So, when you order based on BOM you may run into this disrepancy where the spindle is incorrect.    See the pic below and you'll see how the difference in the location of the inner bearing seating surface would cause problems - tighten it down to where the hub won't wobble and the outer bearing is over-loaded, loosen it to where it turns freely and the inner bearing has 1/8" to wobble.   .   .  

hxxp: www. supermotors. net/registry/media/728442

The Ford part number for the correct spindle is F3TZ-3105-C and the Dana numer 75304X.