Birfield Headache

[cary]

Okay, this is the 1000+ question about birfields. I read through the old posts for an hour and now I just have a headache.

Here is the situation. I need to do the front and rear brakes on my 1996, including rotors. The truck currently has 133k miles, is street driven (was a soccer mom truck). I have some receipts, including a receipt for "front Axle seals replaced" from a dealer at 90k miles for a cost of $600. I currently see no seeping from the knuckles or contamination of the diff fluid.

I do not have the time to do a birfield replacement myself. If I do it, I will have to pay my mechanic (a very competent BMW mechanic that is also a great fabricator and race car builder), so it would be an estimated 8 hours of labor or so. Finally the truck has 32" tires a OME low lift (1") and does not see off roading due to lack of time.

The big question. Do I really need to worry about the birfields being redone right now since most of the problems are form the axle seals? Can I push these further if I watch them? I really am not in a position to fork out the extra $1000 parts and labor right now, but can if I have to. What about repacking the rear bearings? How long does it take, can I/ do I need to when I replace the rear rotors? Is there anything essential to do when replacing the front rotors?

Thanks

Cary

 

[Rookie2]

Cary-

The guros on this board have typically recommended a front axle service interval of 60,000. If you feel confident it was done right at 90 k and don't have any of the symptoms, seems like you should be okay for a while longer. But if it were me I'd plan on the full deal in another 15k, since you don't know what exactly was done before, and since the bearings are probably orginal.


Rookie2

 

[e9999]

good question.
Isn't it unlikely that the $600 axle seal job would have been the real inner seals all the way in since I imagine changing those is really the same as a full Birf PM job (more $$). Or could be only 1 side?
Anyway, if it's not leaking any direction, and no clicking, that seems to suggest that the inner seals are good and the the Birfs are still OK. Doesn't mean that they are greased properly and won't self-destruct shortly, but the latter seems highly unlikely especially since you are breaking the rig's overdesigned mechanical heart by keeping it in mall parking lots. I'd say it'd be probably OK to take a chance waiting a bit if you can't swing the job now (all legalistic blah blah apply in case they do explode tomorrow...!)

E

 

[GXO]

If just doing brakes and rotors and you don't have a click or a contamination problem I would leave them be. Check the bearings for wear while you are in there and repack those. you can even see the inner seal usually while it is off and can tell if there is gear oil in the knuckle.

If you don't see any problem and haven't had clicking...leave em be.

If you are swapping the rotors or the axle seal it takes about 30 more minutes total to repack birfields since you have to pull the axles (birfields attached) to get the seals out. 1 hour if you want to be generous to a person that has never done it before and gets their finger stuck in the carrier....

hehe (that hurt).

 

[nakman]

Cary, doing the rear bearings is pretty simple too, there's a good thread in the FAQ's about it, with a link to Klunky Kris' web write-up. You don't absolutely need the SST to unscrew the hub, but probably do need an impact "smacker" screwdriver to loosen those phillips screws the first time.

I agree with the group on the fronts.. dip a straw down the square plug hole to see what's in there, and a lot can be learned from what drains out of the diff.. hth.

 

[concretejungle]

i asked junk a while back to post the procedure for setting the preload on the wheel bearings. It would be good info to have. The FSM is about as clear as mud on this process.

 

[cary]

This is what I get for not having gone through the procedure in the FSM. How long to do the front rotors vs. doing the rotors + birfields? I am (was) under the impression that the rotors are about a 1.5 hour job total vs. the birfield repack + rotors being about 8-10 hours total.

Cary

 

[Beowulf]

I need to do the front and rear brakes on my 1996, including rotors.

It probably doesn't need to be said but this project should include new pads and a complete flush/fill/bleed of the brake system.

Do I really need to worry about the birfields being redone right now since most of the problems are form the axle seals? Can I push these further if I watch them?

If the front diff drains fairly clean (no diff soup) then watch it and check the level in the birf housing with the "dipstick" method. Your best indicators of a failed seal is heavy grease contamination in the front diff and leaking seals on the back of the knuckle housing. Since yours is OK, you can postpone the birfield repack.

What about repacking the rear bearings? How long does it take, can I/ do I need to when I replace the rear rotors?

You do not have to remove the rear bearings to replace the rear rotor. You should usually plan to inspect and pack the bearings when doing rotors. Of course, this depends on the mileage of your last bearing service. At your mileage I would not replace the bearings unless they show signs of prior neglect or damage. Allow 2 hrs per corner and you should have time for a

Replacing the rear rotors is pretty easy. If you have plenty of time then adjusting the e-brake during the rear rotor service is good PM.

Is there anything essential to do when replacing the front rotors?

Inspect and repack the front bearings and, as mention above, use new pads, and flush the old brake fluid and replace with new. Also inspect the pad wear. My PS front pads were wearing very uneven over the past 2 pad changes so I rebuilt the front calipers. It is a 1 job if you have compressed air.

-B-

 

[e9999]

Btw, I am under the impression from previous readings here -and I also sure as heck am hoping that this is true since I saw this on my truck- that diff oil contaminated by grease may not necessarily mean that the inner seals are shot and could be due only to clogged breathers (vaccuum formed etc), so there may not even be a need to panic if the diff oil looks soupy. But if you open up (extend) your breathers and the oil still comes out greasy, then it may be time to wonder what's going on in there, sealwise...
E

 

[semlin]

you are probably safe to take a chance. post the part #'s listed on that receipt so we can confirm it was the inner axle oil seal they did not the outer wheel bearing seal(or compare them to beowulf's part# post).

If you want to be safe, ask the mechanic to pull the spindles on either side. from there you can see inside the knuckle housing and verify the grease level and spot diff oil contaminaion in there. This step alone adds about 45 minutes a side to you rotor job, plus the need to have on hand a seal and two gaskets Dan can sell you. Where the time really adds up is if you then go on to remove the kunckle housing, pull the birfs, inspect the kingpoin bearings, clean the old grease off everything, replace the inner axle seal and reassemble.

 

[cary]

Semlin,

Thanks, that gives me a better idea of the difference in time. I am going to pull the receipt and see which seal they changed (I don't think they listed a PN, and is was from the prior owner).

Cary

 

[cruiserdan]

The inner seal is a 90310-35010

 

[Rookie2]

Check the bearings for wear while you are in there and repack those. you can even see the inner seal usually while it is off and can tell if there is gear oil in the knuckle.

Huh...??? Dan, you can see the inner axle seal and whether gear oil is in the knuckle after taking the hub assembly off?


Rookie2