Birfs - how bad is "too bad"? (25 Viewers)

[CharlieS]

I brought my rig in for some fluid service at the dealer - I know, I know that is too ...

We'll I'm going on a trip next week and I need to repack the birfs this weekend, so since I don't have time, I figured I'd get the diffs and tranny serviced ahead of time. They're replacing the frontt and rear diff fluids, xfer case fluid, tranny flush and fill, coolant flush and fill, oil change, new belts.

Fact: I have a pretty good click when the wheel is turned to the right at slow speed. What I figured was a classic birf click. I haven't stressed about it since posts here (yes, I searched) said that it is not a big deal. I already have all the parts (from CDan) for the front axle service.

The rig has 181K miles, and a full "front axle service" was done by the PO at a dealer at around 140K miles, so I figured it was no big hurry.

Well, a few minutes ago I got a call from the service writer saying I need to replace my "whole front axle" . Whoa trigger!!

So, I ask for clarification? He tries to explain how the the whole front axle is ruined and I need to replace the whole thing plus CV boots. Ummmm, not quite junior... I try to ask about the birfield, but he gets confused.

So, I ask if I can talk to the tech. No problem.

Well, the guy working on the cruiser is the shop foreman, not some newby tech, which is good. Real decent guy. I ask him if it is the inner axle seal and if the axle is damaged or the birfield, and he is really straightforward about it - he suspects the birf is damaged and could go at any time.

He said that it was the birfield and that the axle seal had gone bad and let diff fluid into the grease at the birfield and that led to the damage.

Said he was concerned because the click happend at a half turn rather than a full locked turn.

I am fairly certain they didn't take it apart, but are basing the recommendation on a test drive.

Th tech said it could last another 50K miles or another 5K miles, but they've seen them go on the landcrusiers, so he recommended having it replaced.

So, I tell him I am going to do a front axle service myself this weekend and he is very good about it - even gives me some tips. Said it should be fine, but suggested replacing the birfs while I'm in there (to the tune of $650 each).

Honestly, I am suspicious about them being all that bad, since Christo has said in an old thread that they don't really grenade under normal use. Mainly, just from hard use rock crawling.

So, I'm tearing it all apart this weekend, and I'd really hate to replace the birf, if I don't need to.

Then again, I want to do it if I need to since I am goign to be on a long trip with the family next week. Even at CDans friendly price, I'm sure they're pretty pricey.

Well to make a short story long, on Saturday, once I remove the axles and clean them up, what level of damage should be an indicator that I need to replace the birfs? Anyone have pictures of one that is really bad, that I can use as a guideline?

Any advice you can share would be great.

Thanks!
Charlie

Info about my rig: '96 80 series, pretty much stock, new head gasket/cap/rotor/plug wires/o2 sensors at 120K, front axle service at 140K, regular service intervals up to 120K, oil changes every 3k and brakes every 10-15K. No other major service. Only non stock items 285 revos, HIR and slee light harness. (OME 2.5" light lift part in house but not installed yet)

 

[e9999]

you sure you want to dig in there right before a trip?
done this before?

most of what I read here before suggests that if there is oil in the knuckle grease that should not necessarily mean the Birfs are susceptible to damage. The latter occuring more with insufficient lube, I would imagine. IOW, you might be OK if you ensure there is diff oil and knuckle grease in there for one trip, maybe? I would not empty the oil from the knuckle cavity, though, as you may not be able to replace it with grease from the outside.

(note: above based on reading here, not personal experience, so worth only the cost of the feedback/advice... )

 

[ryanjl]

The popping you are hearing is slight grooves or indentations that have worn in the "bell" of the birfield, allowing the ball bearings to rattle back and forth under the various forces applied during a turn.

They'd have to wear A LOT MORE for the birf to fail. In other words, the balls have just expanded their slots a little. They'd have to wear through the edge of the slot and into the next for failure to occur.

If grease has seeped into the diff gears, that's one thing. But if it's 90wt in the knuckles, you should be OK.

Your 80 doesn't have "CV boots", so you can write the service writer off as "clueless."

 

[semlin]

um you will have to drain out all that new front diff fluid in order to repack your birfs Charlie


if you get the birf click at half turn that is bad but I still doubt it will break on you. I had a birf grenade during normal use from going dry but I have never heard of a properly greased birf breaking.

Do you have a CDL switch? If so, go ahead and repack your birfs and inspect that birf. If it looks bad order a replacement, put it back together for now and take your trip. You can go oem from cdan or longfield. In the meantime, take your trip but take along the tools you need to tear down the front axle. IF the birf breaks, you will need to pull the birf on that side, stuff a rag in the axle seal hole, drop the front drive shaft and turn on your cdl and you can drive home in 2wd.

If you don't have a CDL switch, do a search to find the link on how to do an emergency CDL switch.

 

[CharlieS]

e9999,

No, I've never done birfs before.

I have done a lot of hobby wrenching before including building supercharged racing motors and building a transmission for a rally car, etc, so I am not particularly intimidated by the mechanical aspects of the birf job.

I already have all of the parts from CDan and all the tools I could need, plus a FSM and all the great archived info I've read here.

At a minimum, I want to repace the axle seals and clean and repack the birfs. seems like a good opportunity to inspect them and get some fresh lube in there, plus prevent the exchange of fluids between the diff and birf.

I am not sure whether I will replace the wiper seals and the trunnion bearings. Depends on how the birfs look I guess. If I'm going to have to tear it all apart again soon to replace the birfs, then I will skip the wiper seals and trunnion bearings. I do have all of the bearings and seals though (thanks CDan), so I might just do the whole enchilada if the birfs are reusable.

I'll probably exten the diff vents too in case that was a contributing factor.

I just don't want to spend the big money on new birfs if I don't need to right now.

Thanks!

Charlie

 

[CharlieS]

Shocker,

Thanks. I agree about the service writer being clueless, that is why I asked to talk to the tech.

Semlin,

I like the way you think!!! I'll bring the tools along and maybe even order a CDL switch from CDan or Slee. I've wanted one anyway. Good excuse to order it!!! (I know I can use a emergency flashe switch in a pinch, but I want a CDL switch)

Thanks guys!!!

Charlie

 

[Biff]

if you do buy births check this out

http://cgi.ebay.com/ebaymotors/ws/e...tem=7972121755&category=33729&sspagename=WDVW

 

[jcolegrove]

hi,
newbie hereto LC's, but spent HOURS reading about the birfs since my '97 rig has 98k and i'm unsure about PO maint.

-- BUT the question above remains-- how to tell if TOO much damage has occurred when one inspects the birfs? i understand grooves are made, so is it too late for the joint at the point any clicking occurs? which leads to------>

i could not find (i promise after reading a LOT)-- by the time there is clicking, does it go away after a repack? or is it there forever once it's there. in that case, one would always want to pre-emptively do a birf repack?

 

[ryanjl]

-- BUT the question above remains-- how to tell if TOO much damage has occurred when one inspects the birfs? i understand grooves are made, so is it too late for the joint at the point any clicking occurs? which leads to------>

i could not find (i promise after reading a LOT)-- by the time there is clicking, does it go away after a repack? or is it there forever once it's there. in that case, one would always want to pre-emptively do a birf repack?

The only thing you can do to remedy the clicking noise, aside from replacing the birfs altogether, is to completely dismantle them when pulled and swap the driver and passenger side outer axles. The ball bearings will then be placing most of their force against the side of the cavities in the respective bells that have not had force put on them before.

Simply re-packing them has had no lasting quieting effect on a clicking noise that was already there, based on experience of people on this board.

Here's a pick of a birf from a FJ40 off of Morgan's rebuild site, where he's getting ready to completely dissasemble the joint:

Here, you can see the balls that run the circumfrence of the birfield cage (attached to the inner axle), all within the birf bell (attached to the outer axle). The clicking occurs when the balls wear a litte of the bell from the rotational force applied from the inner axle to the outer; it doesn't take much wear, just enough to let them "pop" back and forth.

But, for the birf to completely fail, the balls would have to wear all the way through to the next ball cavity. And that's quite a bit.

 

[CharlieS]

Shocker,

Thanks. Is it worth the effort of disassembly and swapping?

I could care less about the clicking. I'm worried about failure and the subsequent damage to the housings from the metal carnage rotating around in there.

Sounds like the concensus in this thread is that it would be fairly difficult for the balls to wear all the way through the cage, which is where catastrophic failure occurs?

Why doesn't it lend itself to failure where the ball wears away at the cage and creates weak spots (stress risers) that could make it grenade when under strain (full turn to lock under load perhaps)?

Thanks for the ebay link. Is CV Unlimited reputable?

Charlie

 

[Rich]

I don't think suffiicent information has been published in this forum that would enable one to examine a worn birfield and accurately determine how much more usage will result in failure. The people who have reported breakage have generally been folks who drive challenging trails offroad, though the same guys have had the final breakage occur under mild conditions.

I think, in the case presented here, the final decision would be based on the Charlie's willingness to risk having to do repeated birfs jobs versus fixing it all in one shot. And also the degree of risk to be assumed that a breakdown will occur on the road.

With respect to how much wear has to occur prior to failure, it would be much less than that required for one groove to wear through to the next. Long before that happened, the birfield would be sufficiently weakened that it would break.

I would hope that 2 new $120 aftermarket birfs would be stronger and last longer than two 181K mile worn birfs. If I were doing a birf job on my truck with 181K miles, I think I would replace the birfs with a inclination to use Toyota birfs. If it was a choice of aftermarket or none, I would take aftermarket.

 

[semlin]

i would NOT assume aftermarket birfs will be better than oem at 181k. CV unlimited's history with "newfields" is not good although I have not heard any roadtests of their latest line of products which may be what is for sale (they sold a bunch of the old ones off recently cheap). They may well be good now, but do a search here on "newfield" for a history lesson.

i think some people have lucked out and had the clicking stop after a repack. I would take the chance myself instead of ordering a new birf before the repack, especially if plan B is an aftermarket birf. It will take you a lot less time to re and re the second time since you will not be cleaning and repacking everything and will not be removing the knuckle housing. If you do it within a few weeks after none of the gaskets will need replacing. Ask me how I know

To switch birf sides, you only have to separate the birf from the axle shaft and switch shafts. no further dissassembly is required. The further dis-assembly will help you clean the grease and inspect the birf but is not critical imho so long as you get the old grease out.

 

[landtank]

Charlie where are you at? If close by and you don't mind paying for gas I'd suggest ordering the birf from CDan and I could come up and take a look see. If you decide not to use it I'm sure Dan will take it as a return, but you might want to ask him first.

 

[IdahoDoug]

Charlie,

If I were you, I'd do the full repack/trunions/outer sweep seals and swap birfs side to side. Clicking is not indicative of failure - just the nature of a half dozen quarter pound greasy balls squirting like watermelon seeds in a bit of normal slack/wear. Fresh moly grease will mitigate further wear, and swapping sides will start you off wearing on fresh surfaces, also. Once you're in there, the outer sweep seals and pounding out the trunion races only add 30 minutes combined and you'll notice better straight line stability with nice tight knuckles vs that wandering feel of loose trunion bearings (they feel like badly loose wheel bearings in terms of tramlining and following cracks).

Don't let a little clicking worry you. Repack and swap and you'll be good for another 180,000. My brother in law's 287,000 mile original birfield '93 is sitting in my driveway right now and it's never had them swapped side to side. It clicks a bit, and it's been to Moab twice in the last year and we wheeled it a decade ago as well (he's owned since new). With stock tire size, you're good to go for road and moderate wheeling. Enjoy the truck.

DougM

 

[TLCgrappler]

I'd swap them from side to side after cleaning and repacking with the proper moly grease.

When you disassemble the joints, you'll see (probably) that the "backward facing" surface of the bell housing (and the "forward facing" surface of the starfish insert) will have slight depressions (grooves, if you want to call them that) worn by the steel balls. The grooves are, understandably, worn exactly where the birf is oriented when the wheels are pointed straight ahead, and they are worn directly across (90 degrees) the channel in which the balls ride.

THe clicking, in my opinion, happens because the balls travel all the way from one end of the channel to the other-AND BACK-during every wheel revolultion IF THE STEERING IS TURNED TO THE LIMIT. IF the steering wheel is turned slightly off dead center, the balls will simply move back and forth a little in the channel. Howver, in any case, each time they cross the normal straight-ahead driving position, they pass over the depression that they have worn in that normal postion. This is where the click comes from, I believe.

THere will also be some wear on the opposing surfaces within the birf. This comes from braking and decelerations where the force gets put onto the birf from the wheel, as opposed to being put on the wheel from the birf. Naturally, the amount of braking and slowing down is far less than the amount of time you drive straight ahead, so the wear is uneven. Swapping the sides changes that and now puts what once was the braking-force-side of the birfs into the driving position.

I did my birfs at 110,000 miles, and I thought (guessed) that they could easily go another 100,000 even without swapping the sides. Switching them probably makes them good for at least 250K, but thats a speculation. I don't off-road my cruiser. The worn "depressions" weren't deep, IMO, but you could see them clearly. The depth was about the same amount as George Washingtons head is raised on a quarter. Maybe thats about 1mm??

Anyway, go ahead and do it yourself and let your eyes guide you. I don't think any of us has any data on this from measuring the wear depressions.

 

[TX_TLC]

if you do buy births check this out

http://cgi.ebay.com/ebaymotors/ws/e...tem=7972121755&category=33729&sspagename=WDVW

NOTICE NO ABS RING....FYI.....

 

[robbie]

Here is what happens to a 80's birf when it fails. The cage brakes due to not controlling the balls in there intended path(due to excessive wear on the star and cage). When you have excessive wear, the ball puts more stress on the cage and bang it goes. That said I too have wheeled stock Birf's with way load clicks and they did not explode. But with in less then 5000k miles have lost two CV unlimited Birf under less stress then I put the stockers through.
So what would I do in your shoes. I would due the full axle service, inclucding the knucle seals, and the trunion bearing, swap the birf from side to side after disassembling and cleaning, reassemble with good quailty moly grease and take your trip. You may still get a slight click or you may not depending on the depth of the groove, but you should not have a failure(no gaurantees). Put on your list of things to buy, either bobbie longs new chromoly birf or stock toyota one. Both are worth the money. Would I buy CV unlimiteds stuff, never again(unless he gave me some and wanted to pay my time for the install, been there and done that with my time and money).
By the way, how long is your trip? It may be good to just stuff grease in both knuckles housing and call it good until you get back. later robbie

 

[CharlieS]

Thanks everyone.

I'm taking Friday afternoon off so I have plenty of time this weekend to get it all done.

I'm going to do the full axle service, wiper seals and trunnion bearings. I'll swap the birfs side to side, and everything should be cool.

The trip is only 200+/- miles one way, but this service is soemthign I've wanted to do as PM anyway. It can't hurt and I've already set aside the time to get it done. Here's to hoping it doesn't rain (or snow like it did this morning!) all weekend, since I am working outside

I appreciate all the advice. I'l let everyone know how it goes, and (if I remember), I'll take a picture of the inside of the birfs as a data point for the board.

landtank,

I am about 4 hours from Boston give or take. I will be glad to pay your gas if you want to make a road trip. But keep in mind I am garage-less and I am working in the driveway since building the garage is on my to-do list for the summer. And, if the crusier gods are with me I'll have most of it done by sundown on Friday.

Thanks everyone. all around

One last question - I'll do a search here too- but if anyone knows off the top of their head - is "moly fortified" the same as "moly disulphide"? I can't find any greas labelled "moly disulfide" grease. I did locate Valvoline "Moly fortified" - is that the stuff, or do I have to keep looking?

Thanks,
Charlie

 

[reffug]

One last question - I'll do a search here too- but if anyone knows off the top of their head - is "moly fortified" the same as "moly disulphide"? I can't find any greas labelled "moly disulfide" grease. I did locate Valvoline "Moly fortified" - is that the stuff, or do I have to keep looking?

Thanks,
Charlie

The Valvoline would be the stuff. Been used by several memebers on the board if memory serves. Good luck, have fun, have patience, and most off all have lots of paper towels.

 

[e9999]

as far as I know, when people say "Moly" it really stands for "Molybdenum Disulphide". If I'm not mistaken it refers to the same thing.