Worn drive flange=birf soup? (1 Viewer)

[Tenzig Norgay]

A little history on the PS front axle. At about 250k the birf and axle broke, but the the truck was still drivable with the center dif locked. Drove it till this way till about 270k, then had a local shop fix it, they just replaced the axle seal, PS front axle and birf. Within a month had birf soup, so decided a front end rebuild was in order, did both sides, and replaced the DS birf. During the rebuild, I discovered the PS axle seal was missing its metal spring, which I found in the front diff when I drained it, and hence the birf soup. Since the rebuild, the PS front birf area has never looked right. Always more seepage, and more gray colored, not pucking soup, but soupy looking.

After a road trip to Colorado for my 40th birthday, first vacation in five years, and first time ever to really beat my truck on some real rocks, I knew something was going on with the PS birf, it was definitly spitting, not a full out puke session, but definitly not right. So I tore it down. The axle seal was fine, and nothing looked amiss. However, the drive flange was original, with 315,000 miles on it. It was definitly worn so I replaced it, along with a new axle seal. Also checked the breather and it was clean and free flowing.

My theory is, the drive flange was worn enough that it was vibrating the whole axle, causing minor seepage. This became more evident on the long road trip with long high speed travel. Does this sound plausable, has anyone else had birf soup that was due to a worn drive flange? I sure hope so, for my sake.

Some pics for your pleasure
1- the evidence
2-Original, 1992 drive flange with 315k
3-New drive flange

 

[Tenzig Norgay]

Some colorado pics too

 

[Tenzig Norgay]

Yup, I'm positive my extremely old and worn out drive flange was causing birf soup. Since replacing the old flange with a new one, its been 18,000 miles and my birf looks great, no soup.

It also cured my woo woo blues.

 

[excessive]

amazing you drove 20K miles with the center diff locked!?

 

[Tenzig Norgay]

amazing you drove 20K miles with the center diff locked!?

I don't think it hurts the transfer case at all. I have the 92 and it came without a Viscous coupler, but don't know if that matters. The very fact it works means everything is working properly. I currently have 329,000 miles on it and it works great though. I think the drive flange is often overlooked in a front end rebuild, at least in my case. The worn out drive flange made all kinds of noise, which I had a hard time locating. The souping seepy birf got me thinking and looking, and most importantly, searching mud endlessly. I noticed the lack of noise immediately after the swap, and now with all the miles and no seepage, i'm sure the old DF was the culprit.

 

[Pin_Head]

I am a skeptic by occupation, so please don't take this personally, but I am having trouble getting my head around how the wear in the drive flange could lead to the type of translational play to cause the axle seal to leak, especially with a spindle bushing that is presumably not worn out. So my questions are:
How do you know what the rate of seepage was before the flange replacement and how do you know what it is after replacement?

Spline wear would be expected to cause rotational play, but not the up/down side to side play that would cause the seal to leak. especially since you have the spindle bushing restricting any motion other than rotation.

 

[Tenzig Norgay]

Thanks for your much respected input pinhead, you always get me thinking. The bushings are original as well, but they didn't look to bad when I examined them, there were grooves still in them and they didn't look too worn. That being said, wouldn't vibration/noise be transfered down the shaft, more so with worn bushings as well. Do the brass bushing really hold the birf, or do they just kind of support it? I thought they just sort of guide the birf and provide room for grease flow.

Before the swap, the steering knuckle had seepage on it, you could see a definite difference between the two sides. It would almost drip off the bottom of the steering knuckle, not enough to puke down the tire, but definitly a nasty mess. Since the swap, both sides look normal, and diff fluid looks fine with no signs of grease mixed in. The noise before and after the swap are huge. I like to mention the noise because noise=vibration, and I had a whole lot of noise, which mostly came from the worn DF.

All seems well, no leaky yet and it has been a year. I'm convinced the worn DF caused the leaking, don't you think all that vibration could effect the axle seal?

 

[Pin_Head]

Yup, I'm positive my extremely old and worn out drive flange was causing birf soup.

How do you really know? How long did it take before it looked like "soup" with the bad flange? Did you take it apart and check for the same "soup" after 18K?

Maybe it took you 50K miles to get there with the worn flange in the first place and you are only 36% of the way after.

I am a big believer in replacing worn parts, but if you are in for a dime, you are in for a dollar. I would have replace the seal too.