[Gwagensteve]

Many of us have had persistent inner axle seal leaks on our sierras running Cromo axles. I’m aware they get stretched/ damaged on installation of the axles, but I’m also curious that the birfield might have a very slightly different pivot point and therefore the inner axles walk fore/aft more than stock CV’s, breaking the seal. Also, the axle is substantially heavier so if there is any float at all it will deform the seal more readily.

I’m wondering if a solution would be to turn up a bronze oilite bush that presses into the bore of the knuckle and locates the axle more precisely on the sealing surface so it can’t float around and push the seal out. My guess is the seal would then last and won’t be dislodged.

Am I onto something or barking up the wrong tree here?

In my case I know my axlehousing isn’t flexing and the housing is straight. My CV’s shouldn’t be binding as they’ve been disassembled and dressed but I am hearing a little bit noise from them at full lock so I need to investigate this. They are VERY old though. The air locker isn’t leaking (another indicator of a bent/bending housing)

[Beery]

I've heard of this problem, but always just thought it was an installation thing. I know I got a bit of a shock when I went to install mine. I lubed the hell out of the entire axle shaft and was very carefull installing it and to this day I have zero leaks, my knuckles are bone dry, so it's never crossed my mind again. Or as you said it could be a bent housing - i checked mine when I shaved the diff (same time the cromos went in) and it was in good shape

On cars that leak is the seal actually broken when you pull it out, or does the axle just stretch it in use?

I might be getting my terminology wrong here, but i'm confused by where you want to put the bush. Bore of the knuckle? Like in the end of the axle tube somewhere?

[Gwagensteve]

I’ve heard of seals popping completely out in use but mine look undamaged when I pull the axles. (Although I haven’t had them out to see what they look like now)

Yes, inside the end of the axle housing. Basically machine a bush with a flange on it that presses into the bore of the inside of the spigot that sits inside the housing (it’s the bit the seal presses into) this has a 30mm bore in 1.3 sierras. If there is a mm or so if spare space (I’m sure there is) then the seal sitting a mm further out won’t matter. The flange is to stop the bush sliding inside the axle housing. They may need to be machined to suit whichever inner axle set you’re using- I’m sure the seal surface has a broad tolerance across manufacturers.

I’m on my phone so posting photos is a pain but I’ll see what I can do later.

[Beery]

Yep, I think I understand.

The only issue I can think of is that the spline that goes into the side gear might be a touch bigger than the sealing surface on the axle. Meaning by the time you make the bush big enough to clear the axle spline for installation it's going to be sloppy on the sealing surface.

I have a spare stock front axle and a rear Side gear laying around (26 spline) so I done some really quick/rough measurements.

with the Vernier seated in the spline of the side gear (simulating a Cromo front axle spline) I get a bit over 27mm (The battery is flat, just look at the little black bit soz.)



And here's that same measurement placed over the sealing surface of a stock axle. the sealing surface on a stock front axle is roughly 26mm. so there will be a bit over a mm of play between the sealing surface and the bush.

My measurements are dodgy, and as mentioned a Cromo axle might have different measurements altogether, but something to check. I do remember my spline being alarmingly tight to get through the oil seal in comparison to the sealing surface though, and obviously a solid bush isn't going to move out of the road like a seal will.



Judging by the seal mark on my stock axle there's plenty of room to move the seal out a bit for the flange if it works out. (again, if a Cromo is similar)

[Gwagensteve]

Interesting. I have some spare inner axles sitting around at home, I’ll have a look on the weekend.

[Gwagensteve]

Just measured a couple of axles here. They're just under 27mm at the spline (~26.86mm) and the seal surface is 27mm, so it's feasible.