79 FJ40 Rear Axle Leaking (1 Viewer)

[Btchnfj]

My FJ40 was found with a rear axle seal leaking. Last night I went ahead and removed the side that was said to be leaking but found no evidence of damage to the seal. I'm an aviation mechanic in the Navy and we commonly will measure the diameter of components to ensure that there still serviceable. Does anybody know what the measurement should be of the axle shaft or does these seals leak regularly?

Also I've been experience a suttle vibration at highway speeds on and off. No particular MHP but a noticeable vibration that rattles everything. lol. Thanks.

Taylor

 

[Fast Eddy]

It's pretty unlikely that the shaft is worn. I'd just replace the seal and reassemble it and see what happens. Maybe use some sealant around the outside of the seal when you install it.

The vibration is most likely the drive shaft being out of phase. You can align the grease zirks or use the search or google for more info.

 

[Stumpalama]

Check your axle breather... If clogged, it could create overpressure in the axle housing that would push gear oil through the seal. Do you tend to park on a side slope to that side of the truck?

 

[Btchnfj]

I did end up buying a caliber to measure both and found that the diameter of the axle is just slightly larger than the seal that's in there now. When I emptied the gear oil out of the axle it was pretty much full, it was coming out of the rear filler bolt. When I removed the axle there was evidence of gear oil being in there but not much. It could be possible that the breather is clogged which caused it initially. I'm going to go ahead and replace the seal, not sure yet if I need to replace or should replace the bearing as well. I never did have the drive shaft balanced and did assume that could be causing it. just wasn't sure. I'll check it out and post back.

 

[Stumpalama]

Meh, those bearings last a good looking time. Mine have been in my axle for hmm 2015-8/1980= 34 years, maybe.

 

[3_puppies]

for the cost of the bearing, I change them when this far into the axle, but that is me.

 

[Stumpalama]

They are an MFer to get out sometimes, require a slide hammer or other special tool and at 120,XXX miles, mine are minty. I do have spares at the ready, of course.

 

[shawnfj40]

From an old Boiler Tech to a Wing Nut. Just replace the seal and try not to worry. Its not going to be flying 10,000 feet or hitting the carrier deck.

 

[Btchnfj]

Ok so spent the day putting it all back together just to find out that I believe that the seal was never truly the problem. When I was taking it apart I removed the back plate where the wheel cylinders are mounted to. So with that I disconnected the brake line. I also replaced the passenger side front brake pads on the stock disc brakes. second time since the restore but the driver side isn't nearly halfway used....???? But when I bled all the brakes, the side I did the work to, the "leaking" side I was having trouble bleeding it. The furthest wheel cylinder was pushing out from the wrong side causing the brake shoes to get stuck within the drum....??? I believe this is where the fluid came from in the drum that was mistaken for gear oil.... is this fixable without buying a new wheel cylinder? And does anybody have an idea why my front passenger side pads wear twice as fast as the other side?

Also I was just price quoting everything on man a fre and saw there rear disc brake conversion....whatcha all think of that? is only about $600....pros cons?

 

[Stumpalama]

You can do a rear disk brake conversion for a lot less, IMHO. Check around here for what the conversion involves. It is best if your parking brake is on your t-case. You need brackets, Chevy K1500 brake disks (with center hole enlarged) and rear calipers, and 10mm to banjo fitting soft brake lines.
EDIT: I see your title says '79 FJ40, so you likely have The parking break on the axle, which complicates the parking brake issue with rear disks.

Check your driver's side front calipers for siezed cylinders. Does your truck pull to the passenger when braking? I would check both calipers for compression and retraction.

 

[shawnfj40]

You might need to look at the surface on you front rotors and make sure they are fairly smooth. More than likely Stumpy is right and you have a sticking caliper on one side or the other. For the rears Unless you want to convert to disk, it is pretty straight forward to rebuild the cylinders. Just get a hone and go for it. Your in SoCal so you should be able to get anything you need. I am pretty sure SOR is right there.

 

[Btchnfj]

Yeah SOR is right up the street..so to speak. I did just recently replace the drivers side caliber due to a different unrelated issue with the rotor mounting bolts being loss causing a loud clank when the brakes were applied for the first time in either direction. I guess it could be a sticky caliber on the other side cause it wear much quicker. I bought all my stuff from Car quest so its an easy warranty replacement. . As for the rear wheel cylinder it appears that the bottom end is pushing out which I assume is causing the leaking. Is there suppose to be a clip within the housing that holds it together? Thanks all for the help.

 

[Stumpalama]

So the bottom end of the shoe is kicking out away from the backing plate?
Pictures would help at this point.