Pinion Seal

[seabeelt]

Decided to tackle this leaking problem this weekend. Got the car up on jack stands ( gotta love the quick pump floor jack) Found all kinds of good stuff once under there. Scary part was that 2 out of the 4 nuts attaching the drive shaft to the rear diff were loose and the other 2 were not all that tight either. So drive shaft came off fairly easily. Used a couple of zip ties to remember where it went when mated to the rear end. Impact gun was great for getting the pinion nut off after I marked its position. The old seal was a bugger to get out. Tapped the new one in slow but sure, put everything back together, drained about a half pint maybe more of old fluid out - black as crude oil. Refilled with 80-90w. Removed about a half pound of greasy crud from the diff and cleaned it off with brake cleaner.

Noticed that the center support bearing seemed to wobble all around in the rubber covering. Not sure what is really in there at this point and why the drive shaft does not wobble all around while driving??????.?. no noise, nothing, but I'm pretty sure it shouldn't have over an inch of play in every direction, definitely the next project.

Noticed exhaust has a small hole just after the resonator and is under the the e-brake cable instead of over it causing the exhaust to ride low and bump the pan hard rod. Most of the rubber exhaust hangers are shot and not helping much. And of course the exhaust has melted the ebrake cable covering

All the bushings for the long and short trailing arms are definitely shot- thank goodness for spares and projects to do.

[4uall]

here is an awesome video as well

https://www.youtube.com/watch?v=ha2Uhl9BTtM

[seabeelt]

Thanks Jay. I actually saw that one a couple months ago. Didn't need his "special" tool to lock up the real end. E-brake did just fine along with the impact gun. Wish he had published a few more items on the Fiat though.
R/

[4uall]

I hear ya

[KidDingo]

That's a coincidence. I just did the same thing. Only, I had to install a rebuilt driveshaft, too. With a gammy shoulder. Wasn't easy, but definitely feel better knowing there won't be any diff oil flinging around under the car and that the diff won't seize up.

BTW, new u-joints, pillow block, and guibo make a BIG difference in the driving experinece.

[4uall]

uhm looks like I may need to do the same soon

[seabeelt]

I would say that is a definite yes. Car will go faster once All the dirt caked oil is remove too

[njoconnor]

+1 on the YES vote on your diff, Jay. Looks like mine used to

Since I was redoing the whole suspension, it made sense to work on my pinion seal and clean/paint the diff with everything off the car. Thinking on the steps, it would be harder on the car than off. Alan (SoFlaFiat) email talked me through the rear axle drop process, and it's really not bad. Instead of using the e-brake to lock the axle, I used quick clamps (padded) to lock the (old) brake discs. Just remember to tighten ANY connection anywhere near the axle (like brake center flex hoses... ).

Once replaced, you realize how nice it is not to see axle fluid on the garage floor....or the drive. Can't say the 72 is faster with less crud, but I still get a kick looking under there and seeing paint. Fall to it; it's worth the effort.

Neil

[fiatfactory]

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[DieselSpider]

As a factory trained mechanic, I fail to see how you all think that this is going to be a suitable solution?

Pre-load on the pinion bearings, as well as the lash between the pinion and crown wheel teeth (determined by the meshing pattern) has a pretty definite factory procedure for doing ... and ensuring that pre-load and lash is actually correct...not just a GUESS, which is all you get with the "mark and return the nut to the same position" method.

Every single time I have replaced a broken differential a tale about how the pinion seal was 'recently' replaced comes out in the wash.... "caveat emptor" for anyone following the non factory approved method.

SteveC

I cringe when I hear people saying all you need is an impact wrench to do this and ensure that you make a mark to set the nut back to the same clock position. Some will even endorse using an impact wrench with a torque limiter such as they use to get lug nuts close enough. You do have to follow procedure and get these exactly correct to prevent problems down the road. Not sure what the failure rate would be but it would seem the be a 50/50 roll of the dice at best when you take the alternate route.

[seabeelt]

Understand all of what you folks are saying, however, for clarification. Depth of threads was counted, position marked and then the nut was removed with impact wrench so as not to struggle with spin of the axel during removal. Installation was done without the impact wrench, nut was returned to original position, and just a tiny bit more pressure on the wench to ensure we have good pressure on the crush washer. Yes there is an assumption that the lash is correct to begin with.Being that this is a front assembled pumpkin, I. E. No inspection cover on the rear, I wasn't about to pull the whole diff apart to change the seal and go the whole bearing and crush washer route. If I have a future problem, it is certainly fixable.

[DieselSpider]

As long as its an informed discision and you are comfortable with it thats all that matters. Some may see this and not understand the risks unless we discuss them in an obvious fashion. There may be some risks that I am comfortable with that you may not find acceptable too.

[chrisg]

I'm curious now...a year or so later, did it work out OK?

I have certainly been witness to "careful replacement" approaches & I'm not actually averse to them in theory (definitely knowing the risks), but real life data is always nice to hear about. factory spec on the flange nut is 14-17 in-lbs I believe, so that amounts to about 1.5 ft-lbs....quite light.

[Boris61]

I'm certainly not an expert, but "factory spec" does not refer to the pinion nut torque. It is the rolling torque required to turn the bearing and shaft without the other parts (wheels, rotors, axel shafts, diff gears). That is why it is so "light". To achieve this the pinion nut has to crush a single-use metal sleeve and that takes a lot of torque (like 150+).

[DieselSpider]

I'm certainly not an expert, but "factory spec" does not refer to the pinion nut torque. It is the rolling torque required to turn the bearing and shaft without the other parts (wheels, rotors, axel shafts, diff gears). That is why it is so "light". To achieve this the pinion nut has to crush a single-use metal sleeve and that takes a lot of torque (like 150+).

Yes and when you reuse it there is a chance that due to wear from use since it was last set that it will no longer be correct when you tighten it back up. You roll the dice by cracking it a bit more to compensate however its still a calculated risk. Everyone's hand and experience is different just like when trying to replicate Nana's bread recipe, while many try and get it almost right few get it exactly the same.