Another leaking pinion seal

[BluePonyGT]

I happen to notice yesterday while under the car adjust the e-brake that I have a leaking pinion seal.

Bummer.

My 2017 has 57,000 miles. Limited slip 3.31 third-member. Manual 6 speed flange. So I have to mark everything, pull the drive shaft. Remove the pinion nut while holding the flange from turning, pull the flange, pull the old seal, prep and install the new one, work the flange back on with the old pinion nut, install and torque the new pinion nut only to where the old one is pre-loaded to. Car will be on jack stands, but I'm ok with all of that.

Questions:

1. What's the best way to measure pre-load on the pinion nut since it is staked to the pinion shaft? I realize having a dial or beam style torque wrench is necessary, but in/lbs? I assumed that nut is on there torqued quite a bit so how exactly am I measuring it? What's the torque spec to begin with? I realize I could mark everything and count threads, etc. to get the new nut to the same location, but I seriously want to know the best way to measure pre-load on the pinion bearing with the existing nut.
2. Should I commit to changing the gear oil by pulling the cover, clean/inspect and reseal/re-fill? If so what's the best gear oil to use? What's used from the factory?
3. I'm planning on the big GT350R brake kit upgrade with new half-shafts in the spring anyway. I plan on replacing the axle seals and bearings for the new half-shafts. Should I wait and do this then? Seems like a good idea, but I'm nervous about waiting.

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[BluePonyGT]

ok pre-load is how many in/lbs it takes to spin the pinion bearings with the nut in place before I remove it, and I write that down. I need to measure what it is before I pull the nut off the shaft. Taking the nut off is going to be a challenge, and then when putting the new one on I have to aim for the same pre-load.

So I need a decent torque wrench that will measure it.

 

[NGOT8R]

Post #2 might have some helpful formation for you.

https://www.mustang6g.com/forums/threads/ring-and-pinion-install-specs.28895/

 

[Cobra Jet]

I happen to notice yesterday while under the car adjust the e-brake that I have a leaking pinion seal.

Bummer.

My 2017 has 57,000 miles. Limited slip 3.31 third-member. Manual 6 speed flange. So I have to mark everything, pull the drive shaft. Remove the pinion nut while holding the flange from turning, pull the flange, pull the old seal, prep and install the new one, work the flange back on with the old pinion nut, install and torque the new pinion nut only to where the old one is pre-loaded to. Car will be on jack stands, but I'm ok with all of that.

Questions:

1. What's the best way to measure pre-load on the pinion nut since it is staked to the pinion shaft? I realize having a dial or beam style torque wrench is necessary, but in/lbs? I assumed that nut is on there torqued quite a bit so how exactly am I measuring it? What's the torque spec to begin with? I realize I could mark everything and count threads, etc. to get the new nut to the same location, but I seriously want to know the best way to measure pre-load on the pinion bearing with the existing nut.
2. Should I commit to changing the gear oil by pulling the cover, clean/inspect and reseal/re-fill? If so what's the best gear oil to use? What's used from the factory?
3. I'm planning on the big GT350R brake kit upgrade with new half-shafts in the spring anyway. I plan on replacing the axle seals and bearings for the new half-shafts. Should I wait and do this then? Seems like a good idea, but I'm nervous about waiting.

Wouldn’t that be covered by the 5/60 Powertrain, assuming you haven’t passed the original purchase date yet?

 

[BluePonyGT]

Hmmm...I haven't. I have less than a year to go, but I may have a warrantee claim here.

I should at least call them.

 

[BluePonyGT]

Post #2 might have some helpful formation for you.

https://www.mustang6g.com/forums/threads/ring-and-pinion-install-specs.28895/

Perfect - thanks.

 

[Bahndvr]

I thought the yoke was just bolted onto the pinion shaft not providing load?

 

[BluePonyGT]

I thought the yoke was just bolted onto the pinion shaft not providing load?

The flange slips onto the splined pinion shaft and a nut holds it on, which introduces pre-load to the pinion bearings and races. The drive shaft end bolts to this, and flexibility is controlled by the boot farther up the shaft rather than at what would normally be the yoke at the pinion. There's still defection to a certain degree and that tiny spring that holds the seal to the pinion shaft can be prone to failure like any other seal of that nature. So after 50+ K miles it just chose to start leaking even though they even put a protective cap over the seal.

This is what helped me understand the overall process to replace it, but also reveals why it may be prone to failure as well:

https://performanceparts.ford.com/download/instructionsheets/FORDINSTSHTM-4851-M8A.PDF

 

[Bahndvr]

I need to replace mine. I didn't know there was more to it but I had a feeling.
Thanks

 

[BluePonyGT]

Update:

Car goes into the dealership on 2/9. They're telling me up front it is a warranty claim, so yee-haw.

 

[glockholiday]

Thats awesome it'll be covered, I came here to mention though, as soon as you said "with a new nut" during reassembly everything goes out the window. The procedure was right but only as long as it all goes back together with the same hardware.

 

[BluePonyGT]

Thats awesome it'll be covered, I came here to mention though, as soon as you said "with a new nut" during reassembly everything goes out the window. The procedure was right but only as long as it all goes back together with the same hardware.

That's not what Ford and/or Ford Performance recommends. The new nut gets torqued and when it's un-torqued its supposed to be "trash". It's also staked around the pinion shaft, so it is permanently deformed once installed.

Take a look at this:

https://performanceparts.ford.com/download/instructionsheets/FORDINSTSHTM-4851-M8A.PDF

Although I assume you could get away with using the old nut I learned the hard way on these spindle and driveline nuts to throw them away and use a new one when I replaced one of my short-shaft seals. I couldn't get the old nut torqued properly and I ended up burning out the hub on that side. So now it's new nuts - period.

This is also why measuring the pre-load is important. If you don't do that you're stuck counting the threads, etc. to know where to put the new one.

 

[Cobra Jet]

Update:

Car goes into the dealership on 2/9. They're telling me up front it is a warranty claim, so yee-haw.

That's good news - I thought it would have been, since you're still within the 5/60 Powertrain.

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