97 f-150 rear axle question - Ford Forums

ronsham · 07-23-2008, 18:54

I have 97 f-150 w/4.6 liter, auto-trans. rear diff has 75-145 synth oil in it. 85000 miles. How can I avoid rear axle brng failure that so many others have?

kaboom10 · 07-29-2008, 05:39

Start by using a good full synthetic like Royal Purple or Amsoil.

tgore3 · 07-29-2008, 20:37

and make sure the fluid level is good so it can get to those bearings

ymeski56 · 09-25-2008, 09:14

I don't recognize the ref #'s. As long as it refers to a Hypoid type gear oil
80-90 wt. There is a special additive that must be included in all units designated as being limited slip types. If you were unaware of this find out which type yours is and include asap if found to be required. Your ahead of the many that have not & will not ever change this oil, and synth. switch further lowers the poss. of failure. Now spread the syth.love w/ the rest of your car. Petrol base fluids are the weakest componants in the tranny & breake system, Synth 's lube better,longer & cooler.if switching,pretreat crankcase oil w/SeaFoam & trans w/ Trans Lube prior to changing to melt and suspend contaminant deposits allowing removal w/oil drain.

847alexc · 09-25-2008, 20:06

Quote:

Originally Posted by ymeski56

I don't recognize the ref #'s. As long as it refers to a Hypoid type gear oil
80-90 wt. There is a special additive that must be included in all units designated as being limited slip types. If you were unaware of this find out which type yours is and include asap if found to be required.

Whoa!! don't put 80-90 in your 97 f-150!

While your right, most limited slips will require friction modifier for the limited slip, that is exactly why the ford OEM is the wide viscosity 75-110. The variable viscosity eliminates the need for friction additive. They did this because so many cars were having L/S clutch problems even with the additive. Some techs I know would use 2 tubes of the stuff just to be sure. The older 8.8 L/S used this stuff and its ok, but the 75-110 is fool proof. It just so happens that its synthetic because its the only way to get those viscosity properties. Without either 75-110 or the right amount of additive you will burn up your L/S, though now even open diffs are meant to run the 75-110 on newer fords.

But as far as the axle bearings, the biggest problem is that the seals are prone to leaking. When enough fluid leaks out the bearings dont get the proper lubrication causing failure. Eventually the bad bearing even wears into the axle it self making the repair much more expensive.

Check you seals for leaks whenever the wheel is off.

ymeski56 · 09-27-2008, 00:55

Quote:

Originally Posted by 847alexc

Whoa!! don't put 80-90 in your 97 f-150!

While your right, most limited slips will require friction modifier for the limited slip, that is exactly why the ford OEM is the wide viscosity 75-110. The variable viscosity eliminates the need for friction additive. They did this because so many cars were having L/S clutch problems even with the additive. Some techs I know would use 2 tubes of the stuff just to be sure. The older 8.8 L/S used this stuff and its ok, but the 75-110 is fool proof. It just so happens that its synthetic because its the only way to get those viscosity properties. Without either 75-110 or the right amount of additive you will burn up your L/S, though now even open diffs are meant to run the 75-110 on newer fords.

But as far as the axle bearings, the biggest problem is that the seals are prone to leaking. When enough fluid leaks out the bearings dont get the proper lubrication causing failure. Eventually the bad bearing even wears into the axle it self making the repair much more expensive.

Check you seals for leaks whenever the wheel is off.

Thanks for jumpin it on that. I was useing my 87' as reference. I new if I could just live long enough, I'd eventually see (or hear about) at least 1 of those "better ideas" Ford always said they kept having when it came to cars & trucks. Maybe their scarcity is yet another prime example of what happens when you don't write things down when something is still fresh in your mind!

847alexc · 09-29-2008, 19:06

I would like to correct my self from my last post.

75-140 or 75-145, not 75-110. But you all knew what I meant.

stuston · 12-02-2008, 14:13

Do you know where I can get a DIY guide online for the rear bearing replacement? Or at least some general proceedures?