Rear end Getting Pretty Hot. Need Help

[CTSV]

Where can i buy some Schaeferrs moly gear oil to try out?

[AMSOILGUY]

Where can i buy some Schaeferrs moly gear oil to try out?

You'll have to find a distributor in your area I believe. I would think that they would have a locator online.

If you have any interest in running AMSOIL here's a link to our gear lubes. AMSOIL Severe Gear Lube

[shmoov69]

Wow, good info Ron!! Thanks!!

[CTSV]

You'll have to find a distributor in your area I believe. I would think that they would have a locator online.

If you have any interest in running AMSOIL here's a link to our gear lubes. AMSOIL Severe Gear Lube

You do offer several but all are synthetic based and was specifically told by Strange and Moser not to run any synthetic in a Tru trac.

[UMI Tech]

Wow, good info Ron!! Thanks!!

Seriously. Ron's advice is always spot-on and includes details I didn't even know existed. But it always makes sense and works.

[AMSOILGUY]

You do offer several but all are synthetic based and was specifically told by Strange and Moser not to run any synthetic in a Tru trac.

I completely understand. Run what your comfortable with. If it were mine I would ask them for a spec and go from there. As Ron said earlier all synthetics are not created equal.

[Ron Sutton]

I completely understand. Run what your comfortable with. If it were mine I would ask them for a spec and go from there. As Ron said earlier all synthetics are not created equal.

They vary a lot. Sometimes they even vary from one type of lube to another within the same brand. There is a brand of synthetic oil I found from lots of testing & experience that has the best gear oil & the worst engine oil. I wouldn't run their engine oil when it was given to us for free, but I'll pay full price to run their gear oil.

It's important to understand "why" Eaton is saying not to run synthetic. It has nothing to do with heat or wear. It is simply that many brands of synthetic gear oil are so slippery (higher lubricity ... which is a great thing for everything else in the diff) that they make the clutch discs slip. So add a friction modifier "posi additive" and party on.

Thanks for the kind words Jimmy & Ramey.

[Ron Sutton]

Mine never puked oil i have about 2.25 quarts of 85-140 oil in mine but was pretty surprised at the heat of the housing under there.

Does anyone know what heat range gear oil can withstand before breaking down and becoming ineffective?

Most mineral based gear oils are good to 240°. Most Synthetic gear oils are good to 280°-300°. But many times the internal components (gears, bearings, etc) fail at temperatures below these numbers if they are made from inferior metals.

When Harley mentioned rear ends running close to 300° & surviving racing conditions, those rear ends have the best components to the nth degree. We ran ours to 280° often with no failures, but we didn't buy crap from the cheapest vendor & throw it together. There is a LOT of care that goes into those rear ends from deburring every edge on the R&P, REM polishing the gears & bearing races, making sure the bearing preload is EXACT, etc. That's on top of buying the every best quality gears, bearings, etc.

I think for most of the ProTouring world, commonly available imported rear end internals will fail somewhere in the low to mid 200's. I do not have personal hands on experience running the cheap-gear-brand-of-the-week in tough conditions, so I can't say at what temp they will fail. So my "low to mid 200's" guesstimate is just that.

[Ron Sutton]

Ron- where is a good website to look up these Timken bearings that you kept talking about in all your threads. Im due to change out alot of parts on my toys and you have me conviced I need to step up to the safer stuff.

Hi Miles!

Are you asking about diff bearings? or other things like hub bearings, etc?

Timken is a big brand and available through a zillion channels. NAPA sells Timken ... but they also sell cheap import bearings too. All bearing companies sell Timken. I have Timken bearings available for hubs & diffs on my website. I'll come back on with some links later.

P.S. What makes Timken bearings so durable ... aside from better maching & quality control ... is they have developed their own version of 300M alloy steel. Their proprietary steel is so tough, other companies needing to make tough parts buy "Timken Steel" from Timken. You can see it here.

[AMSOILGUY]

Our slip lock additive is at the bottom of the page. Comes in a 4 oz container.
AMSOIL Severe Gear Lube

[shmoov69]

Ron, I don't want to hijack the OP topic, but I do have a q about my issues that I had posted on the first page. I have no idea how hot mine was without an IR, but I'm assuming pretty stinkin hot when brake cleaner sizzled and evaporated instantly when I sprayed it (after about 10 minutes of cool down). What kind of damage would that cause or would a fluid change be all that's needed? It's a 9", stock iron case, stock Ford 3.00 gears and a new (in '05) Detroit locker.
Thanks and if its a hijack, you can PM me. ;-)

[Ron Sutton]

Ron, I don't want to hijack the OP topic, but I do have a q about my issues that I had posted on the first page. I have no idea how hot mine was without an IR, but I'm assuming pretty stinkin hot when brake cleaner sizzled and evaporated instantly when I sprayed it (after about 10 minutes of cool down). What kind of damage would that cause or would a fluid change be all that's needed? It's a 9", stock iron case, stock Ford 3.00 gears and a new (in '05) Detroit locker.
Thanks and if its a hijack, you can PM me. ;-)

Hi Jimmy,

Doesn't seem like a high jack to me ... same topic.

The challenge is ... like I covered in a few of the bullet points ... different oils fail (viscosity break down) at different temps ... and different quality components (Steel they are produced with) fail at different temps. We don't know what temp your rear end got to ... or what temp your oil breaks down at ... or what temp your specific parts can & can't tolerate.

My rule of thumb is 240° max with mineral based oil & 290° max with synthetic based gear oils. But gear oil viscosity can play a role in that. A thinner oil could break down at a lower temp ... and even though too thick of an oil adds heat ... thicker oils can survive higher temps. As far as the internals ... the only real way to know is to do an inspection. If they are failing, you will find micro particles in the gear oil, and see slight discoloration on or around the mating surfaces.

For safety's sake, I would go ahead & do an inspection. If everything is ok ... next time you go run ... take an infrared temp gun & shoot the bottom of the housing often & keep track of the numbers. You can come back on here & share or PM me.

[shmoov69]

Thanks Ron!!