Re-gear and diff temperature

[p1michaud]

Folks,
last weekend was the culmination of 3 to 4 months of preparation in the form of reading, building and acquiring tools, buying spare parts, stocking the fridge with :beer: for my helpers, etc....
I was able to re-gear my Tacoma to 4.56 gears. So now I'm in the process of breaking in the gears. Luckily I live 10 minutes from work. This allows me to drive a short distance then let the rear diff cool down for the day then drive home. A few weeks of this should allow for proper break in of the new gears.
I've been regularly checking how hot the rear axle housing gets with my hand. It's been a bit warm, but I'm guessing nothing above say 30 deg. C (86 deg. F) using my calibrated hand...and I'll call this "normal" for the sake of discussion here.
Last night I had some time, so I hit the highway for the second time (5 minute run the first time) for about 15 minutes with two stops to check the rear diff. First stop temp. felt about normal, second stop the temp had climbed to approx 50 deg. C (122 deg. F) I'll call this hot. It was hot but I could still keep my hand on it. So I stopped and let things cool down for about 15 minutes then re-checked. Once it cooled down to the "normal", I hit road again and checked it one I arrived home and it was back to "hot". All this got me thinking, has anyone ever check their rear diff/axle temperature after driving on the highway by just putting their hand on it? I'm trying to get a feel for what is too hot vs. normal temperature. By the way, it's a 1999 Tacoma with E-locker and 4.56 gears. Could anyone feel their rear axle after driving on the highway for a bit and see how hot it gets? I just put my hand on the area where the ring gear would be to the left of the fill plug, see pic below.

As a point of reference the ambiant temperature was 15 deg. C (59 deg. F).

Cheers :beer:,
P

 

[erin]

I know when I did my 4.88's in my 04, I was told to just do the short trips, ie, under 15-20 miles for a couple days by the installer. Like you, I was underneath feeling the housing w/ my hand. When I had it done was during the summer here, so good and hot, 100+ at the time, and you couldn't hold your hand on the diff. After 500 miles, back to the installer for the oil change, and he said everything looked great, so I think your temps are probably good. I would venture to say mine was around 130-140, things get hot here, hahaha. You could also smell the diff oil, see if it smells burnt or such, but it would probably be a little late if this was the case, and not very accurate either.

 

[p1michaud]

Great!

Erin,
Thanks for the information that's reassuring. Out of curriosity, now that you have some miles on the new gears, have you felt your rear diff after a long drive? I could also smell the gear oil, not quite a burnt smell but more like a noticeable smell. Mmm gear oil...
Cheers :beer:,
P

I know when I did my 4.88's in my 04, I was told to just do the short trips, ie, under 15-20 miles for a couple days by the installer. Like you, I was underneath feeling the housing w/ my hand. When I had it done was during the summer here, so good and hot, 100+ at the time, and you couldn't hold your hand on the diff. After 500 miles, back to the installer for the oil change, and he said everything looked great, so I think your temps are probably good. I would venture to say mine was around 130-140, things get hot here, hahaha. You could also smell the diff oil, see if it smells burnt or such, but it would probably be a little late if this was the case, and not very accurate either.

 

[Rockcrawler]

Ugh... gear oil... that has to be about one of the worst smells when working on a vehicle. 120 degrees or so sounds about right. If you're hauling a load or towing, it can get much warmer. Some of the Diesel guys have temp gauges on their diffs for when they are towing heavy and show temps as high as 200 degrees at times. ouch!

 

[erin]

No, I haven't felt in in some time, but everything gets so hot here in the summer, it feels hot before you even start it up? I'm planning on picking up a little temp guage this weekend, which should read to about 250 degrees, so I'll give it a shot next week after my run home from work on the freeway.

 

[p1michaud]

Feeling my diff...

Cool, I appreciate it!

No, I haven't felt in in some time, but everything gets so hot here in the summer, it feels hot before you even start it up? I'm planning on picking up a little temp guage this weekend, which should read to about 250 degrees, so I'll give it a shot next week after my run home from work on the freeway.

 

[DaveInDenver]

Your break-in sounds perfectly normal. Mine got pretty warm on the drive home from the shop, which is about 15 miles. I took it slow, stopped once to let them cool and a couple of times to check them. Be sure to do accelerations and decelerations to break-in both the lead and trailing faces of the gears, change oil often and don't worry, they'll be fine. I know that sounds fine, but I was (and am) the exact same way when I broke in the gears and I'm breaking in my engine now. Did you regear the front, too? That one for me was harder to break-in, had to find good dirt roads and do some driving by myself and I don't think the break-in was nearly was well controlled.

 

[crawler#976]

nuther tip - no towing for 500 miles.

At 500 miles, change the diff juice to clean out all the particals. Don't be surpised to see the fluid is quite dark - the gears are coated with phosphate and as they wear in it discolors the fluid. You will also see some extemely fine metalic flakes - that's also normal.

After a 1000 miles or so, switch to full synthetic. You'll see a very noticable drop in temp.

It's important to leave the dino juice in for the first 1000 miles tho - the synth is too slick to allow proper break in.

 

[DaveInDenver]

You will also see some extemely fine metalic flakes - that's also normal.

Oh yeah, good point. Don't freak out when you see that, that's a result of the two gear faces meshing to each other. Worry if you see big pieces of shavings, but a fine almost powder is normal.

 

[p1michaud]

Thanks guys!

nuther tip - no towing for 500 miles.

At 500 miles, change the diff juice to clean out all the particals. Don't be surpised to see the fluid is quite dark - the gears are coated with phosphate and as they wear in it discolors the fluid. You will also see some extemely fine metalic flakes - that's also normal.

After a 1000 miles or so, switch to full synthetic. You'll see a very noticable drop in temp.

It's important to leave the dino juice in for the first 1000 miles tho - the synth is too slick to allow proper break in.

I was not planning on towing untill at least 500 miles. Great reminder.
Pardon my ignorance, but when you say dino juice do you mean regular old gear oil? I put in plain Castrol Hypoy C 80w-90 Gear Oil for the break in. I had originally planned on switching to a full synthetic after 500 miles, but I'll do a drain re-fill after 500 with Castrol 80W-90 then after anohter 500 miles, I'll switch over to full synthetic.

Oh yeah, good point. Don't freak out when you see that, that's a result of the two gear faces meshing to each other. Worry if you see big pieces of shavings, but a fine almost powder is normal.

Good to know, I'll keep an eye out for metal particles and won't be too disturbed unless they are significant in size.

 

[erin]

Thats a good point about the fronts, I'm sure alot of people forget about those. I was lucky, everything spins all the time now, thanks to the True tracs.

 

[p1michaud]

Front Diff

Did you regear the front, too? That one for me was harder to break-in, had to find good dirt roads and do some driving by myself and I don't think the break-in was nearly was well controlled.

Missed this in my last reply. Yes I did regear the front as well. What a PITA, but after taking it aappart 6 times, to get the proper pinion depth and pattern I've got it pretty well in hand!
I'm heading out for some weekend camping and minor wheeling so I'll be working on breaking in the front diff at that time. No major wheeling or speed involved, just a bit of exploring. Should be nice, it's the first over night trip of the season. :wings:

Cheers :beer:,
P

 

[crawler#976]

yeah - Dino(saur) juice is standard gear oil

 

[Grim Reaper]

I asked Zuk www.gearinstalls.com what would be too hot and his comment was as long as it stays under 200 and you work it in like you are doing, should be fine. When it was breaking in the first hwy run after about 60 miles of short trips (I live 3 miles from work) it hit 170f after about a 20 mile run. That was the hottest I ever saw.

I am over 500 miles now and it stays under 150 even towing. I need to do my 500 mile change soon (its only about 680 miles now LOL ).

 

[p1michaud]

Great link and great guy!

I asked Zuk www.gearinstalls.com what would be too hot and his comment was as long as it stays under 200 and you work it in like you are doing, should be fine. When it was breaking in the first hwy run after about 60 miles of short trips (I live 3 miles from work) it hit 170f after about a 20 mile run. That was the hottest I ever saw.

I am over 500 miles now and it stays under 150 even towing. I need to do my 500 mile change soon (its only about 680 miles now LOL ).

Thanks for posting Zuk's page for others to know about. I've read every toyota article he's written on that page. Excellent ressource and great guy. I was communicating with him before and after the re-build answered my every pestering question.
I spent some great time this weekend breaking in the new gears (both front and rear) on our first fishing/camping/geocahing trip. Put approximately 100 miles on both front and rear diffs. Both were real warm but nothing excessive. Most of my speeds were between 20 - 25 MPH due to the rough roads.