Cleaning Rear Differential

[TTimmons]

HI All,



I'm getting ready to change the oil in my rear differential, and was wondering should i clean it out before adding new oil? If so, what is the procedure, and do you use any type of chemicals?



I will be refilling with Royal Purple 75W140.



Thanks!!

 

[Hoefler]

If you can, drain it warm and over night. If there is no debris like heavy metallic or chunks, just wipe it out and refill. If you have any questionable debris, better find where it came from and repair it.

 

[TTimmons]

Thanks for the info. My truck is 2 years old, and this will be the first time the diff fluid has been changed. I'll be looking for debris and shavings for sure. I'm also thinking about changing the gears from 3. 73 to 4. 10 to help with pulling my travel trailer.



Thanks!

 

[rholcom2]

I cannot speak to the 3rd Gen axels. However, with the Dana's in the 2nd gens the carrier was different between the 3. 73 and 4. 10's. Just a heads up, I am sure someone who knows will chime in. Good luck, I will be changing out my diff fluid here soon.

 

[AWise]

Just changed my front and rear diff fluid 2 weeks ago with 47k on the clock. I did it in the driveway so there would be a slight incline to help the draining. It drains quickly and I just used a clean rag to wipe out the bottom. The old lube was in good shape and the only wear material was the goo on the magnet. Didnt see any need to clean it further as there will only be a thin film of the old lube left. Put on the new Mag-Hytec and filled her up with Amsoil 75w-90. Oo.

 

[GOlsen]

I cannot speak to the 3rd Gen axels. However, with the Dana's in the 2nd gens the carrier was different between the 3. 73 and 4. 10's. Just a heads up, I am sure someone who knows will chime in. Good luck, I will be changing out my diff fluid here soon.

From what I understand, the carrier for the 3. 73 is the same as the 4. 10, 4. 10 being the largest (numerically) set that will work with that carrier. The larger carrier is for 4. 10 and larger gears.

 

[raksasa]

The night before I did my differentials I scrubbed them to minimize the risk of dirt dropping in when I removed the covers.

The gasket is reusable and is made of a rigid rubbery plastic material. Just to be ready, I called the local dealer and made sure he had replacements in stock. It wasn't an issue as they fall right off the differential when you remove the cover.

I wiped out the differential with a rag that had been through the washer a few times and didn't have any lint. I only wiped the very bottom of the housing, not the actual gears and didn't use any sort of cleaning fluid that might have contaminated my oil.

I had to pump the new fluid in as my funnel was useless (the only spill of the entire job).

There was a small amount of fine metal dust on the magnetic plug on the old covers, otherwise everything was very clean. It was the first time the fluid had been changed.

Jon

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Fluid drained and diff wiped down

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Gasket detail

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Another view of the open differential

 

[grabinov]

I just changed my rear diff fluid too. with 48,000 miles. The fluid was pretty dark, but did not appear to be degraded. I run a Mag Hytec rear cover, so I had to refill with 5 quarts (went with 75 - 140)! I tow a big 5th wheel, and there was a fair amount of metal dust on both the Mag Hytec drain plug magnet and the dipstick magnet, but it was very fine. I am assuming normal wear.

I cracked open the front pan only to discover that the fluid looked like new. Given that, I sealed it back up, topped it up and capped it. My guess is the front diff can easily go 30,000 miles unless you spend a lot of time in 4wd...

 

[TTimmons]

Thanks for the great info guys. This should be pretty straight forward to do. I appreciaste everyon'e's comments.



grabinov,



Do you still run a 3. 73 rear end, or 4. 10? I'm thinking about buying a fifth wheel myself, trading in my 26ft. travel trailer for a 37footer, and was wondering about the benefits of upgrading the rear end.



Thanks all!!



p. s.



raksasa,



great pics of the diff!! Thanks!! I'll post some pics of mine when i do it, along with a report of any contaminants.

 

[grabinov]

TT,

I run the 3. 73 rear end with a 33 foot, 11,500 lb. (loaded) fifth wheel. I got in the habit of towing in overdrive - because I can (Thanks Cummins) and I'm a fan of low RPM, good for the engine, etc. Unfortunately what's easy on the engine is not always easy on the transmission, and I ended up rebuilding my transmission at 30,000 due to a blown overdrive piston seal, which cost me the overdrive but did not leave me on the side of the road. In fact I went 1,000 miles home in Drive.

I spent about $4,000 and got a hand built trans with all the good hard parts inside, and it has been running well for 15,000 with the trailer, and I still tow in overdrive.

I think you either have to have the 4. 10 gears and stay out of overdrive or you have to expect to buy a transmission. I am happy with the combination I ended up with, because you can't beat the drivability of the custom trans. I had never driven a built truck/trans like that until this one, and you wouldn't believe how much more pleasant it is to drive. It gets rid of that thing where you come off a light and it feels like the engine is making a lot of noise and spinning really hard, but the truck is not going anywhere.

I can now go on trips without the trailer and get 17mpg (2,000 RPM at about 70 with no trailer) because of the 3. 73 gears, and I can tow the trailer at relatively low RPM when I have it attached. Great versatility but it cost $4K. that said, I would do it again in a minute, particularly before I spent $1K on front AND rear gears for my 4wd truck.

If I buy a 2010 - which I am waiting to see in person - I'll put a torque converter in it after I leave the dealership. It really drives that much better.

 

[Dave04]

Will an after market torque on a stock transmission hurt anything? I have a triple plate billet with stock stall. Not yet on truck.

 

[TTimmons]

Thanks for the great info grabinov. I'll be staying with the 3. 73 rear end. I've been planning on upgrading the transmission sometime in the early part of next year. I've been talking to the good folks at ATS and Suncoast, getting prices and finding out exactly what i need. I just want to do whatever it takes to make it easier for my truck to pull the trailer.



Thanks!!

 

[grabinov]

Dave04

Will an after market torque on a stock transmission hurt anything? I have a triple plate billet with stock stall. Not yet on truck.

I don't think there's any problem with an aftermarket TC on a stock transmission. You'll notice a significant increase in drivability and probably reduced trans temps. While you're there (with the trans removed), replace the flex plate (part is only about $150 and labor is free if you're there anyway). You can do the Valve Body later any time the pan is off without pulling the trans.

Greg

 

[Vaughn MacKenzie]

TT,



I run the 3. 73 rear end with a 33 foot, 11,500 lb. (loaded) fifth wheel. I got in the habit of towing in overdrive - because I can (Thanks Cummins) and I'm a fan of low RPM, good for the engine, etc. Unfortunately what's easy on the engine is not always easy on the transmission, and I ended up rebuilding my transmission at 30,000 due to a blown overdrive piston seal, which cost me the overdrive but did not leave me on the side of the road. In fact I went 1,000 miles home in Drive.

I think towing in OD is OK as long as your EGTs stay down and you don't let the RPM get under about 1750. But if you're working it pretty good under 18-19 RPM it's actually harder on the engine than spinning it at ~23-2400 RPM for hours on end.

 

[DZink24]

here are a few more pics from when i did it last year



https://www.turbodieselregister.com...sions/204118-got-diff-oil-changed-w-pics.html

 

[Dave04]

Can they replace the TC when tighting the bands on my transmission or does to whole transmission have to be dropped?

 

[upsyes]

Trans HAS to be dropped. It is located between the engine and the trans. The flywheel is attached to the crankshaft and the torq converter is bolted the flywheel and the torque converter nose slides through the transmission front seal into the pump housing... it is full of trans fluid.



HowStuffWorks "How Torque Converters Work"

 

[Dave04]

OK cool thanks