Hey y'all, have a few questions on the diffs in my truck - 06 5.7 QC 4X4 63k miles

#1 - I just changed the rear diff fluid with Royal Purple 75W-140 per the manual and this great forum. I had thought I had a LSD but looking at the gears it looks like just an open diff. I believe it's called the spider - it is open and you can see the smaller pinion gears inside. Apologize if my terminology is flawed. I'm electrical by design. Anyway, this would explain the crappy traction in the mud. Can someone tell from a pic?



Okay, #2 - She only took about 60oz to get to exactly 5/8" below the hole. (Used a marked angle bracket to get exactly 5/8") That's 12oz under spec. I let the thing drain for 20 min, and then scraped the bottom a few times so I'm pretty sure it was mostly empty. Is this within tolerance or do I have an extra gear in there?

Last - #3 - Front diff will be done next which calls for 75W-90. I would like to use the 140 I have left (bought 3 qt) since there is about enough left to fill it (and it's $20/qt). So my question is: Does the front diff spin all the time or is the 4WD engaged in the transfer case and on the front hubs? If it does, Ill use the 90wt for economy, but since I'm in 4wd maybe 2% of the time, it's not a concern if it is totally disengaged and just sitting in there.

Yeah it's long winded but I like to give the whole story. Thanks guys!

 

seems to be an open diff, in my old ford the limited slip was accomplished by a thick metal S shaped spring that would help distribute power evenly to both side gears or spiders.. in normal circumstances but would allow it to slip if one wheel had ALOT more traction than the other or when turning..

 

I don't see any clutch packs, but the angle is off for that. If you see this on the driver's side of your diff:



You have a LSD differential. The red circle is around the infamous clutch-pack retainer clip, often referred to as the "c-clip". Above the red circle is the clutch pack.

 

Thanks for the pic but I have the cover on and fluid in there or else would check. Do think it is non LSD tho but I have heard the 2006 big horn package (mine) includes an LSD.

I was comparing it to Johns in the tururial but I see that is a 2500. Possibly that is why.



Any ideas on the 140 in the front, fellas? I'm sure it will be "fine" but wondered if anybody has tried both weights.

 

Spuldup, well your pic looks pretty similar to mine in here
https://dodgeforum.com/forum/3rd-gen...se-inside.html
And you can see I pulled out one of those retaining clips that was loose on the bottom. So I'm thinking you have the LSD as well. MikeH provided such a nice pic now, but I couldn't figure out where the retaining clips went in when I did mine, and after looking at my other pics, I don't have any at the correct angle.
I'm not sure about using the 140W in the front, but I can tell you that yes the gears in the front diff are connected from the hubs and CV shafts and spin with the tires even in 2wd. I believe it's the front drive axle (front diff to transfer case) is allowed to free wheel (or coast) while in 2wd and when in 4wd that gets positively engaged with the rest of the drive train.
One of the real gear heads on here will better be able to explain what part of the front diff does the actual engaging during 4wd, but I do know most of the gears inside rotate with the front tires.

 

The front diffs on a 1500 always turn. Weather or not your in 2wd or 4wd. When 4wd is engaged, the transfer case is locked enabling 4wd and is chain driven from the transfer case. Please use the correct fluid in the front diff 75w 90 and be safe.
As for the op's ? on if it's an LSD..... can't see from the angle of the pic. There's usually a sticker in the front glove box giving that info ok.
Hope this helps?
Al

 

Thanks, will get some 75W 90 and keep the 140 for the next rear change.

 

http://www.compnine.com/vid.php?

enter last 8 digits of your VIN and it should tell you. Its free.

 

Chrysler doesn't use the same design as the OLD Ford and you can't tell by looking straight-on at it.
In this picture here;

Just above the red circle you can see the clutch packs. There are 4 of them. This is the only way to tell by looking at the diff. At an angle behind the ring gear...
RP has limited slip additive in it so it doesn't matter if you have an open diff or not. The crappy traction can be open diff or crappy LSD design. Crappy LSD acts just like an open diff when one tire is in mud and other on pavement. Kinda defeats th prupose, but it really only works when both tires are on the same slippery surface.

In regards to being 12oz below spec, this is normal because you can never get all the old fluid out. There must have been ~12oz of fluid in the axle tubes which seems to be about right. The inner bearings prevent all the fluid from draining out, plus if your on any angle, the fluid from one axle will drain and not the other.

Front diff...Spins all the time. It is the transfercase that engages power to the front wheels. The front driveshaft spins freely inside the transfercase until you lock it into 4wd and then the transfercase grabs onto the gear on the end of the front driveshaft thus engaging it.

 

BadHazard:
That confirms it's a 3.92 open diff. Thanks! So I wont worry about the factory LSD problems.
A good resource to keep in the favorites!

And DD:
Thanks for confirming - I didn't think about the axle tubes themselves.

I remember as a kid the trucks had manual hubs which did disengage the front diff and D-shaft when unlocked. But if they are engaged all the time on our trucks then that explains why we have CV joints opposed to U-joins like my old man's 78 F250. That was a durn sweet truck except the Ford 400M's 6-10mpg!