Diff Rebuild

BillNyeIsHigh

BillNyeIsHigh

TJ Enthusiast
Joined
May 10, 2018
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103
Location
Charleston, SC, USA
Just bought my first jeep. Its an '03 sport with a '44 in the rear end. There was a grinding coming from the rear end at low speed when turning. I thought that this was due to PO not adding friction modifier as they just replaced the diff fluid. My dad was nice enough to drain the diff and take a look inside. He found metal shavings and also that some of the spider gears are missing parts of the teeth.
Gear 1.jpg
Diff Cover.jpg

That said, I am torn on what to do. I am trying to keep this as inexpensive as possible and still do the right thing. My current options are to rebuild the diff ourselves, but would need a bearing press and to rent a bearing puller. I find for ~$100-$150 more I can install a truetrack but that will require someone to install it. Or, I can get an auto locker. I guess it's as expensive as I want it to be.

My plan was to keep an lsd in the rear and eventually add a lunchbox in the front. Any opinions on this? All suggestions are welcome.

Also, life threw a wrench in the plan as of this morning. My frontier decided it wanted to start leaking coolant, so it is at the dealership awaiting what I seem to believe is a new water pump. That money will have to come from the jeep budget.
 
BillNyeIsHigh said:
That's what I am thinking. I feel like I should rebuild the clutch pack while I am in there as well though.
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I don't have a LSD but just watched a Youtube video of it. Seems like it would be the perfect time to do it.
 
Be aware that not adding additional friction modifier had nothing to do with that problem with your spider gears. Friction modifier is there solely for the clutch pack, it has nothing to do with proper lubrication.

Not to mention that 99.99% of all GL-5 gear lubes sold in auto parts stores do already contain the friction modifier. It is very hard to find a GL-5 without it. Any time the GL-5 gear lube's back label says something like "Compatible with limited slip differentials", that indicates the presence of the friction modifier additive.
 
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Few options: Rebuild the entire diff; replace just the spiders; replace the spiders and clutch pack. If the bearings are in good shape, I would replace the spiders and clutches. Pull the carrier and take a look at the bearings. There should be no heavy scoring, roughness, pitting. Grab the yoke and give it a spin. Should be smooth, no roughness/grittiness, with light drag. You can post up pics of the carrier bearings if unsure.

Make sure you clean out and remove all the chunks of gear. They will settle in the channel behind/under the pinion gear. Hose it all out with brake cleaner before reassembly. Probably not a bad idea once back on the road to do an oil change after a couple hundred miles just to flush out any crap left behind.
 
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Couple of questions,

According to my build sheet I currently have 3.73 gears. Eventually I would like to regear to maybe 4.56.

I think my two options at the moment are to rebuild the stock lsd or pay a little more money to upgrade to a truetrack. I see that the truetrack has a 3.73 down and 3.92 up carrier available. Therefore, if I were to add the truetrack at the moment and keep the same gearing I would need the smaller carrier and if I were to regear, I would need to purchase a second truetrack?

I'm reading about thick cut gears. Could I use the 3.73 down carrier with thick cut 4.56 rubi gears and make the smaller carrier work in the future?

I'm trying to figure out the best option for the money at the moment. I was planning on regearing and installing the truetrac until my truck issues took my fun money.

Also, if I were to buy the rebuild kit for the lsd and do it myself, the diff should be able to go back in without setting it up as long as shims are kept the same? Therefore I could just rebuild the internals and put the diff back in with no issues?

Sorry if these are dumb questions, I have just read a lot of different information and would like clarrification. Would like to get this jeep on the road!
 
For what purpose would you upgrade from the Tracloc to the Truetrac, is it for offroading or is it for driving on icy or snow-covered roads? And to me, a Tracloc isn't worth rebuilding. That's a lot of work for a LSD that wasn't all that good to begin with.

Thick cut ring gears are used when you want to use low ratio gears like 4.56 or 4.88 on high ratio carriers designed for ratios like 3.07 or 3.73. At what point you need the thick cut gears depends on the axle...Dana 30, Dana 35, and Dana 44 all have different ratio break points at which you need to either switch to a different carrier or use thick cut gears when you want to install lower ratios like 4.56 or 4.88.

You could rebuild the Tracloc without needing to set the existing gears up again if you replaced the carrier shims exactly as they came out. But installing new carrier and pinion bearings could change things enough that I'm not so sure I'd chance doing that.
 
This jeep will be my DD which I will also use for offroading once this rear end is fixed. I have the dana 44 under my sport which came with the 3.73 gears from the factory. Either the tracklock needs rebuilt or a new lsd/locker/open diff conversion needs installed so I can get it on the road as the spider gears are trashed. Essentially, I am trying to make the most money-concious decision now that will also set me up for success in the future without wasting the money spent now.


So from what you say, I could order a 3.73 down truetrac and eventually use that carrier with thick cut 4.56 gears with no issues?

Sorry if this is confusing, I just want to be able to drive the thing and can't until I get this fixed.
 
BillNyeIsHigh said:
So from what you say, I could order a 3.73 down truetrac and eventually use that carrier with thick cut 4.56 gears with no issues?.
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Yes. But you could also install a Detroit Locker for the same price as the Detroit Truetrac and be much better off for offroading. Detroit Lockers are the best behaved automatic lockers available, they just need a little more attention/care if you're driving on an icy or snow-covered surface. I absolutely loved my Detroit Locker and still miss it nearly ten years after the TJ it was in was stolen.
 
Jerry Bransford said:
Yes. But you could also install a Detroit Locker for the same price as the Detroit Truetrac and be much better off for offroading. Detroit Lockers are the best behaved automatic lockers available, they just need a little more attention/care if you're driving on an icy or snow-covered surface. I absolutely loved my Detroit Locker and still miss it nearly ten years after the TJ it was in was stolen.
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I'm seeing about $150 difference between the two. Is that incorrect?
 
BillNyeIsHigh said:
I'm seeing about $150 difference between the two. Is that incorrect?
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I haven't shopped for either in years, they used to be priced fairly closely to one another. But to me, even paying $150 more to get the Detroit Locker would be a no-brainer if I lived and wheeled where I didn't have to drive/wheel on icy or snow covered roads/trails. Truetracs just don't help on trails that are uneven enough to lift a tire on the axle with the Truetrac up or nearly off the surface.
 
Jerry Bransford said:
I haven't shopped for either in years, they used to be priced fairly closely to one another. But to me, even paying $150 more to get the Detroit Locker would be a no-brainer if I lived and wheeled where I didn't have to drive/wheel on icy or snow covered roads/trails. Truetracs just don't help on trails that are uneven enough to lift a tire on the axle with the Truetrac up or nearly off the surface.
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About a few times a year, I may find myself in snowy conditions. Would a LSD in the back and then eventual lunchbox in the front not play out better? I do not plan on doing a ton of rock-crawling yet. Maybe some-day I will, but by then I would probably be able to install a selectable locker in the rear.

I also live in Charleston now, where when it rains it pours.

By the way Jerry, I really appreciate your help.
 
BillNyeIsHigh said:
About a few times a year, I may find myself in snowy conditions. Would a LSD in the back and then eventual lunchbox in the front not play out better?
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That wouldn't be a bad combination at all. An Aussie or No-Slip (which doesn't audibly click or ratchet in 2wd) would be a great choice up front. I ran the No-Slip up front and in 2wd you couldn't even tell it was there... no steering feedback and no clicking or ratcheting during turns. The Aussie is similar in that it doesn't create any steering feedback on the street but it does click/ratchet while making turns on the street.
 
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Jerry Bransford said:
You could rebuild the Tracloc without needing to set the existing gears up again if you replaced the carrier shims exactly as they came out. But installing new carrier and pinion bearings could change things enough that I'm not so sure I'd chance doing that.
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One last question. I am having trouble finding videos for the dana 44 rebuild. Just one guy who has no clue what he is doing.

Minus the c-clips, is the process for a dana 44 rebuild the same as what is shown in this video for the 35?


If so, would I also be able to rebuild the clutch packs and place back in just like he did?

If it can't be rebuilt in the housing like so, can I remove, rebuild, and place back in, no issues. i.e. bearing removal?

I guess that is if the old bearings still look good.

Edit: Looking at pictures from my diff, it looks like there is less space in the housing openings due to the ring gear. It also looks like the centerpin may not clear the ring gear. Would this mean remove the carrier, remove ring gear, rebuild internals, and then reverse order? No bearing change/alignment issues?
 
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