Differential : Rebuild or Replace?

Jim Henderson

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Location
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Been gone a year or so, family, moving etc issues.

I thought I would be rid of the LS by now but no luck. My son just barely got his license(23yo) but he has no interest in driving.

So I still have the 2004 LSV8 with 180,000+ miles on it. BTW, those who swear they explode in a fiery inferno if you run with regular gas are wrong at least in my case. I have run on regular since about 2007 and put well over 150,000 miles on it. Daily driver but not a lot of hard accerlation all the time, just getting onto the freeway. No ping except during HOT weather and under load(hill, hard accel etc). I do not recommend this, just commenting, and follow the user manual if in doubt.

With 180,000 miles on it I am keeping low budget and shopping for a solution.

Anyway... I have been getting a thumping on moderate acceleration from a stop now. This past summer, I had the tranny rebuilt and the day I drove it home from work, the front flex coupling literally exploded, actually even the shifter knob "exploded" spit out the push button presumably from the shock of the shifter cable being yanked out when the rubber coupling wrapped around it.

The rear coupler also failed later, symptom was vibration after a month and visual inspection showed big cracks. That was replaced under warranty and the next rear coupler also failed. Hummm. The tranny shop finally discovered the differntial input shaft was wobbling. I have been shopping around a bit for either a used diff, $425 from local used parts yard with guarantee, or about the same from a local shop if I bring in the diff for rebuild, I do labor on remove and replace. Or about $250 on eBay including shipping, condition up to honesty of seller.

Back to the thumping, Last week I replaced the rubber coupler(all you need is a 17mm and 18mm wrench). While under the car and with the coupler removed I yanked on the input shaft(Pinion) of the diff. It wobbled (eyeball estimate) side to side and up and down maybe 1/8 inch and moved in and out of the nose of the diff maybe 1/4 to 1/2 inch. Either way the writing is on the wall... I cannot delay this major repair any longer.

So, I am asking the group a few questions... Assuming I can drop the diff and replace it myself, pretty sure I can since I have replaced the CV, Wheel bearing and the coupler, and only 3 bolts hold the diff) what are the best options...

1) Do I Attempt a rebuild myself? The bearing kit is about $100. I can rebuild engines etc but never tried a tranny or diff. I do not have dial guages etc but do have mic's calipers and pullers etc. Is this a job for a shadetree mechanic?

2) Do I go with the local junk yard guaranteed $425 diff?

3) go with eBay and hope for honesty and a decent diff?

4) Does someone on this site know of a decent used diff or a low cost reputable rebuilder in the Riverside Calif area? I also can travel around LA in general if needed. I prefer a "you pull it" to save the built in cost of labor.

I just want to hang onto the LS for another year maybe, but am tempted to keep it longer since I have a "new" tranny and soon a diff. But the LS is a glutton for repairs of all sorts(cooling system, coils and drive line and minor pita stuff).

Now that I am active again I will post more info as I do repairs and or comment on my experiences repairing past issues with the LS.

Thanks,

Jim Henderson
 
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The pinion bearing went out in my '06. I paid ~$850 to replace a ~$50 bearing. Apparently the rear sub-frame needs to be lowered to replace any differential parts.
 
Well, first I am glad you were able to prove the engineers as well as all the people who understand compression and spark timing wrong. Good for you, you saved just enough over the years to repair the problems it will cause.

For the diff, unless you understand how to set the gears, don't do it, but hey you may prove all the diff designers wrong too. I would for the cost above I would at least get the guaranteed one then you put it in. However it may not have a warranty if you install it as they can not cover your work as well so make sure they do not require a professional shop with an invoice to cover it. I would avoid a used one from ebay unless you are rebuilding it as well as who knows it's true condition.
 
Actually from the manual and from what I have seen as I work on this...

You remove both CV axles and disconnect the rubber couplers and remove 3 bolts supporting the diff. BTW the vertical single bolt is tricky, the exposed bolt head is 15mm but the top nut(didn't realize there was one) is 18mm and a beach to get at due to tight clearance. Of course you will need a tranny jack or risk having the pumpkin drop on your head. The CVs are easy to replace btw.

Thanks
Jim Henderson

The pinion bearing went out in my '06. I paid ~$850 to replace a ~$50 bearing. Apparently the rear sub-frame needs to be lowered to replace any differential parts.
 
I'd go with the used differential. Also have you checked the driveshaft center bearing? I had thumping on acceleration and it was caused by a failed driveshaft center bearing. Fairly straight forward fix once you find a new bearing. Are you sure the movement of the diff input is the shaft and not just the flange being loose?

As to running regular ignore the crowd and go with what works. I'm at 175,000 and still waiting for the failures caused by regular gas. I only get pinging if I lug it in gear (I have a MT) at initial tip in as I release the clutch from a dead stop.
 
I'm going to remove the words and get to the meat of the question:

1) $425 for used junkyard pull, plus R&R to install or DIY
2) $425 for local shop to rebuild, plus R&R to install or DIY
3) $250 for ebay special, lots of prayers, plus R&R to install or DIY

I'd go with option 2. Since you sound like you are going to do the R&R yourself just spend the extra $175 for the local shop and not question if the center is any good. It also sounds like you are going to be keeping the car for the foreseeable future so why not invest a little into it. Not like you are talking an engine rebuild here.

The other way to look at it is if $175 is worth the time and hassle of pulling the center section out a second, or third, time if the EBay/Junkyard part is no good and you have to find another.


As far as rebuilding the center section yourself you will need a depth gauge or standard micrometer to set the pinion depth, gear marking compound to set lash, a torque wrench that goes above 100 ft/lbs to torque the pinion nut, and a rolling torque guage to check the pinion preload. You'll probably ALSO want an extra crush sleeve and MIGHT need a few extra shims depending on how close the new bearings are to the old. Setting up gears isn't the hardest thing in the world but there is a bit of finesse to it. With time and patience and an eye to detail you can definitely do it. Just make sure you don't skip any steps or get in a hurry.


Personally what I would do is pull the center section out and crack it open. If the pinion has as much wobble as you say the gears may be ground themselves down and be junk. In that scenario a junkyard is probably your best bet. If you don't feel comfortable gauging the gears yourself just crack it open, drain it, wash it out real good with parts cleaner and take it to the local shop. They'd probably be more then happy to tell you if it can be rebuilt with the gears in it or if they look worn/beat-up. Then go from there.
 
As to running regular ignore the crowd and go with what works. I'm at 175,000 and still waiting for the failures caused by regular gas. I only get pinging if I lug it in gear (I have a MT) at initial tip in as I release the clutch from a dead stop.

Yeah... I guess the the engineers that spent time and money designing the engine and its requirements know less than you. I guess they wasted money printing all those "91+" stickers on the gas door. They also wasted ink printing the "91+" in the OM. From the OM, page (for the '06) 293:

Choosing the right fuel
Use only UNLEADED FUEL. The use of leaded fuel is prohibited by law
and could damage your vehicle.
Your vehicle was not designed to use fuel or fuel additives with metallic
compounds, including manganese-based additives. Studies indicate that
these additives can cause your vehicle’s emission control system to
deteriorate more rapidly. In Canada, many fuels contain metallic
additives, but fuels free of such additives may be available; check with
your local fuel dealer.
Do not use fuel containing methanol. It can damage critical fuel system
components.
Repairs to correct the effects of using a fuel for which your vehicle was
not designed may not be covered by your warranty.
Octane recommendations
Your vehicle is designed to use
“Premium” unleaded gasoline with
an (R+M)/2 octane rating of 91 or
higher for optimum performance.

The use of gasolines with lower
octane ratings may degrade performance. We do not recommend the use
of gasolines labeled as “Premium” in high altitude areas that are sold
with octane ratings of less than 91.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your authorized dealer to
prevent any engine damage.
(R+M)/2 METHOD
91
2006 Lincoln LS (dew)
Owners Guide (post-2002-fmt)
USA (fus)
Maintenance and Specifications
2
 
oh course you can run regular gas without a problem as long as your knock sensors are working great and its pulling enough timing out to keep it from grenading... the issue isn't breaking things (luckily the engineers thought enough to protect the engine) its more about the timing being pulled giving you less power and mileage...
 
I am pretty tempted to have the shop do a rebuild or maybe try myself. But the mechanic at the shop said $425 is a starting point. With as many miles as I have it is very possible some hard parts would also need to be replaced and the cost goes up significantly from there. So he recommended buying from the used dealer that I visited earlier, "good warranty".

I like to tinker, I even on occasion will repair throw away parts like EGR valves, smog pumps etc. Thus my interest in rebuilding the diff. But, I KNOW that I do not have some of the tools and experience to do it properly "for sure the first time". Like most things I work on, usually the first time is an experiment, the next time I get it right for sure.

Rebuilding it myself is low on the list but tickles the back of my mind with temptation, just to get experience. What I will probably do is get a used pumpkin and rebuild my old one just for experience and then sell it.

As far as my comment on fuel octane, that was more of a "Poking the bear" and just commenting that at least for me, no bad things have happened contrary to some who do claim it will explode the engine almost immediately. As with all things, there is a range of what is normal and what will happen when you wander out of normal. As almost always, it is safest to follow the user manual. But then who would modify their cars? Way back when I "hotrodded" my boss said "why the hell do you think you can do better than the engineers who designed it?" , this was from a guy who himself was a hotrodder(Calif dry lakes racer) from the 40s/50s. So I guess I am still poking that bear. It was always a question of experimenting and narrowing my application to a certain niche, realizing there are tradeoffs in driveability, reliability, safety etc. But like I say if in doubt RTFM, read the f manual, and follow it.

I had considered the center bearing carrier as a possible noise source too. I just didn't want to do as the manual says, drop the exhaust system, remove the pan etc. For my "immediate" problem I just wanted to remove the bad coupler and examine the diff. When I do drop the diff I think I will check the center carrier just so I don't have to do more work in the future.

As asked eralier, does anyone know of a decent differential in the LA/San Bernardino area for a reasonable price? Otherwise I will probably go with the guaranteed used, if it applies to do it yourself.

Jim Henderson
 
A 'guaranteed used part' or a junkyard warranty means you just keep getting to replace it as many times as it takes until you either give up or they run out of donor parts. It's not like they open these things up and inspect them.

Your exposure will be how many times you will take it on/off the car and how long it will last. If you are seriously going to sell the car soon then I wouldn't worry about it. If you think you'll still have the car for a few more years then I'd probably want to know it's a good part.

Ideally what you should do is get your junkyard part and check the lash on it. Make sure there's no significant play or noise in the pinion when you spin it. I'd also recommend you clean it out well and put new axle seals and fluid in it. Not really a good way to replace the pinion seal without having to set the pinion depth with a new crush sleeve. I'm not a fan of re-using the old one.
 
If you are looking to do this on the cheap, then finding a low mileage used unit out of a salvage yard would be your best bet. Yes it can be a crap shoot, but it would be a simple bolt-in swap with a fluid fill. New axle shaft seals would be advisable.

Use this sites search engine;

https://www.hollanderparts.com/

Type in the year, make, model info and then click on "Axle" category, then select "Carrier Assembly". Enter your ZIP code to sort by location and find the one closest to you.

You can also search on eBay for the Gen II (2003-06) units listed by salvage yards or folks parting out LS and retro T-birds. Most of those can be had for about $200-325 with shipping.
 
On rebuilding it, it is possible for you to do at home but it's a bit of an art form to get it done correctly. Unless you plan to do this regularly, I'd suggest just going ahead with the rebuild at a shop. They have the tools and the know-how to get it done right. You can still do the drop and reinstall yourself to save a few bucks.

I'll weigh in on the octane thing. I tried the lower octanes, and found that my mileage dropped enough that it wasn't worth saving 1.50 at the pump. I just put 91 in it and call it done now.
 
As for mileage with different octanes, back when I first got the car, I ran premium all the time. Then prices got crazy and I experimented with 89 and 87 octanes.

I keep good notes in my vehicle log and after experimenting over a year or so, I discovered that my LSV8 got best mileage with 89, maybe 1mpg on average better than either 91 or 87.

The 91 ran best, 89 ran pretty much the same with only a very rare ping under heavy load.

87 got about the same mileage after a few tanks as 91(a bit oddly, mileage actually went up for the first tank of 87, guessing before computer adjusted spark advance). The main difference was a definite ping and even the start of knock on hot days with heavy load or acceleration. Since I use this car as a daily driver, I am not constantly full throttle and heavy loading. 30mph a few blocks to freeway, maybe a 3/4 throttle blast to freeway speed and then either steady cruise or stop and go, so little opportunity for knock. I almost never notice a ping now a days, probably since my engine is old and loose.

But as always, YMMV, your mileage may vary and almost certainly your experience will be at least a little different from mine. Use lower grade gas at your risk.

I think because of time, I will just swap the diff and then rebuild the old one for fun as time allows. I really want to learn to rebuild diffs and trannies. Trannys are probably the bigger payoff for me since I have paid thousands over 40 years for rebuilds, but never needed a new diff til now.

And thanks to deaconblue for the search tip.

Jim Henderson

On rebuilding it, it is possible for you to do at home but it's a bit of an art form to get it done correctly. Unless you plan to do this regularly, I'd suggest just going ahead with the rebuild at a shop. They have the tools and the know-how to get it done right. You can still do the drop and reinstall yourself to save a few bucks.

I'll weigh in on the octane thing. I tried the lower octanes, and found that my mileage dropped enough that it wasn't worth saving 1.50 at the pump. I just put 91 in it and call it done now.
 
I really want to learn to rebuild diffs and trannies. Trannys are probably the bigger payoff for me since I have paid thousands over 40 years for rebuilds, but never needed a new diff til now.

Oddly enough I think automatic transmissions are easier to rebuild then a rear. For the most part you are just using a feeler gauge or caliper to check clearances and adjust shims. The hardest part always seemed like getting the preload spring on/off the low drum. After that it was a breeze. Since the LS and most things after 2000 use a solenoid pack instead of a valve body they are even easier.

Here's a video of a 5r55s teardown: https://www.youtube.com/watch?v=hn-jhMVrGTM

Not that much inside these things really. All the magic happens in the valve body or solenoid pack.
 
Get a junk yard rear from a car that

1. Low but not very low mileage. Figure 80,000 max and in the range of 4000 - 7000 miles per year. So you have a car that was operated.
2. A car that was wrecked not junked for unknown reason. This means the car was on the road with a working (maybe noisy but working) differential when wrecked.
3. A car that was wrecked recently so the unit has not been under water while in the yard.
4. A differential with no noticeable play, noise or roughness when operated by hand.
5. Inspect the inside (remove the rear cover) before installing and examine the fluid for water (or see if there is fluid inside).

None of this will insure a good unit just improve your odds that the one that is installed will not have to be removed.
 
Oddly enough I think automatic transmissions are easier to rebuild then a rear. For the most part you are just using a feeler gauge or caliper to check clearances and adjust shims. The hardest part always seemed like getting the preload spring on/off the low drum. After that it was a breeze. Since the LS and most things after 2000 use a solenoid pack instead of a valve body they are even easier.

Here's a video of a 5r55s teardown: https://www.youtube.com/watch?v=hn-jhMVrGTM

Not that much inside these things really. All the magic happens in the valve body or solenoid pack.

having built an AOD and an 8.8 IRS rear, the auto is easier.
the AOD is mostly just stacking and checking tolerances.
 
having built an AOD and an 8.8 IRS rear, the auto is easier.
the AOD is mostly just stacking and checking tolerances.

Between screwing up the crush sleeve and bending the shims on the carrier I am not a fan of rebuilding centers.
 
Well I found 3 donor cars with Differentials at the local junk yars. BTW, this week most junk yards are having a Black Friday 50% off any part sale. So I could get my used diff between $77 and $100.

But there are some issues...

2 diffs are from V6 LS. One is a 99 and one is a 2000. I am almost sure the V6 uses differnt gearing and also that the ring gear is smaller and less robust. I read something like this years back on this website. So I am not sure if I can use these diffs.

The 3rd diff, and lowest cost on sale is from a 2004 LSV8 so should be a direct swap.

However 2 problems with that diff. 1) is that it is apparent that the owner of this car did not take care of it. The tires were well past bald, amazingly so. And other clues said the owner didn't do much maintenance. 2) The axle lock nut which looks like a big nut with sort of a sheet metal castellated cover has one of the fingers of the "castle" twisted over. So most likely my big socket won't fit without either bending the finger back or dremel tooling it. I have the correct socket but have concerns as above.

One other general issue is that these two "You pull it " yards do not allow battery driven tools and there is no power to run a compressor and I cannot drive my car to the "work site". The big axle nut requried my air driven impact wrench to remove in the past and the rubber coupling bolts sure do like having a power ratchet to remove them.

So to summarize.
1) Do either of the V6 diffs look like a swap? I doubt it, but am not 100% sure.
2) At the lo lo price of $77, the V8 diff sounds like almost a can't lose. I suppose I could drop the diff and check for loosness on the input shaft and maybe pull the covers to look at the insides.
3) How to I remove at least the big axle nut without power tools? I do have a 2 foot long 1/2 inch breaker bar and other assorted hand tools. I even have a Lisle Hammer type impact wrench(you whack the head with a hammer) that I never had luck with before but maybe I don't know how to use it properly.
4) Oh one other thing... The cars are all on 2 foot tall jackstands and the rear is unlocked. IE no parking brake(no battery pawer) and can't shift the tranny without the key. So the wheels will turn if I don't lock them somehow.

Any advice is appreciated since I will probably do the job this week.

Jim Henderson
 
BTW when I replaced my CV joint and wheel bearing, one of the first steps was to move the wheel assembly out of the way. This took removeal of 3 bolts and leaving the top cross bolt inplae to allow thw wheel assembly to swingup like a trap door. I suppose I could just remove that bolt and thw whole wheel assembly would drop down and allow the axle and diff to be removed. This may be my fall back But I haven't confirmed that this is all it will take.

Jim Henderson.

Actually I am almost sure this will work since I did remove the wheel assembly to take it to the shop to have the wheel bearing pressed.
 
bring a 5' piece of pipe that you can slip over that breaker bar - that axle nut is torqued to at least 221lb/ft per the specs.....and maybe a spare breaker bar....last time I pulled one of those off an old Honda, I twisted the head off my breaker bar...and use your legs not your back!
 
bring a 5' piece of pipe that you can slip over that breaker bar!

aka "Cheater Handle". Mine was a 3' piece of cast iron plumbing pipe from home depot. Just make sure you cut the threaded ends off and smooth the cuts with a grinder. Only thing worse then going knuckles first into something when a breaker bar slips or lets go is getting the insides of your hands all cut up in the process.
 
Just make sure it's thick-walled and metal. Tried to use a piece of schedule 40 PVC one time and it broke and went flying everywhere. It was not a good time.
 
????? Brain malfunction?

Wasn't the only stupid thing I did in high school. Also learned that double-checking the lug nuts when the car was on the ground was a good idea. That there was a proper method to bleeding and pumping up the breaks. That you should remove a seat from the car before welding a broken seat bracket.

I'm sure i'm not alone :)
 

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