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I just installed a set of 4.10s into my 1998 Lincoln Mark VIII and it was done by a professional, no doubt. All he does in differentials, nothing else. THe second he seen the car he knew about the IRS and all the other little things that it needed.

They made a strange noise for a little while, like two cast iron pans rubbing against each other (it's the only way I can explain the noise), but after 30 or 40 miles, it's 99% gone.

Now, there is a grumbeling, almost grinding when I come to a stop. It feels like my back brakes are going out, but I just did them.

The guy at the shop says not to worry, give it a hundred miles or so, but...... it's a grinding noise and I'm skerd.

What do you guys think?
 

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When i put my 3.73's they made that same noise for about 100-150 miles. Mine sounded like a metal humming/grumbeling noise also. remember you are supposed to baby the new gears for what 50 miles? well, it took me 50 seconds before i got on it then it scared the sh!t outta. i had the j-mod and trac-lok done at the same time and i got chills for the first 30minutes everytime i shifted lol

So, i guess wear em in a lil and dont really worry about it unless it gets louder or worse. If it does get worse contact your tech and have him re-do it

-Mike
 

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My 3.73's do that too. Mine weren't exactly new but were low mileage, done by a pro. Also with TL.
 

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Just my .02 from my experience:

Properly setup new gears will whine/grind/growl for a few hundred miles, and then they should quiet down and be unnoticeable.

Properly setup used gears will "probably" whine/grind/growl for a few hundred miles (just like new gears) but will never get as quiet as new gears (well, maybe after a few thousand miles, they might). IMHO, it has to do with the fact that the gear faces already have a small wear pattern, then you change it when you reuse them. There's no way to get the gears back "dead on" to their original wear pattern.

IMHO, using used gears is like shooting dice as far as them being quiet. They work fine, but you’ll probably hear them for a while. :thumbsup:

Again, just what I’ve learned over the years. :D
 

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94 Daily Driven 4.6L said:
Properly setup new gears will whine/grind/growl for a few hundred miles, and then they should quiet down and be unnoticeable.
How come new gears factory installed never do this? Do they somehow break them in at the factory?
 

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johnaec said:
How come new gears factory installed never do this? Do they somehow break them in at the factory?
Good question and I have no idea. I've never bought a brand new car.... :D

But do you ever get a new car with 0 miles on it, or is there usually some mileage on it? Like I said, homey's never bought a brand new car. :tongue:

I do know that when I swapped out my 7.5 rear end for a FMS 8.8 rear end in my 82 Mustang, they whined for a little while and then got quiet (probably after about 50 miles). And that was a complete 3.55 TL rear end assembly that I bought from FMS. cough cough a few years ago... cough cough :D
 

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Some gears whine and others don't. I put used 3.73's in my car and even tho the setup was pretty much perfect they whined for a little while. I have never really had this problem with new gears.
Alan
 
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