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Discussion Starter #1
I just had a set of FRPP 4.10 gears installed last week. The mechanic told me I may hear a little noise after the install but I've also read quite a few threads about people whose gears are nice and quiet. I've been hearing three distinct noises. First is the faint "whine" I would assume is coming from the gears. Kind of a low-pitch buzzing. Not really too concerned about that but the other two noises I'm getting are a little more bizarre. The second sound is a higher pitched whine when I make a high speed right turn. Say, above 50 mph. And the tighter the turn the more distinct the sound and only when turning right. I'm thinking it could be a clutch in the differential. And finally there's a deep vibration that feels alot like an unbalanced driveshaft to me when I hit about 70 or 80 mph. Haven't taken the car faster than that yet. Kinda scared to. I'm gonna take the car back to the mechanic and take him for a ride and see what he says. But I'm wondering if anybody here have had similar problems with their gear swaps.
 

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Welcom to the party:shigrin
 

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Diff gears can be really tricky to install correctly. I have never done it but know of people who have and it can be a real bit%& if you do not know what you are doing. To me it sounds like he may not have got them dialed in just right. There should not be loud noises. Faint maybe but should not be a concerning noise. I would for sure tell him you are not happy and that you have been told that it should not make those noises.
 

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If you think it's the gears, STOP DRIVING THE CAR IMMEDIATELY!! If they get a wear pattern in them, it's probably too late to save them. Actually, if you've gone about 50 miles, it's probably too late. A little bit of whine isn't the end of the world, but grinding noises are BAD. You can try some friction modifier and see if that helps as well.

You may want to try another shop if you have to get a re-do.
 

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I would talk to the tech. I would go with another bottle of friction modifier
 

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Discussion Starter #7
Yeah I thought I'd try another bottle of friction modifier. Not sure the mechanic even put the original one in. I'm going back to him today. Wish me luck.
 

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Discussion Starter #12
Couldn't go to the mechanic today, he was busy, he said tomorrow. So I put another bottle of friction modifier in it today to see if the high-pitch howl when I high speed right turn goes away. Didn't work. I drained a little oil out before I put in the fric mod and it was pretty muddy looking. The magnetic plug had a few pieces of metal stuck to it too. Might be pieces from a bearing. The car also makes a low growl when I make a slow right turn. Really sounds like a bearing going out. I'm pretty sure he replaced all the bearings when he did the install, the kit had everything but I shouldn't assume he put them in. He's a chevy lover...think he's trying to take another Mustang off the roads, lol. Guess we'll find out tomorrow when I take him for a ride. Hope he has time to put Silver up on the lift and pop the cover. I'll keep ya posted. Thanks guys for your input.
 

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Discussion Starter #13
Okay just got back from mechanics shop and we took 'Silver' for a spin so he could hear the noises. He acknowledged that he heard them loud and clear. So he put her up on the lift and dug into the diff. He claimed he didn't find any metal debris in the oil and no visible damage anywhere. The carrier is tight between the bearings, no slop there. I looked too and couldn't see anything obvious. So I'm just gonna drive it until either the noises get louder or something breaks. Then we'll know what to fix. Gonna do some more research.
 
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