Differential problems...new gears...help please

YNOT

New Member
Jun 19, 2002
18
0
1
St. Louis, MO
My wife's got a 2001 Mustang GT and just this past week she noticed a sound...almost like a whining coming from underneath. I'm leaving it with a local shop tomorrow, but they suspect (as did I) it's something in the differential...possibly a pinion gear or something.

I have a few questions for you experts...

1) The car has been lowered 1.5"...could that have caused some excess wear on the drivetrain/rearend?

2a) Would now be a good time to upgrade to new gears?

2b) and if so...what should we get...4:10's or 3:73's?

She drives it to and from work everyday (5 minutes from the house) and we aren't planning to race it, just want to get some more power out of it. The only other mods are an MAC intake and Flowmaster exhaust. Oh and window tint which surely adds a few extra ponies. :D

For the record, my wife drives it hard on occasion, but she's not ripping the thing around alot. I find it hard to belive that only three years old and it's already having problems. The car has been trouble free up until now that the warranty expired.

Any help anyone can offer would be greatly appreciated.

THANKS!
 
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Thanks for the info guys. What are the differences between 4:10 and 3:73? How do they affect gas mileage? Will there be a significant difference from the stock gears?

Thanks again guys!! We appreciate your help.
 
YNOT said:
Thanks for the info guys. What are the differences between 4:10 and 3:73? How do they affect gas mileage? Will there be a significant difference from the stock gears?

Thanks again guys!! We appreciate your help.
There is very little difference in cruising rpms between 4.10's and 3.73's. In town, you probably won't see any difference in gas mileage. Might actually gain some in town as a steeper gear lets you get moving easier with less time on the throttle. As for the highway, you might see a 1mpg difference between 3.73's and 4.10's.
 
Holy shnickeys!!! Just heard from the repair shop. They think it's the pinion gear thats wore out and they quoted a minimum of $400 to as much as $1200 to fix it. This figures as we only had the 3 year/36K warrnty and it just ran out in March.

I knew I should have stuck with a Chevy product!!!

Oh well...I guess we'll nix the new gears for right now and no trip to Vegas this year either.

Sorry for my ranting...just a little pissed right now! Okay, I'm over it now.
 
YNOT said:
Holy shnickeys!!! Just heard from the repair shop. They think it's the pinion gear thats wore out and they quoted a minimum of $400 to as much as $1200 to fix it. This figures as we only had the 3 year/36K warrnty and it just ran out in March.

I knew I should have stuck with a Chevy product!!!

Oh well...I guess we'll nix the new gears for right now and no trip to Vegas this year either.

Sorry for my ranting...just a little pissed right now! Okay, I'm over it now.

Thats very expensive. You can just buy a new gear set shipped your door for approx. 150 dollars, take it to a local auto shop and they'll charge about 4-6hrs. for labor to do the install. You'll also need 2qts. of rear diff. fluid and 1 4oz. bottle of friction modifier.

BTW, the Bowtie boys are bad about breaking down in the rear end. :nice:
 
get 4.10's for a 5 speed. I got mine for $139 at gefracing plus an install kit for $80 . Then you need a speed-cal from dallasmustang for $89 1-800-mustang. labor for the gears should be around $200 to $300 at most dyno shops. Get the 4.10's though. Buy all FRPP even on the install kit. The speed-cal works great too.
 
40th GT said:
Wait, do I need to buy an install kit even if I pay someone to install the gears?


i'm assuming you have a 04 gt so it's kinda a toss up. if it doesn't have a lto of miles on it & you been fairly easy on it, you can get by without it. if it does have a lot of miles on it &/or has been driven hard, it's probably necesssary :nice: i just did mine with 13,xxx miles on it & i drive it hard on occasion & i didn't need one :nice:
 
The price (400-1200.00) I was quoted was just to replace the pinion bearing and repair anything else that may be broken. This price was not to install "new" gears. I just thought that while it was tore apart I would buy new gears but if it's gonna cost me a fortune I may just leave the stock gears alone unless they are trashed too.

I should get a call from the shop on Monday so I'll see what happens from there.

Thanks again for all of the help.
 
YNOT said:
The price (400-1200.00) I was quoted was just to replace the pinion bearing and repair anything else that may be broken. This price was not to install "new" gears. I just thought that while it was tore apart I would buy new gears but if it's gonna cost me a fortune I may just leave the stock gears alone unless they are trashed too.

I should get a call from the shop on Monday so I'll see what happens from there.

Thanks again for all of the help.

they are trying to take you. PERIOD. 1200 is crazy. even if it was messed up a bit in there, just buy the rebuild kit, which is around a hundred bucks & you're good to go. like i said 650 max. if you would keep the stockers in there, assuming they are ok, it should be very reasonable, 400 max i would imagine
 
40th GT said:
Wait, do I need to buy an install kit even if I pay someone to install the gears?
I would buy the kit, the rear end you dont want to skimp on. If the gears whine you will screw them up. Its better to be safe than sorry. Why even take the chance over $80 ? Make sure you get someone that has done mustang rear ends before. They will be junk if not installed right. :nice:
 
heh damn, mine whines in 1st gear and my car only has 22k miles. I just got it like 3 weeks ago used in immaculate showroom condition. I was planning on buying 4.10 gears soon, but is it BAD that it's whining in first?

I've been driving the car pretty hard (like 5 wot runs from lights a day) and no problems yet. If this is bad, should I make it a priority to get gears and should I get the install kit also since my diff is already whining in 1st?

Thanks for help.