Gear Drama / Please Read
03-17-2011, 08:24 PM
#22
2nd Gear Member
Join Date: Sep 2006
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03-17-2011, 11:04 PM
#23
2nd Gear Member
Thread Starter
Join Date: Jan 2011
Location: Canada
Posts: 303
I guess its a hit and miss situation. I mean if the dealer can f - - k them up too , then anyone's guess is as good as mine on where to install them. I guess I will just turn up the music and live with the noise. If you hear someday that some guy blew his head off while driving a lime green stang GT with a chrome Saleen rims , you will know its me haha.
03-18-2011, 05:14 AM
#24
5th Gear Member
Join Date: Jun 2005
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Posts: 3,319
This is EXACTLY why I decided to stay with my stock 3.55 gears. I'd like to have 4.10s, but I have read too many similiar horror stories, and even had one of my own getting 3.73s in a 2000 Stang. Thanks, but no thanks.
03-18-2011, 06:29 AM
#25
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
Why would they not shim the damn thing properly the first time?
If shimming is the key for proper teeth mesh and also the resulting gear whine, why do not all the shops do it properly the first time?
Or is it hard to determine just how much shimming is needed and it is a trial and error process?
If shimming is the key for proper teeth mesh and also the resulting gear whine, why do not all the shops do it properly the first time?
Or is it hard to determine just how much shimming is needed and it is a trial and error process?
It's possible that the first backlash measurement the guy checked was "good", so he stopped there and called the job done. Wrong answer!
Understand that backlash quite frequently varies over a few thousandths over all of the possible combinations of pinion and ring gear teeth, a couple even in good gearsets. So your optimum setting ends up being a best overall setting that is neither too tight nor too loose. Too tight is worse, because it restricts lubrication (which is the only means of removing heat from the gear teeth).
The car owner's responsibility is to break the gears in correctly, otherwise the gears may locally overheat. Light throttle, varying speeds, just easy on them - which can be hard to do if the owner isn't patient as well.
After the first easy drive (which can be up to 50 miles at least according to some gear mfrs) you will not hold your hand against the diff. I don't consider gears to be fully broken in until you can. It'll still be hot, just not unbearably so like a range top element @ 300°F.
I've done a couple of gearsets on the Malibu, and the only noise I've ever had was a little occasional whine on the coast side of the 3.73's. I do suspect that as the ratios get into the higher numbers it'll be a little more likely that you will get a little whine, simply because the pinion typically has fewer teeth (meaning that each tooth spans a larger arc on the pitch diameter).
Norm
Last edited by Norm Peterson; 03-18-2011 at 06:36 AM.
03-19-2011, 09:16 AM
#26
5th Gear Member
Join Date: Nov 2006
Location: North Fulton, GA
Posts: 2,287
FWIW, I've had bad gear installs by so-called experts in L.A. in a 9-inch. There is sloppy work done everywhere.
As to breaking in gears properly, millions of cars are sold every year with people taking them right off the lot and going on their merry way. If gear break-in was so important (I'm not talking about towing, which owner's manuals often say to refrain from for 500 miles), why aren't cars gears howling from the factory?
03-19-2011, 11:59 AM
#27
Cut & Paste Expert
Join Date: May 2007
Location: NW Arkansas
Posts: 13,322
and if you drove it any distance, the
teeth are now worn in that spot and
reshimming them only moves the contact
patch to the correct location on the gears
teeth. Once they have taken a wear pattern
in the wrong contact patch and then moved
to the correct contact patch with the proper
shimming, if these patches overlap, you have
trouble and noise.
Motives are the noisiest gears out there.
And very few people know how to properly set-up a rear end.
Yet there are thousands getting paid to do it everyday.
http://iihs.net/fsm/?dir=91&viewfile...fferential.pdf
Pinion pre-load is a tricky thing...
http://iihs.net/fsm/?dir=93&viewfile...inion Seal.pdf
03-21-2011, 06:33 PM
#28
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
As to breaking in gears properly, millions of cars are sold every year with people taking them right off the lot and going on their merry way. If gear break-in was so important (I'm not talking about towing, which owner's manuals often say to refrain from for 500 miles), why aren't cars gears howling from the factory?
(1) The factory assembly line is presumably mechanized and more consistent. Plus at the OE level it's easier to scrap a gearset that can't be brought into spec and just grab another ring & pinion. Which begs the question of what happens to at least the marginal rejects that almost but don't quite meet Ford's standards???
(2) People actually pay enough attention to what they assume is only the engine's break in period - or at least drive gently enough long enough - to get the gears broken in.
Norm
Last edited by Norm Peterson; 03-21-2011 at 06:36 PM.
03-24-2011, 07:19 PM
#29
5th Gear Member
Join Date: Mar 2006
Location: ATL
Posts: 2,955
Where did you ultimately get it done here in Atlanta and what did they charge?
FWIW, I've had bad gear installs by so-called experts in L.A. in a 9-inch. There is sloppy work done everywhere.
As to breaking in gears properly, millions of cars are sold every year with people taking them right off the lot and going on their merry way. If gear break-in was so important (I'm not talking about towing, which owner's manuals often say to refrain from for 500 miles), why aren't cars gears howling from the factory?
FWIW, I've had bad gear installs by so-called experts in L.A. in a 9-inch. There is sloppy work done everywhere.
As to breaking in gears properly, millions of cars are sold every year with people taking them right off the lot and going on their merry way. If gear break-in was so important (I'm not talking about towing, which owner's manuals often say to refrain from for 500 miles), why aren't cars gears howling from the factory?