ok i installed 3.42 gears on my car a couple of weeks ago ,and from the time of the install they have been whining whenever i start coasting. the mechanic told me that it is because all the parts i used for the gear swap were used and that the gears were probably whining already. is that so? any other possible causes ? would like to stop the whining. thanks in advance.

 

No knocking you wrenching skills, but it could very well be a poor install, or possibly some glitch. If they are out of alignment they would wine, wear, then break.

 

i didnt install them a mechanic did, he told me it was because the gears were used

 

not to sound like a dick, but anything goes on used parts. you get what you pay for. the mechanic who installed them have previous experience installing gears? might not be shimmed correct or backlash might have too much play.

 

What brand of gears are they? Some are louder than others. And don't forget, you bought used.

 

backlash isn't going to cause any whine, Its probly the pinion depth is off.....did he acctually set it up or just put it in with the factory shim....All housings are not the same.

Either way, a used gear is going to have some noise anyway....pop the cover off and check it out with marking compound .....if the pinion depth is too far off it will break pretty quick.

Backlash wouldn't couse any whine unless it deosen't have any backlash or if it is maybe under 8 thou it could be meshing too deep and make some noise

 

yeah i except the fact of buying used is a risk of course . just wanted to know if it could be anything else, i will get the pinion depth checked

 

you don't need to go that far...marking compound will tell you if there is a problem

good luck

 

it could easily be the backlash on the gears. backlash will cause a whine if there is not enough. the backlash specs for the pricision 4.10 gears i put in my car, were from .007-.010 and mine were causing a whining noise only on deceleration/coast because i put it around .006

after i fixed it though there was no more whine...but theres also a very good chance its pinion depth too

 

what exactly is marking compound?

 

its this thick greay paint type of stuff....you paint it on with a little brush and rotate it around. Then you look at that, probly find you a chart and it will tell you whats up...Also while you have the cover off backlash is easy to check

 

mine was orange

 

how do u check the backlash?

 

with a dial indicator, put it on a ring gear tooth....backlash is the slop or the play in between the ring and pinion....too much it will feell sloppy and cluncky not enough the gears could be too tight to each other and cause the whine.

On a street car you probly want 8-10 thou

 

would autozone have the marking compound and the dial indicator?