gear noise
 

i recently changed out the gears in the rear from 4:10 to 3:55. they were both Ford Racing parts. now when i drive they make a whinnig noise. what is it and how do i fix it?

When installing gears you need to check the pinion depth, backlash, and the tooth contact. If you don't your car will sound like a old school bus. In some cases a set of gears will whine even if there installed correct because of bad machine work. :)

Did you check the items listed in WADS56's post during the install procedure?

E

thanks! i guess i should just go back and check all that and try to reinstall them again.

Yeah mine whine, and I know they were installed correctly. I was standing there. But now my exhaust is loud enough I can't really hear it anymore. hehe.

yes the gears whine just because the way they are cut the more backlash you have the louder they will be

find someone to help you that's been down that road and konws where to start troubleshooting at.

I'm in the same boat as you. Had my 3:73's installed 6 years ago and they are loud. Probably louder than most. Louder than my 2 chamber flowmaster/offroad exhaust till about 3000 rpm. If I'm cruising and I take my foot off the gas, it goes away; but if I just reapply the slightest pressure on the pedal the noise comes back. They are Ford Motorsports and my mechanic said he took a lot of time and effort shimming them. No clunks or thuds, just a loud drone.

The gears don't whine because the weren't cut correctly. I'm sorry, but every gearset is lapped in at the factory to very precise tolerances. The hypoid gear is fairly tolerable of slight misalignments (slight in the world of gear designers). When they were installed, did you see the mechanic measure the pinion depth? What was the final running torque of the pinion bearings? What was the runout on the ring gear and what was the final measured backlash on the setup? What preload did he apply to the carrier bearings? And last but not least, how did the pattern check on both the drive and coast sides with the gearset under moderate preload?

I worked in the engineering lab at Dana Spicer Axle for several years, and passed up a job offer from their hypoid gear group when I graduated from college...NASA paid less at the time, but it looked better than Dana...that's a different story though. Reusing the factory shims as a lot of folks do will work for about 80% of the cases. It'll work, but 99% of the time the new installation is still out of factory specification. The only way to do it right is to measure everything and install to the factory specs. I've assembled hundreds of gearsets over the years, using the pains taking methods of precision assembly. I've never had a single complaint. As a matter of fact, I've got people who swear that they'll never let anyone but me in their rearends! (hehehe)

Do it right and they'll be whisper quite and last a lifetime.

Excellent post, Jeff.

I took my time and measured and measured, and setup the gears 3 times before I had it right. A dial indicator with a magnetic stand is a must. And, as Jeff said, mine are whisper quiet and should last a long long time.

E

thanks alot guess and thanks alot Jeff im gonna try and take it apart the rear end soon when i get time off and check them out. i got one more question though for ya'll if i leave them on and drive with them do they get worst or what? but i am definetly checking them out very soon. thanks guys!