New 3.73 noises

[Leroy_jenkinz]

Ok so I just had some FRRP 3.73 gears installed. He told me there would be some noises in the differentials but should be done by time I get home. It sounds like a grinding noise. Now 4th and 5th gears grindin stopped and today wen I drove it more in 2nd and 3rd the grinding in 3rd stopped. It still grinds in second slightly. They don't whine at all but ever so slightly in 50-55mph. Should I take it back to the shop? Is this normal during he break in period?

 

[JUSTA3V]

Da fuq you talking bout?

Gear box grinding or noises from the diff?

 

[Leroy_jenkinz]

Da fuq you talking bout?

Gear box grinding or noises from the diff?

I'm talking about noises from the differentials. I'm saying when I'm in these gears is when the sounds started and stopped

 

[JUSTA3V]

Okay. Nothing should be grinding from your differential. Ever.

Take it back.

 

[Leroy_jenkinz]

Okay. Nothing should be grinding from your differential. Ever.

Take it back.

Damn. ok thanks

 

[Average]

No noises after my 3.73's were installed. I heard some gearsets can be "whiney" but that's about it.

 

[TexasBlownV8]

NEVER should be ANY grinding after ANY gear install. Noises wont go away, they'll get worse.

Just installed a new set in my '06, and they are whisper quiet at all gears and speeds, like they should be.

 

[07 Boss]

I wouldn't take it back to that shop because they don't seem to know WTF they are talking about. Nothing should ever be grinding in your car except for maybe you and Megan Fox in the back seat.

 

[07 Boss]

I would hit them up for a new gear set though. If it was grinding at certain speeds and then it isn't, all that means is that the gears ground down enough to stop making noise. I bet you have a sludge of metal shavings in there.

 

[Leroy_jenkinz]

I would hit them up for a new gear set though. If it was grinding at certain speeds and then it isn't, all that means is that the gears ground down enough to stop making noise. I bet you have a sludge of metal shavings in there.

I lol'd real hard at the Megan fox comment and made this situation a little less shitty on my emotions thanks. You think the grinding pretty much ruined the new differentials that were just installed?

 

[TexasBlownV8]

Depends on what is grinding, whether the pinion was over or under tightened, backlash not set up right, or any bearing damaged or not installed properly. It is possible the gear set is ok, but it could also be trashed.

 

[Leroy_jenkinz]

Depends on what is grinding, whether the pinion was over or under tightened, backlash not set up right, or any bearing damaged or not installed properly. It is possible the gear set is ok, but it could also be trashed.

Ok thanks for the replies

 

[lenko]

Differential works the same whatever gear you are in. Your problem sounds like something else i.e. the transmission.

 

[07 Boss]

Differential works the same whatever gear you are in. Your problem sounds like something else i.e. the transmission.

Yes it does but I equated the noise in different gears as speed related. You are going to be faster in 4th than 2nd. If the noise was all the time and then started to disappear at the higher speeds, I would think something is getting worn down and now starting to mesh better. The gears should mesh better on initial install, not after wearing them down.

 

[rocky61201]

I just rebuilt my diff with new gears and rebuild kit with new clutch packs. Gear whine from the rear end was loud as hell sounding like an F3 pro-charger. The noise was constant in tempo and pitch and volume increased as speed increased. The gear I was in did not make a difference. Even in neutral. If the noise is changing with gear shifts its the transmission.

FYI - the end result was one chewed up pinion bearing. Probably happened when I had a shop replace a leaking pinion seal about a year ago and they over torqued the pinion nut when putting it back on. Pre-load was way to tight and trashed the bearing. I was getting quoted between $1k and $2k to rebuild my rear end. Got pissed and decided to do it myself. Bought a dial indicator from amazon and did everything myself including new gear set, rebuild kit, and carbon fiber clutch packs for less than $400 bucks. Had a local machine shop remove and press on the new bearings for $20 bucks. Last thing, the pinion nut is 27MM. Had to go to lowes twice to get the right size, grrrr. Checked back lash when I took the cover off and because of the bad pinion bearing my backlash grew to twice what it should have been.

 

[07 Boss]

Ok so I just had some FRRP 3.73 gears installed. He told me there would be some noises in the differentials but should be done by time I get home. It sounds like a grinding noise. Now at 45-70 mph the grindin stopped and today wen I drove it more at 15-45 mph the grinding at 30-45 mph stopped. It still grinds below 30 mph slightly. They don't whine at all but ever so slightly in 50-55mph. Should I take it back to the shop? Is this normal during he break in period?

The grinding is in the rear end. he said so and so did the shop. I've rewritten his post substituting speed for the gears he was in. Does it make sense now?

 

[lenko]

The grinding is in the rear end. he said so and so did the shop. I've rewritten his post substituting speed for the gears he was in. Does it make sense now?

If that's the case, then it's possible something was left in the case. Locktite is used on the bearing cap bolts and it gets pretty hard and may have not been cleaned out properly. Usually the gears will grind that into powder or there may be metal shavings if the case wasn't cleaned out before it was buttoned up. Some bearings will go pretty quick, so it wouldn't hurt to check those as well.

I assume that the shop added the limited slip additive or Ford Friction Modifier.

I just added a solid spacer eliminating the crush sleeve as I had a leaky differential seal and I had everything apart again with new Redline 75-140 synthetic gear oil with the limited slip additive. All pinion preload, backlash and spacer measurements and dimensions were identical as before I took everything apart and they are quiet.