mjr46

they should not whine, I've done a few sets of 4.10's and the most recent 2 I did, did not make any noise

stdyhand

Yep thats what I thought. I am going to tear into it again once the rain quits.

I am going to check the pinion preload again to make sure it didn't back off. I tightened it to 18 in. lbs which was a real PITA to get to. But I want to make sure it isn't a little loose and I doubt it will be.

I am also going to redo the carrier shim and maybe aim for a different backlash. I ended up with .010 this last time but FORD recommends 12-15.

I also used the Valvoline Synpower oil which has friction modifier in it but I was wondering if I should add a bottle of friction modifer anyhow.

Other than the whine the car did ok so I guess I wasn't too far off considering it was my first time tearing into a rear end

lxman1

I just had new FRPP 3.73's and the carbon fiber clutches put in mine along with all new bearings. It's as quiet as the stock 2.73's were back in 88. It has had 3.55's in it since about 1990. The clutches had failed in mine too and filled the housing with shavings. All good now. He set my backlash at .008. My 3.55's were set to .012 and always had a little cruise noise but he said at the time that it would have a better pattern when on the NOS and it never failed after about 130K miles.

I used Royal Purple with the Ford additive. It wouldn't hurt to pick up a bottle from your local dealer. Cheap insurance.

stdyhand

I found the problem, but I've yet to test again. I got the car back on jack stands and pulled the carrier out. The pinion had loosened up.

I torqued it down with a 3 foot cheater pipe until it had 18 in. lbs drag on it. Somehow it loosened up and when I rechecked it there was almost no drag on it.

When I finally tightened it down again and rechecked my wear pattern it was horrible, a nightmare. I ended up back at the machine shop getting the orignal shim I had in the first place, a .027 lol

With the .027 shim on it I rechecked the pattern and it was almost perfect on both sides.

I went ahead and torqued the pinion down AGAIN with a new crush washer and pinion nut and set my backlash to .008 and rechecked the pattern one last time to make sure. The last test showed a good wear pattern still so I went ahead and went with it. I have it filled up with oil again and ready for a test drive in the morning.

Hopefully I'll have better luck this time. I don't mind a little whine at higher speeds but no way I'll accept what I heard the last time. Maybe all will go well and there will be no noise this time.

The pinion shouldn't loosen up again this time because after it was tightened down again I spun the crap out of the flange and lightly tapped it with a rubber mallet just to make sure it wasn't going to work loose again. After constant checking for probably 15 mins it remained the same at a constant 22 in. lbs.

thunderjet429

I bet it still loosens alittle.... every new setup i have seen has that's why i always go to the high side of spec, also unless somthing is out of the ordinary you should never have to change pinion shims.

mjr46

the pinion will loosen up, don't keep adding preload, when you pull a rear apart I always check preload / rotaional drag on used set ups and they almost never have drag 2-3 inch lbs if that, that is fine = loosens up as things wear in and bearings seat

stdyhand

I took the Mustang out for a test drive this morning and got NO noise at all this time so I brought it home to let it cool down and took it back out again a 2nd time after about an hour and still no noise. Finally I made a 3rd trip and still no noise so I drove for a few miles and all seems good.

Looks like I got it all right this time. In the end nothing was changed. The pinion head was .002 larger than the old and I got away with using the original .027 shim despite the bearings being larger.

Hopefully it stays quiet. I still haven't been able to really get on it to check the performance but I can tell its different gears because I ended up staying in 5th gear on the highway through town when I would normally be in 4th and never see 5th gear.

The brake in period is going to really seem loooooong because I want to hammer it so bad to see how the gears really feel

mjr46

hammer it now, you'll be fine