Who's good at reading gear contact patterns? pics inside

[neech]

Hey all,

I apologize for another one of these threads, but I would love to get some input from anyone that has some ideas on this gear contact pattern.

I replaced the ring and pinion a year ago due to a ****ed up install via previous owner, and it started whining about 5 miles in on the first breakin drive. I think I put too much preload on the pinion bearings based on what everything looked like on this tear down.
So anyway, after a year of not having any time (full time work and grad school) I bought a new OEM diff, OEM ring and pinion, new carrier and pinion bearings, and am pretty close to getting it all back together.

The specs as it sits now are:

Backlash: .011" (.008 to .016 spec, I read .012 was optimal??)
gear runout: .002 max
pinion preload: ~20 in-lbs with solid spacer

I have .028 of shim on the pinion and the depth measuring tool that I have is coming out to +- .002" of the desired check distance. It appears that the drive is pretty centered with a bias towards the toe, and the coast is off the heel.


On with the pics:

Anybody have any inpuit? Thanks in advance

 

[cbarile]

No one can look and tell you it wont have gear whine. You could have it perfect and still have whine, Put it together and drive it.

 

[stkjock]

I'm far from an expert here, however I just replaced my ring/pinion and diff. When talking to the tech while looking at the ring and pinion gears he explained that the wear pattern to be even across the teeth (mine were not - the inner most parts were not worn on mine). Based on what I saw and he described on mine those look good.

hope that helps some.

 

[CPRsm]

Try bringing the backlash down. Spec on backlash is .008-.012. I always try for 9.5 or under. Especially with sticks. Less shock to the gears. If you set it up right it will not whine. The pinion looks like it will need to go a little deeper though. Try the backlash first. Try for .008-.085
If it doesn't look better change the depth and the BL should still be in spec.

 

[Seahorse]

To echo what CPRsm said, when I was researching my 3.73 install I was told by many who'd done this already to get that backlash as close to .008 as possible. Used a very experienced installer and that's exatly what he set it up at. I know there's more involved than just backlash, but my 3.73's are whisper quiet.

 

[neech]

Thanks for the good info guys, exactly what I was looking for.

I actually had the backlash almost spot on .008, but backed off a tad since I didn't want to be right on the edge of spec.. I'll definitely go back to .008 and recheck.

CPR: When you say go deeper, you mean less pinion shim, correct? It would seem to me that while deeper might bring the drive side closer to the middle a bit (away from the inside of the ring), that it would bring the coast even farther off the heel than it already is?

 

[Robertt305]

My gears have been redone 3 times cause of whine and were all set up perfect with perfect patterns...

These gears just whine sometimes....

I just ordered a new set of gears to see if this resolves the problem...

I'm starting to hate my 373's especially after my diff just went kaboom

 

[neech]

My gears have been redone 3 times cause of whine and were all set up perfect with perfect patterns...

These gears just whine sometimes....

I just ordered a new set of gears to see if this resolves the problem...

I'm starting to hate my 373's especially after my diff just went kaboom

Out of curiosity, do you have a aftermarket upper control arm? I think sometimes this transmits a lot more of the "normal" drive train noise through the rear seat deck. I haven't been in a stang with UCA and stock rear end though so I can't confirm this.

When I drained the diff oil on mine, it looked like metallic paint in the sun: lots of wear going on in there. That however, isn't normal. Have you experienced anything like that?

 

[Robertt305]

Yes when my clothes in my diff crapped out on me...

The gears were done before the UCA... but I have one now and yes it got louder but was already present from before...

 

[CPRsm]

CPR: When you say go deeper, you mean less pinion shim, correct? It would seem to me that while deeper might bring the drive side closer to the middle a bit (away from the inside of the ring), that it would bring the coast even farther off the heel than it already is?

More shim. Some times it's hard to read the drive until you get RIGHT on within 3-4 or so. Old reliable with me is starting with the coast. Zero in on it by finding the pinion depth that gives you the largest coast pattern. When you find that, you will see drive is close enough to see where to push it. More depth should bring the contact pattern close to the toe, but the heel will still have a pattern there as well. I don't think you are seeing the whole pattern yet. Your drive is also high on the crown, which will come down with depth. You can see at the bottom right of your contact, the paint is almost completely gone in the second tooth. That's where the teeth are contacting most. I actually don't use that, but it's very obvious to see in that pic.
See the "V" the paint mark is leaving in the 3rd tooth ? See how far to the right it is ? When you add more, you will start to see the other side of the V at the crown as it centers. Even if you get a WIDE pattern and it's not that prominent, pay attention to the point. Also sometimes it's easier to read the none painted teeth. Spinning it will transfer to the non painted and leave a better mark sometimes that's easier to read.

My gears have been redone 3 times cause of whine and were all set up perfect with perfect patterns...

These gears just whine sometimes....

I just ordered a new set of gears to see if this resolves the problem...

I'm starting to hate my 373's especially after my diff just went kaboom

What gears and who is installing them ? I have done nothing but 9in and 8.8's and not had a single whine. Old WWI air raid sirens where gears improperly meshed with a mega phone. Gears whine when they are WAY off. What part of FL are you in ? Being forced to vacation in May by the wife and parents.

 

[Robertt305]

The gears were done right, I watched and witnessed the measurements and gear pattern...

I believe it has to do with my gears being made by motive.... So this time around I order FRPP 410's with the A in the part number..

 

[CPRsm]

I'm not trying to be a dick at all, but did you know what you were looking at ? If you did, why not do them yourself ? If they've done it three times, might time to switch shops.
fwiw, motive makes FRPP gears.

 

[Robertt305]

FRPP stopped using motive as of recently as per Tousley ford.

And I'm not comfortable doing gears, and yes I know what I'm looking at ....

 

[sikryd]

More shim. Some times it's hard to read the drive until you get RIGHT on within 3-4 or so. Old reliable with me is starting with the coast. Zero in on it by finding the pinion depth that gives you the largest coast pattern. When you find that, you will see drive is close enough to see where to push it. More depth should bring the contact pattern close to the toe, but the heel will still have a pattern there as well. I don't think you are seeing the whole pattern yet. Your drive is also high on the crown, which will come down with depth. You can see at the bottom right of your contact, the paint is almost completely gone in the second tooth. That's where the teeth are contacting most. I actually don't use that, but it's very obvious to see in that pic.
See the "V" the paint mark is leaving in the 3rd tooth ? See how far to the right it is ? When you add more, you will start to see the other side of the V at the crown as it centers. Even if you get a WIDE pattern and it's not that prominent, pay attention to the point. Also sometimes it's easier to read the none painted teeth. Spinning it will transfer to the non painted and leave a better mark sometimes that's easier to read.

+1... I have set up probably 10 rear ends, and I have done it all by feel. No dial indicator... I have never had a problem with whine from the rear ends I have done. I use the what feels like the thickness of a dime for backlash, and the marking compound. I agree that you are most likely not seeing the whole pattern yet. Setting up gears takes time, lots of in and out, moving shims, ect. Just take your time, and the last shims should have to be tapped in with a hammer or punch. Should be very very tight...

 

[Robertt305]

Just got the gears in by the same shop and gear whine is gone....

I believe I was right about my old gears just whining no matter how they were set up .... These 410s are nice and quiet compared to what I used to have

 

[tvuser]

I've done countless gear installs and my whine,but I know why. My impatient ass went to track with about 50 completely silent miles on them and now I have a slight whine a little louder then the stock ones that can only be heard radio off and widows up with solid uca. I am gonna replace them one day and break them in properly. They should be silent if installed and broken in correctly.

 

[slowr w/o blowr]

Motive gears will have noise. I've had 2 sets of aftermarket gears in my 8.8. OE 3.55's had no noise, FRPP 4.10s had no noise, but these Motive 3.27s have whine around 55-70 mph at low load.