Gear pattern

[GambleS197]

Looking for some opinions on my ring gear pattern. Rebuilt the axle with a new true trac and ford performance 3.73. On my test drive got some decel whine figured it needed more in the pinion. Dropped back out added another.003 sitting at about .036 right now just want someone’s opinion who can read these better than me before i put this thing back in the car and have problems again.

 

[Red-Candy-Metallic]

I don't have the expertise to evaluate your ring gear pattern, but I have a factory 3.73 rear end that whines. I thought that that particular ring and pinion combination was prone to that, but I can't say that with certainty. I would expect those who know will chime in soon.

 

[Midlife Crises]

I am certainly not an expert at setting up gears but I think the pattern is too close to top edge of the tooth. I would feel better with the heaviest contact in the center of the tooth and not sweeping the entire tooth. Something more like this.

 

[cavero]

Also not an expert, but I'd agree if anything it does look like it's a little more towards to the end of the tooth but from some angles it doesn't seem that different from Midlife's pics except it seems like yours is engaging more of the tooth .

FWIW, my factory 3.55's whined too, became really apparent after getting an aftermarket UCA/mount. I got Ford Racing 3.73's, had a shop put them in and haven't had any whine since (15+ years now).

 

[GriffX]

I did this only twice, sooo....... What is your backlash? I adjusted it to the lower value of the tolerance range. It looks like the contact can go down to the root a bit.

 

[Red-Candy-Metallic]

I thought this was a pretty good article: Two Cut vs. Five Cut Ring & Pinion Gears
I am not sure that it will change your approach, but I thought it was interesting just the same.

 

[GambleS197]

Currently set at in lb on my drag. .036 on the pinion depth. Backlash sitting at .009

 

[GambleS197]

Also not an expert, but I'd agree if anything it does look like it's a little more towards to the end of the tooth but from some angles it doesn't seem that different from Midlife's pics except it seems like yours is engaging more of the tooth .

FWIW, my factory 3.55's whined too, became really apparent after getting an aftermarket UCA/mount. I got Ford Racing 3.73's, had a shop put them in and haven't had any whine since (15+ years now).

That’s odd my factory 3.55 did not and neither have any of the ones I’ve been in I did just go with aftermarket uca lca and a one piece driveshaft all while I had the rear end out the first time. All I know can cause some noise problems this just seemed way noisier than what I think all that should cause

 

[Lokli]

Looking for some opinions on my ring gear pattern. Rebuilt the axle with a new true trac and ford performance 3.73. On my test drive got some decel whine figured it needed more in the pinion. Dropped back out added another.003 sitting at about .036 right now just want someone’s opinion who can read these better than me before i put this thing back in the car and have problems again.View attachment 105155

View attachment 105156

when you checked the pattern did you put some load on the ring gear, that will change the pattern slightly. Did you set the pinion height according to the +/- numbers etched on the end of the old and new pinions? See page 65 of the attached Eaton installation instructions for ring gear patterns and how to adjust. https://www.eaton.com/content/dam/e...control/Eaton-differentials-owners-manual.pdf

 

[GambleS197]

when you checked the pattern did you put some load on the ring gear, that will change the pattern slightly. Did you set the pinion height according to the +/- numbers etched on the end of the old and new pinions? See page 65 of the attached Eaton installation instructions for ring gear patterns and how to adjust. https://www.eaton.com/content/dam/e...control/Eaton-differentials-owners-manual.pdf

Load was put on the gear yes. Didn’t see a number outright etched onto mine may pop it apart again and check. Also morning update reshimed tried to go pretty deep upped to about .048still seems high on that tooth to me but could be looking at that wrong

 

[Midlife Crises]

I would go back to about a 0.030” shim on the pinion

 

[GambleS197]

So that’s .028 which was my factory depth with the 3.55 I removed

 

[GriffX]

Try to spread the paint around, I guess in general it is not bad. That was my pattern. 0.01 backlash
Correction, yours looks a bit like high contact.

 

[GambleS197]

Try to spread the paint around, I guess in general it is not bad. That was my pattern. 0.01 backlash
Correction, yours looks a bit like high contact.
View attachment 105241

I agree it looks high contact but in my opinion it’s looked high no matter how much I’ve added to it. Apprehensive about changing it further when I initially built it it had about .0335in the pinion thought that was money but apparently not got decel whine so back out she came. Have gone from .020-.048 with not that noticeable of depth changes races have all been checked every is seated.

 

[Midlife Crises]

The pattern with the 0.028” shim is very close. Try 0.030” shim. Hold tension on the carrier with your hand and turn the pinion with the other. Moving the backlash a couple thousandths back and forth as needed should produce the pattern you are looking for.

 

[GambleS197]

So that’s where we’re at with .030 and .011 backlash

 

[Midlife Crises]

Looks to be making contact in the center of the tooth and not sweeping off the heel or toe. I would have to choose between 0.028” and 0.030” at this point. Which has the best pattern after the backlash is in spec. would be my choice.

 

[lenko]

I always use the MHD Master Housing Dimension method and follow this guide. You can get the precise pinion shim size and end up with quiet gears. https://www.bing.com/ck/a?!&&p=bd2c...tL3RlY2gvZHJpdmUvZ2VhcnMvZ2VhcnMuaHRtbA&ntb=1

 

[lenko]

One thing I will admit, 373s are harder to set up then 410s. When I first tried 373 in my Mustang, they whined, but the 410s I did later I used the MHD method to get the correct pinion size worked. If you look at the first photo above, the pattern is near the toe nice and oval and consider to be a good "Race Pattern."

 

[RocketcarX]

Tighten the lash to .007, it will loosen up on the first drive