How To Read A Differential Gear Pattern: A Beginner's Guide. ( Gear Tooth Contact Pattern )

How To Read A Differential Gear Pattern: A Beginner's Guide. ( Gear Tooth Contact Pattern )

In this video I'm going to show you how to correctly read a differential gear pattern. Reading a differential gear pattern is done by painting gear marking compound on the ring gear and rotating the pinion until the paint on the ring gear is removed by the pinion gear.

You can analyze the mark in the paint to tell you how the ring gear and the pinion gear are meshing with one another. Based on what you see in the gear pattern tells you what adjustments you need to make to the differential.

Here are links to the other 2 parts of this series:

Links to the tools required to rebuild a differential:

Chemicals:

Parts used in this Ford 8.8 build:
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#differential #axle #explained #gears #ford

Chapters:
00:00 Intro
00:10 What is a differential gear pattern?
2:26 How to get a readable gear pattern
4:54 Parts of a ring gear tooth
7:06 Pinion depth adjustments
11:10 Backlash adjustments
15:00 Drive side vs coast side patterns
16:21 My final pattern
17:37 Outro

Disclaimer:
The information, demonstration and any content contained in this video is for informational purposes only. The user Repair Geek makes no warranty, express or implied, regarding the effectiveness or safety of the contents of this video. In no way should the contents of the video, including the tools used, be repeated or tried by anyone. Viewers should only seek the help of a trained professional located at a licensed auto repair shop for any fix, modification, alteration, or any change to their vehicle. Repair Geek shall not be liable for any injury, damage, or loss to any person or property that may result from use of the tools, equipment, or any content contained in this video. In addition, there is no way to guarantee that the video is not altered or modified or is not in the final form submitted by Repair Geek and therefore, Repair Geek does not warrant that the video is unaltered or not modified. The links on this video to products are for informational purposes only and in no way are an endorsement of the safety or effectiveness of the particular product. Viewers understand that anything contained in this video or linked to or from this video is the sole responsibility of the viewer and in no way provides an express or implied warranty as to the safety or effectiveness of any linked tool, product, or video. Therefore, viewer agrees to release, waive, and discharge Repair Geek or anyone affiliated with Repair Geek, from any and all liability, claims, demands, actions, and causes of action whatsoever arising out of or related to any loss, damage, or injury, including death, that may be sustained by the viewer, or to any property belonging to viewer, regardless of whether the loss is linked to the use of the contents of this video, or otherwise and regardless of whether such liability arises in tort, contract, strict liability, or otherwise, to the fullest extent allowed by law.

[RepairGeek]

Links to the tools required to rebuild a differential:

Chemicals:

Parts used in this Ford 8.8 build:
Help support the channel, buy using my Amazon links
As an Amazon Associate I earn from qualifying purchases and your cost is exactly the same.

[jimmyfreeze]

This is the best gear pattern video you will find on youtube. Not sure why search fails to list this video at the top.

[mattritz]

Getting ready to re-gear my Dana 80 and Dana 60 to 4.11. This is one of the best videos I've found on gear patterns. Great job, man! Thanks!

[msc]

Thank you this was a great video for the ring and pinion set up. I have an old 1993 Jeep Wrangler, and I plan on rebuilding the rear with everything. This video is exactly what I was looking for. Thanks again sir.

[saltymethods]

This is awesome. Thank you for this information.

[David-yylb]

Awsome explanation....I have Yukon 4.56 gears in my AM 11.5 differential when I ran the pattern my tooth contact on the ring gear was dam near identical to the pattern Yukon gear recommended pattern was not to deep or to high my backlash was .006 and that's been 200k+ miles ago with no noise in the differential

[steveschrader]

Great video for sure. I'm having my dif rebuilt here soon. I'll definitely go in knowing a lot more. Thank you.

[norbertrivera]

Wow! i learn a lot with you, i wish to said thank you for share your videos and your knowledge.

[TheBFHGarage]

The BFH Garage has great videos on setting up gears including pattern interpretation.

[webstella]

What does it mean when you take the cover off and it looks like someone stuffed it full of steel wool? That diff ran fine up until I decided to change it out with a low mileage unit just incase. I discovered the "steel wool" inside at 160000km, cleaned it out and ran it till 330000km. Pinion ate deeply into ring gear during that first 160k. Pretty sure it came that way from factory, it was a one owner Jeep XJ Chrysler 8.25. Didn't even make noise.

[edselbritting]

Excellent, thank you, i purchased spicer 4.88 gears to replace oem dana spicer 3.73 hopefully all goes well ...
Ps. I remember you mentioned in another video when you disassembled the mustang rear that it had timken and koyo, i purchased yukon master overhaul kits and they both (front n rear jeep diffs) have timken and koyo on the pinion, after some research it appears (i may be wrong) that koyo bought out/ merged w a portion of timken business, from what i understand although Japanese company most of the differential koyo bearings are manufactured in usa ?

[Personalized_Workshop]

Yikes! I pulled the carrier of a 12 bolt GM already without checking gear pattern first. The dealership diagnosed and recommended all bearing replacements to cure noise. That’s what we bought. Trusting they used a stethoscope. The noise was constant and didn’t increase with acceleration. If I don’t see that the carrier or pinion bearings have any defects, I’m not going to be so confident that the truck will be noise free after reassembly. Based on what you’re saying, I don’t have the original pattern to compare to and unless it looks really bad, I would just have to go with it.

[impactodelsurenterprise]

The machines to cut spiral bevel gears are insanely expensive and it takes a highly skilled and experienced machinist to cut it right.

[gregsmithracing]

Avoid using terms like thicker/thinner pinion shims. On axles like 14 bolt/9” a thicker pinion shim does the opposite of say a Dana 60, try to use terms like move the pinion closer/further from the ring gear.

[theslimeylimey]

Why do you HAVE TO stay in the specified range for backlash? Isn't the mating pattern of the teeth far more important than a couple thou out of spec backlash?

[brucelangereis]

Does the contact pattern change when under "significant" load on the gears? If yes should the pattern "without" load be set to adjust for movement to significant load?

[ben]

Great video! One

I'm rebuilding an 8.8 as well and my gear pattern (drive side) looks good, coast is far to the toe, BUT I have 0.090 pinion shim!😮 I know this is way more than expected. Yes, it is a cheap hear bad.... I'm poor....should I be worried about the amount of pinion shim? Or just roll with it because the pattern is good? Thanks so much. This is my first rebuild.

[donboschman]

How do you pull inner pinion bearing on and off for shim changes without damaging bearing

[beadblaster]

Does tightening pinion depth, say .10 down to .06 create more gear noise. Also you do not see many people talk about carrier preload. Some people just wail away on the diff trying to get it as tight as possible and other is just about falls in. Some builders will use a case spreader to get in as many shims and get it as tight as possible. I am concerned mainly about try to stop gear whine. I am installing a set of 4:56 nitro gears in my colorado and they are notorious for being noisy. One person who got his set to be quiet was to get the pattern very close to the toe and get it center from crown to heel.What would you do to try and minimize the noise. Thanks

[paulnoone]

Where did you discuss the drive or coast side?