12 Bolt Rear End Noise Diagnosis and Repair

This 1972 Chevy Nova with LS power has a really bad noise coming from its 12 bolt rear end. In this episode I take you through the process of diagnosing and repairing this noise. I also cover backlash, pinion bearing preload, bearing installation, setting pinion depth, reading gear tooth patterns, installing new gears, and other tips and tricks to make sure that the differential in your vehicle stays quiet and strong.

I hope you find this information useful!


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Sorry I don’t have direct links to the parts used in the video as they were brought to me along with the car. These are the places where I get most of my differential parts and accessories.

Summit Racing: https://www.summitracing.com

Randy’s Worldwide: https://www.randysworldwide.com

Info on Identifying 12 Bolt Differentials: https://www.onedirt.com/tech/drivetrain/12-bolt-rearend-guide/

Diagnosing Ring and Pinion Issues: https://www.onallcylinders.com/2014/03/21/gear-doctor-quick-guide-diagnosing-common-ring-pinion-issues/


Pinion Depth Measuring Tool: https://www.raceplumbing.net/TD-Machine-11001-Pinion-Depth-Gauge-Deluxe-Dial-Indicator-Fixtures-GM-Dana-Ford-Mopar-Kit_p_84187.html

Dial Indicator Set (Checking Backlash): https://www.jbtoolsales.com/central-tools-3d102-dial-indicator-set-with-on-off-magnetic-base#oid=1002_1

Bleepin Jeep Pinion Tool: https://store.bleepinjeep.com/product/yoke-wrench-tool/

Astro Pneumatic Bushing/Seal Driver Kit: https://www.jbtoolsales.com/astro-pneumatic-7824-bearing-race-and-seal-driver-set#oid=1002_1

Shim Installation Tool: https://www.summitracing.com/parts/yga-56077?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-yukon-gear-axle&gclid=CJ6Dj-DSxc0CFQgaaQodKbgFjA

Milwaukee Angle Die Grinder: https://milwaukeetool.com/Products/Power-Tools/Metalworking/Grinders/2485-22

Inch Pound Torque Wrench: https://www.jbtoolsales.com/precision-instruments-d2f150hm-torque-wrench-dial-with-memory-needle-3-8-dr-150-in-lb#oid=1002_1

CRC Brake Cleaner (5 Gallon): https://www.amazon.com/gp/product/B000M8PYRY/ref=ppx_yo_dt_b_search_asin_title

Brake Cleaner Sprayer: https://www.jbtoolsales.com/titan-tools-tekz-19419-spot-spray-non-aerosol-sprayer#oid=1002_1

CRC Rags: Sorry, I believe these are discontinued

Related Videos

What’s That Noise in My Differential?: https://youtu.be/lv94-bItw-I

How To Use a Pinion Depth Measuring Tool: https://youtu.be/S61Ut8tOu1o

ETCGDadsTruck Axle/Differential Rebuild (Part 1): https://youtu.be/F439MFi6qIk

ETCGDadsTruck Axle/Differential Rebuild (Part 2): https://youtu.be/vkSvYCqrlOI

How To Clean, Prep, and Paint a Differential FairmontProject: https://www.youtube.com/watch?v=il8nDlCepyc

Ford 8.8″ Differential Complete Tear Down FairmontProject: https://www.youtube.com/watch?v=Plvg0NTLraA

Ford 8.8 Assembly & Set Up (Part 1) FairmontProject: https://www.youtube.com/watch?v=5fARhE7v5Bg

Ford 8.8 Assembly & Set Up (Part 2) FairmontProject: https://www.youtube.com/watch?v=npUBF9Wj1Iw

Ford 8.8 Final Assembly FairmontProject: https://www.youtube.com/watch?v=P3Pb_eNLkQc

ETCGDadsTruck Playlist: https://www.youtube.com/watch?v=kCepnacqRuI&list=PLSzhQ6St-ov1g_GML2aVq6EN-_ShJ9G2o

The FairmontProject Playlist: https://www.youtube.com/watch?v=L22GsHQi7tU&list=PLSzhQ6St-ov2nxWVKCeU14Vt7JJ_QSZvs

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Stay Dirty


Due to factors beyond the control of EricTheCarGuy, it cannot guarantee against unauthorized modifications of this information, or improper use of this information.  EricTheCarGuy assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. EricTheCarGuy recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video.  Due to factors beyond the control of EricTheCarGuy, no information contained in this video shall create any express or implied warranty or guarantee of any particular result.  Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not EricTheCarGuy®.


Author: Rafael


31 thoughts on “12 Bolt Rear End Noise Diagnosis and Repair

  1. Glad you mentioned the break in on the gears. That’s key as you know to gear longevity. Your really a fantastically thorough mechanic. Folks are blessed to have you doing the fixes.

  2. I’ve got a slight vibration in my rear at 70-75 mph. 7.5 gm with a 3.73 posi. Feels like a ujoint or a driveshaft balance issue. Really sux on the highway. Any information as to how to narrow down the cause? Great video ETCG!

  3. Really nice video! I really hope if you were in UAE, that you can fix my RRS 2013 Supercharged V8. My RRS has a whining noise similar to this video, but I am not sure where it comes from, either from the rear differential or from the propeller shaft

  4. I recently acquired an experience-based Faux Expert Leisure rating on differential service for our ‘71 Caprice (hubby drive it in HS, but I’m doing most of the rebuild 🤓

  5. Part 2: This video completely legitimizes all of my home repair shop tool purchases, including the 20 ton press that I just couldn’t resist when it was on sale. Just saying…

  6. Excellent video but you were unclear on whether you liked the 4.11s or not. Ha ha!!! What transmission is in the Nova? Thanks. Cheers mate!!

  7. I ordered the BleepinJeep pinion yoke tool about five minutes before watching this so that's good new. Good video. I still dread this job though.

  8. What cleaning fluid to you use? I'm a DYIer and been using brake cleaner, but I go through way too many cans of the stuff; it gets expensive. Thanks for the video. Love the channel.

  9. I said camaro last muscle great car I went Pontiac fiery bird, transAm. 2016' yeah end of game the satanist had a concept fiery trans Am they wanted to bring back out but they r playing 1 script serving satan & we r on a new script concept blown.

  10. GM made three “types” of 12-bolt carriers (Type 2, Type 3, and Type 4). Thats the issue you ran into with the pinion difference. Here is a good page on a GTO forum that explains how to tell the 2,3,and 4 carriers apart. http://www.iegtoclub.com/Tech%20Lib/gto_axle_identification.htm Also you want to put some of the GM or Ford limited slip additive in even if the gear lube claims it has the additive in it from my experience. Makes for a less noisy rear at low speeds.

  11. Nice to see you again, hadn't been here since the Fairmont saga killed your channel for me.

    I'm trying to put together a parts list foe a 5 lug conversion on a cb7.

  12. Bought Timken axle bearings for my Son's Ford 7.5 inch differential and guess what came in the box!!
    Koyo bearings in a Timken box. "Life is like a box of chocolates; you never know what you're going to get!" Forest Gump

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