nelio
Junior Member
- Joined
- Sep 2, 2024
- Posts
- 9
- Reaction score
- 1
- Location
- orange county
- First Name
- nelio
- Truck Year
- 1980
- Truck Model
- chevy c10
- Engine Size
- 4.8
Gm 12 bolt gear pattern help. ?
- Thread starter nelio
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
- Joined
- Oct 30, 2019
- Posts
- 3,125
- Reaction score
- 7,254
- Location
- Downingtown, PA
- First Name
- Wayne
- Truck Year
- 1974
- Truck Model
- Jimmy
- Engine Size
- 350
You must be registered for see images attach
Welcome to the forum. Please note the drive side of the ring gear. Your pictures are showing the coast side.
You must be registered for see images attach
The top picture is what you want, drive side. Coast side is just that, coast side not important.
nelio
Junior Member
- Joined
- Sep 2, 2024
- Posts
- 9
- Reaction score
- 1
- Location
- orange county
- First Name
- nelio
- Truck Year
- 1980
- Truck Model
- chevy c10
- Engine Size
- 4.8
- Joined
- Oct 30, 2019
- Posts
- 3,125
- Reaction score
- 7,254
- Location
- Downingtown, PA
- First Name
- Wayne
- Truck Year
- 1974
- Truck Model
- Jimmy
- Engine Size
- 350
So your pinion needs to move closer to the ring gear. Keep in mind the gears need to be loaded when checking the pattern. Easiest way I have found, use a pry bar between the housing and the outside edge of the differential or the outside edge of the ring gear. Spin the pinion making the diff spin while adding the resistance. Two people make this easier.
- Joined
- Oct 30, 2019
- Posts
- 3,125
- Reaction score
- 7,254
- Location
- Downingtown, PA
- First Name
- Wayne
- Truck Year
- 1974
- Truck Model
- Jimmy
- Engine Size
- 350
Oh, then reset the back lash.
59840Surfer
Full Access Member
- Joined
- Oct 8, 2020
- Posts
- 206
- Reaction score
- 335
- Location
- Montana
- First Name
- Joe
- Truck Year
- 1986
- Truck Model
- K5
- Engine Size
- 350 Stroker to 383 with a 400 crank, Crane Cam, Q-Jet, single 3.5" exhaust..
Backlash is what's left over after the patterns are correct.
There's too much emphasis on backlash - and it can be understood as it's the machining process and matching of the gears at the machining stage.
Every gear-cutting machine process will produce tolerances and differences which are built into the gears, and this is why they are not individually replaceable.
Get a better pattern --- yours is kinda high on the teeth - and the backlash will be what it will be.
There's too much emphasis on backlash - and it can be understood as it's the machining process and matching of the gears at the machining stage.
Every gear-cutting machine process will produce tolerances and differences which are built into the gears, and this is why they are not individually replaceable.
Get a better pattern --- yours is kinda high on the teeth - and the backlash will be what it will be.
- Joined
- Oct 30, 2019
- Posts
- 3,125
- Reaction score
- 7,254
- Location
- Downingtown, PA
- First Name
- Wayne
- Truck Year
- 1974
- Truck Model
- Jimmy
- Engine Size
- 350
@59840Surfer Backlash is set last. Backlash IS very important to get the correct pattern.
- Joined
- Oct 27, 2016
- Posts
- 2,506
- Reaction score
- 6,482
- Location
- MO
- First Name
- Spencer
- Truck Year
- 1971, 1̶9̶7̶4, 1976, 1979,1̶9̶8̶5, 2002
- Truck Model
- Dart Swinger, Sierra 10, C10 Cheyenne, C10 Big Ten, Silverado 10, Ram 2500
- Engine Size
- 225/6, 350 c.i., 350 c.i., 5.9l Cummins
Thin your marking compound with a splash of gear oil and mix it well. Looks fairly thick.
As mentioned more pressure when running the pattern.
What pinion shim and what was the old oe shim?
New or used gears?
As mentioned more pressure when running the pattern.
What pinion shim and what was the old oe shim?
New or used gears?
59840Surfer
Full Access Member
- Joined
- Oct 8, 2020
- Posts
- 206
- Reaction score
- 335
- Location
- Montana
- First Name
- Joe
- Truck Year
- 1986
- Truck Model
- K5
- Engine Size
- 350 Stroker to 383 with a 400 crank, Crane Cam, Q-Jet, single 3.5" exhaust..
If you move things around to get to what you THINK is the correct lash, you mess up the tooth pattern again.
Stop with good pattern and let the chips fall --- it won't be bad - it's the way it's gonna be.
Old Guy Bill
Full Access Member
- Joined
- Sep 10, 2023
- Posts
- 428
- Reaction score
- 1,321
- Location
- KY
- First Name
- Bill
- Truck Year
- 1978
- Truck Model
- K20
- Engine Size
- 400
Send it…
nelio
Junior Member
- Joined
- Sep 2, 2024
- Posts
- 9
- Reaction score
- 1
- Location
- orange county
- First Name
- nelio
- Truck Year
- 1980
- Truck Model
- chevy c10
- Engine Size
- 4.8
I will clean it and use less marking compound. I did use excessive .
nelio
Junior Member
- Joined
- Sep 2, 2024
- Posts
- 9
- Reaction score
- 1
- Location
- orange county
- First Name
- nelio
- Truck Year
- 1980
- Truck Model
- chevy c10
- Engine Size
- 4.8
I did use excessive marking compound . Or shim was .034 new shim after measuring the pinion depth was I believe .038
New gears
nelio
Junior Member
- Joined
- Sep 2, 2024
- Posts
- 9
- Reaction score
- 1
- Location
- orange county
- First Name
- nelio
- Truck Year
- 1980
- Truck Model
- chevy c10
- Engine Size
- 4.8
Attachments
- Joined
- Sep 1, 2018
- Posts
- 1,036
- Reaction score
- 2,184
- Location
- Washington State
- First Name
- Craig
- Truck Year
- 1973 (have two), 1985
- Truck Model
- K10, K20, C20
- Engine Size
- 350, 454, 6.2 Detroit
that is eighty thousands, I think you meant .008 or eight thousands. If it is the latter, that is probably good, slightly tight, but I have set them tighter without problems. Also I mark my ring gear is three equal places, and check each one, because it is possible that it is loose/tight at different spots. I set mine at .010, as the tolerance closes as the rear end gets hot. To tight and the gears will gull. here is more info: https://www.randysworldwide.com/blogs/gear-backlash
Last edited:
