Ring and pinion swap

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.

Savageftr

Member
Joined
Mar 5, 2021
Posts
33
Reaction score
44
Location
Elie, Manitoba Canada
First Name
Alex
Truck Year
1986
Truck Model
C15
Engine Size
355
I have an 86 c15 with 3. 08 gears and a th350.

I'm pulling a camper with the truck and it seems a bit too steep for this.

Any issues just buying a 3.73 ring and pinion set? I should just need a new crush washer and set the depth, lash and pinion bearing preload again right?


I'm plan on just keeping it an open diff.
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,135
Reaction score
4,983
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
For the same price as a ring and pinion set and an axle rebuild kit, you could just get a 14bff with open 4.10's or 3.73's... just an option :emotions33:

I have a 2011 Suburban that has 3.08's and we also pull a camp trailer, its a dog. I bought a set of 4.10's for both front and rear with the axle rebuild kits for both as well. I went with 4.10's since we have a 6L80E that has a double overdrive and we pull a lot through mountains here in the Pacific North-west.
 

Savageftr

Member
Joined
Mar 5, 2021
Posts
33
Reaction score
44
Location
Elie, Manitoba Canada
First Name
Alex
Truck Year
1986
Truck Model
C15
Engine Size
355
For the same price as a ring and pinion set and an axle rebuild kit, you could just get a 14bff with open 4.10's or 3.73's... just an option :emotions33:

I have a 2011 Suburban that has 3.08's and we also pull a camp trailer, its a dog. I bought a set of 4.10's for both front and rear with the axle rebuild kits for both as well. I went with 4.10's since we have a 6L80E that has a double overdrive and we pull a lot through mountains here in the Pacific North-west.


My buddy actually has a 14 bolt full floater I can have for next to nothing but I want to keep my stock rally wheels. I thought a ring and pinion swap would be the cheapest. about $250 plus/minus.

The semi floating 14 bolts are hard to find I've heard and not cheap either.
 

C10MixMaster

Full Access Member
Joined
Dec 6, 2016
Posts
756
Reaction score
1,420
Location
Kingman AZ
First Name
Ben
Truck Year
1977
Truck Model
C10 BIG10
Engine Size
ZZ4 350
I have an 86 c15 with 3. 08 gears and a th350.

I'm pulling a camper with the truck and it seems a bit too steep for this.

Any issues just buying a 3.73 ring and pinion set? I should just need a new crush washer and set the depth, lash and pinion bearing preload again right?


I'm plan on just keeping it an open diff.

get an install kit there not that expensive ~ $70. you will need the shims / seal / crush sleeve / lock nut at the minimum. and if your going that far do the bearings and ring bolts to , which are all in the install kit.

GM 12-Bolt rear diff UPGRADE: Positraction and gear swap | Hagerty DIY - YouTube this will give you an idea of what needs to be done.
 

Snoots

Full Access Member
Joined
Jan 23, 2013
Posts
8,158
Reaction score
15,957
Location
Georgia
First Name
Roger
Truck Year
1973
Truck Model
Jimmy Sierra
Engine Size
350
I like the gear swap (3.73) but I'd spring for a posi carrier.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
5,882
Reaction score
9,622
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
For the same price as a ring and pinion set and an axle rebuild kit, you could just get a 14bff with open 4.10's or 3.73's... just an option :emotions33:
Why would one go through that brain damage of making a 8 lug axle work under a 5 lug truck and not look like a pos with mis matched wheels?
Can't tell by the :emotions33: if you are serious or joking.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
5,882
Reaction score
9,622
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
I have an 86 c15 with 3. 08 gears and a th350.

I'm pulling a camper with the truck and it seems a bit too steep for this.

Any issues just buying a 3.73 ring and pinion set?

Depends how fast you want to drive on the highway.
If your truck actually has a Turbo 350 swapped in it, it will be screaming at highway speeds with deep gear and the little tires that are on it.
Think about what you want out of the truck. If just for towing, 3.73s or even 4.10s will be great, but not if you drive it 70mph+ on the highway. That's 3000-3300 rpms (3.73 vs 4.10) at 70 mph in drive.
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,135
Reaction score
4,983
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
Why would one go through that brain damage of making a 8 lug axle work under a 5 lug truck and not look like a pos with mis matched wheels?
Can't tell by the :emotions33: if you are serious or joking.

Mostly joking... but it is still a valid option. For a 2wd, it's pretty easy to convert to the bigger 3/4 ton 8-lug front rotor and caliper also... but if he has nice wheels and tires that's obviously not a good one.
 

Savageftr

Member
Joined
Mar 5, 2021
Posts
33
Reaction score
44
Location
Elie, Manitoba Canada
First Name
Alex
Truck Year
1986
Truck Model
C15
Engine Size
355
Depends how fast you want to drive on the highway.
If your truck actually has a Turbo 350 swapped in it, it will be screaming at highway speeds with deep gear and the little tires that are on it.
Think about what you want out of the truck. If just for towing, 3.73s or even 4.10s will be great, but not if you drive it 70mph+ on the highway. That's 3000-3300 rpms (3.73 vs 4.10) at 70 mph in drive.

The TH350 is factory not swapped. Its the MX1 rop code for a TH350C with the converter lockup. I'm happy driving 55 or 60 on the highway.

The only longer trips I will be taking will be pulling the camper. I want to be able to drive 55 ish on windy days and not smoke the trans. Right now when its really windy you can tell the trans is under some serious load, hoping lower gearing should help take some stress off the engine/trans.
 

Savageftr

Member
Joined
Mar 5, 2021
Posts
33
Reaction score
44
Location
Elie, Manitoba Canada
First Name
Alex
Truck Year
1986
Truck Model
C15
Engine Size
355
I like the gear swap (3.73) but I'd spring for a posi carrier.

It would be nice but I'm not racing it or driving in the mud so the only use for it would be the occasional burn out...

I figure less traction = less breaking ****

I have lots of other **** I could spend $700 on right now that I actually need
 

Savageftr

Member
Joined
Mar 5, 2021
Posts
33
Reaction score
44
Location
Elie, Manitoba Canada
First Name
Alex
Truck Year
1986
Truck Model
C15
Engine Size
355
I like the gear swap (3.73) but I'd spring for a posi carrier.

It would be nice but I'm not racing it or driving in the mud so the only use for it would be the occasional burn out...

I figure less traction = less breaking ****

I have lots of other **** I could spend $700 on right now that I actually need
 

WesN

Full Access Member
Joined
Feb 15, 2018
Posts
209
Reaction score
565
Location
Edmonton Alberta Canada
First Name
Wes
Truck Year
1981
Truck Model
C1500
Engine Size
350
Be aware that there is two different ring and pinions (thick vs thin) that will depend on which carrier you have. Carriers are made for a certain range of gear ratios and it will determine which gears will work with you stock carrier.
 

Ken Boellner

Junior Member
Joined
Jun 30, 2020
Posts
4
Reaction score
1
Location
Arizona
First Name
Ken
Truck Year
1980
Truck Model
C10
Engine Size
302
Just changed the 3:08's in my to 3:73. You have to change the carrier also.
 

MikeB

Full Access Member
Joined
Apr 4, 2014
Posts
1,745
Reaction score
935
Location
Justin, TX
First Name
Mike
Truck Year
1969
Truck Model
C10
Engine Size
355
Carrier "break" for 8.5" 10-bolt is 2.56/2.73. That means 3.73 gears would work with your carrier even if your truck had 2.73 gears. Simply google it.

Also, I would opt for a crush sleeve eliminator kit (spacer+shims). That way you don't need to torque the pinion nut to 300 lb/ft or more to crush a sleeve, and then throw it away if you mess up. https://www.yukongear.com/productdetails.aspx?ProdID=8280
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
3,656
Reaction score
6,589
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
Someone's about to go down a rabbit hole. On the plus side, if your truck has the factory 305 you ain't gotta worry bout breaking anything.
 

Latest posts

Forum statistics

Threads
41,849
Posts
903,439
Members
33,362
Latest member
Dhatch84
Top