06-18-2018, 02:26 PM | #1 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
posi rear end gears
My 87 Silverado is finished except for the posi rear end. I have the 350 engine with the 4 speed (overdrive) transmission that came in it. The right rear tire will light up but the drivers side doesn't. Some tech lines say 373 is best all round.I'm not racing it. Just a cruiser but would like both tires to spin and get reasonable mileage. What are other 350 guys installing that fits the bill.
Thanks, Eric my project can be viewed at : https://www.fuelcurve.com/1987-chevy-c10-pickup/ |
06-18-2018, 02:47 PM | #2 |
Account Suspended
Join Date: Jun 2015
Location: No longer here
Posts: 1,000
|
Re: posi rear end gears
If you have a true posi differential than I would think both tires should lay down the rubber....if you dont, you can add the posi carrier without replacing the gears...Good luck on smokin both tires !!!!!
|
06-18-2018, 11:38 PM | #3 |
60-66 Nut
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,248
|
Re: posi rear end gears
Beautiful truck!
What gears will partly depend on what the diameter is of your rear tires and what you want out of a gear change. Are you looking for better performance or lower RPM's at highway speeds? Lower rpm's don't always mean better MPG's. The engine needs to run in it's 'sweet spot' for best efficiency.
__________________
Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
06-19-2018, 02:11 PM | #4 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
I have 20” Mickey Thompson tires ! All I want to do is spin both tires. I can live with current gears. Thanks !!!
|
06-19-2018, 11:33 PM | #5 |
60-66 Nut
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,248
|
Re: posi rear end gears
20" diameter tires..........what are those on 13" wheels?
If you want a posi, then you will have to either install one or have it installed.
__________________
Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
06-20-2018, 03:06 AM | #6 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
|
06-20-2018, 03:11 AM | #7 |
Registered User
Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,629
|
Re: posi rear end gears
Get a Detroit True Track...Eaton brand.
|
06-20-2018, 03:46 AM | #8 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
|
06-20-2018, 11:40 PM | #9 |
60-66 Nut
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,248
|
Re: posi rear end gears
The OUTSIDE diameter of the rear tires is what is needed to determine the optimum gear ratio for the desired usage, not the wheel diameter. Your original post sounded like you were wanting a gear change also.
__________________
Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
06-21-2018, 03:26 AM | #10 | |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
Quote:
Thank you for helping ! |
|
06-21-2018, 09:58 AM | #11 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,461
|
Re: posi rear end gears
I’d say 3.73s maybe 4.10s. With either gear the drivetrain won’t be working as hard, so tho seems backwards but would get better mileage, while having fun at the same time lol...
|
06-21-2018, 10:21 AM | #12 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
|
06-21-2018, 10:50 PM | #13 |
60-66 Nut
Join Date: Mar 2007
Location: Coeur d'Alene, Idaho
Posts: 23,248
|
Re: posi rear end gears
What gear ratio do you currently have?
__________________
Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE |
06-22-2018, 12:48 AM | #14 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
|
06-22-2018, 09:45 AM | #15 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,461
|
Re: posi rear end gears
Believe that is 3.23.....
|
06-22-2018, 09:46 AM | #16 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,461
|
Re: posi rear end gears
Wow, it’s 2.73s.....
|
06-22-2018, 12:20 PM | #17 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
Thank you b454rat ! Should I just do the locker on those gears or change. If change to what & why ?
|
06-22-2018, 08:23 PM | #18 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,461
|
Re: posi rear end gears
Change the gears for sure!!!! At least 3.73s. Any posi that isn't the grenade lock.
|
07-01-2018, 01:18 PM | #19 |
Registered User
Join Date: Jul 2015
Location: 2nd left past the stump on a dirt road.
Posts: 2,629
|
Re: posi rear end gears
If you go from 2.73 to 3.73 gears your going to kill any mileage you got from that thing. It would dramatically change they way they whole drivetrain responds to the engine. I would bet that thing is a dog right now with those gears.
|
07-01-2018, 03:21 PM | #20 |
Registered User
Join Date: Oct 2016
Location: Dallas Texas
Posts: 3,103
|
Re: posi rear end gears
That is a very nice looking square body right there! If you really do have 2.73 out back and a standard 700r, 1st gear off the line is probably OK, but 2nd gear must be a let down ( I'm thinking WOT here ).
If you don't want to change your current mileage/driving characteristics, don't change the gear ratio. If you want to change the way your truck gets down the road and/or increase the fun factor stop light to stop light, change the gear ratio. I would first make sure you know what you have currently. Determine that for certain then decide what you want to do with respect to the ratio. -klb
__________________
67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold |
07-01-2018, 03:53 PM | #21 |
Registered User
Join Date: Jun 2018
Location: Charlotte
Posts: 14
|
Re: posi rear end gears
The glove compartment sticker is:
|
Bookmarks |
|
|