12 bolt rear - The 1947 - Present Chevrolet & GMC Truck Message Board Network

thump16 · 03-14-2013, 02:48 PM

so how many of you Task force guys are using 12 bolt rears from 73-87 trucks and are there any clearance issues when using the stepside bed? My reason for asking is that i have the porterbuilt 55-59 IFS and i ordered the A-arms/73-87 drop spindles with plans to run 5x5 lug pattern and I want it to be the same pattern front and back. I have access to plenty of 12 bolts just wanted to make sure there was room betwen fender and tires/rims in back.

Kabwe · 03-14-2013, 03:53 PM

We need to know the width of the rearend. I like measuring mounting point to mounting to point. Some prefer flange to flange. Are you going for a stocked look? Well if you are, I believe the original is 62 inches mounting point to mounting point. If your 12 bolt is close to that you will be fine but it still depends on the look you are after.

There are so many questions you have to ask yourself that its really not that simple. What size wheel do you want to run in the rear? What backspace are those wheels? Its not a one size fit all, you also have to consider the other choices you will make. Case in point I could have run my Chevy 10 bolt at its stock width but my truck would not have had the look I was after so I narrowed it so that I would have less backspace which means more lip (dip dish) look I was after.

By the way axles can be redrilled to different lug patterns and its not expensive to do so. Also if your planning on running different width, or size wheels lug pattern is not as important because you can't rotate your tires anyway. Well if you already have the wheels lug pattern is important.lol But if you are anything like me you want them to match anyway because I'm nuts.

LDO · 03-14-2013, 04:01 PM

I'm using the 12 bolt out of a 64 C10 on my 57 truck. After I welded on the spring perches and changed out from 17 spline axles and spiders, I was GTG. 64 was the last year for the 17 spline axles. Thanks to Capt Fab for all the 12 bolt knowledge he dropped on me.

**mr48chev** · 03-14-2013, 06:45 PM

I'm thinking that the width isn't too far off up through 68 or 69 and then the rear axles get somewhat wider.

Kabwe covered all of the bases in his post. You have to calculate all of the variables in before you really start putting things together and wheel/tire choice is big one when it comes to rear axle width. That 70's look with three inches of tread sticking out past the fenders isn't cool anymore even thought the local rednecks still seem to think so on their 4x4 trucks.

izonme13 · 03-14-2013, 08:33 PM

I have a 77 chevy 12 bolt with captain fab mounts to use discs with lt1 calipers. Mine is just over 64" now. So I will be narrowing it alot! but I believe they are somewhere around 63" with drum brakes.

thump16 · 03-14-2013, 09:14 PM

I def want the option of being able to run a deep dish rim. I will keep looking for axles. tYard I go to has quite a bit of trucks.

thump16 · 03-20-2013, 02:41 PM

So I pulled the trigger on a 94 impala SS rear just shy of 63 inches side to side plus I have an issue of classic truck magazine in which they used a 96 impala ss rear end. I am using 5 x5 lug pattern from 73-87 c10's. So i will have 4 wheel disc front and back.

Now just have to wait on PB A-arms.

Sledge

03-14-2013, 02:48 PM	#1
thump16 Registered User Join Date: Jul 2005 Location: Valdosta GA Posts: 708	12 bolt rear so how many of you Task force guys are using 12 bolt rears from 73-87 trucks and are there any clearance issues when using the stepside bed? My reason for asking is that i have the porterbuilt 55-59 IFS and i ordered the A-arms/73-87 drop spindles with plans to run 5x5 lug pattern and I want it to be the same pattern front and back. I have access to plenty of 12 bolts just wanted to make sure there was room betwen fender and tires/rims in back. Last edited by thump16; 03-14-2013 at 02:56 PM.

03-14-2013, 03:53 PM	#2
Kabwe Certified Car Nut Join Date: Jan 2005 Location: Inglewood, California Posts: 3,118	Re: 12 bolt rear We need to know the width of the rearend. I like measuring mounting point to mounting to point. Some prefer flange to flange. Are you going for a stocked look? Well if you are, I believe the original is 62 inches mounting point to mounting point. If your 12 bolt is close to that you will be fine but it still depends on the look you are after. There are so many questions you have to ask yourself that its really not that simple. What size wheel do you want to run in the rear? What backspace are those wheels? Its not a one size fit all, you also have to consider the other choices you will make. Case in point I could have run my Chevy 10 bolt at its stock width but my truck would not have had the look I was after so I narrowed it so that I would have less backspace which means more lip (dip dish) look I was after. By the way axles can be redrilled to different lug patterns and its not expensive to do so. Also if your planning on running different width, or size wheels lug pattern is not as important because you can't rotate your tires anyway. Well if you already have the wheels lug pattern is important.lol But if you are anything like me you want them to match anyway because I'm nuts. Last edited by Kabwe; 03-14-2013 at 04:09 PM.

03-14-2013, 04:01 PM	#3
LDO Registered User Join Date: Feb 2011 Location: Senatobia, MS Posts: 1,297	Re: 12 bolt rear I'm using the 12 bolt out of a 64 C10 on my 57 truck. After I welded on the spring perches and changed out from 17 spline axles and spiders, I was GTG. 64 was the last year for the 17 spline axles. Thanks to Capt Fab for all the 12 bolt knowledge he dropped on me. __________________ Once a Marine, always a Marine! My (Her) 57 Build "Beverly" My 66 Build "Betty" My 85 C10 "Old Blue" Help Me Find "Old Blue" OLD BLUE PART II

03-14-2013, 06:45 PM	#4
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,711	Re: 12 bolt rear I'm thinking that the width isn't too far off up through 68 or 69 and then the rear axles get somewhat wider. Kabwe covered all of the bases in his post. You have to calculate all of the variables in before you really start putting things together and wheel/tire choice is big one when it comes to rear axle width. That 70's look with three inches of tread sticking out past the fenders isn't cool anymore even thought the local rednecks still seem to think so on their 4x4 trucks. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

03-14-2013, 08:33 PM	#5
izonme13 Registered User Join Date: Apr 2009 Location: medford, OR Posts: 80	Re: 12 bolt rear I have a 77 chevy 12 bolt with captain fab mounts to use discs with lt1 calipers. Mine is just over 64" now. So I will be narrowing it alot! but I believe they are somewhere around 63" with drum brakes.

03-14-2013, 09:14 PM	#6
thump16 Registered User Join Date: Jul 2005 Location: Valdosta GA Posts: 708	Re: 12 bolt rear I def want the option of being able to run a deep dish rim. I will keep looking for axles. tYard I go to has quite a bit of trucks.

03-20-2013, 02:41 PM	#7
thump16 Registered User Join Date: Jul 2005 Location: Valdosta GA Posts: 708	Re: 12 bolt rear So I pulled the trigger on a 94 impala SS rear just shy of 63 inches side to side plus I have an issue of classic truck magazine in which they used a 96 impala ss rear end. I am using 5 x5 lug pattern from 73-87 c10's. So i will have 4 wheel disc front and back. Now just have to wait on PB A-arms. Sledge



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