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79 El Camino 12 bolt swap rim and tire Questions

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ratengine
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79 El Camino 12 bolt swap rim and tire Questions

Post by ratengine » Sat May 14, 2016 9:55 am

I have a spare 12 bolt off of a 71 Chevelle. I have the rear upper and lower control arms swap kit it's offset for the angle difference. I will move spring perches up top. Shock mounts not a problem.
My questions, rims and tires for the rear. I know the 12 bolt is little wider. I Plan on running the Torque thrust II, rim size 15 X 8 and rim backspace 4.5" inches.
Rear Tires I'd like to run size is a P275R15 . Has any one run a 12 bolt with this size tire and rim combo without any issues? Lips have to be rolled? Chassis clears?
For those who have installed a 12 in a 78- 87 G body what size rim and tire worked for you?
What's the best size rim and tire for the 79 El camino with a 12 bolt rearend, for a street car no track time!
Thanks Dave

ratengine
Amateur Racer
Posts: 195
Joined: Sun Mar 30, 2008 3:37 pm
Location: Chicago, IL

Re: 79 El Camino 12 bolt swap rim and tire Questions

Post by ratengine » Thu Jun 09, 2016 5:08 pm

Well it's done. Note: Rim Sizes for the rear swaps are 15 X 8" with either 3.5'"or 4.5" back space. Some myth busters to not worry about to install a 12 bolt in a 79 Elcamino. Don't have to change spring mounts to top of the rear axle. You have to shorten the drive shaft. Best to get the offset upper control arms, they have some nice USA made ones sold on Ebay. 3.5" rear back space rims are the best fit with a 8.5 or the 7.5 rears. With a 12 bolt 4.5 B/S with a P275/60/R15 will clear lip on rear quarter, and not rub against rear inner frame rail. The 68 thru 72 Chevy 12 bolt is 1/2 wider on each side. If you run a 4.5"B/S with a P275/60/R15 on either the 7.5 or 8.5 rears you will rub the on the rear frame rails and need 1/4" wheel spacers ,1/2" will give more clearance to clear rear frame rails. With the Chevy 12 bolt install no spacers needed with a 4.5 B/S rim. I just finished installing a 8.5 and 12 bolt in 2 elcaminos, And I have both 3.5" and 4.5" B/S rims. with 60 series tires. The 8.5 swap is a direct bolt in yes but you must cut the driveshaft on the elcaminos and a Grand national driveshaft of 55 1/2" is to short, so have yours cut and balanced for the elcaminos. Now for malibus and other G bodies your on your own your better off using a 8.5 or a 67 12 bolt, good luck finding one. When it's all said and done it's worth it. Hope this helps others doing the swap.

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bowtie81
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Re: 79 El Camino 12 bolt swap rim and tire Questions

Post by bowtie81 » Thu Jun 09, 2016 6:09 pm

I have a 67 12 bolt and using 15x8 rims 275 60's and 5.5 b/s, fits perfect on mine.
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