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Old 08-23-2007, 06:12 AM
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8.875 chevy truck rear

i have a bunch of rearends from 73-81 fullsize chevy trucks(8.875 12 bolt, not car). my plan was to cut one down to fit an s10 2wd. i was gonna use the backing plates from an original s10 7.5 rear and then have custom axles made. does anyone know if the backing plates will interchange?(bolt up from the 7.5 directly to the 8.875)

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Old 08-23-2007, 10:25 AM
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I dont think the plates will interchange. When you cut the housing, go back with a housing end of your choice and use a press on bearing instead of a c-clip. You can then use ford or chev drum brakes or one of the many rear disc conversions.
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Old 08-24-2007, 11:16 AM
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the outside diameter of the 8.875 truck rearend axle tubes are 3 inches measured with a dial caliper, the s10 is around 2.600. would it be best to make the brackets for the backing plate out of 1/4 inch steel cut with a plasma cutter?
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Old 08-25-2007, 12:05 AM
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Buy tube ends from someone like Strange Engineering to connect up to the brakes you want to use. Early S10's had a very goofy 3-bolt backing plate flange that held the wheel cylinder in with a snap-ring. You would be better off using a more common and getting new brakes.

You might also want to look into trading all those truck 12-bolts for an 8.8" explorer or 9".
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Old 08-25-2007, 06:35 AM
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The truck 12 bolt is a nice step up, but its really only about as strong as an 8.5" 10-bolt. The pinion shaft is smaller than a car 12 bolt.

The truck 12 is fine though, and like has been said, most of the axle companies can sell you axle tube ends to put darn near ANY brake package on there. The 8.8 Ford ends have common and cheap explorer disc options. The 8.5 10-inch has great but expensive discs. The 14-bolt brakes have massive 8-lug drums that are bulletproof. Mix n' match if you want... or just put the 12-bolt drums back on. They're acceptable
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Old 08-25-2007, 03:04 PM
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i have to disagree, the 8.875 is far better and stouter than any 8.5 10 bolt. ive used alot of these trucks pulling and hauling and never damaged one yet. ive seen alot of 10 bolt 8.5s explode, the only reason i can see why gm swithed to it in 1982 was it cost less to make. thats my guess.
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Old 08-25-2007, 09:14 PM
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Don't confuse the truck 8.875 with the CAR 8.875. The truck 12 bolt uses the same pinion shaft and input bearing size as an 8.5" ten. Most parts of the truck 12 are stronger, but since an axle is only as strong as its weakest link (and since the pinion shaft is the same as an 8.5), it is not really any stronger than the 8.5.

Keep in mind also that the 12 bolt truck was installed for LOAD capacity, not torque. The truck 12 was installed during the years that 180 hp was "lots." The point of using a 12 in the truck was for load carrying and towing, not hot rodding with monster power numbers and sticky tires.

Like I said, there is NOTHING wrong with it, its a very strong axle, but just don't confuse it with a car 12 just because the ring is the same size.
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Old 08-26-2007, 09:33 AM
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it would have to be stouter than the stock 7.5, and i havent tore one of those up yet. i just have about 7 of those truck 12 bolts laying around and i thought i could make a good upgrade for a sb s10. i dont use drag slicks or race at the track with them either, just run the roads, fast.
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Old 08-26-2007, 02:38 PM
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Sometimes it just isn't cheaper to use something free.

I don't know of any 5 on 4.75" brakes that will bolt up to the 1/2-ton backing plate flange. The old S10 flange is not ideal and the ID of the bearings are small for a 30-spline axle. If you had a newer (~89-up) 7.625" axle it would have brakes that would be usable.

That leaves you with needing to buy:
-Ford 9" type axle tube end
-Custom axles w/ new bearings and retainers
-Brakes
-New U-bolts to fit the larger axle tubes
-New Spring perches to weld on.
-Shorten drive shaft and change rear yoke

It adds up to more money then you would think even if you use j/y brakes. You would end up with a great axle.

I had a free 8.5" 30-spline 10-bolt that I was thinking of narrowing to put under my S10 and steered away from it because of all the money and time it would take to make it fit under my S10.

I have an S10 8.5" with disc brakes...but they are not easy to find. If you sold or traded some of those 12-bolts for a Exploder 8.8" you might be ahead of the game.
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