Question about stock rotors

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1981lowrider

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I am wanting to lower my ride. Can anyone tell me the stock width of my rotors on my 81 box ? I found new/used Drop Spindles and i want to make sure they fit. Any help is appreciated, I'm guessing they are 1"?
 

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They came with both 1 in and 1 1/4 in. Just measure the rotor thickness, there is now way we will know by just the year given.
 

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BTW if your rotors are not the size of the spindles you found all you have to do is swap the rotors and inner bearings. Outer bearings are the same and caliper fits both.
 

1981lowrider

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Thanks John, I appreciate your help, makes things alot easier!!
 

bucket

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BTW if your rotors are not the size of the spindles you found all you have to do is swap the rotors and inner bearings. Outer bearings are the same and caliper fits both.

There's no way they use the same caliper. I just did the front brakes on mine, I have the narrow rotors and there's no way those calipers would have opened up far enough to accommodate a rotor that's a 1/4 inch thicker.

Either way, rotors and calipers are dirt cheap and it wouldn't be the end of the world if you have to switch.
 

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There's no way they use the same caliper. I just did the front brakes on mine, I have the narrow rotors and there's no way those calipers would have opened up far enough to accommodate a rotor that's a 1/4 inch thicker.

Either way, rotors and calipers are dirt cheap and it wouldn't be the end of the world if you have to switch.
Case in point to my earlier post, this truck had 1 1/4 in rotors/spindles. I gave him a set of drop spindles that are for 1 in rotors, cross referenced the parts and the only parts that came up different were the inner bearings and the rotors. He needed a brake job anyway so he bought the parts and everything fit.
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bucket

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I could see where it would work if the wide caliper was used on the thin rotor. But once the pads wear down, the piston is going to be out of it's bore more than it should, possibly causing it to blow and leak brake fluid.

Like I said, it would not be possible for my calipers to work on the thick rotor. My caliper's pistons were fully seated and the pad surface was flush with the caliper body, yet there still wasn't much clearance to slide them over the rotor.
 

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I don't know John, you know I just lowered my truck, and up grades to drilled and slotted rotors that are 1.25. I had to buy new calipers, because my 1 inch calipers wouldn't open far enough. I know you have lowered a **** load of SB.

When I got my drop spindles, I got the larger 1.25 spindle, so I could up grade all the brakes on the front to the heavier 1.25. I know the calipers are wider, and it even uses different brake hoses.
 

bucket

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I just checked Advance and NAPA, there are two different caliper sizes.

JB1 and JB3 is the thin caliper (manual brakes and light duty power brakes)

JB5 and a couple JD codes (hydroboost) is the thick caliper
 

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Aint that some ****, I stand corrected, lyin ass parts store.

But we did have to completely colapes the piston to get the 1 1/4in caliper with new pads on to the new 1 in rotor.

EDIT: Do calipers too with regards to post #4.
 
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