Brake spindle question

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Ron Gusack
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Brake spindle question

Post by Ron Gusack » Sun Jan 22, 2017 2:07 pm

I'm thinking about putting front disc brakes on my 70 Nova drag car. The car had discs originally and we changed them to drums. I can't remember if we changed the spindle or not. The aftermarket brake people all have different part numbers depending on the spindle. The Strange tech told me he didn't know the difference and I would have to talk to GM. The Mark Williams tech wants to send them the spindle. Does anyone here know the difference or where I can find some information?
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Re: Brake spindle question

Post by Greenlight » Sun Jan 22, 2017 10:25 pm

As far as I know, the only difference between the spindle for the disc vs. drum is the height of the upper mounting boss. The drum brake version has a mounting boss that is taller (~1/2" or so). If you wanted to convert a drum brake car to a disc brake car you could just cut/machine/grind the boss down.

The boss that I am referring to, is shown with a gold colored bolt installed in the link below.
http://www.speedwaymotors.com/1964-74-G ... gQoduMgB8A
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Re: Brake spindle question

Post by Ron Gusack » Mon Jan 23, 2017 5:22 pm

Greenlight wrote:As far as I know, the only difference between the spindle for the disc vs. drum is the height of the upper mounting boss. The drum brake version has a mounting boss that is taller (~1/2" or so). If you wanted to convert a drum brake car to a disc brake car you could just cut/machine/grind the boss down.

The boss that I am referring to, is shown with a gold colored bolt installed in the link below.
http://www.speedwaymotors.com/1964-74-G ... gQoduMgB8A
Thank you for that info, it really helps me out. I appear to have the drum spindles because that boss is tall enough to meet the backing plate where the big top brake pin screws in. I guess if someone has drum brakes they have to have drum spindles or a spacer between the backing plate and the disc spindle.
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Re: Brake spindle question

Post by bracketchev1221 » Tue Jan 24, 2017 9:06 am

Wilwood kits I thought worked on both spindles. My chevelle is a drum brake car, and I put the wildwood disk brake setup right on it.

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Re: Brake spindle question

Post by Ron Gusack » Tue Jan 24, 2017 1:03 pm

bracketchev1221 wrote:Wilwood kits I thought worked on both spindles. My chevelle is a drum brake car, and I put the wildwood disk brake setup right on it.
The Wilwood site asks which brakes you currently have.
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Re: Brake spindle question

Post by psychomotors » Tue Jan 24, 2017 8:20 pm

Greenlight wrote:As far as I know, the only difference between the spindle for the disc vs. drum is the height of the upper mounting boss. The drum brake version has a mounting boss that is taller (~1/2" or so). If you wanted to convert a drum brake car to a disc brake car you could just cut/machine/grind the boss down.

The boss that I am referring to, is shown with a gold colored bolt installed in the link below.
http://www.speedwaymotors.com/1964-74-G ... gQoduMgB8A
This is the right info. I also own a 70 and did this research years ago after being told by many uninformed people who didn't do the leg work necessary to figure this out. They use exactly the same bearings and seals too.
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Re: Brake spindle question

Post by pdq67 » Wed Jan 25, 2017 9:36 pm

Ron Gusack wrote:
Greenlight wrote:As far as I know, the only difference between the spindle for the disc vs. drum is the height of the upper mounting boss. The drum brake version has a mounting boss that is taller (~1/2" or so). If you wanted to convert a drum brake car to a disc brake car you could just cut/machine/grind the boss down.

The boss that I am referring to, is shown with a gold colored bolt installed in the link below.
http://www.speedwaymotors.com/1964-74-G ... gQoduMgB8A
Thank you for that info, it really helps me out. I appear to have the drum spindles because that boss is tall enough to meet the backing plate where the big top brake pin screws in. I guess if someone has drum brakes they have to have drum spindles or a spacer between the backing plate and the disc spindle.
I took a caliper bracket and bolted in one of the bottom holes and rotated it up to the boss. I think all you really need is a thick spacer instead of the thicker boss because if not mistaken, the bolt threads way deep in with no threads towards the end of it. I figure that this kept GM from messing the threads up when they machined the boss shorter. I want to say the top bolt is either 9/16" or might be a 5/8" bolt I do know that when I torqued mine down, I grunted and crushed a rotten molar on my upper left side.

Not fun at all but it never hurt.

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Re: Brake spindle question

Post by psychomotors » Wed Jan 25, 2017 11:01 pm

Drum brake spindles have the boss that has to be milled/cut or ground down, pdq67. If you were wanting to install drum brakes on a disc brake spindle (for some really weird reason) then you would have to make up the .610 or approx. 5/8 difference with a spacer.
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Re: Brake spindle question

Post by Ron Gusack » Thu Jan 26, 2017 10:45 am

Mark Williams no longer asks if the application is drum or disc. Now there's one part number and they say spindle modifications required. Wilwood and Strange still separate disc and drum. Thanks to your responses I now know what I have.
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Re: Brake spindle question

Post by pdq67 » Fri Jan 27, 2017 9:04 am

psychomotors wrote:Drum brake spindles have the boss that has to be milled/cut or ground down, pdq67. If you were wanting to install drum brakes on a disc brake spindle (for some really weird reason) then you would have to make up the .610 or approx. 5/8 difference with a spacer.
No, I was just checking for when I installed my homemade, "pdqCBB", big single piston caliper bracket so I could mount a 13", '88 'Vette front rotor.

I have both type spindles.. I also used 2-piece rotor hubs without the rotors here...

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Re: Brake spindle question

Post by psychomotors » Sat Jan 28, 2017 9:55 am

As usual - I give up.
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Re: Brake spindle question

Post by pdq67 » Sat Jan 28, 2017 12:48 pm

psychomotors wrote:As usual - I give up.
Why?

We should just be having fun here, right...

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