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Old 10-20-2014, 12:17 PM   #1
mechanixman
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DIY 8 lug Disk Brake Conversion

Hello all,
Just a little introduction. I have a 1 ton truck with the 8 lug bolt pattern. I was missing a majority of the brake parts in the front drums, and in the beginning, thought I could convert to disc brakes for roughly the same price repairing the front drums. Only problem was, there was no conversion kit on the market. So I decided I would do all the leg work and post my progress so someone wanting disc brakes could build their brakes for a little more effort than just getting a kit. I have just about finished the conversion, so I wanted to let everyone see it.


Here is what I started off with;
Empty wheel cylinders and zipties holding the shoes. No springs, no tension adjusters, no pistons.

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Old 10-20-2014, 12:34 PM   #2
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Re: DIY 8 lug Disk Brake Conversion

First step is to remove the drums. The only things holding the drum to the hub are two screws, you can see them in the second picture, at 12:00 and about 5:00. I couldn't remove mine, a drill made short work of that.
The rotors we'll be using sit on larger lugs. We can increase the size of the lugs to 9/16 and still have the original wheels fit. Now the shank of the new stud won't fit in the original hub, so you'll need a 19/32 bit to make it fit. Don't worry about these odd size of the bit. Even Home Depot carries them.
After that, I suggest cleaning and painting the hubs. It's not that much extra work, and it makes them look 100 times better.
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Old 10-20-2014, 04:38 PM   #3
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Re: DIY 8 lug Disk Brake Conversion

Next step is to press the studs into the hub.
The rotor is from a 2001 to a 2014 3500 truck or van.
If you shop at Oreilly, then the product number is 56999RGS

You can see in the pictures how well the rotor fits the hub.
The last picture is the van I pulled my brakes off of.
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Old 10-20-2014, 05:13 PM   #4
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Re: DIY 8 lug Disk Brake Conversion

Next step is to make the caliper brackets.
Now this may seem like a daunting task, except for the fact that I have already made a set, made templates of them and attached them to this thread.
All you need to do is print them, cut them out, and transfer the template to the metal plate. I understand it would be helpful to know the dimensions to the center of the holes, so once I rebuild my computer, I'll post the dimensions here.
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Old 10-20-2014, 05:18 PM   #5
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Re: DIY 8 lug Disk Brake Conversion

Here are the PDF templates
Now the part I left out was the upright rectangular bar pieces. That's because you can find the length of those based on the PDF files, and the height is up to you. I made mine in the neighborhood of 1 and 1/4 inches.
If you make that taller, then you can add a washer between the caliper and bracket, making it more adjustable and giving you more leeway in case something wasn't cut or welded properly.
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File Type: pdf Caliper Bracket axle side.pdf (222.2 KB, 264 views)
File Type: pdf Caiper bracket caliper side.pdf (109.8 KB, 248 views)
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Old 10-20-2014, 05:22 PM   #6
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Re: DIY 8 lug Disk Brake Conversion

Once you have all the parts, it's time for assembly.
First, You start off with the bare knuckle.
Second slip on and bolt in the caliper bracket.
You can see in the 4th picture how well everything sits together.
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Old 10-20-2014, 05:27 PM   #7
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Re: DIY 8 lug Disk Brake Conversion

Then you slip on the rotor and and bolt in the caliper!
Please keep in mind that I couldn't find any M16 bots of the right length to actually bolt the caliper in, so I have smaller bolts in there for the picture.
Once it's bolted in the spacing looks a lot better.

I believe that's everything.
If anyone has any questions, please let me know
Thanks,
Nick
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Old 10-20-2014, 06:17 PM   #8
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Re: DIY 8 lug Disk Brake Conversion

I love that Nick! Great Job!!!!

You just made my day.

I know the rotors are from 2003 and newer vans, What about the calipers?

Do the wheels turn lock to lock without hitting anything? That was one of the issues I ran into early on.
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Old 10-20-2014, 07:56 PM   #9
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Re: DIY 8 lug Disk Brake Conversion

Thanks!
I'm so glad to hear that.
Same for the calipers. Both pieces come from the same vehicle.
They do indeed go lock to lock without hitting.
When I get back home I'll take some pictures of the full turning radius.
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Old 10-20-2014, 08:10 PM   #10
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Re: DIY 8 lug Disk Brake Conversion

Nice write up and thanks for sharing the info.
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Old 10-21-2014, 09:54 AM   #11
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Re: DIY 8 lug Disk Brake Conversion

Nick, I can't tell for sure from your pics, but it looks like the way you have your calipers mounted isn't going to work. The caliper should be mounted so that it can slide in the direction that the cylinder pushes it so that the pads center themselves on the rotor. The outer pad doesn't move in relationship to the caliper so the caliper has to move. In the pic it doesn't look like the caliper can move as it is against the bracket.
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Old 10-21-2014, 10:01 AM   #12
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Re: DIY 8 lug Disk Brake Conversion

Thanks farmersid.
Russell, I appreciate the concern. The way it sits in the picture, the rotor doesn't rotate. But that is because I don't have the caliper bolts to bolt it in properly. Once the caliper is sinched to the bracket, everything looks and works well.
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Old 01-09-2015, 11:19 AM   #13
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Re: DIY 8 lug Disk Brake Conversion

Nice work! I have a 50 3600 that I am going to attempt to convert to disk brakes. I'm an engineering student at eastern michigan university so I have access to most of their cad and CNC systems. Do you happen to have prints with dimensions? I would end up putting it into either solidworks or master cam and then cut the plates via CNC or plasma-cam. Thanks for the help and dig the truck!
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Old 01-09-2015, 02:50 PM   #14
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Re: DIY 8 lug Disk Brake Conversion

Great job Nick. You are a true hottrodder and machinist. Very nice. Thanks for posting, Rick
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Old 01-09-2015, 03:25 PM   #15
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Re: DIY 8 lug Disk Brake Conversion

Quote:
Originally Posted by Russell Ashley View Post
Nick, I can't tell for sure from your pics, but it looks like the way you have your calipers mounted isn't going to work. The caliper should be mounted so that it can slide in the direction that the cylinder pushes it so that the pads center themselves on the rotor. The outer pad doesn't move in relationship to the caliper so the caliper has to move. In the pic it doesn't look like the caliper can move as it is against the bracket.
The abutment is bolted to the fixed bracket, the caliper slides in the abutment
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Old 01-10-2015, 01:43 AM   #16
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Re: DIY 8 lug Disk Brake Conversion

What part # wheel studs did you use
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Old 03-18-2018, 09:38 AM   #17
Dan Bowles
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Re: DIY 8 lug Disk Brake Conversion

Bringing this back from the ages...do you have dimensions on your bracket? I think the Hollister Road kit had the spacer on his in order to make this all flat stock. 1 1/2" IIRC so your 1 1/4" is reasonable. Dave has passed on and the shop is closed so no more brackets from Hollister Road!

Last edited by Dan Bowles; 03-18-2018 at 09:41 AM. Reason: updated dim
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Old 03-19-2018, 09:09 AM   #18
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Re: DIY 8 lug Disk Brake Conversion

Nick, AKA Mechanixman has some more links on what he did here. I think there may even be a CAD drawing somewhere.

I played around with an 8 lug kit myself. Using rear rotors from a 99 and up 2500 truck or 03 and newer van will keep you from needing the thick spacer. Maybe 1/2-3/4" is all that would be necessary. The 1 ton late model calipers like what Hollister used are overkill for these trucks, in my opinion. Calipers from a Tahoe or Van would more than do what we need.

I just recentlty came across rotors from an 80's Dodge 3500 van. From a dimension standpoint, a spacer may not even be needed. I haven't tried them though. I've invested way too much money and time in it already.
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Old 03-22-2018, 05:29 PM   #19
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Re: DIY 8 lug Disk Brake Conversion

Can any of you report if the stock 15 inch 3600 split rims to clear this disc and caliper set up? Would love to run disc brakes but I don't want to give up my stock wheels and hubcaps.

Thanks,

Steve weim55 Colorado
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Old 03-23-2018, 09:24 AM   #20
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Re: DIY 8 lug Disk Brake Conversion

That particular rotor is close to 13." It won't fit inside a 15" rim with the caliper. It needs to be a 16" or bigger wheel.
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