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Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1147540 Mon Feb 01 2016 12:23 AM
Joined: May 2005
Posts: 9,134
G
Grigg Offline OP
.
What truck is this brake swap good for?

The late model brakes, and more importantly, the rotor comes from a single wheel pickup. Note that the rotor slips over top of the hub then the wheel is installed.

The brakes as they came on the late model axle will not fit in a 19.5" dual wheel. PICTURE
However, by locating the rotor behind the 14 bolt hub which has a thickness of 1.520" (measured) you gain that much more room.
Here is a picture of this rotor and caliper sititng behind a 14 bolt hub all inside a 19.5" wheel. There is plenty of room. PICTURE
The same in an original 18" dual wheel also fits quite well, no trouble. PICTURE

This swap will also work with a single wheel AD pickup (and many others). Although likely a small wheel won't fit over the 13" rotor and caliper. I have not tested but don't foresee any issues with 19.5", 17", or even 16" single wheels.

Judging by the fit as shown above in a 19.5" wheel which leaves the caliper somewhat below the outer surface of the tire and how that tire/wheel fits the original truck with about 1" clearance between the springs... Indicates there should be plenty of room between the caliper and the leaf spring while keeping the original ~63" WMS.

Should be a good swap for single and dual wheel AD 1 ton trucks (and others) when also doing a 14 bolt axle swap.

Grigg

Last edited by Grigg; Mon Feb 01 2016 01:06 AM. Reason: fix link

1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1148499 Fri Feb 05 2016 05:27 PM
Joined: May 2005
Posts: 9,134
G
Grigg Offline OP
.
Today I ordered 4 flanges waterjet cut from 5/8" plate.
They'll come with a bore a little smaller than 3-3/8" so I can bore to suit and face one side leaving a pilot to register the caliper bracket.
Drawing



1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1148674 Sat Feb 06 2016 07:47 PM
Joined: Mar 2008
Posts: 1,957
W
Whitedog Offline
Shop Shark
Sorry it's been a few since my last post.

What I was refering to with the 6 lug... 8 lug rotors, etc... Is specific to van components. Which is what I'm working with. the 03-05 2500 vans have 2 different axle options. Both are semi-float axles. The 8 lug actually being a Dana 60. The both use the same brake caliper bracketry. The only real difference is the 6 lug version has slightly smaller pistons. What I'm planning on doing is using the smaller caliper with the 8 lug rotors. Confusing? Yes. Since the 3600 is quite a bit lighter the the late model van and I can get away with a smaller master cylinder, is why I chose this option.


Anyway, centering the rotor. My plans are to use a couple lug nuts to center and hold the rotor to a hub. Then use the existing holes as a sort of pilot and drill the rotors for the tapered bolt. I know this will need to be repeated anytime the rotors are replaced. How often is that going to happen?

Anyway. Best of luck . Keep up the good work.

Chris


1954 3600 Chevy Truck
"The Fake Truck"
In the Stovebolt Gallery
More pix on Photobucket
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149594 Thu Feb 11 2016 04:09 PM
Joined: May 2005
Posts: 9,134
G
Grigg Offline OP
.
Thanks for the clarification. I don't mind using a larger bore MC to match the larger calipers I have. Good to know there is another smaller option if needed.

At this point I've decided to use the 86828 rotor (came on my 2007 3500HD axle) fit on back of 14 a bolt hub.
This will require a bushing to adapt the approximatly 4.59" hub pilot to fit the approximately 4.83" bore in rotor.
Filling the gap as seen in this PICTURE

You could do the same bushing idea and rotor on the outside of your Eaton hub. Avoiding the countersunk screws. As far as machine work goes the bushing I figure is about as easy, and only have to do it once. I'd also be concerned about shearing the countersunk screws because they would try to take the torque if the studs don't fit the hoes in rotor. I suppose if the lug nuts are snug it might not happen, but it is possible.

Picked up hopefully the last 14 bolt rear axle I'll need today.
PICTURE
This one has the 3.73 gears I want and with luck the gears and housing are in good shape, disassembly, cleaning, and inspection will soon tell.

Grigg


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149613 Thu Feb 11 2016 06:46 PM
Joined: Dec 2006
Posts: 208
T
thoroco Offline
Shop Shark
Originally Posted by Grigg


Both Right Gear and Axle as well as The Hollister Road Company use a rotor equivalent to NAPA # 86830 which is very very similar to the rotors that came on my late model axle but these have a 4.641" bore (measured)



The Bendix brand I have here measures 4.63" which is obviously different than 4.641. The reason the tolerances are so different is that having axial run-out doesn't affect braking on a Disc the way it does a drum. Lateral run out on a drum doesn't affect braking the way it does on a Disc. So a few thousands on a disc to hub fit is not as critical as on a drum. If its to far out you could get a high speed vibration in theory. Disc rotors expand when hot so you do need some room for them to do that on the hub so a .005 fit is not a good thing in this instance.

As for the Right Gear adapters they no longer make the kits and have no idea when they will again. I tried to purchase their cad file because they had no idea when or if they would do these again, but they actually subbed it out and had no file, this was as of last month.

Were I doing the larger bore rotor I would used a centering ring to make it hub centric rather than lug centric but not as close as your thinking.

Rings Link to hub centric rings

Last edited by thoroco; Fri Feb 12 2016 12:54 AM.

Dave Chapman
The Hollister Road Company
713-937-0387
info@hollisterroad.com
www.hollisterroad.com
www.thoroco.com
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149760 Fri Feb 12 2016 03:58 PM
Joined: May 2005
Posts: 9,134
G
Grigg Offline OP
.
Thanks Dave,

I agree that a rotor should be primarily centered for balance reasons and a drum is centered just as much for braking reasons too.

From the 2007 axle/hub/rotor I have the following measurements.

Hub pilot diameter (for rotor) 4.830"
Rotor bore (pilots on hub) 4.834 to 4.835"

This is about 0.004 to 0.005" clearance on what I'm pretty sure are factory parts, not aftermarket or replacement rotors. This is the sort of fit I want and I have no concerns about. Also don't see any problem if the rotor gets warm, expands, and later contracts back to normal.

Thanks for the hub centric ring link, that pretty well illustrates what I've had in mind, we're thinking the same thing here. I want to make them from steel with a light shrink fit on the hub. This will bring the hub I'll be using up to match the diameter of the original hub that fits the rotor I'll use.

The other rotor option suggested, measured at 4.63 to/or 4.64 is still 0.040-0.050" over the 4.59" hub. In my opinion not an appropriate fit without another method of centering the rotor. Judging/comparing by the factory fit of both drums and rotors on their intended hubs with about 0.005" clearance; 0.040" is not close enough to serve the purpose of centering the rotor.
Because a bushing to correctly fit this rotor on the hub would be very thin I've decided to use the rotor with larger bore, easier to make and fit a bushing with a thicker wall.

For what it's worth that's how I see the situation and how I'll deal with it to suit my needs/desires.

Grigg


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149767 Fri Feb 12 2016 04:22 PM
Joined: Dec 2006
Posts: 208
T
thoroco Offline
Shop Shark
There is certainly more than one way to skin a cat. We use stud inserts to center up the rotor and that works well for our application and easy for the novice to add discs. It is odd that the rotor bores vary so much between aftermarket makers.


Dave Chapman
The Hollister Road Company
713-937-0387
info@hollisterroad.com
www.hollisterroad.com
www.thoroco.com
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149790 Fri Feb 12 2016 06:07 PM
Joined: Jan 2016
Posts: 23
G
gentrysgarage Offline
Wrench Fetcher
I had missed this write-up, I was building the same thing almost. Got everything but the mounting bracket. How much are the laser cuts costing? I wanted to get more of a registering lip than you have drawn.
Thanks


Proud caretaker of U.S.A. truck 3219442-S 1943 Chevrolet Cab Over Engine 1 1/2 Ton 4x4
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149805 Fri Feb 12 2016 07:21 PM
Joined: May 2005
Posts: 9,134
G
Grigg Offline OP
.
I'd like to see how your swap is coming along and any troubles you've run into.

Had the brackets waterjet cut, cost me $40 each. Just the shape and holes, I'll turn the pilot. Probably cheaper to have plasma cut but I decided not to, I don't have a local contact for laser cutting so I didn't look into that.
The pilot or registering lip as drawn at 1/8" long is more generous than on the 2007 axle at approx 0.100". It could be longer than 1/8" but I see no need.

Grigg


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Late model GM disc brake swap -- with parking brake [Re: Grigg] #1149817 Fri Feb 12 2016 08:13 PM
Joined: Dec 2006
Posts: 208
T
thoroco Offline
Shop Shark
$40 each is a good price. Who are you using for water jet?


Dave Chapman
The Hollister Road Company
713-937-0387
info@hollisterroad.com
www.hollisterroad.com
www.thoroco.com
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