Converting from a single brake line to dual


Golden Jubilee
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Post Wed Aug 26, 2015 1:48 am

Re: Converting from a single brake line to dual

I can not tell you what you want to hear, so, I'm going to put this on ignore and move on.
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Golden Jubilee
Golden Jubilee

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Post Wed Aug 26, 2015 9:04 am

Re: Converting from a single brake line to dual

Bill,with a truck of this size (1500) you can't count on a 50/50 VOLUME split. the rears will take more then 50% of the brake fluid volume. so by splitting the system, you may be in for a lot of trouble and end up with the back half not having enough volume or pressure. When you start messing with where the booster is, where will the residual check valve be located? Are you sure the booster you choose is of the same volume and pressure ratio of the original single line system? Can the split master provide the correct volume to each 1/2, with enough reserve to allow for brake wear?
If you had a newer truck with all the same brakes, same wheel cyl, same shoes but a split system, then it would be a fairly safe bet to transfer one to the other. Anything less is a world of headaches, and if you get it wrong....
I think you would be far safer to make sure the original system is 100% good, new lines new cyl and new lineings, and leave the "engineering" alone.

Rusty Driver
Rusty Driver

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Post Thu Aug 27, 2015 12:46 am

Re: Converting from a single brake line to dual

CB, thanks for the info. It's the missing part I need to know. I hope to find an original MC for it, then let it alone. But I do appreciate the input, it will save headaches and other problems later. Thanks, Bill

Freshly Restored
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Post Thu Aug 27, 2015 9:29 pm

Re: Converting from a single brake line to dual

Bill,There may be a way to convert your brakes,without an axle transplant. to keep your brakes up-to-date,(readily available parts),you will not be able to keep you truck 100% IHC,but you'll be SAFE! Look for (EXAMPLE,works for G.M.C./Chevrolet vintage iron),3500H.D. 1-ton brake M.C. It has the same bore as a (Chevy) 2-ton/hydrovac. Should be VERY similar. Another option,is to find a motor home,or bread truck,with dual hydrovac's. They're already balanced for front/rear,and no guess work. The point is,newer 1-tons have about the same,(or greater G.V.W.R.,than "our" old 2-tons. Plus they are engineered to go 20-30 M.P.H. faster than "our" trucks were designed to,and stopping power was engineered into the "newer" trucks. Sadler Power Train,here in Cedar Rapids,Iowa, can re build one for about $300.00.if you plan on restoring your original system,which should last another 50-Plus years,if done correctly.
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Golden Jubilee
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Post Fri Aug 28, 2015 2:07 am

Re: Converting from a single brake line to dual

I whole heartedly agree with CB.

Besides,one thing I can't see a way to do is mount a clutch master cylinder on the firewall if a hydro-boost was used,there's no room for both.

(FYI for those unfamiliar with the model,the MC is both the brake and clutch Master).

Bill M,do you have the original MC?

I looked it up first and while the clutch side is the same for all models,the brake side uses different kits.
For the 1200,1300 & 1500A;
868445R91 Kit,clutch side
868443R91 Kit,brake side

For the 1000 & 1100A
868445R91 Kit,clutch side
868444R91 Kit,brake side

This is what I could find...
http://www.ihpartsamerica.com/store/FS- ... C-KIT.html

Dorman;
TM33160 Brake side kit
https://www.dormanhdsolutions.com/mobil ... 33160.aspx

https://www.google.com/?gws_rd=ssl#q=Dorman+TM33160

CMK35433 Clutch side
https://www.google.com/?gws_rd=ssl#q=Dorman+CMK35433

Complete new MC
http://www.raybestosbrakes.com/magnolia ... er=MC36154

https://www.google.com/search?q=MC36154 ... 8&oe=utf-8

Good price
https://www.rockauto.com/catalog/rafram ... plate=true
12 yrs.exp. in IH dealer parts dept.
Never argue with a fool...
If you don't have anything nice to say...say nothing.
If you don't learn something new everyday...you weren't paying attention.
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Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Fri Aug 28, 2015 2:53 am

Re: Converting from a single brake line to dual

Scottso, I really wish I did have the original MC. I wouldn't be in this mess if I did. I work this week-end, but I'm off next week-end. 10 days on, then 4 off at a local hospital. When I'm off, I can recreate pictures showing how to mount a brake booster next to a hydraulic clutch. Long story short, a '71 cab I bought for parts has a booster mounted away from the firewall far enough to fit a hydraulic clutch next to it, but just barely. As far as mixing how much fluid displacement is needed for the front as compared to the rear, that is the piece of the puzzle I don't know, but wish I did. What changed in brake fluid displacement between '66 and '68 that the company could go from single to dual brake systems? That's what I wish I knew more than anything. I'll post pictures of how to fit the clutch MC in just over a week. Bill PS, the '68 doesn't have any metering valve I could find. I wonder if that is part of my answer?

Golden Jubilee
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Post Fri Aug 28, 2015 7:48 am

Re: Converting from a single brake line to dual

Bill McPherson wrote:Scottso, I really wish I did have the original MC. I wouldn't be in this mess if I did. I work this week-end, but I'm off next week-end. 10 days on, then 4 off at a local hospital. When I'm off, I can recreate pictures showing how to mount a brake booster next to a hydraulic clutch. Long story short, a '71 cab I bought for parts has a booster mounted away from the firewall far enough to fit a hydraulic clutch next to it, but just barely. As far as mixing how much fluid displacement is needed for the front as compared to the rear, that is the piece of the puzzle I don't know, but wish I did. What changed in brake fluid displacement between '66 and '68 that the company could go from single to dual brake systems? That's what I wish I knew more than anything. I'll post pictures of how to fit the clutch MC in just over a week. Bill PS, the '68 doesn't have any metering valve I could find. I wonder if that is part of my answer?

What changed is this: with a single line system you get the whole stroke of the master cyl going to all the brakes and how much fluid they require is not an issue( if it was sized right by the factory) because there is no division between them. if the front took 10% and the rear ninty, the fluid could split that way at the T fitting. WHen you go to a split master, each 1/2 only gets to use 1/2 the stroke of the whole master, and are divided from eachother by a barrier. Now how much fluid each 1/2 requires becomes and issue, even if the total volume output of the master remains un changed, the volume requirments of each 1/2's output must be matched to the masters ability to supply, with the split master only having 1/2 the stroke on each section of the original.
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Golden Jubilee
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Post Fri Aug 28, 2015 5:39 pm

Re: Converting from a single brake line to dual

Bill, in my last post there are links for a new original replacement MC and at 108 bucks from Rockauto,that really isn't bad.
If you need the push rods you'll have to go with the universal aftermarket type,I ran the IH pn's with Google and none even open a search.
Did a couple searches for the above.
https://www.google.com/?gws_rd=ssl#q=ma ... od&start=0

https://www.google.com/?gws_rd=ssl#q=Un ... er+pushrod

What the MT-118 shows are 2 piece rods for both brake and clutch so the adjustable universal type is probably what to look at.

Btw, 4 wheel drum brakes don't use or need proportioning valves.
12 yrs.exp. in IH dealer parts dept.
Never argue with a fool...
If you don't have anything nice to say...say nothing.
If you don't learn something new everyday...you weren't paying attention.
THINK! Be sure brain is connected before mouth is in gear.

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Sun Aug 30, 2015 1:58 am

Re: Converting from a single brake line to dual

To all, thanks for the valuable input. Nothing would be more frustrating than to take the truck out on it's first trip and wrap it around a tree trying to avoid something on the road I didn't want to hit. I'll stick with what is stock, and drive easy with it. But I'll still have it this way. All I have to do now is the other things on my honey-to-do list, and then get the part from RockAuto. I never changed the push rods, hopefully they will work still. Again, thanks. Bill

Freshly Restored
Freshly Restored

Posts: 227

Joined: Sun Mar 08, 2015 12:59 pm

Post Sun Jan 24, 2016 10:28 pm

Re: Converting from a single brake line to dual

Bill,here's a '76 I.H.C.1750,with a dual reservoir system! Maybe this would be a bolt-in,(same firewall).http://chicago.craigslist.org/sox/cto/5412214867.html
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