Brake Adjustment
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Freshman User
Joined: Jul 2016
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From: Hampshire,Uk
Brake Adjustment
Hi All,
1946 1/2 ton Jailbar
After over 2 years work I am almost on the road, just one problem, brakes.
I have a standard fully rebuilt drum brake system with 1/4” pipes. Dual reservoir master cylinder fitted with a conversion plate, sold as a kit by mid west ford and the original pedal cluster.
After adjustment I end up with a very long pedal movement, I asked the kit supplier if residual valves were required on the lines but they were unsure.
The master cylinder is 1” bore and looks like a drum/drum mustang. I think the original master cylinder was 1 1/16” bore, so that could be the reason for the longer movement.
Has anyone used a similar master cylinder conversion? Is there a larger bore master cylinder that fits the same conversion plate?
Any advice, suggestions welcome.
1946 1/2 ton Jailbar
After over 2 years work I am almost on the road, just one problem, brakes.
I have a standard fully rebuilt drum brake system with 1/4” pipes. Dual reservoir master cylinder fitted with a conversion plate, sold as a kit by mid west ford and the original pedal cluster.
After adjustment I end up with a very long pedal movement, I asked the kit supplier if residual valves were required on the lines but they were unsure.
The master cylinder is 1” bore and looks like a drum/drum mustang. I think the original master cylinder was 1 1/16” bore, so that could be the reason for the longer movement.
Has anyone used a similar master cylinder conversion? Is there a larger bore master cylinder that fits the same conversion plate?
Any advice, suggestions welcome.
More Turbo
Joined: Mar 2010
Posts: 705
Likes: 78
From: SoCal - Redlands
Can't help you on the brake problem but I'd ask over on the HAMB and Ford Barn as well. Lots of discussion over on those boards about m/c issues in general and old Ford systems in particular. JMO
More Turbo
Joined: Mar 2010
Posts: 705
Likes: 78
From: SoCal - Redlands
One word of advice, if you join the Hamb (no charge) so you can post, make sure you do an intro before posting. That way you won't start out on a bad note. The Hamb is for traditional pre '65 vehicles so never use the word rat rod or refer to EFI or other modern stuff. Still a lot of good info there. You can have EFI or other modern stuff, just don't mention it in your posting.
Mountain Pass
Joined: Jul 2009
Posts: 197
Likes: 2
From: Brisbane, Australia.
G'day Daggers, on my '42 1 1/2 ton I used a dual circuit master cylinder off a 70s F250 , it has the same bore size as the original ... 1 1/4'' . I also fitted 10lb residual valves, one for the front
circuit, one for the rear . Some master cylinders have residual valves in the ports, the F250 master cylinder I used didn't. Brake circuit diagrams show residual valves in line, 10lb for drums,
2lb for discs. My brake pedal pedal travel is about 1''. Maybe the smaller bore in your master is enough to upset the system by not displacing enough fluid.
Cheers, Steve.
circuit, one for the rear . Some master cylinders have residual valves in the ports, the F250 master cylinder I used didn't. Brake circuit diagrams show residual valves in line, 10lb for drums,
2lb for discs. My brake pedal pedal travel is about 1''. Maybe the smaller bore in your master is enough to upset the system by not displacing enough fluid.
Cheers, Steve.
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Freshman User
Joined: Jul 2016
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From: Hampshire,Uk
Hi Steve,
I think you are correct, I would guess that the swept fluid volume is less therefore the pedal movement has increased.
My pedal travel is over 2”, for my non power dual drum system.
I will now, armed with your advice, start looking master cylinders from later ford pickups.
I think the problem will be that most will use front discs and possibly power systems.
Will post results later, thanks for the reply, it really is appreciated.
All the best
Daggers
I think you are correct, I would guess that the swept fluid volume is less therefore the pedal movement has increased.
My pedal travel is over 2”, for my non power dual drum system.
I will now, armed with your advice, start looking master cylinders from later ford pickups.
I think the problem will be that most will use front discs and possibly power systems.
Will post results later, thanks for the reply, it really is appreciated.
All the best
Daggers
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Mountain Pass
Joined: Jul 2009
Posts: 197
Likes: 2
From: Brisbane, Australia.
G'day, I have a reprint of the original Ford shop manual, now it looks like the supplier has supplied a master cylinder for an F1 , your truck isn't an F1. You have to match the master cylinder
to the wheel cylinders, hopefully the charts I'll attach are readable.
Cheers, Steve.
to the wheel cylinders, hopefully the charts I'll attach are readable.
Cheers, Steve.
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Freshman User
Joined: Jul 2016
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From: Hampshire,Uk
Hi Steve,
thanks for the info, I compared the above with the data in my handbook and my slave cylinders seem to total more than the above. So me using a smaller master cylinder bore cant help the pedal travel.
Today I spoke to a experienced car restorer and he advised me to look closely at all the elements in the system closely before changing the master cylinder. In his experience of 1940’s ford braking systems, which is considerable, 90% of brake problems come down to out of spec components and bad adjustment.
So I am taking each corner in turn checking drum diameter, ovality, cylinder action etc.
He also advised to isolate the front and back systems and confirm that the pedal action is equal to both.
Also taking much more care in adjustment.
Not too sure if this will help, but I will give it a try as I am desperate to get on the road after over 2 years work.
Daggers
thanks for the info, I compared the above with the data in my handbook and my slave cylinders seem to total more than the above. So me using a smaller master cylinder bore cant help the pedal travel.
Today I spoke to a experienced car restorer and he advised me to look closely at all the elements in the system closely before changing the master cylinder. In his experience of 1940’s ford braking systems, which is considerable, 90% of brake problems come down to out of spec components and bad adjustment.
So I am taking each corner in turn checking drum diameter, ovality, cylinder action etc.
He also advised to isolate the front and back systems and confirm that the pedal action is equal to both.
Also taking much more care in adjustment.
Not too sure if this will help, but I will give it a try as I am desperate to get on the road after over 2 years work.
Daggers
Cargo Master
Joined: Nov 2012
Posts: 3,156
Likes: 196
hi guys ! last weekend i was bleeding my brakes on my 42. i have a original style master cylinder, which i installed in 2014 and it was working the rear brakes only. i add front brakes and hydro boost this winter. my old but new mastercylinder started leaking at rod. just saying new stuff now a days is not always good !
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Freshman User
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From: Hampshire,Uk
I too have had a couple of issues over the last two years with new parts failing or just not fitting correctly.
Just spent the last couple of days checking all parts of the braking system.
Checked the drums and found a problem on the rears.
Fronts O/S+52thou over stock, ovality ok, parallel across contact faces ok.
Fronts N/S+52thou over stock, ovality ok, parallel across contact faces ok.
Rear O/S +152thou over stock, ovality poor, parallel across contact faces poor.
Rear N/S +85thou over stock, ovality poor, parallel across contact faces poor.
Also found one of my new rear brake cables has a badly formed return spring, and was jamming the inner cable.
New rear drums on order, takes a couple of weeks to ship over to UK.
Corrected the cable with the aid of a dremel and grinding stone.
Hope this helps with the adjustment, we will see.
Daggers
Just spent the last couple of days checking all parts of the braking system.
Checked the drums and found a problem on the rears.
Fronts O/S+52thou over stock, ovality ok, parallel across contact faces ok.
Fronts N/S+52thou over stock, ovality ok, parallel across contact faces ok.
Rear O/S +152thou over stock, ovality poor, parallel across contact faces poor.
Rear N/S +85thou over stock, ovality poor, parallel across contact faces poor.
Also found one of my new rear brake cables has a badly formed return spring, and was jamming the inner cable.
New rear drums on order, takes a couple of weeks to ship over to UK.
Corrected the cable with the aid of a dremel and grinding stone.
Hope this helps with the adjustment, we will see.
Daggers
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Freshman User
Joined: Jul 2016
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From: Hampshire,Uk
Hi Paul
that something I am looking at as the original pedal arm has two sets of holes at the master cylinder end. I am at the moment using the set that is closest to the pivot thus the shortest travel. Am going to move the master cylinder rod to the other set giving longer travel.
At the moment I cant test this as brakes are disassembled awaiting new set of brake drums.
I have a couple of repairs to do on the rear wings so its I'm happy to wait until I get the new drums. Cant believe that I removed the rear wings quickly, all nuts came off easily and no rust on either wing or bed.
that something I am looking at as the original pedal arm has two sets of holes at the master cylinder end. I am at the moment using the set that is closest to the pivot thus the shortest travel. Am going to move the master cylinder rod to the other set giving longer travel.
At the moment I cant test this as brakes are disassembled awaiting new set of brake drums.
I have a couple of repairs to do on the rear wings so its I'm happy to wait until I get the new drums. Cant believe that I removed the rear wings quickly, all nuts came off easily and no rust on either wing or bed.
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