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  #31 (permalink)  
Old 12-20-2012, 10:35 AM
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Quote:
Originally Posted by malibudave View Post
Sorry to hear that. I have spent a B-load of money also to get to the point I am at. There is not reason that you should have gotten zero pressure when using a 1” bore master cylinder when I am getting pressure with a 24mm bore master cylinder using a 2.75” bore Wilwood calipers.

Things to try if you haven’t already:
1. How was the F100 brake lines mounted? Back brakes on the front port and Front Brakes on the back port (nearest to the firewall). How are yours usually mounted on the Maverick? I would think that you will need to match the brakes lines to what the f100 had, if the Maverick was not set up like the F100.

See pic below, this is the Grenada master but the F-100 is nearly identical. You can see the TEE to the front circuit under the blue 2# resid while the red 10# resid feeds the rear circuit.

2. If you didn’t bench bleed the master cylinder, take it off the firewall and bleed it on the bench to make sure you get a full piston stroke.

I always do this.

3. Make sure your bleeder screw, on the front calipers, is pointing strait up when mounted on the spindle to make sure all the air gets out. If not, remove from spindle, C-clamp the piston in the open position, clock the bleeder screw strait up, and then bleed that caliper.

With the Wilwoods, I had to do this. I used a 1" thick hardwood block in place of the rotor.

4. Make sure you’re your brake pedal is adjusted as far back toward the drivers seat as possible. Unscrew the brake light switch as far as you can with out it falling out easily, and then adjust the brake pedal pushrod out toward the piston of the master cylinder.

I made my pushrod adjustable, and the pedal is at the stock height.

5. Measure the piston stoke at the pushrod attachment point. I should have 7/8” to 1” of travel.

Hmmm, this I will take a look at. I can adjust it some, but really don't want my pedal a foot off the floor!

6. Make sure your brake pedal pushrod is just barely touching the back of the piston in the master cylinder. DO NOT PRELOAD the Master Cylinder piston.

The pushrod is clipped into a groove in the piston so it cannot come out. On the other end, the pedal has no stop so it can float freely.

7. The brake pedal pushrod should be inline with the master cylinders piston’s center line. If not inline, you will not the same pedal stroke and also wear out the master cylinder quicker.

Everything is comparable to stock as far as alignment goes.

My sister had a manual brake Maverick from the factory (25, or so, years ago). I cannot remember if it was front disc brakes or the year (I think 1976). But it had a very high pedal. I cannot remember how it stopped, but I know when the pedal released, it made a thud sound when returning to the depressed position.

Let me know what you find out.

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  #32 (permalink)  
Old 12-22-2012, 09:58 AM
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Dave,

You say this works, Wilwood says it works... It doesn't work on my car. This is making me think there's a problem with the rear circuit. Even though I have had as much as 30 PSI on my pressure bleeder, the rear wheels would still turn by hand. I get good flow from both rear bleeders and these were new, complete drum kits from Ford. Maybe they were built wrong? I didn't spend any time looking at them, just slapped them on. Would defective rears give me an extended pedal stroke? Now I'm wondering if I should remove the drums and see what's happening on a pedal press?

Russ
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  #33 (permalink)  
Old 12-22-2012, 04:52 PM
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Quote:
Originally Posted by S10xGN View Post
Dave,

You say this works, Wilwood says it works... It doesn't work on my car. This is making me think there's a problem with the rear circuit. Even though I have had as much as 30 PSI on my pressure bleeder, the rear wheels would still turn by hand. I get good flow from both rear bleeders and these were new, complete drum kits from Ford. Maybe they were built wrong? I didn't spend any time looking at them, just slapped them on. Would defective rears give me an extended pedal stroke? Now I'm wondering if I should remove the drums and see what's happening on a pedal press?

Russ
The combo valve need reset? Rear brake shoes adjusted to just barely brush drums?
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  #34 (permalink)  
Old 12-23-2012, 10:32 AM
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Originally Posted by cobalt327 View Post
The combo valve need reset? Rear brake shoes adjusted to just barely brush drums?
No combi valve, since I am running "bigs and littles". If I can ever get the rear brakes to do their part, I may add a prop valve. I have manually adjusted the rear shoes until I can hear them scraping, yet 30# on my master will not actuate them at all? My next step will be to pull off the drums and watch the pistons under light pedal pressure. One thing I have noticed, the older drum vehicles usually have 1/4" line from the master to the rear TEE fitting and I used 3/16" all the way...

Russ
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  #35 (permalink)  
Old 12-24-2012, 04:35 PM
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OMG!

You'll be happy to know the problem has been solved! There were (at least) two issues at work here:

1) After removing the rear drums (which I had so "carefully" adjusted) I found the PASS side to be spot on while the DR side had at least 3/8" clearance between the shoes and drum. This was causing a lot more master cylinder "stroke" to be absorbed by the rear circuit = increased pedal travel.

2) The bleeder screws were not at the highest point on the big-bore calipers, so I had them off the spindles and was using a 1" block of oak to simulate the rotor while bleeding them. What I wasn't seeing was that the oak block was actually deforming under the pressure. This time, after removing the air, I replaced the calipers on the spindles and finally had a good pedal. The car drives and stops better than before, so all is GREAT!

Russ
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  #36 (permalink)  
Old 12-24-2012, 05:14 PM
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Glad to hear that you're stopping well again.

I have seen cases where, during the adjustment of the drums, the entire brake shoe assembly gets pushed to one side. This will give a "false" sensation of the shoes dragging slightly, making it seem that the shoes are adjusted w/a light brush w/the drum. But once the brakes are applied the shoes center themselves, and there's no dragging, or if there is still some drag, the shoes are still not out far enough.

I've gotten in the habit of taking the adjustment down far enough that the brakes are almost locked, then loosening them to the lightest drag setting.
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  #37 (permalink)  
Old 06-21-2013, 09:21 PM
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Here is a list of strait bore master cylinders that will bolt up to a G-body’s angled firewall when using a flat, manual brake adapter plate. This is a list from smallest to largest.

21mm (0.826”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Hard to find.
• Light in weight.
• Advertised as 21mm, but may be delivered in 7/8” or 24mm bores. Measure bore size before you buy. Rebuilt/Used ones will have a “1” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

7/8” (0.875”) bore 1978-1980 GM G-body manual brake master cylinders.
• Can buy new or used. Rebuilt are fairly cheap. New are fairly expensive.
• Reservoir too small for rear disc brakes. The reservoir from 1979 Buick Riviera with four wheel disc brakes can be retrofitted to this master cylinder.
• Advertised as manual brake units, but may be delivered as a 24mm, vacuum power boosted unit. Measure bore size before you buy.
• Bolt in.
• Cast iron body – new, used, or rebuilt. (no aluminium)

7/8” (0.875”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Easier to find.
• Light in weight.
• Advertised as 7/8”, but may be delivered in a 24mm bore. Measure bore size before you buy.
• Rebuilt/Used ones will have an “8” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

24mm (0.944”) bore 1978-1980 GM G-body power brake master cylinders.
• Can buy new or used. Used are fairly cheap. New are fairly expensive.
• Reservoir too small for rear disc brakes. The reservoir from 1979 Buick Riviera with four wheel disc brakes can be retrofitted to this master cylinder.
• Bolt in.
• Come in cast iron and aluminium. 1978-1979 are cast iron. 1980 is aluminium (some models i.e. El Camino).
• New master cylinders will most likely be cast iron regardless of year.
• Rebuilt units come in cast iron and aluminium (1980 – some models).

24mm (0.944”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Easiest to find.
• Light in weight.
• Advertised as 24mm, but may be delivered in a 7/8” bore. Measure bore size before you buy.
• Rebuilt/Used ones will have a “4” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

24mm (0.944”) bore 1993 Dodge Dakota master cylinder (other years and models may work)
• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. The fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.

1.0” bore 1979 Buick Riviera with 4 Wheel Disc Brakes.
• Can buy new or used. Used are fairly cheap. New are fairly expensive.
• Reservoir is made for rear disc brakes.
• Bolt in.
• Come in cast iron and aluminium.
• New master cylinders will most likely be cast iron.
• Rebuilt units usually come in aluminium.

1 1/32” (1.03”) bore 1985 Dodge Diplomat master cylinder (other years and models may work)
• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. Fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.

1 1/8” (1.125”) bore 1985 Dodge Ram master cylinder (other years and models may work)• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. Fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.
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