John Lee's Power Drum Brake Conversion

[Sharps40]

Hang on more to follow tonight.

Minor tweak resulted in major changes for the better.

[Sharps40]

When I left off....the power brakes were fully installed and I'd adjusted the shoes and set the pushrod at the pedal for 2/10" freeplay. It was much better, sensitivity gone but still just a touch sensitive and no feel in the pedal in the top third of the stroke.

Decided to reduce the ratio from manual to something less, more suitable for power brake systems.

I drilled a new brake rod mounting bolt hole exactly 1" CTC lower on the pedal. (The hole is 3/8" dia.)



With no changes to the length of the adjustable push rod, I moved it to the new lower hole (lowering the ratio). Bolted it up.



Checked the free travel just in case, just a bit over 1/8".

Took it out for a ride....no soft in the top pedal, comes on with big toe action, stops the truck, feels like a firm pedal on a properly adjusted brake system.

I'm leavin it as is. Very very very happy with this set up.

Get er done, its a good swap. And its cheeper than ya'd think.

[Indian113]

I can't wait to do this to my 64, Have too wait for spring because I can't tie up garage in winter.

[Sharps40]

I did the brake split and dual manual master install in a single weekend (cylinders were replaced same time, shoes and drums had already been done.)

Then we basically bolted the booster behind the master with Captainfab's handy bracket, welded up the push rod, made some adjustments and done.

Basically, pull in to the garage on two or three Friday evenings, drive it out each of the following Monday mornings. No garage lost and the truck stays on the road thru the entire process.

Have at it. I can't decide which is better, the 5 speed or the power brakes. But, the 5 speed demands the power brakes so I guess the 5 speed is the winner for favorite.

[Indian113]

That would be great if that's all I was planning on doing. I have a tilt wheel to install and I want to put power steering on it. My wife wants to drive it to Back To the Fifties in June, so I need to get it wife proof!!!!

[Sharps40]

Do the brakes on 3 weekends. Do the steering 2 weekends. Done and drivin by mid/end Feb 14, well before the taxes even come back.

[dashaund]

Thanks for these great write-ups. Looks like you and I are on the same page as far as what upgrades we desire, as we both are looking for make daily drivers out of our trucks. It looks like brakes is going to be my first rebuild/upgrade. I will had the dual master cylinder first, and then add the bracket and power booster. I'm a little unclear on the connection between the booster and the original push rod. Basically, I saw off the loop of the booster and weld the push rod to the booster rod? Is there an adapter one can purchase or is it pure fabrication?

[Sharps40]

Just ran 500 miles in the West NC mountains and back. No problems with power drums...perfect function no fade, even workin all day on 6 to 9% grades and switch backs. T5 was marvelous and the 250 six accelerates up those grades clear to the top in 4th.

Pure fabrication is the way....weld on a sleeve or slip one on and cross drill and pin or bolt both rods in the sleeve if you don't weld.

[BigSix]

I just did a booster onto a single circuit too. Same thing - top third isn't much and then hold on! Honestly doesn't bug me but maybe there is a single circuit master from a different vehicle that would give more linear braking? Maybe a car master cylinder?

[Sharps40]

That's not the master causing that issue.... and no master cylinder change will cure the limp top third then WOAH Hold On!

The cure is converting from the 6 to 1 pedal ratio off the manual brake system to the 4 to 1 ratio of the power system. The correction requires drilling a hole in the pedal, 1" further down and relocating the pedal push rod.

For more info check out the power brake suppliers to the hot rod industry and check out the factory pedals of cars that came with power brakes as an option....the hole close to the pivot provides 6 to 1 for manual and the hole further down the pedal provides 4 to 1 for the power brakes.

Once this is done, balance the brake adjustment at the shoes front and rear and ye'll have very well mannered brakes and it won't be Woah Hold On! or lockin the rear until you need it to be!

[tincan1966]

One concern I have with these type conversions- what happens when or if the booster goes bad. What do you do about warranty since the part has been modified?

Just think this should be considered, since so many gripe about places not honoring warranties. Once modified, that part is yours, a replacement, if needed, will be your responsibility.

[BigSix]

Originally Posted by tincan1966

One concern I have with these type conversions- what happens when or if the booster goes bad. What do you do about warranty since the part has been modified?

Just think this should be considered, since so many gripe about places not honoring warranties. Once modified, that part is yours, a replacement, if needed, will be your responsibility.

My booster was something like $60-70 from the parts store so I'll just eat the cost. If I was doing those expensive chrome/cad-plated show style boosters I would be worried $$$

[aggie91]

Originally Posted by tincan1966

One concern I have with these type conversions- what happens when or if the booster goes bad. What do you do about warranty since the part has been modified?

Just think this should be considered, since so many gripe about places not honoring warranties. Once modified, that part is yours, a replacement, if needed, will be your responsibility.

The master cylinder nor the booster are modified when doing this. Only the brake pedal arm has an extra hole added to to provide the correct ratio for the brakes.

[Sharps40]

Tincan is talkin, I believe, bout cuttin the loop off the 67 C10/Impala booster to weld/sleeve to the brake pedal pushrod. If the booster craps out in warrenty, a smart counterdog would catch it and refuse the warrenty but most ain't gonna catch it I spect.