Help..Need brake question answered..

[**grumpy**]

Well, told ya it wouldnt take long. I picked up a 65 short stepper thursday. Its a pretty decent truck.
350 sbc, TH350 auto. Pwr steering, pwr brakes.

My question is..
It has a power booster with dual m/c. And it has proportioning valve below..but its still 4 wheel DRUM brakes.

I replaced a blown brakeline today, and bleed my way around the truck, twice.

It stops ok, but pedal is 3/4 way to floor. Is this normal for pwr with drums? Or is there adjustment in there somewhere?

Thanks all. Heres pics of said booster etc..

[bama63]

pedal height depends on rear brake wear and or adjustment, also if your booster is not a factory item some mods are needed to raise the pedal ratio by re-drilling the push rod hole about 3/4 to 1 inch higher up on the pedal i hope this helps you.

[fryer1979]

The pedal sits at 3/4 to the floor, or are you pushing it 3/4 to the floor to stop it?

If you're pushing that far, worn out old rubber brake lines could be flexing. Also as mentioned above the drums could just need some adjustment, but both the front and rear should be considered.

If the pedal sits that far down, there could be a push rod issue, or it could just be a broken or missing return spring. Once figured out you may still want to try the other things I listed to bring the pedal play into taste.

[**grumpy**]

Ok. My bad.

I have to push til it hits about 3/4 way to floor before it begins to stop. Once it grabs, it stops just fine. But its a weird feeling pushing that far.

Makes me semi-panic because it just feels "wrong"..

I may bleed my way back around once more, and mess with the adjusters.

[Rich 5150 69]

Does it feel spongy, soft pedal...? It could be wrong placement on the rod as they said or rod not long enough...

[**grumpy**]

Mmmm..no. Not terribly spongey..
It seems to grab and stop, just alot lower than I would like or expect.

I have no idea what booster m/c combo that is. The PO didnt know anything much about it other than drove it..

[Sick5]

pump the brake as you stop
does it grab higher as you pump?

[apachedaddy]

Looks like a set up off a 67 - 72 truck if that helps anything.

[**grumpy**]

Welp. Got the new pig running and driving today. Replaced brakeline last night, and today put new ignition switch in, and ran new wires to rear so lites work.

Dove it around today.

High pressure line on pwr steering pump is dripping...

Radiator seems to burp alittle fluid up after driving..not too much but alittle.

And after coming home from a local sunday cruise-in, I jacked front up and spun the wheels..

Them babys free-spin like mad..so Im guessing PO didnt adjust anything after putting new brakes and hareware in

So I pulled drums on pass. side and adjusted it in somewhat. I'll do drvs side tomorrow after work.

I was always taught that if adjusted correctly, it should feel a slight drag and spin 3-ish times if adjusted right..

Sound ok to ya'll ??

Think Im gonna do the 3 other corners, rebleed around again, and see what happens.

Baby steps

[fryer1979]

Originally Posted by **grumpy**

And after coming home from a local sunday cruise-in, I jacked front up and spun the wheels..

Them babys free-spin like mad..so Im guessing PO didnt adjust anything after putting new brakes and hareware in

So I pulled drums on pass. side and adjusted it in somewhat. I'll do drvs side tomorrow after work.

I was always taught that if adjusted correctly, it should feel a slight drag and spin 3-ish times if adjusted right..

Sound ok to ya'll ??

Think Im gonna do the 3 other corners, rebleed around again, and see what happens.

Baby steps

Sounds like you're on the right track, and what you are thinking as far as those drum adjustments sounds about like what I was taught. Once you make that adjustment all the way around, you should have a much better pedal.

[**grumpy**]

Well, I did run the adjusters in, and have some drag on the drums now, but still dont have a great pedal.
I may have to look into that drilling another hole in the rod, thing...

It stops, but just has soft pedal. It still goes too far towards floor for my liking

[glendale]

my 65 has stock drums and power brakes. so granted our systems are a bit different. but my truck the pedal barely moves and it would throw you through the windshield in a panic stop. have you looked for any numbers on the master? maybe it's a disc/drum?

[Captainfab]

I can't say for sure if this would cause your issue, but that certainly looks like a disc/drum master with a drum/drum proportioning valve. On a drum/drum master both reserviors should be the same size.

[Chevy Fleetside]

looks like a disc/drum master to me also. This one is from mid 70's.

[**grumpy**]

Oh..
The reservoirs are not the same size...
So maybe thats the issue.

Is there a cheap over-the-counter drum/drum M/C I can just bolt on?

[Chevy Fleetside]

That would be probably from 67 to 70. They had drum brakes with dual masters.

http://shop.oreillyauto.com/ProductL...pe=230&PTSet=A

[mikie 1954]

When i did mine i had to lengthen the rod from the mc to brake peddle, mayby they didn't do that?

[**grumpy**]

Ok. Lets rehash.
I called Advanced Auto. The have, in stock, a 70 dual m/c with equal resevouirs(sp). Its only 20 bucks.

So...
IS a power assist m/c any difference from a manual m/c for 1970? Or they all bolt on the same?

Do I need to bench bleed it as if it was a disc/drum set-up?

Id love to grab it tomorrow morning and throw it on before we head back 25 miles to the weekend show we've been going to.

I put 125 miles on it since yesterday, all while being a nervous wreck, worried sick about having such a low, spongey pedal.

Thanks for the advice..

[Captainfab]

The power brake masters are different from the manual masters. Both will bolt up to the firewall, but the bore in the backside of the piston is different. Yes you will need to bench bleed it just as any other master cylinder.

[**grumpy**]

update..
I bought a dual drum m/c today. Their computer didnt specify a different number for manual or power, so I took what they had.

I know the bore is 1"

And both reseviours are same size.

Is the 1" bore for power?

Id hate to put this on and it be wrong, then Im stuck with it.

Something that shouldnt be such a big deal is beginning to get under my skin...lol

**And edit....Pumping brakes as I stop doesnt do much of anything. I doesnt bring the pedal up for sure.

[MikeN]

Foud this thread via search function. I'm having the exact same problem as the original poster. Just installed a booster from a mid-90's S-10 and a master from a 70 Impala. Drums on all four wheels. The brakes work well, but the pedal is WAY low. I'm satisfied that the system is bled properly and I have no leaks.

The pedal sits at the corrrect height at rest, but you have to push it within 3-4 injches of the floor before the brakes begin to apply. But from there they feel great. I just can't figure this out.

This is on my 64 2WD C10.

[Hx16457]

The proportioning valve is more than likely set up for the dics drum set up (master) you started with.

Someone in the past put a 72 and up disc drum booster valve and master on it, but never put disc brakes on the front.

Is the truck still 6 lug or has it been converted to 5 lug? If it is 5 lug then you could get a 72 and up disc brake set-up (for the front) from a pick and pull, and get back to what you had on the truck before you started all the parts buying.. (drum, drum master)

Otherwise you might need to change the valve out to and adjustable one, then adjust it to get what you need.

Oh and you will have to pump the pedal either way to build pressure!

Just my 2 cents!

[luvbowties]

Originally Posted by **grumpy**

Well, told ya it wouldnt take long. I picked up a 65 short stepper thursday. Its a pretty decent truck.
350 sbc, TH350 auto. Pwr steering, pwr brakes.

My question is..
It has a power booster with dual m/c. And it has proportioning valve below..but its still 4 wheel DRUM brakes.

I replaced a blown brakeline today, and bleed my way around the truck, twice.

It stops ok, but pedal is 3/4 way to floor. Is this normal for pwr with drums? Or is there adjustment in there somewhere?

Thanks all. Heres pics of said booster etc..

Grumpy, look at rear of 'new' mc. Does the rear of the piston have like a mere dimple in its middle? or does the center have like a drilled (or cast) hole or inset about 1.5 inch deep? Look at booster rod. Does it extend 1.5 inches or so or is it about flush with surface of booster drum? If flush, and if mc has the deep inset, you need to make an insert to fill that mc-hollow(about flush with rear of mc piston)--long enough to fill hole but just short enough to allow NO interference when pushing mc up to booster, & all should work just fine. GM makes 2 types of systems. Generally, the flush rod booster uses a mc with a dimpled piston in mc; and the extended rod booster uses a mc with a recessed hole. Make the adapter from a bolt with threaded end and head cut off, using smooth part of bolt grind to bullet-nose on end to go into mc and flat on end closest to booster rod end. Try & find a bolt whose diam closely fills--but does not bind inside--the hollow. May hafta bench-grind a tad if too tight. BTW: Some kits you buy will include such an adapter but not show you what it looks like.

Learned this the 'scientific way'--most call it trial and error where all errors are first ruled out and correct solution is only alternative left! HTH,
sam

[luvbowties]

Originally Posted by **grumpy**

Well, told ya it wouldnt take long. I picked up a 65 short stepper thursday. Its a pretty decent truck.
350 sbc, TH350 auto. Pwr steering, pwr brakes.

My question is..
It has a power booster with dual m/c. And it has proportioning valve below..but its still 4 wheel DRUM brakes.

I replaced a blown brakeline today, and bleed my way around the truck, twice.

It stops ok, but pedal is 3/4 way to floor. Is this normal for pwr with drums? Or is there adjustment in there somewhere?

Thanks all. Heres pics of said booster etc..

Another thing. Pls read thread on 9-30 by dcramos72. May help.
sam