good peddle , poor braking ???

[Yankee Transplant]

I have a problem ,, I have good brake peddle but it will not slide the tire ,, even on dirt,, I was told maybe a mix match on caliber and size of master cylinder ..This is a threw together 1930 truck and it never has had good brakes since I got it . Its supposed to have 65 chevy truck shoes on the front so Id say 65 chevy brake cylinders . ???? who knows on the master, it had a single line master on it when I got it .. I put a dual line master on it , and split the lines to front to back , this didnt help..also , 89 model Camaro rear end .. I know , this is messed up , but any suggestions on fixing the problem without alot of $$$$$$$[S

 

[Sam_Fear]

You're probably right about the master mismatch. But it ain't easy to lock up old truck drum brakes with a non power assist master.

Have you thought about a disc kit?

 

[Yankee Transplant]

well I could lock up my 65 f-100 with out much effort , but this isnt going to happen with this set up, Ill have to find a master , with the 1" bore then put big lines on the hole truck .. this way it will all be uniform or mached . if this dont get it I dont know what else to do . On this 30 chevy the peddles are hanging from the dash and the master is on the firewall , so there is no room for a booster .

 

[Sam_Fear]

... the peddles are hanging from the dash and the master is on the firewall , so there is no room for a booster .

??? I don't get it. The booster would go on the firewall and the master bolts to the booster. Is the motor in the way?

My 63 F100 was horrible before I put disc on it. My previous 64 F250 stopped better with a load.

 

[Bamamav]

Your master cylinder may be too big. A smaller bore will have more pressure than a llarge bore will. Large bore will have more volume, but may not have enough pressure to fully extend the shoes. You do have the shoes adjusted snug to the drums don 't you?

 

[BlueNorther]

Bamamav is correct that 1" bore should be on a power booster.

with manual drums you would want a smaller bore MC, something around 3/4", and line size doesn't effect pressure at the wheel, in fact too large a line will require a big volume MC.

check your pedal ratio, the hanging pedal set-up might be from a vehicle that had a booster in there, and the ratio would be less than 6 to 1, which is ok for power brakes but would suck for manuals.

see if you can increase the pedal ratio to 8 to 1, or 9 to 1, this and a 3/4" MC would lock those bitches up.

 

[Yankee Transplant]

??? I don't get it. The booster would go on the firewall and the master bolts to the booster. Is the motor in the way?

My 63 F100 was horrible before I put disc on it. My previous 64 F250 stopped better with a load.

Its a 30 chevy truck no room ,, if you were to put the booster on then the master would hit the side of the hood

 

[Yankee Transplant]

Your master cylinder may be too big. A smaller bore will have more pressure than a llarge bore will. Large bore will have more volume, but may not have enough pressure to fully extend the shoes. You do have the shoes adjusted snug to the drums don 't you?

yes , they scrub , but not enough to get them hot .

 

[Yankee Transplant]

I had something come up today so the truck will be setting to the side for a few days, but when I get back to it , now that ive read all this ,, I may just have a master problem I just need to be sure on which one to get , I just went out to look again and a booster is not an option .. end of master is about 2" away from hood now and the valve covers will hit under it . Thanks for all this help guys . I had already scratched the shoes up and drums a while back . Thinking they were glassed or some thing , but it didnt make much difference.

 

[BlueNorther]

I can't tell from the pictures, but you should have the front brakes connected to the rear chamber on MC and rear brakes connected to front reservoir of MC.

also when adjusting the brakes it is not enough to stop when you hear the shoes rubbing a little on the drums. one shoe may not move as easy as the other and you won't have full contact.

keep turning on the adjuster until the brake is locked up solid, and back it off around 6-8 clicks, do all 4 brakes exactly the same.

also check to be sure the "short" shoe is on the front or leading side of axle, and the "long" shoe is on the backside.

 

[Torch]

Hydroboost
When setting one up where it has never been before you do not need a power steering pump with 3 fittings
Insert a T fitting into the power steering return line and plumb the return from the hydroboost to it.
the hydroboost has very little return fluid and will not impact the power steering setup.
If you do not have power steering...
I don't know if a power steering pump has an adequet bypass for running just the hydroboost
you can try a hydraulic pump from an pld f600 with hydraulic assist or just try a PS pump and see if it works

On master cylinder selection I changed my old 71 firebird from manual disc-drum to manual disc-disc using all factory parts.
I had a 454 chevy in it with a 4 speed could lock up all 4 with very normal pedal effort but th epedal took more travel and felt more "spongy" than on a power brake car but it was not.
I set it up manual because the pontiac 400 I have I was going to put back in it is running 320 degrees duration and .520 lift (stock ram air Iv cam) and it had marginal vacuum at idle


there is a difference in piston size on the GM master cylinders but no difference on disc or drum options at the master cylinder.
The GM manual brake MC has a smaller piston matched by longer travel to make up for the difference in displacement

on the GM manual brake cars there is a different hole your pin for the MC pushrod attatches to the pedal with.
On manual cars the pin is closer to the pivot point of th pedal to gain more leverage
I believe there is a residual pressure valve employed in one of the systems
GM places this valve in the proportionng valve
So what you would need there is to make sure you have a drum-drum; disc-drum; or disc-disc proprtioning valve to match what kinds of brakes you have front and rear.

my good freind Jim bought a 79malibu where the previous builder had simply removed the booster
Jim did not take my advice about relocating the pushrod pin but he did buy an aluminum master cylinder with a plastic resevoir and a smaller piston designed for a chevy truck or something that made it stop good

 

[Yankee Transplant]

Hey torch . I'll have to find out if you can get a dual line MC for a 65 chevy truck , if not I;ll have to move up some years till I find a dual line with the same bore size and maybe this will fix the problem .. Im thinking I just bought a MC that had 2 lines ,, not knowing it wouldnt work .. But it didnt work with the single line either [S but I'll get back on it later next week . Kinda got some other projects that took over , Thanks for the imfo ..

 

[Yankee Transplant]

BlueNorther ,, the lines are correct and I did the shoes like you said. lock them up then back off .. I knew about the one shoe touching deal and not the other I'll do some work on it and more scratching ..

 

[Yankee Transplant]

Here you go 31modA

 

[bob w]

Have you checked your pedal arm ratio? With the master cylinder mounted that low on the firewall it's possible you don't have enough leverage on the pedal arm.

BlueNOrther brought this aspect up but I didn't see any response.

 

[Yankee Transplant]

at the bottom of the pedal, it will move maybe 1&1/2 before it gets hard . and the top moves 1/2 to 5/8 maybe don't anything move a lot . I thought about getting the pedal system out of a 98 suburban and using it , the man is going to junk it anyways .. just havnt had the time to get it yet kinda tied up with other stuff at the moment . But I did check that and it didn't seem right .but I don't know much about this other than it don't work right and it never did ,

 

[bob w]

If the distance from the pivot point to the master cylinder pushrod is 2", then the distance from the pivot pint to the pedal should be 14" to 16". That would be a 7 to one to 8 to 1 ratio. You could measure your setup and see if you are in that range.

Is it possible the shoes/pads have had brake fluid, diff grease or wheel bearing grease on them? Even if they have been wiped off the friction quality could be diminished.

 

[Yankee Transplant]

Hey bob w .. if I get the set up from the burb, and put the pedals the same distance from the master as they are on the suburb. do you think this will fix my problem ? or do I still need to get a 3/4 master bore ? or just get both ...

 

[bob w]

I'm far from an expert on brake systems. I've mixed and matched parts and never had a problem. None of my drum/drum manual set ups needed a 3/4" bore master cylinder. I make sure my pedal ratio is as I stated earlier. Assure the wheel cylinders are in good shape and have the drums turned if there are ridges or grooves or if they are glazed. The shoes need to be free of any contamination. You can try cleaning the shoes with acetone and sand them a bit and see if that helps.
My roadster has a Chevy van front axle and a 8" Ford rear end. I have a Mustang single "Fruit Jar" master cylinder. Not sure on bore but probably close to 1". It stops fine, except when I had a wheel cylinder leak that put brake fluid on one set of front shoes. It wanted to make a hard left with even light pedal pressure.

Dual master cylinders add a good measure of saftey, but millions of cars were built with simgle master cylinders. By keeping all the components in good shape the risk I am taking is minimized.

 

[Yankee Transplant]

Il just have to modify some things to get the suburban peddles to fit . im sure and may have to raise the master up some too . don't know yet .. but its crappy you know you cant depend on the brakes for a sudden stop .. It will take a while to get this figured out . but I bumped this thread up for modA .. he has the same problem . so I figured he could look threw hear and maybe get some ideas on his .. (I am leaning to my peddle set up , being wrong)