Having a problem stopping correctly.

[ba60]

I have just completely rebuilt my brakes. I replaced the master cylinder which is a Chevy unit that has the petal built in to it with a new one. It is for a 40s to early 50s Chevy. I bench bled it before installing it. The drums and shoes were replaced last fall and have maybe 100 miles on them. The brakes seemed to work pretty well last fall with the new drums and shoes except the mc was old and leaking. I replaced it and the lines except for the stock rubber one over the winter. There was no pressure valve or proportioning valve in the system. The mc is mounted under the floor and is alittle higher than the bleeders in the wheel cylinders. The rear end is an early 70s Chrysler 8 3/4" 489 with 11" drums. Should I just convert it to dicsc brakes? I really would like to leave the wire wheels on the front with no brakes as I like the looks but I need to get the rears working correctly.
Bill

 

[ba60]

I forgot to say it has a really hard petal with almost no travel.

 

[Screaming Metal]

Well, I thought you would've had some help by now! hahaha....guess all the guys are busy. I'm a motor building Guru....not a brake specialist. I'll have my brake guy come in an write at ya after he gets his Job finished he's on, that'll be later this afternoon, he just started on a race car.
But, for now, to me, sounds like you have all the air out, just no mechanical advantage.
The piston in the MC and the pistons in the wheel cylinders are either off, ie, not matched right. OR, you don't have enough leverage at the pedal.

IF, and this is me talking, with a light car, with a strong motor, and if you want to run the spools up front, MY PERSONAL RECOMENDATION is to run disc's on the rear. Alot more stopping power.
Since you don't have brakes on the front....I think we need to look at this from a safety standpoint. But, if your not running a rear to where you can go to the salvage yard to get stuff and switch it over....I know its a expensive proposition. But it just might save your life....fooling with bad brakes is dumb....its not worth loosing your life over!


So, there are all kinds of kits out there, from mild to wild! Watch out for some of the Hurst/AirHeart....thats go-kart stuff. Go online and search by what rearend is in your T. You might be lucky, and theres a car that'll switch over. You never know....

But, just in case you want to stay with drum brakes, we need info....
Look at the brake cylinder and see if there are any #'s cast onto the body, like 1/2, 3/4, 1 1/8's....something like that.
Secondly, we need to see how long your foot pedal is above the pivot. And then also measure the pivot point to MC actuator arm...the length there.
Third, we need to know what your Wheel cylinder bore's are....what the piston size is.
What I'm thinking, you might have to swap out your master cylinder for something that has a smaller bore.
http://members.tripod.com/~Mojo_Page/chry875.htm

 

[ba60]

Screamin, I think this is the original setup on the car. It must have worked ok before this. Actually it worked better last year before I replaced everything. I'm really considering converting to discs. Would I have to change the MC also? I don't have a problem spending the money for quality brake parts. What would be the best disc setup to go with? Any suggestions? It has a Chyrsler 489 rear. I believe its a 1973?

 

[Rogers23T]

You might have a sezed piston in one of the drums. Or a horrible restriction in one of the lines. Personally sucide brakes scare the hell outta me, but I would agree with changing to disk... if you're gonna run with no front brakes go to someone like Wilwood buy a bad ass set of disk brakes. Looking cool is one thing but to risk a life isn't worth it.

 

[RPM]

You might have a sezed piston in one of the drums. Or a horrible restriction in one of the lines. Personally sucide brakes scare the hell outta me, but I would agree with changing to disk... if you're gonna run with no front brakes go to someone like Wilwood buy a bad ass set of disk brakes. Looking cool is one thing but to risk a life isn't worth it.

I personally would not recommend or use Wilwood. A good friend of mines dragster, had Wilwood brakes on the rear end only. One of the linings on a pad decided to come unglued. Thank God for 2 parachutes, still ran the car off the end of the drag strip. He now runs 2 calipers per disc on the rear only with 2 master cylinders.

 

[ba60]

I'm going to buy a conversion set from Summit. Has anyone used their brand?

 

[2old2fast]

I've had a problem on 2 of my trucks, turns out the rubber brake hoses collapse internally ,1 wouldn't release the brakes ,the other restricted the fluid the other way . Might be something to check especially if it's got some age on it !!

dave

 

[ba60]

I replaced the rubber hose today. It didn't help. I think it's off to Summit tomorrow for me to buy the disc conversion.

 

[Keeper]

While it will be nice to have discs on the rear, I would still be trying to figure out why you have a hard pedal before throwing more parts at it.

Have you pulled a drum to see if the brake pads are moving when you push the pedal?

This all started with the new MC, I would start there, pop off the lines and look for an obstruction, re-bleed the MC and go from there.

 

[ba60]

When I was bleeding the brakes with the speed bleeders about a 1/4 turn open the petal went right down and put out alot of fluid. It doesn't appear to have any obstruction. I ordered the Summit disc conversion kit today. I should have it by Wed. It includes the parking brake.

 

[Keeper]

Okay got ya.

So if you take a drum off and hit the brakes, do the pads move? I know you are moving to discs (which is a great idea) but now its a challenge...lol

 

[putz]

I agree with keeper if we did this at auto shops I worked in I would not be alive today. Do you happen to have aluminum drums? I have had problems with these. Also make sure short shoe is installed on the front side. On left and right.

 

[ba60]

I agree keeper, it's a challenge. I won't get the discs until the middle of the week. The drums are iron and almost new. The shoes move but it seems like either they aren't making complete contact with the drum or not enough pressure is applying to them. Also I have the short shoe in front on both sides.

 

[ba60]

Hi guys, I wanted to give you an update. I ended up buying the Wilwood floor mount petal from Summit along with a Wilwood 3/4" MC. I ended up installing it on my welded on plate that my old MC was mounted on. I mounted the remote resevore on the firewall behind my steering box. I did have to extend the petal about 3 inches. gives me an 8to1 ratio. Anyhow it works great. I can actually lock up the brakes if needed. Next winter I will change the MC and add some front brakes. But for now this should get me through the Summer. Thanks for the help and suggestions. The support on here is so great for us newbies

 

[Keeper]

Thanks for the update, glad you got things sorted out!