427-390

Greetings,

I searched the archives for an answer and came up empty. I have a '68 with manual brakes and instead of having a soft, spongy brake pedal, like most of the problems, my pedal is extremely hard whenever I go to brake. At times, I use both feet on the brake pedal at stop lights. When backing out of the driveway, (It's downhill once I clear the door) I'm really pressing hard just to keep the car from rolling. No loss of fluid is evident. I've had old Fords with mechanical drum brakes converted to juice brakes that stopped better then the vette. I've had the vette about 3 months and it has braked like this since the day I've owned it. Any ideas?

Thanks,

Tony

427V8

It might have cheap (lifetime ) pads.

It might be a conversion from power brakes that someone did wrong.
two things could be wrong if it's a conversion. Wrong pedal ratio and wrong Master clyinder.

Push rod;
You can check the pedal push rod and make sure it's in the upper hole, not the lower one. The brake light bracket goes there on a manual car.

Master clyinder;
Unbolt it from the firewall and measure the diameter of the bore. It should be 1" if it's bigger it's wrong ( bigger being like 1 1/16")

Last idea is your distribution block could be messed up and you are not getting fluid to either the front or the back. try bleeding your brakes and make sure you get a good stream of fluid from all wheels...

terry82

i would bleed the brakes and check for a good flow ,your hoses to the brakes could be bad . jack up the car .have some one put a fair amount of presure on the brake pedal ,try turning the wheels by hand one at a time .it might be a easy find. m/c are cheap and easy to replace .

427-390

427V8,

Wow! That's great information. I'll keep all of this in mind. I do not believe that it's been converted from PB to manaul though. I will howver bleed the system and possibly replace the M/C. I'll start with the easy stuff (Push rod) and work out from there. Is there any fix for the distribution block? I'm assuming it's the block that is located in the brake line below the M/C?

Thanks!

Tony

redvetracr

a powerbrake master cylinder is 1-1/8 and I think you have one.......
...redvetracr

ffas23

I had a similiar problem like you are mentioning on my 73' with manual brakes a couple of years back. For some reason the pushrod going into the back of the master cylinder kept coming loose and I would have to reach under to readjust it. At one point it was out of ajustment pretty good plus the M/C went bad and gave me a hard break pedal that wouldn't stop the car for nothing. Cure was to replace the M/C and readjust and tighten the pushrod nut once finally adjusted properly. A word of advise. It is very hard to get a wrench up in there to tighten this nut. I ended up having to purchase a set of shorty open end wrenchs to be able to get up into the dash to tighten the nut properly.

Don't know if this is your problem but it wouldn't hurt to check that pushrod.

427-390

Thanks everyone for the information. I will start with the easiest solution and work my way to the most difficult. I'll post a progress report when I get started in the next couple of weeks.

Thanks,

Tony

70 LS1

I vote for a power master cylinder as well. When I did my brake conversion, I had bought a replacement manual master cylinder at the local parts store. It had the right part number, but it was a power master. I didn't realize it until after I drove it and had a very hard pedal just like you described. I took it out and it was indeed a power master measuring 1.125".

You should be able to unbolt the msater from the firewall and move it forward enough to measure the bore without disconnecting the brake lines.

427-390

70LS1, et al,

Sounds almost unanimous on what my problem could be. I'll look into it in the next 1-2 weeks.

Thanks!

ffas23

This could possibly be the case. The back of both M/C's are different. One has the hole inside the plunger for the pushrod deeper then the other. Maybe someone changed the pushrod also to the wrong one.

70 LS1

The early C3's have the same size hole in them so a power master can directly bolt up in place of a manual master. Up to 76 I believe. The later C3's were power only and had the more shallow hole.

427-390

I'll be checking the diameter of the bore tonight or tomorrow night. If it is indeed over the 1" diameter, is there a good source for a replacement? NAPA? I don't want to go to the discount part stores if possible.

Thanks,

Tony

rihwoods

Try these guys..my friend swears by them..he says very good service and quality...he just bought/installed one of their brake kits on his 69 El Camino...

http://www.piratejack.net/mastercylinder.html



Rich

427-390

rihwoods,

I'll keep them in mind if I need to replace the M/C.

Thank you,

Tony

427-390

70LS1,

You were right on target! I checked the bore on my M/C, and the ID was over 1" in diameter. I'll be ordering a new M/C now.

Thanks,

Tony

70 LS1

Make sure you measure the new one before you install it. That was my problem, it was a power master in a manual box.

Ed Blue 03

I had a similar problem on my 73 with manual brakes. The correct master cylinder for manual brakes on a 73 has a larger primary reservoir than the secondary reservoir. When I first bought the car I replaced the master cylinder and they sold me a power steering master cylinder by mistake, it did work but not very well.
I put Hawk Street brake pads on the car to improve braking. Also, stainless steel Kevlar lines. It brakes much better now.