My ‘68 L68 powered convertible has manual steering and manual brakes.
Its a numbers matching car so I want to keep it as factory as I can but the brakes could be better. The manual steering I can live with but though the manual brakes are adequate for everyday driving I’m worried that if the need for a panic stop comes up it will come up short. Seems everytime I take the car out someone feels the need to zip around me cutting it close getting in front. Tesla drivers mostly it’s like they feel the need to prove something, ok whatever but I’ve had some close calls. I try to just do my thing but the car is a magnet for it.
I’m thinking that if I stay with proper ‘68 parts swapping over to power brakes wont hurt the cars originality or value. Am I right ?
I haven’t looked hard at the conversion yet but is it more that much more than installing a power booster and master cylinder?
I assume it is simple but since I’ve been wrenching this car I’ve learned Vettes have their own uniqueness and quirks to deal with.

 

The car will not stop any better with power brakes. The only difference is the force required to push the brakes. I can easily lock up my manual brakes with my foot.

 

You need to loosen the brake rod under the dash.
The bolt holes in the firewall and the big hole needs to be enlarged.
To secure the new booster you will need a universal that is duct taped to stay straight.
You might need a different brake light switch.

 

i’d try a pad and tire upgrade before swapping to a factory power assist system. pedal feel sucks at best with power.

 

The problem with factory power is lack of feel. Just like manual steering, the car is way more like a race car with manual brakes. The road feedback and feel is way more fun to drive…..if you are capable of knowing the difference.

 

As stated above, the stopping distance or quickness won’t be any better with power assisted brakes.
It does seem that way when you compare the 68’s manual brakes to your new daily driver.
About the only true way to improve the stopping distance or quickness and efficiency of your brakes would be to replace the oem four piston calipers and 11” rotors all around with a set of larger six piston calipers in the front and four piston calipers in the rear, and increase the brake rotors to 14”.
This would increase the amount of contact or grabbing area on the rotors and greatly increase braking efficiency.
Wilwood has several package kits available that will fit with the oem rally wheels, or you can contact their customer service technicians who can help you build the right braking system for you needs.
The only down side is going with larger diameter rotors may cause you to replace the 15” rally wheels with 17” wheels and tires.
The plus side is no one would know you made any changes (if you choose an option which will fit with your rally wheels), and changing the calipers and rotors is all bolt on.
You wouldn’t have to drill any holes or make any modifications to your car that can’t be easily swapped back to the oem brakes.
I went with Wilwood’s D8-6 six piston calipers in the front and their D8-4 four piston calipers in the rear and will be replacing the oem 11.25” rotors with new 11.25” rotors.
I did a test fit and the new calipers and rotors will fit using the original rally wheels, however I did increase my wheel and tires to 17” so I can install better tires than those available in 15”.

 

that is true. Honestly the VW beetle I had was even better for that with its manual brakes and steering
As for the calipers the rear does have the 4 piston as did replace them with factory correct pieces. The fronts, I’m pretty sure they’re auto zone replacements which I’ll deal with this winter. One of the rear brake hose collapsed on me about 2 weeks back locking up the right rear caliper. New hoses in back fixed that and improved brake feel. I bought hoses for all 4 corners but haven’t done the front yet. I suspect that may improve the brake feel further yet. Perhaps semi-metallic or ceramic pads may help too.

 

Well the one point everyone is missing here is reaction time. Having driven, and raced, both systems, I would prefer one for the high speed track (manual) and the other for the street (power). On an autocross, where quick reaction time becomes so important, it may even be a toss-up.

The point about improved feel on the manual brakes is very valid. But realize that is most useful when you are threshold braking at the limit of adhesion, near 1G, preferably on a race track. Not something you do very often on the street. The quickest stop is when you have about 10% tire slip, just like in a turn, and you have to be able to modulate it precisely to hold it there. The power brake system has more hysterisis?. You can back off the manual system say 5% and feel the difference, where the booster "numbs" the feel down enough that you back off 10-15% before you feel the difference. So it is easier to hold the tires at their limit with the manual system. On the race track, where you might need to lose 60-80 mph, this could really matter. But in an autocross, where you just jab them for a sec, to scrub off 10-20 mph, not as much. On the street it would not matter at all, because you just do not (ever) brake that hard, to slide the tires.

But the manual brakes also require almost double the distance to move the brake pedal, to get the same amount of force. The smaller bore MC piston requires more stroke to move equivalent fluid. (The pedal movement specs were in the manuals somewhere). That takes time. The other thing is the manual brake sat higher off the floor on my car. I guess they all do? ( 2 year old Stone stock 75). I had to lift my ankle and leg off the floor to reach the pedal. On a power brake car the pedal was lower and my ankle can stay on the floor and just quickly rotate the foot over to the brake pedal. The difference in rection time will be substantial. On a race track it would not matter, because you are carefully planning exactly when you want to apply the brakes, so the extra pedal feel of the manual system would take precedence. But OTOH on the street, when some moron unexpectantly cuts you off, your reaction time to get your foot on the brake pedal and the pedal to floor will be much less with the power system. At a velocity of 88 ft per sec (60mph), even fractions of a sec will make a huge difference in impact distance. I would not care about the feel in a panic stop situation, I just want it on the floor, ASAP.

They each have their place.

 

All the science that makes all work on the track is something I’ll never do, at least past a dragstrip.
Getting cut off by a moron whose mind is on anything but driving and anyone else is all too common as I live on the Jersey Shore. It’s that much worse during summer tourist season.
Driving a valuable classic thru summer traffic is like everyone else is behind the wheel of a bumper car.
I’m guessing I’ll take what I’ve got and make sure everything in it, every inch is as good as it was designed to be if not better with more modern pad designs available.
I appreciate everyone’s input on this and it greatly helps my decision making process. If I were more in the pines where traffic is low it wouldn’t be an issue. Here closer to the shore just taking the car the few miles from home thru beach traffic to Asbury Park to drive the circuit can rattle your nerves. Once your there your among car minded people and it’s a safe place but getting back home you have to drive thru the gauntlet of idiots again.

Oh ya, we are also heavy with deer out here.

Greetings from Asbury Park !

 

Everything about these decisions is about the “Experience” you want to get out of the car. All other factors aside, I choose that first…..otherwise I just drive a modern car. I just bought a C6……it’s fun, comfortable, and fast……but it’s not the same as my 77.

 

Excellent points raised by the other respondents.

If you want to stay with stock components, you’ll need a lot more than just a power booster and master cylinder. You will need to change the relay rod, the pitman arm, obtain the power steering pump, steering cylinder, power control valve and related hoses, steering cylinder bracket, pump brackets, pulley and belt.

Know also that the factory power steering doesn’t have the best record. Fairly prone to leaks. The force exerted on the left frame rail from the steering cylinder is known to result in frame cracking.

A very popular conversion to power steering is the Borgeson unit. The downside to the Borgeson is you need to collapse the steering column ( effectively destroying the collapsible column safety feature).

 

I actually like the manual steering though it is tough parking. I like it over power steering for that feel. There was a lot of slop in the steering when I brought the car home but I freshened that up taking care of that issue. It’s the brakes I wanted more from. The plan now is to freshen up everything in the brakes too and re-evaluate it when that’s done.
I’ve got a bunch of vehicles new and old and even my Tacoma seems to hold the road better at speeds near 100.
I love these because they are brutal and primitive. The entire experience is exhilarating. Could use more from the brakes though.
This car has the HD 3.08 posi in it and from the power it puts out and what it’s tach’ing on the highway it feels like it’s quite capable of pinning the speedo.
Not with me driving it though . The guys who did that with these in factory trim on biasply tires back in the day were nuts !

 

To do the power brake conversion just like factory, you would need a power brake pedal box, different brake light switch bracket, pushrod and master cylinder. Not a horrible job, but the pedal box swap is not much fun.

I went the other way, from power to manual, and much prefer the feel of the manual brakes.

Bill

 

My dad's '70 has manual brakes. With equal pads, compared to my '69 power assist car I prefer the manual system.

 

I have the exact same car and the exact same issues as you with shitty drivers and a car that at best would slow down but not stop, especially in an emergency. As to what you need to do, the first thing you can do is change pads to ceramic pads, I didnt but the old pads stopped the car on a dime after the power brake upgrade. They will stop the car really well but are really dusty...But if you have the wrong master cylinder in there or its just the way your car is as mine was they swap is fairly straight forward. THe hardest part is getting the nuts off the bolts up under the dash. You best bet to make this bearable is to remove the steering column so you have plenty of room as well as the drivers seat. The 68 does not have the same brake light switch as the 69 and later cars and it has to stay where it is.
You have to cut and egg shaped hole in the firewall and the metal support is already shaped the way it needs to be so you can cut it easily with just a sawsall blade with out the tool. I have a small write up about it and you can find alot of how tos. The best bolt in master and booster combo I have used is made in the USA by Tuffstuff. You have to pay attention to the part number as the list them as 4 wheel drum, disc/drum and disc/disc.
https://www.summitracing.com/parts/t...ette/year/1968


you have to change the length of the pushrod that attaches to the pedal or buy the appropriate one

https://www.corvetteforum.com/forums...onversion.html

you should also have the power brake hole on the pedal arm as the manual brake is the top one and the power brake is the lower one i believe

 

My 66 had manual brakes and a single reservoir, never had a problem stopping that car.

 

Hi Lt.Mike, I went completely through the manual brakes on our '68 bb last year. Replaced everything - lines, hoses, calipers, rotors, pads, mc, etc. I bench bled the mc, motive bled the systems 2 times while I had it hooked up. Great pedal, great feel, and I really like them. Properly set up, I think the brakes on C3s are very, very good. I feel the same as you and others about stupid drivers. I'm considering installing a diesel type horn on it.........................

 

I am pondering power brakes on my 68 also. I'm leaning into a Hydroboost rig though. Looks like it might be simpler.

 

Never done one, it operates off of a power steering pump i believe so you have to fit that in there somewhere.....i think someone was selling one here recently...glanced at it as i had no need

 

found this...some good info
https://www.powerbrakeservice.net/ne...ydroboost.html