gator79

for those who have done this what was involved? the car is a 71. this is a conversion kit from zip.
http://www.zip-products.com/Zip/prod...CF250346AE3AD1
is this all I will need?

GS977

i'll buy your man brake setup or swap you my power brake setup off my 72 that works fine for you man system.

ratflinger

For that money you can go with a hydroboost unit. I've got a good vacuum booster off my 79. If you insist on vacuum, then you can have it. Either pay shipping or I'll be in Lake Charles sometime the week of April 17

memLT-1

You know I would think you would need new brake lines because the master cylinder will be moved forward because of the new booster.

gator79

I bought a new booster for $82.00, when I ordered my complete brake line kit I ordered it for power brakes so I have the correct master cyl. lines. I already had a new master cyl. so I should be able to do this swap for around $100.00, hydraboost is better but vacuum works just fine. thanks for the offers on parts

gator79

why are you going back to manual? is there something about power brakes I should know?

gator79

here are some pics

you can see the firewall will have to be re drilled so the hole is in the center of the 4 bolts that mount the booster. notice the pushrod location.


this is a pic of the brake pedal from under the dash (sorry for the poor quality) you can see where the bracket is bolted for the brake light switch and the pushrod is above it. it looks like you could just move the pushrod to the lower hole and replace the switch bracket for one with power brakes

BBShark

Gator, Use the 2 bottom holes and drill the top 2 holes 3.50 inches up. There is a 2.25 hole dead center. Your old manual bracket is NOT the same as the power bracket (see picture, manual on right and power on left). You will have to drill new holes on the top of the bracket (for the vacuum booster studs) and drill out the weld nuts on the bottom.

The Zip brake switch bracket looks like mine. It attaches to the lower hole. This is what I don't understand, the brake switch bracket cannot attach to the same hole as the booster clevis.

gator79

here is a pic of my friends 69 vert that has factory power brakes. you can see the clevis in the lower hole and the brake switch bracket in the upper hole. just the opposite of mine with manual brakes. drilling mine like you said should work fine. i am also going to glass in the original hole before I drill the new center hole. I still can't believe this is not a common upgrade, I would have thought it had been done many times.

BBShark

Gator, thanks for the pic and link to the Zip kit. I called Zip this morning and the bracket they have is for power brakes, ordered it. Iv'e been trying to find out what the deal is with this for months. Thanks again.

gator79

here is how you need to drill your firewall to mount the booster.

BEFORE


AFTER


you need to drill out the two lower nuts, where the lower bolts were and redrill two new holes for the top holes. also drill the large hole in the center. I will put a reinforcement plate inside the firewall at the top bolts just for extra stregth. I could not find much about this swap anywhere so I hope this helps the next person that wants to do it. vacuum brakes work fine and are used on 90% of todays cars plus this cost me less than $100.00 thanks BBShark for your input.

70 LS1

resurecting an old thread here. My booster is showing up in the next couple of days and this will help a lot.

Couple of questions. Do the new upper holes go through the metal of the existing bracket? And, what size does the large center hole have to be?


Thanks.

BBShark

The center hole is 2 5/16" and the stud holes are 13/32. All holes are in the metal reinforcement plate (inside of firewall).

I have seen that you were looking at a late C3 booster. Are you switching? Does the later C3 booster offer more vacuum assist? Just curious.

gator79

looks like BBShark answered your questions. it is not a hard conversion at all. hardest part was working under the tight dash. When I did mine I could not find any info on this swap. I felt like myself and BBShark were the only ones who ever tried it. thats why I posted pictures. glad I could help.

70 LS1

The boosters are the same with the exception of the shaft between the booster and the master. 68-76 uses the deep hole masters where the 77-82 use the shallow hole masters. I am using a C5 master which has a shallow hole so I needed the later booster.

Incidently, the C3 and C5 boosters are the same internally as well. I thought that was pretty interesting since there is a 30 year time difference.

ken69

I recently did an upgrade to power brakes on my 69 corvette. I can not seem to get the brakes to work as good as when they were manual. I purchased a power bleeder and bled all calipers. The new master cylinder was bench bled. The car will lock up the left front brake sometimes. It will stop, but not what I expected. The pedal is hard sometime and other times not. Does anyone have any ideas on what is going on. I recently purchased 06 Z51 6-speed convertible from a Forum member. It is a great car. I have owned the 69 since 83'. Numbers matching 70K miles.
Thanks
Ken69
Thank-you,
Ken

carriljc

and they sell a booster w/ master cylinder for 116 bucks (combo platter)......

http://www.autozone.com/autozone/par...5_131640_8550_


plus I guess you'd need this seal?

http://www.zip-corvette.com/ProductDetails/ProductDetails.aspx?pid={3713cea1-f089-4e20-bb2c-c0954bd56e51}&gid={BCCF57FB-D75C-41E8-9ACE-6BD12B9454B2}&pname=68-82+Power+Brake+Booster+Firewall+Seal&Ref erer=&Alias=&ptct=&CTitle=&

Or, I guess you could make one yourself if you knew what it's made of??? What is that seal made of?

I guess that I could not use my existing manual brakes master cylinder? Anybody know?

gator79

no you can not reuse the manual brake master cylinder, they are different bore size internally. I sealed my firewall with dynamat then reflectix.

SuperBuickGuy

you've made sure you have vacuum to the booster? An old hot-rodder trick to get better brakes is to use the manual master cylinder with a booster, so there's little need to change the master cylinder unless you have too much brake pedal. (IIRC manual = 1" bore, power = 1 1/8" bore)

Also, when you connected the rod, did it contact the master cylinder plunger? how have you adjusted it? I know some systems require just a bit of "free pedal" to engage the booster - so if you have the system put together tightly, it doesn't get the opportunity to help you stop

L84s R Us

In doing all of this, the one thing I am not hearing is the adjustment of the plunger rods.

All the booster does is help push the plunger. So if your left front tire is locking up, it has nothing to do with the booster.

You have to make sure there is plunger rods are not pushing when there is no pressure on the pedal.

You have the rod coming off the actual pedal into the back of the booster, and you have the rod coming from the booster going into the back of the master cylinder.

Boosters are the most basic component on these cars. A spring, diaphragm, and a check valve. Very very little to them. But, the adjustment does need to be close to where it should be to work just as it should.

Glad to see you guys are doing it. One of the easiest things you can do to improve your car. One of the cheapest too
.
As we all know, there not too many things you can do to these cars to improve them that does not cost a ton.

I have an extra booster or two if anybody needs one. I have an extra 63 booster (very rare) and a C-3 booster or two laying around.
Best of luck.