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Discussion Starter #1
So I've been dating a girl who has a '55 2 door sedan for awhile now and suggested she change the original brakes to front disc conversion. To say it's scary to drive it is an understatement! I've read about Toms brakes on ebay and we bought a kit. However, her dad, who's been a tri five restorer for 50 years is pretty knowledgeable guy and very sharp about stuff even in his 80's now. He mentioned that the firewall was not built thick enough to handle the weight of a vacuum booster hanging off the firewall and thought it needed a plate to help reinforce it. I read as many threads as I could on disc conversions and nowhere did I see anything about this concern. So I respect his thoughts but also asking the community on yours??? Any considerations here would be greatly welcome!!??

Thanks??

First post and a pic of the car!

322155
 

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have never heard about the weight of it being a problem. nice 55 and cute(GF).
 
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Trifive Automotive Electrical Wiring Expert
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Welcome to the site.
The firewall is not what supports the booster or master. There is a pedal support brace under the dash that has studs going through the firewall for the booster and master. It has support rods that strengthen the brace also.
P.S. With a car like that, she's a keeper.
 

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Nice car!

A booster is way too light, and well braced to ever be a concern for weight. Can you imagine how much force is applied to the firewall when braking with manual drum brakes? Consider how much it will be reduced when changing to power assist disc/drums! A lot less strain on the firewall with a power booster, than with manual braking.
 

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Discussion Starter #5
Ok thanks so much guys!! It is kinda weird to think the metal on the firewall is too thin to handle it since old cars were built like tanks! Just wanted to make sure before diving into it!! Thanks again!!! I'm sure we will get it together!!
 

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My guess is that an aftermarket booster and bracket is lighter than the stock power brake booster - so not to worry about this.
 

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As others stated, it's supported by the pedal bracketry which is pretty thick steel bar. Your or her biggest problem is the auto city kit which isn't the greatest
 

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As others stated, it's supported by the pedal bracketry which is pretty thick steel bar. Your or her biggest problem is the auto city kit which isn't the greatest
I had read that a lot of people where happy with that kit and we've already received it so I guess no going back now.... what are the downsides in your opinion??

Toms Brake Kit
 

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If you need a tech article that covers the installation of the from Tom, send me a PM with your email address.
 

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Discussion Starter #10
If you need a tech article that covers the installation of the from Tom, send me a PM with your email address.
I'll send message right away!! I'm pretty good working on cars but I've never done a brake conversion nor have I really worked on this car at all........ so I don't know what I'm doing and instructions are a nice thing!! My real concern is mounting the brake booster and how much room there is to do it. I recently changed one on a '99 suburban and it wasn't easy. Btw, this car was meant to be a daily and has a '89 5.7L engine/transmission in it......
 

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Dave...Received your PM and have articles on your way. :)
 

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I had read that a lot of people where happy with that kit and we've already received it so I guess no going back now.... what are the downsides in your opinion??

Toms Brake Kit

lets see where to start, Small metric calipers. Moves wheels outward close to an inch. Bracket and spacer installs between spindle and steering arm greatly reducing vehicle turning radius, can't make a U turn, other alignment problems, general low quality components.
 

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lets see where to start, Small metric calipers. Moves wheels outward close to an inch. Bracket and spacer installs between spindle and steering arm greatly reducing vehicle turning radius, can't make a U turn, other alignment problems, general low quality components.
Great stuff SLIM...I knew that it moved the wheels out, but did not know about the metric calipers.
 

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Discussion Starter #14
lets see where to start, Small metric calipers. Moves wheels outward close to an inch. Bracket and spacer installs between spindle and steering arm greatly reducing vehicle turning radius, can't make a U turn, other alignment problems, general low quality components.
What does metric caliper mean exactly?
 

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For me, the biggest single issue is the terrible turning ability and the overall alignment issues. Shortening the tie rods 3/8" is not a good thing
 

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The calipers used in these kits are the same calipers GM used on almost all size cars from late 60's to 1988. Before 1978 they weren't metric, but the size didn't change over those years.
Yes, they're smaller than post 1988, but they've got plenty of stopping power, and a great deal more than drum brakes. I use these same calipers on every car I've converted to disc brakes, and they always stop much better than they did with the drum brakes.
As for the wider track width, that's part of almost any disc brake conversion due to the rotors and how they sit on the hubs. Unless your car has very wide front tires, there shouldn't be much issue. And U turns might take slightly larger turning radius, but how many stock '55-'57 Chevs can do a U turn on a two lane road? I know I rarely do one, and the only time I have is when the road is wide enough to be sure I can.
Your girlfriend will love the better power disc brakes, and see easier, and safer stopping than she has with those manual drums.
 

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The calipers used in these kits are the same calipers GM used on almost all size cars from late 60's to 1988. Before 1978 they weren't metric, but the size didn't change over those years.
The most common conversion caliper is the one for a 69-72 Chevelle/69 Camaro/69-74 Nova and similar BOP cars. It is bigger than the "metric" caliper. The Chevelle caliper is 7" between the anchor pins, has a 2-15/16" piston bore, and takes a D52 pad. The metric caliper is 5.5" between the anchor pins, has a 2.5" piston bore, and takes a D154 pad. They began use in 1979.

There are other 70s/80s calipers but they are just variations on these two. Things like brake hose location, etc.

So there are two calipers from 1969 to 1988, and there is a significant difference between them.
 

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Best kit going IMHO is the zero-offset one from mgchevyparts....You get 68-72 Chevelle type, big piston calipers and it uses 11.2" rotors, and brackets that do not make your wheel stick out any further....Nor does it require a tie rod adjustment and subsequent alignment....Additionally, all parts that can wear out can be purchased over the counter at any auto parts store.....Here's a link to the kit: 1955 1956 1957 CHEVY BEL AIR BIG BRAKE ZERO OFFSET DISC BRAKES BOLT ON | eBay
 
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