1970 C50 Brakes

[bts2]

Hi all,

new to the forum - I've got a 1970 Chevy C50 dump that I acquired with some property. It's been sitting for a while and I am going through it to get it running and stopping. Engine is almost there - still going through carb and sticky valves - bad old gas.

Now I am over to the brakes - I have none - pedal to the floor. Booster falling apart. Before I start getting into some bucks for obscure parts, I read in another thread to consider replacing the single MC and remote booster with a standard firewall mounted dual circuit MC/Booster.

Is this a good idea? any pointers on years and parts from donors? How do I ensure I maintain the load capacity of the truck (with the DMV?)

Thanks for your help,

BT

[cerial]

Breaks are the most important part of a truck with steering coming in a close second.

Running Hydroboost is highly recommended.

But, I can tell you right now that the DOT does not like any modifications so you need to ask yourself what you will be using this truck for. On the state level you should contact more then one shop that does inspections to get a unbiased opinion to see if your are going to have trouble with the updated and improved system.

As far as maintaining the pressure with hydroboost. You will. If you are using vacuum/hydro then hydro boost will make enough if not more pressure then the stock system.

There is nothing wrong with running vacuum/hydro. It is a good system and can be maintained easily enough. Just be glad you have a Chevy. I have restored a few old trucks to stock "show points" condition before. Short version is that I will never do another air/hydro Power Wagon again. The less expensive dual circuit in my current 67 "points" project was bought based on the nightmare finding air/hydro parts and getting bent over by the big 4 who still sell parts.

I would suggest moving up a few years when you replace the master cylinder to give you a dual circuit and don't think one person except for a points judge at a show is going to say anything bad about the upgrade. The rest of the system is good in stock form. Just replace the wear components and call it done.

[colgad]

Replace both the vacuum booster and the dual master cyl as a set. Is your booster under the cab or on the firewall? If under trash it and put your new on on the firewall.

Be prepared to spend some cash on the wheel cylinders, there are two for each backing plate and they are large. Your going to need a friend to remove the drums or you will forever have back issues. Replace all of the steel lines, along with the ones that run from the top wheel cylinder to the bottom wheel cylinder.
I have told myself that I will never do this again I am swapping front and rear axle to get disk brakes on my current 67 C50.

[bts2]

Should I put the booster on the firewall like a conventional car/light truck - between the pedal and MC? Right now, it's under the cab and it's spent...

Current MC is a single circuit. If I go dual, can you recommend a MC and booster to use - year of donor vehicle?

How would I split the system? The 70 C50's have an odd split where the fronts and one of the rear cylinders is one circuit, and the other rear cyl is the secondary circuit. Do it that way? diagonal? Front/rear?

don't think I'm ready for discs just yet - maybe later... Thanks for the headsup on the drums though - everything on this truck is heavy.

Thanks again,
BT

[colgad]

Spilt it front and rear.

Yes Booster on firewall

I am using a TopKick Master and booster but I am using hydroboost
Do you have power steering? If so you can use it too.

But Ill look around and see what may work with a vacuum booster

I had a 72 C50 with the booster under the cab and a second master down there too. all though mine was still all one system. Loose one brake seal and it's all over.
Post a photo of your truck! Here is my first one (sold) and my current one.

[bts2]

I do have power steering so hydroboost would be an option. I want to keep the GVWR if I can and the dump bed and maybe put this thing to use

Nice trucks - I'll get a pic soon - mine's still a little rough...

thanks

[colgad]

Originally Posted by bts2

I do have power steering so hydroboost would be an option. I want to keep the GVWR if I can and the dump bed and maybe put this thing to use

Nice trucks - I'll get a pic soon - mine's still a little rough...

thanks

Thinking about picking this up but I don't know why. But it's just so cool.
http://sarasota.craigslist.org/cto/4582688095.html

[mrolds88]

Is your MC like this? My C50 has the Hydrovac system. Parts aren't quite as obscure as one might think. I can't speak for the other type setup with the booster on the firewall. I am pretty sure that the pressures are different between the two systems.

[bts2]

Yup, same single circuit MC and same 350 small block. Booster under the driver side cab.

I've found most of the parts at Carquest here but since they're all bad on my truck, instead of sinking money into an outdated braking system on a truck where originality doesn't count, thought I'd investigate a more modern layout. Doesn't have to be hydroboost, but that does seem cool- my diesel pickup has a similar layout. I just wanted mostly to get a more failsafe dual circuit system. If I can save a little with a more common booster or a hydroboost, and get better braking, all the better.

thanks

Originally Posted by mrolds88

Is your MC like this? My C50 has the Hydrovac system. Parts aren't quite as obscure as one might think. I can't speak for the other type setup with the booster on the firewall. I am pretty sure that the pressures are different between the two systems.

[mrolds88]

Originally Posted by colgad

Thinking about picking this up but I don't know why. But it's just so cool.
http://sarasota.craigslist.org/cto/4582688095.html

Gak!!! Thats stupid money for that!! It smells of a pickup conversion!!

[bts2]

That's a great truck. It's got the right frame and axles, trans and air brakes to not be a pickup, no?

[84rzv500r]

Originally Posted by colgad

Spilt it front and rear.

Yes Booster on firewall

I am using a TopKick Master and booster but I am using hydroboost
Do you have power steering? If so you can use it too.

But Ill look around and see what may work with a vacuum booster

I had a 72 C50 with the booster under the cab and a second master down there too. all though mine was still all one system. Loose one brake seal and it's all over.
Post a photo of your truck! Here is my first one (sold) and my current one.

Funny, I have been to Lutz Fl many times.. my aunt used to live there... I am over in palm beach...

Which year top kick MC and GVWR rating if you don't mind me asking? I have to modify my diver side valve cover on that big Detroit to clear the MC if I use a Hydro-boost and MC from an 87 C-50. Its a little hard to see as the picture is fuzzy but you get the idea.... I have all new brake lines run for a dual line system and just need to figure out this last piece for brakes...

[colgad]

Originally Posted by 84rzv500r

Funny, I have been to Lutz Fl many times.. my aunt used to live there... I am over in palm beach...

Which year top kick MC and GVWR rating if you don't mind me asking? I have to modify my diver side valve cover on that big Detroit to clear the MC if I use a Hydro-boost and MC from an 87 C-50. Its a little hard to see as the picture is fuzzy but you get the idea.... I have all new brake lines run for a dual line system and just need to figure out this last piece for brakes...

92 TopKick not sure of the Weight sorry. I have scraped the cab.

[84rzv500r]

ok,, that what i thought... I run a similar set up on my 71 corvette and wilwood calipers. think the issue will be master cylinder piston size/volume... have seen is the cars and small trucks run 1 inch to 1.125 MC bore and the larger trucks run from 1.250, 1.50, or 1.75 depending on the brake system.

It's a pascal's law thing. I am going with a 1.75 MC and a hydroboost from 87 C-60 that has the same brakes as my truck.

Thanks for the info.

[colgad]

Originally Posted by 84rzv500r

Funny, I have been to Lutz Fl many times.. my aunt used to live there... I am over in palm beach...

Which year top kick MC and GVWR rating if you don't mind me asking? I have to modify my diver side valve cover on that big Detroit to clear the MC if I use a Hydro-boost and MC from an 87 C-50. Its a little hard to see as the picture is fuzzy but you get the idea.... I have all new brake lines run for a dual line system and just need to figure out this last piece for brakes...

I meant to tell you earlier that what a great job lengthening the bed. Like to talk to you about how you cut it. And did you take the bed sides off the bed floor or did you keep it all together. What are you going to do for flares. I have though of stepside fenders cut down to size and even though I have a fleetside bed also I have thought of having a widened step side.

[84rzv500r]

Originally Posted by colgad

I meant to tell you earlier that what a great job lengthening the bed. Like to talk to you about how you cut it. And did you take the bed sides off the bed floor or did you keep it all together. What are you going to do for flares. I have though of stepside fenders cut down to size and even though I have a fleetside bed also I have thought of having a widened step side.

I just used a Sawsall and cut it apart... took a while to get it jigged up to weld back together and have the lines look good. i am using parts of the donor box as repair panels and patches for the bed floor. I am trying to decide if I am going to lengthen the inside to match or not... I am planing on mounting the fuel tank in the 28" long front section and have a couple options there... regarding the rear flares. I bought a C-65 Dumptruck and cut the 8" wide front fender flares off to make rear flares from... they line up very well and look good but they are in rough shape rust wise and will require a LOT of metal work to get right... SO if i can find a set of C-60/65 front fenders and lower extensions i will go that way.. I am also looking at using 2006 ish Dodge megacab shortbox dually fenders as a backup plan... I dont like the stepside fender look so I ruled that out early on.

[colgad]

Originally Posted by 84rzv500r

I just used a Sawsall and cut it apart... took a while to get it jigged up to weld back together and have the lines look good. i am using parts of the donor box as repair panels and patches for the bed floor. I am trying to decide if I am going to lengthen the inside to match or not... I am planing on mounting the fuel tank in the 28" long front section and have a couple options there... regarding the rear flares. I bought a C-65 Dumptruck and cut the 8" wide front fender flares off to make rear flares from... they line up very well and look good but they are in rough shape rust wise and will require a LOT of metal work to get right... SO if i can find a set of C-60/65 front fenders and lower extensions i will go that way.. I am also looking at using 2006 ish Dodge megacab shortbox dually fenders as a backup plan... I dont like the stepside fender look so I ruled that out early on.

If you see any more C5X front fenders let me know I like that idea. Tough to find used C50-60 sheetmetal anywhere

[colgad]

Here is the HydroBoost from an Astro I have on my 67 C10. I may try this on my 67 C50 depending on the cost of the TopKick version.

[colgad]

Yea, that sounds like a good plan. And would like to know how that goes.

By the way my Daughter used to live in WPB now married in Coral Springs.
When I get down that way Ill see if I can drop by, love to the the truck and the vette.
I have a vette buts it's an 04 Z06, not a classic but still a fun car!

[bts2]

Thanks! I'm good with the hose routing, what I'd like to see is the actual hy-power booster and m/c installed on the firewall. Is there no electric motor like on the smaller cars and trucks? Why did GM offer the "hy-power" and the "dual power" options where the dual power also has a vacuum booster?

[colgad]

Electric motor? I have an hydroboost on my 67 and trust me there is no electric anything on it.

[bts2]

Sorry for the noob response. I am familiar with hydroboost where there is either a gas accumulator or electric motor as backup. Since I don't have a donor, I'm going off of diagrams and random pics that indicated an electric motor backup for the hy-power option, whereas the dual-power option has the traditional vacuum booster behind the hydro-boost. I'm still learning - if you have pics of the setup under the hood, that would be awesome. So it goes like this:

pedal-rod-hydraulic booster-M/C-balance valve-wheel cylinders. Guess I need to hit a junkyard. There's a rod in between the booster and MC right?

[84rzv500r]

the medium duty Hydra-boost has no nitrogen charged accumulator...

yo u can google and/or ebay to get pics and specs for the components.. it matters a bit what size slave cylinders you have...

[bts2]

thanks - i've googled away and found pics of the booster and MC but not the whole system. I don't want to go on a parts bin shopping spree without understanding the whole system first. I'll keep looking for pics of an actual truck or look around the yards here. I gotta pull the old stuff out too from the 1970 to get the bore diameters and such.

[bts2]

Guys, further research here... the 83-87 Hy-power brakes have an electric motor under the hydraulic booster to back up the boost when there is no flow from the steering pump (engine off, pump failure, blown line...) The other brake option those years is "Dual power" which uses both a vacuum booster AND a hydraulic booster, where each backs up the other.

Now, mind you, I haven't laid hands on either yet but I have talked to the rebuilders and got several system diagrams. See attached shot from the Chevy Medium Truck 87 Service Manual.

Are you guys sure about the no electric motor backup ?

Colgad, can you post pics of your 67 booster setup - would be awesome to clear up my fuzzy mind.