The Stovebolt Site Forums The Shop Area Driveline 3100 disc brakes 6 lug PIA

Hi....Chevy 1954 3100 PU...with 235 ...we still have the single chamber MC. I don't mind it but my wife will not drive in the truck unless I do something.....replace MC with dual chamber...along with disc brakes but no power booster. I want the MC in the same under floor position and don't need boost.......but the problem seems to be it's 6 lugs with OEM 15" wheels. Is there a complete kit out there that will solve the problem? Do I need to buy some new type of wheel like a steel smoothie? Or have five on the front six in the rear .....thanks for your help as always.
Steve

There are kits available from several aftermarket vendors that will allow you to keep your 6 lug configuration. Speedway, CPP, Brothers Trucks and even Golden State Trucks (in Calif) all should be able to help you out. I would suggest you contact anyone of their Tech lines and let them know what you are wanting to do, most are more than willing to assist. Good luck

Classic parts offers 6 lug conversions.
https://www.classicparts.com/1947-5...ed-Drilled-Rotors/productinfo/71-975W6//

You can get a power dual MC disk kit in 5 to 6 lug that will fit under floor.

Non power disk setup would be a HUGE mistake.


Many of the vendors are selling variations of the same kits and end up being dropped shipped from the “manufacturer”.

I’ve been looking at the powered dual MC conversions and it seems that they are made for trucks with automatic transmissions. What mods are needed get them to work with the original 3 speed and keeping the original under the cab location?

Steve,
I have done several 6 lug disc brake conversions using the stock wheels on TF trucks. I believe that the brake components are the same for AD trucks with the exception of the booster/MC configuration. I get my conversions from ABS Power Brake in Orange, CA. 714-771-7329.
I also would recommend using a booster.
Fred

Thanks for the help.....but why is not having a booster a huge mistake? I don't want to change pedal location and certanily do not want a ugly booster can in my engine compartment.....could you elaborate....thanks Steve

If you are dead set against power, do yourself a huge favor and stay with drums. There are kits available from all the major suppliers to install disc brakes and power assist while retaining the original under the floorboard mount. You are also able to keep the 6 lug wheels. Any modification whether just changing M/C or going full out power discs will require some amount of fiddling to make it all work. It’s just the nature of the beast. Good luck.🛠

Steve,
As for your question about power brake booster and a manual transmission, the clutch linkage is usually the biggest issue. It can be done with a manual it just takes some creative engineering. I't hard to say what your actual configuration will be as there are a lot of MFG for the brake boosters and mounts. Most of the Kits are for under floor use though.

I have followed these posts about disk brakes for many years as I would like to do the conversion. I have heard that using a late '60s early '70s dual master from a Corvette will work without power. Those Corvettes (from what I can gather) had non-powered disk brakes. Apparently, this master has a 1" bore. Now people are saying don't go without power, stick with drums. Just curious and would like more information and hear from anyone using non-powered disk brakes. I have a'47 1/2 ton with a 4 speed. I don't know if I have the ability to creatively engineer something.

Two separate questions. MC and Disc.
You can buy whatever Dual MC you wish. Boosted or not. As said, they both fit under floor. Whatever one you choose, from what ever vendor, contact them for any insight to what mods will be needed. Also search our archives and the internet to read a bunch of How-to's and get further educated as to the mods if any. It is nice to have boost. It is easy to plumb. Up to you.

The disc kit shown in the Brothers video includes a spacer. I believe that is to space the stock wheel outwards to clear caliper. Sometimes a little grinding on caliper casting/housing is necessary. No big deal. No pedal change. Search this also.
Expect these kits to move wheel outwards a little.

Can't convert these old trucks sometimes without a little mod here and there. These kits have been installed by thousands of DIY'ers. You are not the first.

Rusty, I would recommend buying a kit. I would not venture out and buy parts on your own if that is what you are thinking. The Master cylinder is a standard GM and they do use what is a called a 7" diameter "corvette" booster.

As far as booster or not. A booster allows for easier foot pressure. It does not stop any faster. It is nice to have while you are already doing the job anyway. That's all there is to the story.

Those who say drums are OK are correct for a standard truck. If truck gets "heavier" with Mods: motor, tranny, monster mudders or whatever, it may need Disc. Many like disc brakes no matter what the weight. That's all there is to that story.

The kits are designed for the DIY person. With the use of the internet, you will have no problems that standard tools won't solve.

In the beginning, ladies did not drive a lot. It was difficult to steer and stop. Too much effort, so engineers invented power brakes and power steering. Ladies were shown in all the advertisements after that, to sell more cars. Then "oh yeah, why don't we put that stuff on trucks too"

They don't stop faster or turn sharper. But really nice to have on a old truck.

The kits use the stock pedals and the booster and MC are out out site.
Non boosted pedal pressures are too high for most people that want great brakes with a modern feel. Your wife will not be happy with non boosted pedal pressures.

Bartamos, thanks for the advice. Does anyone know if an aftermarket transmission crossmember would allow the booster to be used with a manual transmission?

Depends:
Some report no conflict with the cross member.

Some report slight modifications required to stock member.

Many trucks no longer have the rear transmission cross member in place. Have been missing for years. There some debate on which models had the rear cross member. Several factory shop manuals make mention of the member with certain models.

The aftermarket universal cross member can be used if required. Small amount of fab work required.


There are several prior post on the rear cross member topic the above sums up the consensus.

Hey this is getting more interesting..... disc MC can be installed in original location under floor board with a booster where would we draw the vacumm from? Also, interference with clutch? Our truck has the sm420 and cross member. Now which kit meets all our needs. The best kit we have looked at ABS brakes. And thanks for the video link. This all seem too far out of our wheel house. Perhaps we will just get a dual chamber MC and stick with drums. This disc brake conversion sounds like a mine field and being an Army vet. I don't like mine fields..
Thanks you guys are great!
Steve

A simple hose from the intake manifold down to the booster inlet is all it takes for vacuum. It's not a mine field. You are the only one who thinks that. The kits are designed for DIY with possible light mods. The video shows the fellow doing it right on the shop floor. Many of us would do it on the bench with a vise and press and etc.

A dual master will not do much. It's a tad safer.
If you are not able to do disc or possible mods for MC, that's OK. That's how mechanics make a living. Most folks who own old trucks like to work on them with a little help from Stovebolt. You have received much info here of all kinds. It's all up to you to decide if the stated goal of........ "wife will not drive in truck until you do something" is met.

Let us know if you need further intel. Refer to my comments at #1333787 and other member comments in this post.

Safety is sissies............I would say dual master is a WHOLE lot safer. Single master: If the driver is keenly aware of the brake feel and there’s a leak at the wheel cylinder. The brake feel will change slightly.........but..........there’s a point where it goes from long travel soft brakes to NO BRAKES. Dual master leaks go to less braking but not zero.

On the mod list post: brakes and seat belts are on the top of list.

I don’t want to hijack this thread, but it’s in line with what I would like to do. In my case, I have a manual 3 speed with “three on the tree” in a ‘52 1/2 ton. I have heard that the linkage for the shifter also causes interference. Do we have any “bolters” that have made this dual MC w/ booster conversion, that can share their experiences?

I am sure there are others in the same boat and could benefit from this info too.

Funny I was just reading an article in the January 2020 issue of Hot Rod magazine page 88 thru 91, that goes into a lot of depth about disc brake swaps.
There is discussion about rotor size and wheel clearance on page 89, and about master cylinders on page 90 & 91.
Good luck!!
One other thing, I have checked out a lot of the disc brake kits and none of them say you can use 15" original wheels with there kits. From my reading I do believe it can be done with some grinding.

Probably a dumbo question from a rookie, but I would like to know anyway: So I have my vacuum line for my windshield wipers already connected to my manifold intake, I also connect my power brake booster there?

Thanks as always

No, you need about a 1/2 inch I.D. hose for more flow

I run the dual corvette style M/C with drums all around and I have very good braking action. Better than the single M/C.

With no booster, it wont fit with a hydramatic transmission in the original position under the floor.