The Stovebolt Site Forums The Parking Lot Big Bolts Big Bolt Brake Solution!

THIS IS NOT A FOR SALE/ADVERTISEMENT POST. THIS IS FOR RESEARCH PURPOSES ONLY

Hello everyone,

I am curious as to how many people would be interested in a direct Bolt in replacement front disk brake setup for the 1.5/ 2 ton big bolt trucks? I know many have struggled with this issue so i'm keen on coming up with a solution to make everyone's life easier when updating your stopping power, so you all don't have to hunt down old parts modify them, and piece it all together. This will determine whether i create a one off set or put in extra work to have them produced on a larger scale.

I am also looking for someone who is exceptionally knowledgeable with any differences between year/ model/ straight axle as it will help me help all of you!

Thank you guys!

in my opinion (others may chime in as well) you need to do both front and rear since on a big bolt, most if your braking happens at the rear axle as opposed to a car or light duty truck where most braking is done at the front axle.

That said, 55 and earlier have the 5/10 lug setup, where in 56, they went to the 6 lug pattern. I may be beneficial if you are making them, to have an option of bolt pattern.

While i agree with you 100% offering a rear disk kit first would seem... strange to most. One step at a time, first front and if that works well then rear. When the time comes ill be collecting information on rear axles and differences between them so everyone can benefit from it.

My idea for the front would have included all designs if possible (1.5/2ton) with different lug patterns, I would like to be able to help everyone out with their project as much as possible since these trucks are so neglected in the upgrade/ parts department.

GMC discs are available for the 5/10 on 7.25" bolt pattern.

Ed

EdPruss, please tell us where these discs are for sale and who sells them? Simply stating they are available doesn’t help anyone are you talking about the GM 3500HD front discs from 1994 to 2000? This isn’t the same center pilot circle as our older trucks. Such a conversion isn’t a bolt on and would require different rims and much more. I’d love to buy a disc conversion for a 1.5 ton, but so far I’ve not seen any info whatsoever that shows a decent conversion.

https://www.rockauto.com/en/catalog/chevrolet,1998,c3500+pickup,7.4l+v8,1303490,brake+&+wheel+hub,rotor,1896

See if that link works

1991-2002 Chevrolet made the c3500hd. It was a 15000 gvw truck. They use the same 5/10 on 7.25 bolt pattern as our AD big bolts. The had discs all the way around and would be a good source for parts.

I've got the dana80 rear axle out of one, and plan on turning the hubs down to 4.75" diameter so our original 20" wheels would bolt up to a modern disc brake rear axle with a ton of different gear options and plentious parts.

Tony,

GMC factory parts for P-3500 HD solid front axle trucks. Build proper sized spacer for rotor ID to fit front spindle/rear hub diameter, use companion calipers, clamp to rotor with air, build mount.

Probably need power brakes or hydrovac, min. 19.5 wheels. Not a hardware store exercise, but I'm sure there is someone in Idaho they could do that. Good luck.

Ed

I think it would be easier to just swap in the entire front 3500HD axle and deal with adapting the steering and lead spring mounts than to try and cobble together the brakes over from the new axle to the old.

Might be too wide, that is why Grigg's idea with P-30 spindles works.

Ed

Basically my thoughts are to keep it simple, & easy. Literally no thought process. If you can turn a wrench you can install the setup. Unbolt your old spindle take it right off the axle bolt on a complete ready to ride spindle, hook up your new brake hose and you're done. (Figureatively speaking) we all know that the brakes have to be bled, the wheels have to be put back on master cyl needs to be changed etc. My idea is to take out all the guesswork for everyone else when it comes to the hardware, no need to piece together, modify, research what will and wont fit correctly. I want it to help people with their projects. These trucks were fantastic back in the day but, speed limits have increased, traffic has increased, stopping distance needs to decrease. Our 1/2 ton counterparts are lightyears ahead we are basically sitting in the stone age. Ideally, when im "done" ill have updated front & rear brakes, steering, and powertrain swap. Ready to 100% modernize your big bolt. Im using mine as the guinea pig and hopefully everyone can benefit from it. Thats why i put out this feeler, to see if im making a one off set or if everyone wants a piece of the pie.

I like the idea, I wont lie, but simultaneously, likely wont go the route ever. For the cost, even if kept super cheap, one would be able to reline and continually rebuild their drum setup for years upon years, and that's assuming they use the truck weekly and cover a lot of miles. For most with these trucks, they may only need to do brakes once or twice in a lifetime given that most just don't work these old girls like they used to be. Also, and I cannot nor will not speak for everyone on this, but technically you "shouldn't" even use the brakes all that much, its all about downshifting and engine braking. The brakes really only come into play with 2lo rolling stops. This doesn't factor in emergency hard braking though, there would certainly be a benefit there.

That said, I am more interested in how you plan to run the brake system. Maintain the factory hydrovac and 1 line setup or go for something better. Id be all for a different system that wouldn't break the bank like running a dual hydrovac setup. Dual hydrovacs aren't hard to do, but hydrovacs in general are just, ehhh, expensive to have rebuilt, and then the whole doubling it and trying to generate what size units you need for front vs back. Hydroboost is an option, but if the truck doesn't have power steering then there is a process of modification just to make that work.

In short, cool idea, how do you plan to plumb and power it? Also, fluid pressures for drums vs discs are different in modern setups; have you accounted for that in this swap?

The availability of disc brakes in an all in one package might just keep some of the bigger girls from going to the scrap heap.🛠

"If wishes were horses, beggars would ride!" Asking someone else to do all the thinking, research, and development on such a conversion isn't very realistic. If it were that simple, don't you think somebody would have figured it out by now? People have made several very good suggestions about possible donor vehicles, but all of them involve including a really nasty 4-letter word - - - - - -"WORK!"
Jerry

WORK!

You had to live in that time to understand Work!

(Maynard G Krebs - my hero)

You would change the master cylinder to account for the change in brake hardware/type. At that point you could would also run your own lines. i think thats pretty simple for anyone to do but i do understand everyone's skill level is different.

This is exactly my point. Not for nothing these trucks are everywhere and nobody touches them because its so difficult to update them, Nobody makes anything for these trucks.

Well, im actually going to be partnering with someone to redesign the spindle to accept easily accessible brake parts. So i am going to be doing the hard work.

Be careful with GM 3500 axles, there are at least two styles of steering arrangements I know of. One is the box is in front of the axle, drag link moves fore and aft, may be specific to 'P' models. Other is box is inside of frame, Pittman arm moves port and starboard, tie rod moves to starboard side of frame. One is not interchangeable with the other.

P-30 spindles(disc brake) suitable for our trucks have the box inside the frame, behind the axle, shaft goes through the frame, horizontal drag link moves fore and aft, hooked to curved steering arm, tie rod behind axle.

Ed

I would definitely be interested in a bolt on disc brake solution. I have a 1955 Chevy first series 6400 2 ton truck. I am restoring it to haul firewood from the mountains, steep trails, so I need all the braking I can get. The rear brake shoes are 4" wide, front are 2 1/2" wide. I'm not sure what proportion of braking the rear brakes do but I do know that front disc's would improve the overall braking. Please keep updating your post as you make progress.

It sounds like you have adequate shoes for the load you have in mind, is your hydrovac working properly? Modern Chevy and GMC 3/4 or 1 ton trucks and Toyota trucks have proportioning valves hooked to the rear axle with a simple rod so when there is a large load, more power is sent to the rear brakes. One could get one of those valves and hook it up as designed, or
Make you own connection. Your truck might not have enough differential height to work properly as designer for modern trucks.

Ed

For me if the cost gets into the neighborhood of what I could buy a modern chassis for I would probably do a body swap before I paid some good money to upgrade the old axles. The only kicker is on my 57 I really like the 6 lug wheels so something to retain those would be cool.

I have been making bolt on kits for these big trucks for years. I have it all figured out with parts list. Uses a 15" rotor, dual piston calipers a dual circuit vacuum busted master. I have sold about a dozen kits and have another 10 being put together right now for a few customers. Used to have a right up on Stovebolt, but think it was lost in the server update a few years ago.

Anyway, it's already been done. but I found that most don't want to pay what it is worth to buy the kit!

Link?
Photos?
Part list?
Cost?

You say most don't want to pay what what YOUR kit is worth... I would have to point out what was said above. Most of these trucks aren't daily drivers and aren't full custom builds, if the price point isn't comparable to rebuilding the original brake system how do you plan on trying to justify a presumably MUCH cost on a truck that is probably not going very far, very fast or very often.

I can't remember if the front hub is integral to the drum... I think it is like the rear where the drum is separate-in that case:
The only way I think it will every be economically feasible is a rotor and hat to replace the drum and mount on the existing hub
Custom rotor (diameter, thickness and swept area to match caliper below) and hat (aftermarket 2-piece) $200 X4
Custom caliper bracket $150
Off the shelf caliper from a comparable GVW GM truck $150 X4
Off the shelf master cylinder from same truck as above $100
Off the shelf booster $250

The rotor hat would be the hardest part, getting it to move the rotor inboard away from the wheels far enough and keeping the diameters small enough to get a common caliper (like a modern 1 ton size). still the inner diameter has to be big enough to clear the large hubs.

That adds up to about a $2000 'kit'

If your old parts are no good and you have to buy some thing anyways... wheel cylinders, shoes, lines, master cylinder, booster... offsets the cost some.

The “KIT” Randy puts together has been engineered to fit right the first time. As he said the kit has been available for years with no complaints that I’m aware of. He used to donate a little from each sale to Stovebolt.com and we had a link to his company in our left margin. I don’t know what the cost of the “Kit” is because I have no need for one but I’m sure it beats having to Engineer your own kit. Call the number listed in his signature line and chat him up.

I'd call if I needed a new brake system...

For the benefit of the forum - it would make more sense to post the information so that everyone can access it.

The current pricing with the off the shelf parts and the fabricated parts puts you between $3,000-3,500. This isn't something that I have marketed outside of the Stovebolt forum, so I don't have a web page or anything like that.

I also will not post my parts list!

If interested, feel free to send my a private message, email, phone call or text!

Thanks,

Do you sell just a master cylinder setup for the 57 6400 2 tons? Retaining the original drum brakes is just fine for my use but dual circuits would be nice to have.

Hello Captain Hook,

This post should really be in the driveline forum as it is a sidebar to the disc brake conversion.

Cheers,
Super 55

My 2 cents... Blackviking60 has it right! A reasonably complete bolt up get me on the road kit woud be delightful!

A cheap conversion would be great but personally what I did is I went and picked up a set of axles out of a 82 truck that someone was parting out for only a few hundred bucks. Granted a axle swap is a lot of work but I needed a cheaper solution to get away from my widowmaker rims than spending 2500 dollars for a set of aluminum rims that I didn't really like and my brake system already needs rebuilt anyway.

On the topic of a master cylinder solution through several weeks of research I found that a 2005ish npr or w5500 cab over truck has a vacuum system and the mastercylinder is a dual resevior deal with a similar bore to the power brake master in the truck the axles came out of so that is a possible solution for upgrading a master cylinder

Good luck finding someone to insure a vehicle with a cobbled-together brake system! Even a fender bender with minor injuries would be an ambulance chaser's wet dream if the modified brakes (or suspension and/or steering) ever became known to the "injured" party! I've been on standby to be an "expert witness" several times when I was doing warranty claim investigations. All the cases were settled out of court once the legal beagles read my detailed written report on the systems I was hired to inspect. I don't think anyone wanted me to actually take the witness stand!
Jerry

Hy AlexB, we have many different opinions represented in all of our forums. Many Big Bolts provided years of service with their factory designed single circuit brake system with very few catastrophic failures, that being said, as engineering of braking systems improved the newer Big Bolts were equipped these engineering improvements. What we are discussing here is the marriage of newer braking system technology with original front axles and replacing single system master cylinders with dual circuit master cylinders with a different method of achieving boost for those master cylinders. I believe most of us who attend here are not certified mechanics or engineers and the marriage of the two different technologies must be done properly and with everyone's safety in mind. As far as I am aware our Big Bolts single system brakes are not ILLEGAL, and as I previously stated were used safely for years until technology in braking systems improved. If one chooses to "improve" his Big Bolts braking system with newer technology he should have the appropriate knowledge to accomplish the task, or take it to someone with that knowledge, an engineers certification of the modifications would also be a good idea. It sounds like one of our members has come up with a kit to convert our front drum brakes to disc brakes, he has done all the work for us if we choose to purchase his kit, if that is the case all we have to do is install the kit and a dual master cylinder system to make it work. If we choose to restore the original single system braking system we can be confident in its ability to safely stop the truck when loaded as designed. If one chooses to upgrade the braking system on his truck the work should be done by a certified mechanic or the finished project inspected and passed by an engineer.

The world is full of people who fancy themselves to be more intelligent than the designers and engineers who make a living using their millions of dollars' worth of research lab to produce brake, suspension, and steering systems that work for hundreds of thousands of vehicles. With a resume' like that, those hotrodders should be working for General Motors, Chrysler, Ford, or maybe Peterbilt!
Jerry

3B I think maybe your right in saying not Illegal on brakes,seems like a better lever brake system on the driveline that can be applied as a smooth additional braking force in the form of a large disc brake that is also a parking brake when stopped. Someone commented much earlier about brake application using the value of the differentual gearing either ratio. I have never had my 2-speed axle go into a neutral situation in 13,000 miles,so can't see much problem there. Seems like I have seen a disc on the driveline ,maybe at the gravel pit on the big Cat loader.

I have no complaints with the parking brake on my LCF, it'll lock up the driveline with no problem, original 2 ton double shoe drum on the tranny.

AlexB I think maybe that urge to go on the interstate kind of fuels this brake dilemma,tandem master cylinders are a help but a little hard to incorporate . Can't think hundreds of big bolts are still out there if the brakes aren't able to do the job. However it's a new problem when interstate speed mostly hinges on a speed of about 80 M.P.H. In the service manuel gearing speeds are listed at about 52 M.P.H.

Finding brake parts to maintain my 2-ton dump has been a joy, but thankfully the crusty old guy at my local Napa that knows what book to look in hasn't retired, yet. Living in an agricultural community has it's perks too, between farm trucks and old tractors the local truck shop sees a lot of off the wall jobs and has been a great help.

I rebuilt everything from the pedal to the shoes, even chased down a NOS hydrovac, but finding replacement drums? Fat chance! Fronts are OK but my rear drums are in need. Still, even with 5 yards of damp soil in the box the factory system stopped way better than I expected, and empty it would stop like right now.

A dual circut upgrade to disc would be a dream, when parked too long seems like one of the 4 rear slaves leaks and drains the system, it gets *real* exciting when I suck air into the system, not a fan! Not hauling w her any more, but 9,000lbs of not stopping,...
Moot point at the moment, no place to work on her and broke a line last time I was trying to do a quick hone/rebuild on the culprit slave.