Brake pedal/master rethink

There's a pretty good chance that I'm going to have to chuck all the acquisitions and plans I had for my pedal and master cylinder set up. My joint issues have progressed to the point that having a hand control at least for the brakes has gone from "probably someday" to necessary now. All of the off-the shelf hand control systems I've found, and sites for installers of those systems, say power brakes are mandatory. This means that my manual dual master cylinders setup will not work.

Up front, I do not want to go to the cost and complexity of hydraulic or electric boost. Also, I do not want to go to a firewall mounted booster set up...The booster and master would look almost as big as my little V6...LOL.

It's looking like the best compromise of cost and simplicity is going to be what I've been trying to avoid...an under floor system. Or in this case, a semi under floor system. The bottom of my frame rails will only be about 6" off the ground, so I do not want anything hanging below the rails. That means the top 1/3 of the booster and the top of the master will be above floor level. To squeeze the linkage between the pedal and the booster over the transmission crossmember, the pedal pivot will have to be at floor level. All of this adds up to all the bracketry and pedal assembly having to be custom made, as far as I know...which generally is not very far. If anyone knows of any off the shelf bracketry and/or pedal assemblies that may help, please let me know.

 

To address the manual vs power issue, with the increase of leverage of a longer hand lever, I would do some research before committing.
Locating the hand lever in an ergonomic area might allow the master cylinder to be under the seat area or not near the firewall or foot area.
I would definitely stay with the push to stop arrangement, allowing you to use the back of the seat for support for arm movement.

 

Know of no brackets available, but you can mount the booster and m/c back far enough to place it under the seat area, and not let it hang down further than the oil pan. A Toyota booster is about 7" in diameter. The push rod to the m/c would be long, or articulated in a way to make it work.

I made the first hand control system for a WWII veteran that my dad was in the Army with back in the 70's. he had no legs, but could get around better than me. His truck did not have power brakes, and he drove just fine. On your bucket, all you have to do is change the pedal ratio to get more lverage out of the hand controls. Just a Thought.

 

T-TEST, why were things crossed out ?

John

 

You will more than likely have other components hanging below the frame such as the oil pan, as mentioned, maybe steering components, etc, so the frame bottom isn't necessarily the bottom of the car. If you mounted the master and booster under the seat, you would have ample room without any ground clearance issues. Keeping the push orientation is a must in my mind, not just for leverage, but also to negate the effects of g force when stopping. You wouldn't want to have to pull against the force of your body moving forward during a sudden or rapid deceleration, imho. Also, I imagine most of the off the shelf hand controls are intended for cars that weigh more than double what a bucket weighs, so that would help with the power assist issue.

 

Unfortunately, the off the shelf hand controls are pretty much variations on the same theme. I've not seen any with long enough levers to make a difference...and all I've found require power brakes.

There is one unavailable exception...there is a European company that makes custom fitted units that mount to the floor or seat, and are operated by levers next to the thigh. They look kind of like 2nd stick shifts. One uses an electronic "head" with a control lever, and the other just a long mechanical lever. Both VERY pricey and require the vehicle be in Europe for custom fitting.

Those things are out of the question, but they did trigger a brain fart of an idea. Every once in awhile I see the old long pistol grip hand brake levers on ebay. If I could come up with bracketry to mount one to the transmission like a shifter, and a substantial enough cable to loop around to the back of the brake pedal, it would make a cool looking setup with enough leverage that a power booster might not be necessary. But that's all pointlessly beyond my fabrication abilities these days.

 

The initial idea is to mount the booster and master under the seat as you say. Putting them back under the seat seems to present no problems other than relatively simple custom bracketry. It even lines the linkage up to pass through about an inch gap between the floor and the transmission crossmember. What I haven't figured out yet is the pedal assembly. Based on the dimensions I found for an off the shelf pedal lever, and the position of straight shot linkage to the booster, the pedal pivot point would be above the floor. That may or may not end up being a problem...I just haven't really given the details much thought yet.

 

So far, keeping impact sensitive stuff above the bottom of the frame rails has worked well. The low center sections of both crossmembers are below the frame. The transmission x-member is easily removable and replaceable. The drive shaft loop x-member has excess depth and with a bit of surgery can be shortened. In both cases they are well above the scrub lines, and still have 5" or more ground clearance. The heims on the ends of the front lower 4-bars will be about half below the rails, but a couple of skid blocks welded to the bottoms of the frame rails should protect them. There are a pair of potential problem points. The nuts on the bottom of the perch bolts, and the lowest points of the shock eyes, will both be about 1/2" below the scrub lines. The only solution would be an axle with less drop...an option I can't afford.

I agree that the push orientation is the way to go. I'm not so sure about the lower weight compensating for the lack of power assist. It would be an expensive gamble. There would be nothing useable in a power system, if I finished the work-in-progress manual system and it did not work out.

 

Wow, you seem to be wanting a real low rider. I thought that my car was low with the frame being 7 1/2" to the pavement at the cowl and 9" at the kick up in the rear.



Jim

 

I have 6" at the cowl from road to bottom of the rail. Just keep away from speed bumps and sharp grades.

 

It's not a matter of want, it's a matter of necessity.

The 6" figure was a ballpark guesstimate. Based on the CAD drawings, at the cowl it would be 6-1/4", and at the kickup around 7-1/8". Also, at this point the plan is for the body to be unchanneled.

I need to get the seat low enough that with the enlarged driver side door I have planned, I can simply back up to the seat and sit down...no climbing. With the lowest part of the seat sitting on the floor, and the floor sitting on top the frame, the front of the seat barely falls under the upper limit for no climbing. If I can't keep the seat low enough I'll be forced to automate the rear air bags to lower the car for getting in and out, then raise it for driving.

 

That's a nice clean layout you have there...I like!

 

I have no idea? Have never been able to do that when I wanted to or to underline a word or phrase.

 

[QUOTE="Zandoz, . There are a pair of potential problem points. The nuts on the bottom of the perch bolts, and the lowest points of the shock eyes, will both be about 1/2" below the scrub lines. The only solution would be an axle with less drop...an option I can't afford.

If you don't meet the scrub line safety requirement, please don't drive the car on the highway.JMO 1st in any build should be SAFETY FIRST. Not a drag car but NHRA and AHRA safety rules are there for a reason.

 

In theory I agree with the safety first mantra. and where reasonably possible I try to abide by it. But in reality these cars in general are rolling violations of safety first. I don't think I've ever seen a street T-Bucket that would come remotely close to AHRA or NHRA safety rules. Building, driving, and being a passenger in these cars is an exercise in acceptable risk.

Think about this. Which vehicle would you rather be onboard when there is a catastrophic failure of a front tire...a typical T-Bucket that the tire failure would result in a suspension component hitting the pavement...or a motorcycle? I'd take the T. Should all motorcycles be removed from the highway? No.

As I pointed out this is a known less than preferable situation. I'd prefer it not to be that way, but for the foreseeable future I accept the risk until I can find an acceptable affordable solution.

 

W/a spring over axle , how could anything connected to the spring be below the scrub line ? I must be missing something
dave

 

With a spring over axle setup, the spring perch is fastened to the axle with a long bolt passing through the axle with a nut on the underside of the axle. When tube shocks are used with this configuration, a long used method for the lower shock mount is a bracket that is fastened under the axle with that perch bolt and nut.


The pick shows a spring over axle setup with the shock mounts under the axle. It's a configuration more frequently used on Model As and later rods, but are occasionally used on Ts. I chose the spring over axle configuration because it makes for a shorter wheelbase. Where the configuration has scrub line issues is when the drop of the axle is enough to put the shock mount below the wheel. In my case, I have a 5" drop axle, and it's enough to cause the problem with 15" wheels.

 

That mount is 2 1/2" below the axle [actually probably have to be closer to 3 -3 1/2"] ? BTW , that's the spring PIVOT bolt , perch is the middle of the spring .... no other way to mount the shock ?
dave

 

Those shock mounts add no more extension below the axle than the diameter of the shock loop that mounts on them...around an inch and a quarter to an inch and a half. What you call a spring pivot bolt, Speedway calls what I got from them an adjustable spring perch Forged Adjustable Spring Perches, Polished Stainless
Different strokes for different folks <shrug>.

Yeah there are always other ways, but at this point I've not found one that would not entail scrapping close to $300 in parts...on the heels of what I'm going to have to scrap switching directions on the brakes. I can't keep making expensive changes of direction if I'm ever going to have a chance of even coming close to building a functional car before my health issues put and end to the project. If I come across an affordable alternative mounting I'll jump on it. For now those shock mounts will be acceptable to me risks, and be high on "the future to do" list.

 

In theory I agree with the safety first mantra. and where reasonably possible I try to abide by it. But in reality these cars in general are rolling violations of safety first. I don't think I've ever seen a street T-Bucket that would come remotely close to AHRA or NHRA safety rules. Building, driving, and being a passenger in these cars is an exercise in acceptable risk.

I beg to differ with you on that point. You can pass an NHRA inspection at any Good Guys event, and in some cases you must pass this test before entering some shows/contests.
Granted you don't want to spend extra money or change things up, but it is not just your life on the line if you wreck and endanger others because you wouldn't follow safety rules.JMHO