Brake pedal/master rethink -- update

[Zandoz]

Over the last month or so I've acquired most of the major components for the change in direction.

• Speedway Universal T-Bucket Brake Pedal Kit
• MBM Corvette style universal 1" Bore Aluminum Master Cylinder
• MBM ProLine 7" Dual Diaphragm Booster

The booster and master will be located under the seat.

Having the hard parts to measure and play with has confirmed an expected problem. The output rod from the pedal assembly and the input rod on the booster, are misaligned by about 3-1/4". Most of the misalignment is due to trying to keep the bottom of the booster above the bottom of the frame rail. In the vicinity of the booster, the bottom of the frame rail is anticipated to be around 6-3/4" above ground.

With the under seat placement of masters and boosters becoming more common, I expected such alignment issues not to be uncommon. Of course that has proven wrong. Soooo now I have to come up with a safe way to "Z" the rod between the pedal and the booster.

 

[Spanky]

Do you really need the booster? I considered one for my T-bucket, but was encouraged to try not using one, and I'm happy with the brake performance with my manual system (rear drum/front disc). Just be sure the pedal ratio is 6:1 or higher, and you should have no problems!

 

[Zandoz]

I'd initially planned on not using a booster, but my mobility issues have progressed to the point of requiring hand controls...and they require power brakes

 

[Spanky]

Gotcha! It sounds like you may need some 'engineering' to locate things so they will work properly. There are some really creative fabricators on this site . . . maybe one of them can step up? (Also, photos of your build would help.)

 

[Zandoz]

Yeah I'm beginning to think that the offset linkage I thought was going to be easy, is not going to be. The folks here are amazing. I wish I had a fraction of the abilities of some of the folks. I've been a gearhead almost since birth, but for the most part I've been a wrench turner...not a fabricator.

No pics yet...right now it's just growing piles of parts. Currently I'm trying to work out all the subsystems like the brakes in my CAD system...to be sure there's a reasonable shot at fitting the frame I've designed. I want to have the frame built yet this year. Then I can start assembling all these parts into something photo-worthy.

 

[T-Test]

Over the last month or so I've acquired most of the major components for the change in direction.

• Speedway Universal T-Bucket Brake Pedal Kit
• MBM Corvette style universal 1" Bore Aluminum Master Cylinder
• MBM ProLine 7" Dual Diaphragm Booster

The booster and master will be located under the seat.

Having the hard parts to measure and play with has confirmed an expected problem. The output rod from the pedal assembly and the input rod on the booster, are misaligned by about 3-1/4". Most of the misalignment is due to trying to keep the bottom of the booster above the bottom of the frame rail. In the vicinity of the booster, the bottom of the frame rail is anticipated to be around 6-3/4" above ground.

With the under seat placement of masters and boosters becoming more common, I expected such alignment issues not to be uncommon. Of course that has proven wrong. Soooo now I have to come up with a safe way to "Z" the rod between the pedal and the booster.

Bell crank should work for it.

 

[Zandoz]

Bell crank should work for it.

I've thought about a bell crank. It would have to be custom made, as would the mounting bracketry. I'm hoping for a simpler solution, but a bell crank is the fall back solution.

 

[Zandoz]

Here are top and side illustrations of the pedal/booster/master configuration

The only problematic point is the "S" bend rod between the pedal and booster. Right now the plan is for 5/8"OD fluted aluminum rod, threaded for 3/8-24 to match the booster rod, but I'm not sure if 5/8"OD would be sufficient with the bends.

 

[Intrepid]

My issue is the trany support.
where is yours in relation with the pics?

 

[choppedtop]

I think with a booster, you will not be putting near the pressure on the rods as you would without the booster. Thats the purpose of the booster. Of course you know that, but may be over thinking it a bit. If it really is an issue, just gusset the bends. If not for the booster, it may be sketchy. JMHO

 

[old round fart]

Why aluminum rod?worried about weight? lol. Is the bend to go around the trans mount? Can you use a straight rod through the mount?

 

[Zandoz]

My issue is the trany support.
where is yours in relation with the pics?

This shows the footprint of the tubular crossmember on the frame

 

[Zandoz]

I think with a booster, you will not be putting near the pressure on the rods as you would without the booster. Thats the purpose of the booster. Of course you know that, but may be over thinking it a bit. If it really is an issue, just gusset the bends. If not for the booster, it may be sketchy. JMHO

Yeah, I know the booster will lessen the force on the rod over a manual set up, but never having done this before I do not trust my guesstimates on a safety critical area.

 

[Zandoz]

Why aluminum rod?worried about weight? lol. Is the bend to go around the trans mount? Can you use a straight rod through the mount?

No, it's not for weight. I found a source of made to order, including bends, solid fluted aluminum rods...for a reasonable price. To me it seems that the solid material with flutes would be stronger than comparatively thin wall swedged tubing, of steel or aluminum. <shrug>

Straight rod would leave the booster hanging below the frame rail, with no room to get the booster in line with the pedal side-to-side without fouling the frame rail

 

[Spanky]

Bill - I saw this on another web site, and thought it related to your situation. The guy has a nice T-bucket with a blown Ford engine. Necessity really IS the Mother of Invention!!! Just leave it to hot rodders!

"I don't drive it much anymore as age has caught with me and my hips and knees make it difficult(oh to be young again) I have done a few modifications to make it more comfortable for me to drive, I have relocated the shifter to the left of my left leg and now shift left handed(no need to shift often) I have relocated gas pedal further up and away from the column and converted the brake to hand operation all to make it easier for me to operate. Still having fun with it but I don't know for how long."

 

[mountainman]

Spirit uses a bent rod on their power brake option. Rod is not pictured in catalog but is mentioned. Josh can give you details. Mine looks just like what you have drawn except it is offset horizontally whereas yours would be offset vertically.

 

[Zandoz]

Bill - I saw this on another web site, and thought it related to your situation. The guy has a nice T-bucket with a blown Ford engine. Necessity really IS the Mother of Invention!!! Just leave it to hot rodders!

"I don't drive it much anymore as age has caught with me and my hips and knees make it difficult(oh to be young again) I have done a few modifications to make it more comfortable for me to drive, I have relocated the shifter to the left of my left leg and now shift left handed(no need to shift often) I have relocated gas pedal further up and away from the column and converted the brake to hand operation all to make it easier for me to operate. Still having fun with it but I don't know for how long."

Yup...sounds like he is in a somewhat similar situation. I'm planning on using a cable shifter, so I can relocate it where ever out of the way. Accommodating a hand brake is the reason for the booster. I had a much simpler system worked out (and most of the parts acquired for), prior to finding out a booster is a necessity for hand controls.

 

[Zandoz]

Spirit uses a bent rod on their power brake option. Rod is not pictured in catalog but is mentioned. Josh can give you details. Mine looks just like what you have drawn except it is offset horizontally whereas yours would be offset vertically.

Interesting. I'll have to see what I can find on that. Thanks.