I'm looking for some feedback on the strength of the design for my version 1 (well probably more like V 0.85) brake pedal setup. As shown above in my build log, I'm using the Wilwood balance bar kit. It's a pretty heavy duty unit. Here's a photo from their website. I can tell you it's been improved since this photo was taken. The main tube that holds the spherical bearing unit is much better steel than the photo, and it's very nicely machined now. It's wall thickness is slightly over 1/8". The clevis's and pins are much better too. Here's the old unit:
Attachment:
Wilwood-Balance-Bar-Sm.jpg
My pedal construction looks like this:
Attachment:
Brake Pedal 1.jpg
Attachment:
Brake Pedal 2.jpg
The sides are 14 gauge cold rolled steel plate. The steel cross tubes are 1/2" x 16 gauge (2 places) and 3/8" x 16 gauge at top. I show the pedal pad as 14 gauge too, but that probably wont happen as I don't have a way to roll 14 gauge. Most likely, it will be 19 or 20 gauge with stiffening ribs put into it with a bead roller, and maybe doubled and welded if I don't think that is strong enough after making it.
The balance bar will make up a big portion of the pedal. The pedal proper (above) will be welded onto the 1-1/4" x 1/8"+ tube. An axis of rotation for the unit will be created using a 1/8" flange welded to the bottom of the tube and drilled to suit. It looks like this:
Attachment:
Brake Pedal Attachment Flange.jpg
Putting all the above together into a functioning pedal, it looks like this:
Attachment:
Pedal+Flange+Balancer.jpg
When I started out, I had a vision of a kind of fancy pedal box structure made up of 16- or 14-gauge plate. However, for simplicity, I wanted to work out all the geometry with a simple prototype unit. For that, I choose 1-1/2" x 1-1/2" x 1/8" angle, which I had a model for, and it's a pretty simple platform to start modeling with.
Subsequently, I'm asking myself, "Why not use the angle for real?" There's only one really good reason not to - aesthetics. The angle is just an unattractive, fairly crude structural piece, but will probably work fine. In the model(s) below, I show the angle unbraced, but in a production piece, it would be secured to the chassis side rails and the 16 gauge steel plate undertray. So, in spite of what you see below, assume the angle is securely attached, and is stable.
Attachment:
Pedal in Context - Small.jpg
Attachment:
Pedal in Context + Mount - Small.jpg
There are some factors that forced me to make certain choices. I could only move some components (the master cylinders, for example) a certain amount, and that was it. To get the pedal ratio I wanted (5.5:1), it further constrained my geometry. I can't move things but small fractions of an inch from where they are now. Here's the setup:
Attachment:
Pedal Ratios Graphic.jpg
My real questions relates to the operation of the pedal itself. Does anyone see anything that just screams out "failure" in this picture? My main concern is the area of the pedal flange and the 1/8" mounting plates it attaches to. I could use 3/16" plate, and increase the depth of the flange down into the space between them to give more lateral strength, for example. It would be a tight fit, however. I had to downsize to a 1/4" bolt as the pivot for the pedal flange. The geometry is too tight to use 5/16" or 3/8" bolts. Th huge size of the 1-1/4" balance bar tube limits things. However, I don't see much of a chance for a 1/4", grade 8 bolt to fail here.
What do you think? Do you see an obvious source of difficulties? Constructive input is sought and would be appreciated.
Cheers,