Continuing the work to finish up the footbox and revisiting the pedal assembly.
Back on post 90 I covered the approach on adapting the Tilton pedal assembly to actuate a 2010 Camaro power brake booster. Although the initial design was pretty good there are a few issues with it and warrants a redesign. So I’ll consider the first design a prototype and remake some of the parts in this post.
Here is a video explaining why the prior version needed to be re-done, review and install of the new assembly....
1)The pedal ratio based on the bell-crank lever I scavenged from the Mopar kit created too low a pedal ratio. I calculated a 2.9 final pedal ratio where it really needs to be something between 3.5 and 3.8 based on the feedback from Johan. The stock Camaro pedal ratio is 3.8. So I’ll fabricate a new bell-crank lever with a different geometry.
2)Was not satisfied with the way the bell-crank bracket over lapped the base plate of the adjustable pedal slider. Ideally the bracket should have a bolt in front of the pivot point of the bell-crank lever since the force when applying the brakes is trying to lift the bell-crank bracket up from the front. The way I mounted it, it is secured from behind the pivot point which I just don’t think is ideal. I’ll remake the bell-crank bracket to be 1.25” longer and use a bolt forward of the bell-crank lever pivot point when attaching it to the floor pan.
3)Also, as luck turns out, the bolt mounting the front compartment floor to the chassis pan interferes with the bell crank bracket. Since I was going to remake the bracket based on issue number 2 above, I’ll use a 1/2” wider base which will allow that front compartment floor bolt to also secure the bell-crank bracket to the floor.
4)Since the redesigned bell-crank bracket is not going to overlap the base of the adjustable pedal assembly I had a choice of either moving the pedal assembly toward the driver by about 1.25” or change the design of the system. After thinking about it some more I decided to simplify the system and match it up better to what I really want to accomplish and need.
5)Lastly, was not sure if the NJ safety inspector would appreciate all the complexity of the adjustable pedal slider, bell-crank and multi-hole actuator rod. This was another consideration in changing and simplifying the design so I could pass NJ inspection.
The rational for the adjustable pedal assembly was to have the ability to really nail the forward/backward pedal location so I would be comfortable in the car. It wasn’t necessarily to have something instantly adjustable. Also, by introducing a power brake booster into the design the setup still requires you to duck deep into the footwell to move the slave pedal actuator rod to a different position.
So thinking more about the requirements decided to not use the RCR adjustable pedal slider and simply install a plate with multiple mounting holes where I can move the pedals forward or backward.
So here we go, pic of the before and after of the bell-crank lever. Pedal ratio goes from around 2.9 for the original one to 3.6 for the new lever.
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Below are pics of the pedal ratio calculations. By having the middle hole on the slave pedal 68% as high as the top hole, you can adjust the Tilton pedal pads to get a final pedal ratio from 3.5 and up to 3.9. That’s a pretty good spread and should do the job.
Dimensions and pedal reduction ratio of the new bell-crank lever...
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The various final pedal ratio calculations given the new bell-crank lever...
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Pic of the before and after bell-crank bracket. This design allows the new bracket to be bolted to the floor in front of the bell-crank lever pivot point. Since it is .5” wider the front compartment floor pan bolt can also secure it to the floor pan...
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Pic of the new adjustable pedal base vs. the RCR adjustable pedal slider. Both have about 6” of travel. The new adjustable pedal base has the holes spaced in 1.1125” increments so it can move back a total of 2.2” and forward 3.3” from the setting that is most comfortable for me...
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Below is a pic of both assemblies for comparison. The New bell-crank actuator rod is made out of 1/4” steel bar for actual use. The aluminum one was just a prototype. Also, because I had to move the mounting point higher to get the desired pedal ratio, the longer multi-holed prototype rod now fouls the brake booster housing in the most forward position. So to further simply things decided to use an individual actuator rod for each pedal location...
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Pic of new assembly with Tilton pedals mounted. I like the balance of adjustability while keeping the design simple...
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Bell-crank lever and bracket installed in the chassis. Lines up nice with the brake booster. It was a little tricky to line up, measure 10 times and drill once!!!
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Pedal assembly now placed in the foot-box, the wood section is there to insure a 1.5 degree angle so the pedal base match the angle of the steering column and seat. The design is to run bolts up from underneath the chassis to secure the adjustable base in place and screw the pedal assembly in from the top making this a one man job to install and remove...
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Below is a pic from the front. I made the pedal mounting plate a little wider and longer than necessary to machine in a lip around the front and sides so carpeting could be tucked under giving it a finished look. I expect that after adding sound deadening, luxury liner, and carpeting the pedal plate will be at about the same height as the carpeting...
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I’ll install it in place after I finalize the seat brackets which is next on the list.