The car is an original automatic car, I had to decide between using the '99 pedal set I got with the LS1 or finding a set of used 70-81 pedals. I was most concerned with the safety of the brake system. After some investigating I decided that I was more comfortable modifying a ‘81 set than chopping and hacking the '99 set.
After scouring the local junkyards and coming up empty I found a pedal set on eBay.
I measured the ’99 pedal ratio and the stock ’81 ratio and found that if needed I could relocate the master attachment point in the ’81 pedal closer to the pivot point for more leverage and less travel. I spent quite a bit of time on the bracket to try and get it at the same leverage and travel as in the '99. I drilled a new hole in the clutch pedal arm that gave me the same ratio as the '99 pedal set this also reduced the travel on the master cylinder since I had way to much to start with. Other than I will still have to reduce pedal travel I believe I will at least have similar pedal feel and pressure as the original ’99.
· Stock ’99 pedal
o Overall length 12”
o Attach point 2.125” from pivot point, approx .875” travel of attach point
o 5.65 pedal ratio
· Stock ’81 pedal
o Overall length 11.5”
o Attach point 2.5” from pivot point, approx 1.25” travel
o 4.6 pedal ratio
· Modified ’81 pedal
o Overall length 11.5”
o Attach point 2” from pivot point, approx 1” travel
o 5.75 pedal ratio.
The template I made from heavy paper cardboard for the clutch master cylinder bracket. I used a mockup firewall from a piece of old junk sheet metal to test the clutch bracket since the firewall on the '81 is almost flat at the booster. I created the bracket out of 14ga steel using the template as a guide. I plan to bolt it between the booster and the firewall and did not want to drastically change the distance between the booster and the brake pedal. A 17degree bend on the bracket was used but after some hindsight I probably should have gone with a 15degree bend. This angle changed depending on how high or low the clutch master cylinder is mounted on the firewall. I will be using two of the steering column bolts to help hold this bracket as well as a few 90degree bends made with my vise as a sheet metal brake.
This is the final clutch pedal, red arrow is the factory 81 attach point, green arrow is new attach point, yellow arrow is small plate welded on for contact with clutch start switch from the 99. The pedals and all underhood steel will be painted with PPG DP90LF a satin black two-part catalyzed epoxy primer.
This will be all for the clutch assembly for a few weeks. I still have to work out a limit stop to keep the clutch master cylinder from bottoming out in the bore. I'll get to that later once I'm ready to install in the car, for now it's back to the motor mounts and subframe.