Thanks guys, appreciate it!
I have been driving the car for about a month now with the new T56 Magnum transmission… the Corvette ZR1 twin disc clutch… Fidanza aluminum flywheel… and the hydraulic clutch conversion. The ZR1 clutch is the best clutch I’ve ever had in the car! Very smooth engagement, quiet (no rattles), and the grip is excellent. I bought the modified ZR1 Clutch that is rated for 960 lb-ft torque, and I used a GM ZR1 throwout bearing. Even with the high torque rating the clutch still takes very little effort at the pedal and is extremely smooth on engagement.
I went with a Fidanza 12 LB aluminum flywheel to offset some of the extra weight of the GM twin disc clutch. It takes a bit more RPM to get going but still very easy to drive. I like the feel of the engine with the lighter flywheel.
The T56 magnum transmission has a very short throw, and just seems to click into gear with very little effort.... shifting up or down. The trans shifts at higher RPM with no problems at all. Shifting at peak RPM took a bit more effort on the lever but it still shifted great. I have the close ratio T56 with 0.80 5th gear and 0.63 6th gear… with a 3.73 rear axle in the car it felt just about right in 1st gear. Cruising at 75 mph in 6th gear the RPM is just over 2K.
The only issue I had on the transmission conversion was with the hydraulic clutch kit. The kit came with a Tilton ¾” bore master cylinder with a 1.1”stroke. I ended up using all of the stroke to get the clutch to disengage. I drove the car for about a week with this set up… but didn’t like the feel of the ¾” bore master… it took too much travel on the pedal to disengage the clutch… and it was difficult to shift quickly. Maybe the GM twin disc clutch just takes more travel to disengage than a single disc clutch. I ended up replacing the ¾” bore master cylinder with a Tilton 7/8”bore and now it’s much better. The action is quicker and the clutch feels just right.
Here is pic of the 3/4" bore master cylinder on the bottom, and the new 7/8" master on the top
Ready to go back in the car
Here is a list of part numbers for all the bores sizes of the Tilton clutch master cylinder kits for anyone interested. I bought the kit from Summit.
It took a couple of months work and a lot of time spent under the car before I could stick this part on
That’s it for the trans and clutch conversion… everything is working good now.