Photography by Tim Suddard
When hopping up an early Mustang, like our 1965 vintage racer, usually you’d run a standard or lightened 157-tooth flywheel mated with a 10-inch clutch. In the past, we have used clutches from Centerforce and others and have had good luck.
This project would be different. Our expert, Curt Vogt, told us that for an all-out race car, we didn’t need the streetability that this traditional setup offered.
[Cobra Automotive Shows Us How to Build a Vintage Race Mustang | Project Vintage Race Mustang]
Instead, he said to run a two-disc setup. He supplied us with a flex plate from an early Mustang and suggested that we use a 7.25-inch Tilton button flywheel; two-disc, 26 spline, racing clutch; and hydraulic, internal throw-our bearing.
[Project Corvette Z06: Why a Multi-Disc Clutch Saves Weight While Increasing Clamp Load]
We bolted the very light flywheel to the flex plate with ARP bolts that we sourced from Cobra Automotive.
Then we bolted the clutch to the flywheel (employing a traditional centering tool) using the hardware supplied by Tilton. We sourced a used bell housing from Cobra Automotive that had already been modified to mount a Tilton hydraulic throw-out bearing.
One thing we learned the hard way: Our Roltek transmission is Chevy- and not Ford-based. While not a big deal since crossover parts are available, we went through two incorrect transmission mounts and couldn’t figure out why the pilot bearing wouldn’t fit. Once Curt sent us the correct parts, things went a lot smoother.
[Sourcing a real road race transmission | Project vintage race Mustang]
Next, we moved to the throw-out bearing. First, we sourced some braided lines to bleed and supply fluid. Our next dilemma showed its face when we bolted the throw-out bearing in place: Our throw-out bearing needed to span 0.892-inch to activate the clutch. No throw-out bearing will move that far, we figured.
A call to Tilton quickly solved this problem. They make a variety of pistons that have different lengths. We ordered their longest piston (part No. 62-6009) that’s 0.600-inch longer than the first one that we tried.
Tilton recommends 0.170-0.230-inch clearance between the hydraulic throw-out bearing and the clutch release fingers. With the longer piston, we would still have 0.292-inch clearance.
At this point, we put a thin washer underneath each leg of the hydraulic throw-out bearing mounting stand and got our clearance perfect at about 0.190-inch.
Now we could move to the next step.
As always I have questions; what are the real world advantages to this set up?
I'm assuming the smaller diameter in effect works like a lighter flywheel and this clutch set up is less likely to slip.
Are the advantage worth the trade off? (I'm sure that answer will vary by user)
In reply to Tom1200 :
For racing absolutely. But••• do not drive it on the trailer or off. Buy yourself a winch. Try not to get stuck in pit traffic.
Do not ever attempt to drive it on the street. If I sound like I'm warning you not to slip the clutch I am. Those thin disks get real thin when you do.
If I'm not mistaken the Mustang is going dog ring? If so that's absolutely the application for a triple disk.
No blow proof? I realize there is less mass there to blow up, but...
0.190" is "perfect" between 0.170-0.023 ?
Suggestions:
"clutch forks" should read: pressure plate tongues, fingers or release levers.
The hydraulic throw out bearing replaces the conventional "fork"
Cheers!
fearlesfil said:0.190" is "perfect" between 0.170-0.023 ?
Thanks for catching that. It's meant to read 0.230 and not 0.023.
"clutch forks" should read: pressure plate tongues, fingers or release levers.
The hydraulic throw out bearing replaces the conventional "fork"
Confirmed that "clutch release fingers" is more correct than "clutch forks" for this application.
Tom1200 said:As always I have questions; what are the real world advantages to this set up?
I'm assuming the smaller diameter in effect works like a lighter flywheel and this clutch set up is less likely to slip.
Are the advantage worth the trade off? (I'm sure that answer will vary by user)
I have a similar clutch in the frankenferari. I originally installed it because a single disc clutch that would handle the upgraded hp made the clutch pedal so stiff it was basically undrivable on the street. With the triple disc 7.25 clutch it will handle 800ft-ld torque with the softest spring they offer and the pedal is honda civic soft. Huge improvement in dirvability.
The perfomance benefit is way reduced flywheel effect as you'd postulated. The clutch much lighter but its also much smaller diameter and ineria is an r^2 term iirc so for me it ended up about 1/4 the inertia of the heavy duty single disc it replaced.
...and it looks pretty cool which has got to be worth about 100hp 
Are we posting race clutches now? Cause I got a tiny one!
In reply to Kendall_Jones :
I didn't have the nerve to do a 5.5...the specs said it would be fine but I chickened out 
In reply to mke :
And this one is a SINGLE plate clutch - most parts are NLA. I'm a little concerned myself! :)
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