As we said, this clutch was...
As we said, this clutch was used hard, and after only a few months it was completely haggard. The heat scoring on the pressure plate was an obvious sign of the slipping we were all too aware of.
Diaphragm clutches are much lighter in pedal effort for a given clamping force, have no centrifugal effect, and don't use ridged release levers, using flexible spring-steel levers instead. Generally, the diaphragm clutch is considered too delicate for full competition use. On the other hand, Long pressure plates have a quicker-releasing 4.8:1 lever ratio and is the preferred style for true competition use. Long's operate through a combination of static and centrifugal clamping, gaining centrifugal assist directly from weighted levers imparting the additional clamping load. Since the conventional Long cover won't fit in a Mopar application, this is where the McLeod Borg and Beck/Long fills the gap. The McLeod B&B/Long combines the operational features of a Long clutch in a heavy duty B&B-style hat. Though the Dart isn't a race car, with the way it's continually hammered on, a B&B/Long was the choice for our application. The McLeod B&B/Long pressure plate will accept either a 10.5- or 10.95-inch disc on a common Mopar 10.5-inch B&B bolt pattern flywheel.
The last choice was in the clutch disc. Again, McLeod offers a wide range of discs, from street replacement types to iron-faced, to multi-disced street/strip and race units. We consulted McLeod's tech line and let them pick the disc for our combination. We went with a No. 260821 Dual Performance 10.95-inch disc, which features a combination of Kevlar(tm) and asbestos facings on the flywheel and pressure plate sides, respectively. Though it's a high-performance disc, the marcel layer under the friction lining provides a smooth take up. Rounding out the parts list was a new throwout bearing, which comes from McLeod already installed on a new slide collar.
The McLeod components bolted-up with the ease and fit of OE replacement parts, but on the road the Dart's new clutch setup bites like no OE clutch ever could. The performance grip was there, but what really got our attention was how smoothly the performance clutch engaged and disengaged. Off-the-line chatter is nonexistent with this combo for silky-smooth starts in normal driving. Sidestep the clutch, on the other hand, and the bite is right now, setting the tire ablaze. Okay, Comet dude, bring it on now....
The flywheel was also showing...
The flywheel was also showing signs of damage, not just heat glazing and scoring, but some serious-looking heat cracks riddling the surface. It may clean up with machining, but that new steel wheel comes with a lot of peace of mind.
The new McLeod SFI certified...
The new McLeod SFI certified flywheel just bolts in place of the old one. We used LockTite on the bolts and torqued it to 55 lbs.-ft. Notice that we have our new headers in place here: a set of tti 1 5⁄8- to 1 3⁄4-inch step pipes. These tuck up much tighter than our old headers, so they aren't as likely to get torn up on the street.
The McLeod B&B/Long clutch...
The McLeod B&B/Long clutch and disc bolt in just as easily as the OEM components; no tricks here. Just pull the clutch cover down against the disc with the bolts, bringing them down a little at a time against the pressure plate's spring tension in a criss-cross pattern until the cover is seated. Then torque the 3⁄8-inch attaching hardware to 30 lbs.-ft. Again, we used LockTite. Make sure a clutch alignment tool or an old input shaft is used to center-up the disc while the clutch is being installed; otherwise, the trans will never go in.
Next, the bellhousing was...
Next, the bellhousing was bolted on, and we rigged a dial indicator to check the runout of the bellhousing pilot bore. We have a special clamp, which mounts to the pressure plate, but a regular magnetic base can be used if the bellhousing is mounted without the clutch installed. Make sure the indicator is centered in the bore and at a right angle to the surface for an accurate read. Read the indicator while the crank is spun through a full revolution, and note the runout. McLeod recommends a maximum runout of .008 inch (the total indicator reading is double the runout or .016-inch TIR max here). We were within specs at .006-inch TIR. If correction is required, Mopar Performance has an offset block dowel package under PN P4120383. The bellhousing should also be checked for parallelism by rigging the indicator to read off the transmission-mounting surface just outside the pilot hole. The max here is .006-inch total indicator reading. Correction for parallelism error is by blanchard grinding the bellhousing (the best fix), or using shimstock between the housing and engine block (it will get the job done).
With the clutch installed...
With the clutch installed and everything checking out, the transmission can go back in. The shift fork and throw-out bearing should be loaded into the bellhousing and the transmission input shaft threaded through and into engagement with the clutch. The trans has to be lined up to go in, so work the jack to align the transmission square with the bellhousing. Some long bolts (arrow) or studs in the mounting holes will help line things up. If the splines on the trans' input shaft don't line up with those of the clutch, the transmission will hang up about 1 1⁄2 inches from all the way in. Insert a yoke in the output side of the trans, put it in gear and turn it until the splines line up. Never try to squeeze the transmission to the bellhousing by pulling it on with the mounting bolts.
With the transmission bolted-up,...
With the transmission bolted-up, reinstall the crossmember, shifter and linkage, driveshaft, clutch linkage, and the minor hookups. Clutch adjustment is accomplished by measuring the amount of clutch departure, or the clearance between the disc and the pressure plate/flywheel. While an assistant depresses the clutch fully to the floor, the gap between the flywheel and the disc is measured with a feeler gauge. McLeod recommends .050 inch for a B&B/Long clutch like ours, .040 inch for a regular B&B, and .030 inch for a diaphragm clutch.
Clutch adjustment is made...
Clutch adjustment is made at the threaded pushrod between the bellcrank and shift fork. Wind the adjustment nut out, increasing the pushrod's effective length to increase departure or shorten the effective length to decrease clutch departure. Once it's set, replace the clutch housing's cover plates, and burn rubber, not disc.