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2001 LS1 Trans AM Spec Clutch - Forward Motion
A Spec Clutch And Updated GM Hardware Endow Our LS1 Trans Am With The Gift Of Go
Mar 1, 2006
Thonotosassa, FL 33592
Bessemer, AL 35022
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2001 LS1 Trans AM Spec Clutch - Forward Motion
Good to 680 lb-ft of torque and carrying PN SC093, the Stage 3 clutch kit from SPEC fits all 1998-2002 LS1-powered F-bodies and retails for $449. Included are a pressure plate, clutch disc, clutch alignment tool, throwout ("release") bearing, and slave cylinder spacer. SPEC says their Stage 3 Plus kit is better in every way (driveability included), but you'll have to pull another $149 out of your bank account to enjoy its 850lb-ft capacity.
In lieu of resurfacing the stock flywheel, we chose to go with one of SPEC's steel flywheels, PN SC75S ($249). An aluminum version is also available, but its reduced mass will hurt street driveability as well as dragstrip performance. Go with the steel, unless you're a hardcore road racer, and save the $150.
By virtue of the transmission being tucked up into the Trans Am's aptly-named trans tunnel, a decent number of parts have to be removed in order to get the T56 out and gain access to the clutch. Start with GM's wavy plate, an item which exists solely for the purpose of adding a few extra pounds to your car, as it can't possibly contribute meaningfully to structural rigidity.
The torque arm needs to be removed, and this process starts at the rear axle assembly, where the nuts holding the two large thru-axle-housing bolts must come off. Do not even attempt to remove the bolts yet, as the torque arm is under tension and is holding onto them for dear life.
Using a transmission jack, the rear axle assembly must now be supported in order to remove the torque arm and driveshaft. Be careful not to raise it too far or else the entire car will begin to rise off of the lift's pads, creating a potentially dangerous situation.
After removing the four bolts clamping the driveshaft to the rear axle yolk, a couple of hammer taps will likely be needed to unseat it. Interestingly, GM refers to the driveshaft as a "propeller shaft," a clue that perhaps Firebirds were originally designed with winged flight in mind, or possibly even seaworthiness. (Editor's note: author Chris Werner wrote this piece while institutionalized, please bear with us.)
With both the torque arm and driveshaft detached from the rear axle, the rear axle assembly can be lowered and the transmission jack temporarily set aside. The driveshaft then slips out of the rear of the transmission; a large hairy man can prove indispensable for this step.
The torque arm will refuse to part with its close friend Mr. Tremec unless one removes the bolt clamping the torque arm into this rubber mount at the very rear of the transmission. It's located just above the transmission crossmember. With the bolt removed, the mount splits open and the torque arm can slide out.
It seems like everything underneath an F-body is attached to the transmission in some way, and the exhaust system is no exception. We detached our Trans Am's SLP Y-pipe via these two bolts on the passenger side of the car. (Now is also a good time to pop the shifter out of the interior of the car, a step we somehow neglected to snap a single photo of; get the plastic trim out of the way and you can remove the four shifter-to-transmission bolts.)
Eight bolts hold the transmission to the flywheel housing. Don't let the orange decal on the transmission fool you, this really is a T56 manual tranny, but it uses automatic transmission fluid. These suckers are so tough they've been rumored to operate even with no fluid in them whatsoever. Now is also a good time to disconnect every bit of wiring that's either attached to or plugged into the transmission.
A few of the transmission-to-flywheel-housing bolts are difficult to access as they reside fairly high up in the trans tunnel. Some very long extensions will be needed to get at these, often enough so that they extend to or beyond the transmission crossmember. One such bolt toward the passenger side holds a vent line bracket beneath it and is particularly difficult to access.
The transmission jack now gets its chance to live up to its name; put some tension on it and be sure to use the safety chain so that $2,000 worth of Tremec doesn't accidentally come down on your foot, Labrador Retriever, or-heaven forbid-garage cat. The transmission crossmember can now be safely removed. (Note: while this author currently has no garage cat, he does have a "garage grandpa" in that dearly departed Fred now resides on a shelf next to a model Corvette. If the author's mother actually reads his articles as she claims to, her husband is now in some seriously deep $@#&.)
With a little bit of mojo, the transmission will begin to slide away from the flywheel housing. As this happens, it is critical that the clutch slave cylinder be removed from the front of the transmission. There simply isn't enough slack in the hydraulic clutch line for it to move very far, so a wrench must be slipped between the tranny and housing and the two bolts holding the slave cylinder removed.
As the transmission is moved backward, the shape of the transmission tunnel necessitates that the rear of the transmission be simultaneously lowered. At this point, a massive amount of transmission fluid will begin rushing out of the rear of the tranny and pouring all over your father, friend, or-God willing-garage cat. One can avoid such a catastrophe by draining the transmission's fluid prior to its removal.
With the transmission moved far enough from the flywheel housing, the tip of the transmission input shaft will finally emerge from the flywheel housing and the slave cylinder can be slipped between the two and out of the way.
At this point in the installation, a brooding horror fell over the shop as we inspected the clutch slave cylinder and found it stamped with a "0." This meant that our vehicle had been equipped from the factory with the inferior 2000-earlier model clutch hydraulic system. A trip to the nearest GM dealership was near at hand. Slave cylinders stamped with a "1," "2," or greater are OK but it's always a good idea to replace them anyway while the system is in pieces (they're a wear item).
With the transmission finally out of the way, the goal is in sight, as the clutch is finally visible. The discerning reader will also notice that every single bracket had to be removed from the rear of the transmission in order to coax it to come out, as clearance between the rear of the transmission and the Y-pipe was an issue during removal.
There are a total of eight flywheel-housing-to-engine bolts, but even when they're removed, the flywheel housing will hold its ground. The trick to dislodging it is to pry at its very bottom with a flathead screwdriver as well as in this secret pry spot up on the passenger side of the housing adjacent to the catalytic converter. If you don't pry at this spot, we promise you, the housing will NOT come off. (If that sounds like a wager to you, it is.)
Santa Claus happened to be chillin' at the Werner residence at the time of this install, so he was kind enough to pose for this photo of removing the flywheel housing. Immediately after this photo was taken, we discovered that Prancer had left us an early Christmas present in the yard and that the family black Labrador was eating it. Cleanup ensued.
The only thing standing between you and the flywheel now are six bolts; turn 'em quick and the motor won't spin over. We should have mentioned long ago that the negative battery cable should have been disconnected to prevent accidental spinning of the engine at any time during this installation. The clutch disc and pressure plate are fairly heavy, so be ready to grab them as that last bolt comes out.
The six flywheel-to-crankshaft bolts are best removed using an air-powered wrench, NASCAR style. After they're all loose, some fairly hard hits with a rubber mallet about the perimeter of the flywheel will be needed to unseat it from the crankshaft. Note that even if you aren't replacing the flywheel with a new one, you'll still need to remove the stock one, as it needs to be taken to a shop to be resurfaced and rebalanced to match the new clutch assembly.
After the stock flywheel came off, we put the new billet SPEC unit in place and it was time to replace the pilot bearing. The very front of the transmission input shaft rests inside this bearing, ensuring everything between the crankshaft and the transmission remain properly lined up. SPEC demands that this bearing be replaced, and one is included. Though other methods exist to get the sucker out of the back of the crank, the best way is via a pilot bearing puller, as seen here.
No special tool is needed to install the new pilot bearing; just a socket of the appropriate diameter and a hammer. Gentle taps are all that are needed to get the bearing started and going in straight. The bearing should only be installed until it is flush with the back of the crankshaft; pushing it too far can purportedly cause a pressed-in oil galley plug to be disturbed.
The flywheel-to-crankshaft bolts are ready to go back in, and it's critical to use some red threadlocker on them, regardless of what the GM repair manual says. We reused the stockers, but it's probably best to pick up some new ones. Final torque specifications for these bolts are 74lb-ft on LS1s, but this reading needs to be preceded by two passes of 15 lb-ft and 37 lb-ft, respectively. Be sure to tighten them in a criss-cross fashion (i.e. tighten one bolt and then skip over the next one as you move in a circle).
Lying side by side, it's clear the stock clutch disc (right) differs greatly in design and construction from the Stage 3 SPEC unit (left). The new unit is a "6-puck" design with carbon semi-metallic friction material and high-torque sprung hub. If the Stage 3 Plus is ordered, the disc will actually look more like the stocker as it will be a full-faced type disc.
In order to hold the clutch disc in place while the clutch pressure plate is installed over it, the SPEC-provided clutch alignment tool is simply popped in place. Its tip sits in the pilot bearing, ensuring that the clutch disc stays put while the pressure plate is torqued in place. Make sure the sticker on the clutch disc that says "FW Side" (i.e. "flywheel side") isn't visible at this point!
The clutch pressure plate is then popped atop the clutch disc and the new SPEC-supplied bolts installed. It's worth mentioning at this point just how this type of clutch works: when the clutch pedal is depressed, the slave cylinder pushes the throwout bearing against the "fingers" seen here, lifting the pressure plate off of the clutch disc and allowing the transmission input shaft to turn independently of the engine. It's what is known as a "push-style" clutch.
Torquing the clutch pressure plate bolts requires the above-mentioned criss-cross pattern and three passes of 20 lb-ft, 40 lb-ft, and 52 lb-ft respectively. Remember the threadlocker here too. Since the engine will want to turn over as the bolts are torqued, a flathead screwdriver or similar instrument must be used to hold the flywheel. Make sure it rests against a suitably thick part of the engine block. (If your hobbies include wasting money, there is such a thing as a GM flywheel holding tool.)
As stated earlier, we needed new GM clutch master and slave cylinders, and here they are. The master is GM PN 12570277 and the slave is PN 15046288 (new throwout bearing included); the grand total for everything came out to just over $300 for us. Amazingly, they both come pre-filled with fluid so that the quick connection can just be popped together and the system should be ready to go.
To get the stock master cylinder out, a bit of crawling beneath the dash is required. Two nuts affix a U-clamp which holds the master cylinder against the firewall. Beyond this, all that must be disconnected under here is a clip at the end of the shaft leading to the top of the clutch pedal.
At first, we couldn't understand why the U-clamp didn't want to come out, but then we realized GM had installed one of these grab-and-hold washer thingies, for lack of a better term. The only way to get it off is to slowly turn it counterclockwise with a flathead screwdriver. Interestingly, only the one leg of the U-clamp had one.
The new master cylinder comes with a reservoir attached, so the stocker must go; just pry it out of its bracket. The plastic pop-rivet will be reused. Underneath the cap of the reservoir, one can find the same type of stamping as on the slave, indicating the master is of the inferior "00" and earlier pedigree, which can't pump as much fluid as the revised version.
As the braided line leading from the master cylinder down toward the slave cylinder is sandwiched between the car's body and this heat shield, it needs to be removed before one can get the master cylinder to come out. Make sure to route the new line in this same fashion.
We'd love to show you the new master cylinder and its U-clamp being installed on the firewall, but like so many other areas on the Fourth-Gen F-body, their lair is physically impossible to photograph. You'll have to work blindly by sticking your hand under the brake booster; an assistant inside the car can look through the holes under the dash and tell you when you've got the U-clamp lined up.
To get the flywheel housing back on, a good amount of bashing with a rubber mallet is going to be needed. The reason is that there are a couple of protruding alignment knubs that stick from the engine block into orifices in the flywheel housing, and the suckers are a tight fit. Just lube 'em up a bit, hammer away, and you'll be through before you know it.
At this juncture, we made the mistake of popping the quick-connect between the master cylinder and slave cylinder hydraulic lines together. One is supposed to wait until the slave cylinder has already been reinstalled on the transmission-and the transmission bolted to the flywheel housing-before doing this, as it leaves little slack to work with. Plus the suckers don't come apart without a special tool, as far as we could tell.
Before bolting the new slave cylinder to the front of the transmission, it's critical to install this SPEC-supplied spacer between them. By shimming the slave cylinder toward the clutch assembly slightly, the "crashed pedal" situation that many F-bodies experience during hard driving is avoided (i.e. a soggy, reduced-throw pedal during road racing).
As the transmission is about to be bolted to the flywheel housing, our above-mentioned quick-connect mistake and consequent slackless braided line necessitated bolting the slave cylinder to the transmission whilst there was very little clearance in between. The throwout bearing went in there, too, of course. All this wasn't terribly difficult, but any little bit added to our headaches to come...
The absolute worst part of the job ended up being getting the transmission and flywheel housing to line up. The tranny must be at just the right orientation to get the transmission input shaft to slip into the pilot bearing, and any rough play here can potentially cause damage. A trans jack with adjustment knobs for rotating and pitching the transmission is absolutely crucial here; after well over an hour of frustration, we finally got the two to pop nearly together and eased them the rest of the way by slowly and evenly tightening the transmission-to-flywheel-housing bolts.
A main culprit in the difficulty of transmission alignment turned out to be this pesky lip around the opening for the shifter, just above the transmission tailshaft. One can even see how it got a bit bashed up in the process, as it wouldn't allow the rear of the transmission to pitch upward enough for the input shaft to go into the pilot bearing straight. Do yourself a favor and cut this lip off while you have the tranny out-for sanity's sake!
Since our nitrous-huffing Trans Am would now be well into the 12s in the quarter, we needed an NHRA-legal driveshaft safety loop, like this one from BMR (PN DSL-001). It's a total bolt-in design, retails for $99.95, and can be had in a variety of powdercoat colors. A bunch of shims are included to help adjust its location to compensate for the particular vehicle's exhaust setup.
BMR's loop bolts up where the crappy factory wavy plate used to be, using the stock bolts. Ample room is afforded for large aftermarket exhaust systems, though the loop's crossbrace doesn't hang so low that it becomes a speedbump problem. Its heavy-duty construction surely does a lot more than the stock plate in terms of reinforcing the car's floorpan.
We should have done this just as we were taking the transmission out, but better late than never: the transmission fluid drains out of a clearly-marked "drain" plug. On the opposite side, there's another that says "fill," but this doesn't mean that fluid will be pumped into there; rather, it indicates that fluid is to be poured into the transmission until it begins to trickle out of the "fill" plug.
It turns out that the ATF capacity of the transmission is almost exactly one gallon, so we dumped in just that through the shifter hole prior to reinstalling the Pro-5.0 shifter. It's important not to use synthetic fluid in these Tremecs as it has been known to cause leaks. That said, we went under the car, let some fluid trickle out of the "fill" plug, and after reinstalling the shifter and interior trim we were ready to roll!
2001 LS1 Trans AM Spec Clutch - Forward Motion - GM High Tech Performance
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