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Project VW MK4 GTI 1.8—SPEC Stage 2+ Clutch Kit Install

Mk4 history | Hybrid clutch and flywheel install steps | Driving impressions

Justin Fivella
Aug 11, 2015

When the fourth generation Volkswagen Golf (MK4) hit showrooms in mid-1999, it blew enthusiasts away. It was a game changer for both the industry and VW fans alike. VW's gamble, moving the Golf/Jetta upmarket paid off big in sales numbers.

No longer wanting to be seen as an entry-level car, VW blessed the exterior with handsome and timeless lines. Inside, the indigo and red gauges along with a classier ambiance were a huge leap forward in its class. But it wasn't just about show; it also had plenty of go. The 12V VR6 received some enhancements and was later replaced with the 24V 2.8L VR6 and later yet, the 3.2L 24V VR6 in the R32, however it was the addition of the 1.8T that rewrote hot-hatch history.

The VAG community had never seen an engine that took so well to mods. Simply uncorking restriction and upping boost produced tremendous gains without penalty to fuel mileage, it was the best of both worlds.

Much like the rest of the package, the chassis was also a sizeable leap forward over the outgoing MK3. Rigidity was greatly increased and while it still utilized a MacPherson strut front suspension and a torsion-beam out back, the MK4 was a solid foundation for the aftermarket to build upon.

The MK4 was replaced by the MK5 in 2005. Over the subsequent years, as VW has moved through the MK6 and now the MK7, the prices on clean and well-kept Mk4s has continued to fall. You heard it here first, much like clean BMW e30 prices hit rock bottom several years ago and have climbed back up in recent years, the prices on well-kept Mk4s will start to increase.

Of course the newer Golfs are great, but with bargain basement prices on the MK4s these days, we thought it the perfect time to start a couple of budget-friendly Golf builds. For the Euro rookies in the house, you'll soon see how tremendously capable the MK4 can be, even on a tight budget.

The test subject

After copious amounts of searching, we found our first test subject, a one-owner, 2003 Silverstone Grey GTI 1.8T with 130,000 miles on the clock. The hatch was largely stock, save for some Neuspeed springs, Koni STR.T shocks/struts, an older AEM CAI, a Forge MS diverter valve and an old school Autotech cat-back exhaust. A keen eye might catch the period-correct Kamei mesh grille and the Caractere hatch wing as well. No need to read that again, the car was still on the factory software! How many un-chipped 1.8Ts do you think are still out there?

Project mk4 vw gti project car Photo 2/27   |   Project Mk4 Vw Gti Project Car

The exterior was an easy 8/10 with a few dings and dents along with some clear-coat issues on the roof, but other than that, it was in great shape. After some haggling we managed to get the car for $3800, which we considered a great deal considering the condition and it's a one-owner vehicle. Our searching had unearthed examples on both sides of that price tag, and while the allure of a 337 or a 20th AE car was tempting, we decided to opt for a clean standard example.

After a complete tune-up and a fluid change the car ran great, save for some issues during baseline performance testing. In addition to erratic boost (which will be addressed in coming updates), the stock clutch was slipping during hard driving. We knew that this would only get worse and had to be taken care of before anything else. Thankfully a quick call to SPEC Clutch unearthed a world of possibilities.

One killer clutch

Despite what many enthusiasts believe, selecting a performance clutch, pressure plate and flywheel combination for a street car isn't simply about clamping force. In fact, there are many considerations beyond just the torque rating; pedal pressure, hub construction and clutch material along with flywheel material and weight, and many other considerations.

In order to better help the techs at SPEC select our clutch, we decided on acceptable parameters. The ideal clutch would need to withstand at least 350 lb-ft of torque at the wheels, have pedal pressure that was only marginally stiffer than stock, have enough flywheel inertia to make stop-and-go traffic manageable without too much flywheel weight that rev-matching a chore. All this with only a marginal increase in NVH (noise, vibration, harshness).

After reading our laundry list of requirements, SPEC advised we run a Stage 2+ Hybrid unit with a billet steel flywheel. Starting with the pressure plate; it features a double-sprung hub (application dependent) with spring cover reliefs for flexibility and heat-treated components. The unique pressure plate design keeps pedal pressure to a minimum while greatly increasing clamping force. In our case, this clutch and flywheel combo is rated for 420 lb-ft of torque. SPEC recommends a 10-15-percent torque capacity buffer be added just to be safe.

A great pressure plate doesn't mean much if it's paired with an insufficiently engineered clutch disc. SPEC made sure we'd have the best blend of performance and civility by selecting a Hybrid clutch disc. Rather than a single clutch material on both sides, Hybrid units feature a full-faced, multi-friction disc with a carbon semi-metallic surface on one side and a Kevlar surface on the other. The combination increases bite while minimizing chatter. When paired with our Stage 2+ pressure plate, the unit settles nicely between the Stage 2 and Stage 3 units on the SPEC roster with the civil driving manners of the Stage 2, but with a 20% higher torque capacity.

Another important aspect of a killer performance clutch for a street car is flywheel weight. Stock 1.8T cars utilize a heavy dual-mass flywheel that not only weighs a ton and makes rev-matching difficult, but at higher torque and RPM limits, they are prone to failure.

SPEC offers a feathery 8-pound aluminum unit but doesn't advise using it for daily driven cars. The more mass a flywheel has the easier it is to get a vehicle moving from a stop, but at the expense of throttle response. Consequently, the lighter the flywheel, the easier the motor will stall, but also, the quicker it will rev. Instead of the 21-pound stock unit, the billet steel SPEC flywheel checks in at 12.4 pounds.

The billet steel flywheels are also quieter than aluminum, which for those that have never owned a vehicle with a noisy flywheel, you might find it odd, but trust us, noisy flywheels can be tiresome on the street.

When we say that SPEC is run by a bunch of enthusiasts who know the industry, we're not kidding; they've been designing and building clutches for 35 years. Chances are good that someone at SPEC owns or has owned the same vehicle as you and can speak from firsthand experience about what a given clutch kit is like in the real world. If that's not legitimate, I don't know what is.

Project mk4 vw gti spec clutch stage 2 hybrid combo Photo 3/27   |   Project Mk4 Vw Gti Spec Clutch Stage 2 Hybrid Combo

When we asked SPEC to spec us (pun intended) a killer clutch and flywheel combo that could handle over 350 lb-ft of torque and still have feathery pedal pressure, we were unsure just how close they could get to perfection. As it turns out, this Stage 2+ Hybrid combo is just that, perfection!

Project mk4 vw gti pressure plate assembly Photo 4/27   |   Project Mk4 Vw Gti Pressure Plate Assembly

The pressure plate assembly on the SPEC Stage 2+ features a double sprung hub (application dependent) with spring cover reliefs for flexibility along with heat-treated components to withstand the abuse of drag racing, autocross or road racing.

Project mk4 vw gti billet steel flywheel Photo 5/27   |   Project Mk4 Vw Gti Billet Steel Flywheel

Since the GTI is a daily driver that sees regular stop-and-go traffic on the dreaded 405 freeway in Los Angeles, SPEC recommended its 12.4-pound billet steel flywheel en lieu of its more feathery 8-pound aluminum unit. The stock dual-mass flywheel checked in at 21 pounds, so both options are considerably lighter that OEM.

Project mk4 vw gti spec clutch stage 2 multi friction disc Photo 6/27   |   Project Mk4 Vw Gti Spec Clutch Stage 2 Multi Friction Disc
Project mk4 vw gti spec clutch stage 2 multifriction disc Photo 7/27   |   Project Mk4 Vw Gti Spec Clutch Stage 2 Multifriction Disc

The Stage 2+ utilizes full-faced, multi-friction disc with a carbon semi-metallic surface on one side flanked by a Kevlar surface on the other.

Project mk4 vw gti spec clutch throw out bearing and install hardware Photo 8/27   |   Project Mk4 Vw Gti Spec Clutch Throw Out Bearing And Install Hardware

SPEC seriously thinks of everything; like the quality throw-out bearing and the associated hardware for a worry-free install. As they say, you get what you pay for!

A proper install

Quality components are nothing without a solid installation, and when it comes to watercooled VWs, few people rival Scott Wood of Stray Dog Garage in Orange County California. Wood knows the modern VAG products, but his real specialty is the old-school stuff like Mk1s through Mk4s.

Prior to opening Stray Dog Garage, Wood had been working on VWs for over 25 years. In fact, he was a tech at the legendary VW Specialties before venturing out on his own. He's one of the only people we know of to build a turbocharged 1.8L 16V-powered, rear-drive dragsters from the ground up.

As if his dedication and know-how of the VWs isn't unique enough, Wood's commitment to the hobby branches well beyond his shop space.

"I know how hard it can be to find a tow company that works with modified and lowered cars, especially VWs, to ensure that they're safely and properly transported," Wood said. So what did he do? He opened his own towing branch within the Stray Dog Garage so any VW enthusiasts in the area that needs a tow has a mod-friendly expert option.

With his legendary experience and his easy-going demeanor, it only made sense that we turn to Wood for the clutch, pressure plate and flywheel installation portions of the build. Wood had our GTI in and out in less than a day.

Project mk4 vw gti oem shifter counterweight Photo 9/27   |   Project Mk4 Vw Gti Oem Shifter Counterweight

After removing the battery and the battery box, it's time to ditch the OEM shifter counterweight.

Project mk4 vw gti upper bell housing bolts Photo 10/27   |   Project Mk4 Vw Gti Upper Bell Housing Bolts

Once the shifter cables, the ground strap and the 45-degree transmission support bracket have been released, it's time to start removing the upper bell-housing bolts.

Project mk4 vw gti clutch slave cylinder Photo 11/27   |   Project Mk4 Vw Gti Clutch Slave Cylinder

Next comes the clutch slave cylinder, remove the two bolts and pull the unit outward. Remember to take care around the hydraulic line.

Project mk4 vw gti starter removal Photo 12/27   |   Project Mk4 Vw Gti Starter Removal

Start by removing all the plastic splash guards beneath the car. The starter is the next piece to leave the building. Be mindful of the power-steering lines that surround it.

Project mk4 vw gti swaybar end link removal Photo 13/27   |   Project Mk4 Vw Gti Swaybar End Link Removal

It's time to make our way outboard in preparation for the axles to be removed. This process starts with the removal of the swaybar end-links. Then the ball-joints must also be removed so the hubs can float outward enough so that the axles can drop out of the way.

Project mk4 vw gti drive axle bolt removal Photo 14/27   |   Project Mk4 Vw Gti Drive Axle Bolt Removal

Next on the list is to remove the inner drive-axle bolts that secure the axles to the inner drive-bells.

Project mk4 vw gti inner drive bells Photo 15/27   |   Project Mk4 Vw Gti Inner Drive Bells

The inner drive-bells are accessed once the axles have been removed. A large hex-head bolt secures them; once those are removed, simply slide the cups outward. After the wheels and the large axles nuts are removed, it's time for the axles to be lowered out of the way.

Project mk4 vw gti dogbone mount Photo 16/27   |   Project Mk4 Vw Gti Dogbone Mount

Now the infamous dogbone mount can be removed.

Project mk4 vw gti custom engine support brace Photo 17/27   |   Project Mk4 Vw Gti Custom Engine Support Brace

Stray Dog Garage knows VWs like the back of their hands and it shows with their many special tools, like this custom engine support brace that allows the engine to securely sit in place without the mounts attached. Speaking of mounts, start with the driver's side upper mount.

Project mk4 vw gti transmission bolt removal Photo 18/27   |   Project Mk4 Vw Gti Transmission Bolt Removal

Next, dive inside the inner fender on the driver's side to remove the rest of the bolts securing the transmission to the motor.

Project mk4 vw gti custom vw box tool Photo 19/27   |   Project Mk4 Vw Gti Custom Vw Box Tool

Remember the part about Stray Dog Garage truly being a VW Specialty shop, well, here is another awesome tool they fabricated to hold different VW boxes. It bolts to the transmission before the entire unit securely bolts to a traditional transmission jack.

Project mk4 vw gti transmission removed Photo 20/27   |   Project Mk4 Vw Gti Transmission Removed

With some finagling, the transmission finally leaves the building.

Project mk4 vw gti oem clutch pressure plate flywheel assembly Photo 21/27   |   Project Mk4 Vw Gti Oem Clutch Pressure Plate Flywheel Assembly

Here's a look at the busted OEM clutch, pressure plate and dual-mass flywheel assembly. Despite 130,000 miles, it still held for daily duties, but any speed shifting had it slipping in protest.

021 project mk4 vw gti loctite Photo 22/27   |   021 Project Mk4 Vw Gti Loctite

Don't forget the blue Loctite on the flywheel bolts!

Project mk4 vw gti spec billet steel flywheel install Photo 23/27   |   Project Mk4 Vw Gti Spec Billet Steel Flywheel Install

After inspecting the rear-main seal, it's time to install the SPEC billet steel flywheel. Don't forget to tighten the bolts in the proper star-like sequence and torque the bolts to spec using the same sequence noted by SPEC.

Project mk4 vw gti spec clutch disc Photo 24/27   |   Project Mk4 Vw Gti Spec Clutch Disc

Next comes the SPEC clutch disc that should be installed following the prompts on the sticker adhered to the hub that makes it bonehead simple. There is a flywheel-side and a pressure-plate side, so take note. Also, it's always a good idea to check that the clutch disc fits the input shaft of the transmission prior to installing the transmission in the car to prevent a ton of headaches later on.

Project mk4 vw gti pressure plate Photo 25/27   |   Project Mk4 Vw Gti Pressure Plate

The supplied SPEC alignment tool makes the installation easy. Tighten the flywheel in the proper star-like sequence to insure it's properly seated. In order to torque the pressure plate to spec, Scott used his flywheel lock and a quality torque wrench.

Project mk4 vw gti bearing sleeve Photo 26/27   |   Project Mk4 Vw Gti Bearing Sleeve

Before reinstalling the transmission in the car, Stray Dog Garage likes to lightly lube the throw-out bearing sleeve, the fingers of the throw-out bearing and its pivots; they also clean the input splines and make sure everything on the inside is up to spec.

Project mk4 vw gti transmission install Photo 27/27   |   Project Mk4 Vw Gti Transmission Install

Once the transmission is raised back into place, it's time to install everything in the reverse of removal and then enjoy your killer SPEC clutch.

Driving impressions

The first time we hoofed the clutch-pedal, we nearly dented the floorboard. The pedal pressure of the stock clutch was already light, but the SPEC Stage 2+ Hybrid has even less pedal pressure than the OEM unit. Nope, that's not a typo, the SPEC unit can not only hold more than twice the torque of the factory unit, but its pedal effort is light and smooth—it makes driving in traffic tremendously easy and hard launches a cinch.

Speaking of smooth, it's not just about pedal pressure, it's also about engagement, and the Stage 2+ Hybrid unit is buttery. The two compounds on the hybrid clutch disc cuts the chatter normally associated with performance clutches.

As mentioned, another aspect many enthusiasts overlook when specing a clutch and flywheel combo for street cars is NVH. SPEC has gone to great lengths to create capable clutches and flywheels without all the racket, and in our case, the Stage 2+ Hybrid is barely louder than stock. As for its performance, the billet steel flywheel is just light enough to aid in rev-matched downshifts while still retaining enough mass that taking off in first gear remains like factory.

Unlike most aftermarket upgrades that boost performance at the expense of civility, the SPEC drivetrain upgrades were truly like having our cake and eating it too. Not only did clamping forces increase, but pedal pressure decreased, and throttle response was also heightened—if someone would have told us prior to the install that we could tick all of these boxes, we would have laughed. Having seen and felt the transformation ourselves, we are believers.

Sources

SPEC Clutch
Bessemer, AL 35022
800-828-4379
http://www.specclutch.com
By Justin Fivella
63 Articles

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