ACT Clutch Install Review, Pics & Graphs:
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06-11-2009, 12:55 PM
Join Date: Oct 2007
Location: Los Angeles
Posts: 309
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ACT Clutch Install Review, Pics & Graphs:
First off, the clutch really is perfect! It's the perfect mix between an after market high performance clutch & the luxury element of driving a BMW that you lose w/ most after market clutches. It's stiffer than stock but VERY drivable. IE: If I had never driven a 335 manual & this was my 1st, I wouldn't question that it's the factory clutch which is possible because ACT utilized the stock fly-wheel. The clamp load is a 45% increase but it's not over-whelming which is really important to me because this is my daily driver. I definitely recommend this clutch to ANYBODY looking to upgrade their stock. Not to mention, the guys at ACT are some of the nicest guys I've ever dealt w/. I met Daryl of ACT at Bimmerfest, we were just talking cars, & he started asking questions regarding upgrading my clutch, I let him know I'd been thinking about it a lot & had ACT clutches on both my Evo's but knew ACT didn't have one out yet for the 335, he let me know they had already been working with one of our reputable members on E90post & that I should consider upgrading as well, so he gave me his card & 2 days later I wrote him an e-mail & couldn't say no, partly because these guys couldn't have been more courteous, professional & an overall pleasure to deal with.
Here is a 'tech bulletin' from ACT that will explain gear rattle, which is the reason for a dual-mass flywheel. The dual-mass flywheel dampens the motor’s vibrations in order to keep the transmission gears from rattling.
Gear Rattle Tech Bulletin
Gear rattle can be explained as an audible noise transmitted from the impacts between the transmission gear teeth. The separation and resulting impact of the gear teeth are caused by the engine’s torsional vibrations (momentary angular acceleration) when passed through to the transmission. In general, gear rattle is not harmful to the transmission but can be an annoyance to the driver. It can also become a serious concern if misdiagnosed as a transmission problem. Gear rattle is not to be confused with clutch chatter or out-of-balance vibrations; both of which are conditions mostly felt and not as much heard.
Traditionally, automakers have dampened the torsional vibrations by using a clutch disc with a sprung center design. More recently however, many have started using a dual mass flywheel to silence the gear rattle in the transmission. Typically, when a dual mass flywheel is used, the disc will have a solid center instead of the sprung center.
When switching from a dual mass flywheel to a solid flywheel like an ACT Streetlite or Prolite, a sprung center clutch disc should be used to dampen the torsional vibrations, and quiet the gear rattle. A solid center type of disc can be used, and will not cause any damage to the transmission.
Other factors that can contribute to gear rattle are the condition of the motor/transmission mounts, mileage/condition of the vehicle, level/condition of the transmission fluid.
The other 2 graphs are of the pedal loads and pressure plate clamp loads. FAQ: Clamp load is a 45% increase.
Pics:
What is visible after removing all the plastic covers from the underside of the car. Incase you're not clear as to where this is, you can see the RR mid pipes & down pipes just to the right.
The driveshaft after removing the exhaust and heat shields
Slave cylinder and CDV
Rear of the transmission w/ the driveshaft removed
The bellhousing bolts that have a blue head are aluminum and can only be used once. A new set must be used each time and they must be torqued to the correct specs.
Transmission removed. Notice the huge 1-3/8”x26 spline input shaft. Also notice, the pilot bearing is in the input shaft instead of the flywheel or crank like normal.
Stock dual-mass flywheel. Here, you can see the pilot shaft protruding from the center of the flywheel to locate the input shaft.
ACT Heavy Duty Pressure Plate and Performance Street Disc installed
New pilot bearing and release bearing installed
Slave cylinder installed w/ CDV removed
Here is a 'tech bulletin' from ACT that will explain gear rattle, which is the reason for a dual-mass flywheel. The dual-mass flywheel dampens the motor’s vibrations in order to keep the transmission gears from rattling.
Gear Rattle Tech Bulletin
Gear rattle can be explained as an audible noise transmitted from the impacts between the transmission gear teeth. The separation and resulting impact of the gear teeth are caused by the engine’s torsional vibrations (momentary angular acceleration) when passed through to the transmission. In general, gear rattle is not harmful to the transmission but can be an annoyance to the driver. It can also become a serious concern if misdiagnosed as a transmission problem. Gear rattle is not to be confused with clutch chatter or out-of-balance vibrations; both of which are conditions mostly felt and not as much heard.
Traditionally, automakers have dampened the torsional vibrations by using a clutch disc with a sprung center design. More recently however, many have started using a dual mass flywheel to silence the gear rattle in the transmission. Typically, when a dual mass flywheel is used, the disc will have a solid center instead of the sprung center.
When switching from a dual mass flywheel to a solid flywheel like an ACT Streetlite or Prolite, a sprung center clutch disc should be used to dampen the torsional vibrations, and quiet the gear rattle. A solid center type of disc can be used, and will not cause any damage to the transmission.
Other factors that can contribute to gear rattle are the condition of the motor/transmission mounts, mileage/condition of the vehicle, level/condition of the transmission fluid.
The other 2 graphs are of the pedal loads and pressure plate clamp loads. FAQ: Clamp load is a 45% increase.
Pics:
What is visible after removing all the plastic covers from the underside of the car. Incase you're not clear as to where this is, you can see the RR mid pipes & down pipes just to the right.
The driveshaft after removing the exhaust and heat shields
Slave cylinder and CDV
Rear of the transmission w/ the driveshaft removed
The bellhousing bolts that have a blue head are aluminum and can only be used once. A new set must be used each time and they must be torqued to the correct specs.
Transmission removed. Notice the huge 1-3/8”x26 spline input shaft. Also notice, the pilot bearing is in the input shaft instead of the flywheel or crank like normal.
Stock dual-mass flywheel. Here, you can see the pilot shaft protruding from the center of the flywheel to locate the input shaft.
ACT Heavy Duty Pressure Plate and Performance Street Disc installed
New pilot bearing and release bearing installed
Slave cylinder installed w/ CDV removed
Last edited by GT3 Chuck; 06-11-2009 at 01:03 PM. Reason: gratuitous advertisement for non-sponsor
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