Tag Archives: Maserati clutch

Why Do I Need A Scan Tool After F1/E Gear Clutch Replacement

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So every once in a while I will get this question about replacing an F1 Clutch by an owner who’s looking to have someone install it that doesn’t have the scan tool to re-set all the clutch parameters on an F1/E-gear car.  Some come up with these ideas about what’s happening in the car’s TCU or NCR obviously unfounded by any true understanding of the system. But yet and still they are willing to take parts that cost anywhere from $2000-$4000 and mess them up instead of paying to tow the car to someone that can do exactly what I am going to write about here.

Let me start off by saying this first. There is a ton of data now available on-line that did not used to be available to change one’s own clutch or have an independent shop do so. I wrote one such article years ago, documenting the process on Maseratilife.com before anyone else had in order to help facilitate people to do so. I’ve since moved all of those photos here to this web-site. However, even before I owned my own scan tool, I knew enough to know, to tow the car to Aston Martin of New England to have all the parameters re-set so as not to mess up a new clutch. So let’s talk about this, let’s discuss why you should just pay the $300 or so dollars to have the clutch parameters reset after such a costly repair.

Another misconception going into this is that the clutch wear algorithm is somehow inaccurate in these cars’ computer systems. So that when it states it’s 50% worn, that number in all actuality could be incorrect, and the clutch really could go at anytime. This ignores the fact, that the friction disc build thickness can vary in thickness size, and whether the flywheel has hot spots or the friction disc material itself has developed any sub-par issues like glazing from an incorrectly set up clutch. This is most evident in early model F360 cars that had auto-calibrated Kiss points. The build thickness isn’t taken into account when there is a build tolerance from one new friction disc to the next. In the algorithm the number is set to 5.56mm (depending on the clutch and tolerance build). A person literally could be running at 100% worn and the clutch be somewhat fine when that variance is in their favor. The car can “sense” hot spots, glazing,  (or basically slippage) but it doesn’t tell you which one it is. Under the scan tool parameters it will be called Clutch Wear Index, Clutch Degradation Index or something similar.  You could only be 50% worn and need to replace a clutch for this issue or a number of other ones.

Let’s talk about just four important parameters the TCU of F1/Egear cars store. We aren’t going to go into all of the sensory data because this would be very long and drawn out.

New Closed Clutch Position (NCCP)

Closed Clutch Position (CCP)

Clutch Wear Index

PIS/KISS point.

New Closed Clutch Position/Closed Clutch Position:

The NCCP is basically the closed clutch position from when the clutch was brand new. This figure is in millimeters written into the car’s computer from the Tech that usually installs the brand new clutch. This is the figure that all of the rest of the above parameters are built on.

So for instance, the car’s clutch wear percentage is an algorithm built from this number as it’s foundation. When this isn’t written in correctly a few things can go wrong, which is why it needs to be re-written immediately after installing the clutch and before bedding in or driving it.

One can learn quickly that writing in a measurement to far from the actual foundation point  into the computer that’s not accurate can severely mess with how the clutch engages.

Additionally, the reason why this has to be re-written for every clutch change is because every new clutch doesn’t sit it the same location as it’s predecessor. So in sum, using the previous written data could either cause the clutch to engage or not engage correctly.

Closed Clutch Position:

This is a number automatically calculated by the TCU of the car, that CANNOT be changed by a Tech, in millimeters, telling the system the exact location of the clutch’s position. This is based off of the vehicle’s clutch position sensor, and the sensory data provided by it. This measurement is also why no matter how worn a clutch is the KISS or PIS is still accurate. (Although as the car’s clutch beds/wears in, periodic resetting could be beneficial to the life of the clutch to help it better engage).

Clutch Wear Index:

This is a figure given between 0-10,000 in the data log of information explaining whether the clutch is biting aggressively 0-3000, or slipping and not biting correctly at all 5,000-10,000. The target number is usually between 3,000-4000 in a new clutch. This torque transmissiblity  curb is very important data as it tells you exactly whether slippage is occurring and at what rate.

This data is also reset with a scan tool after installing a new clutch, and adjusting the Kiss point. You want it specifically reset so that you can tell how the new clutch engagement is graduating. It helps to catch or identify an issue early on should something in the install have went wrong.

 

Kiss Point/ PIS

Now this is the one of the most discussed topics usually addressed in changing a clutch. Ironically, you can get away with just throwing a new clutch in a car and not changing it because this is always based off of the current closed closed position which we already have discussed cannot be played with. Now is it wise to do so, I think not.

Let me give you a working definition of KISS point or PIS. Essentially it’s this. Imagine you were in a three pedal car stopped at a light. The light turns green, you raise your foot to engage the clutch. The moment it begins to bite is the KISS or PIS point. That is what is being written into the TCU of these cars. The lower the point in MM written the faster, and less slippage that occurs. The higher point that is written, the more slippage that occurs. A previous PIS point can work on a newer clutch, but isn’t advisable because it could be too hard or too soft for a brand new clutch. Additionally, I always reset the PIS after the clutch has been properly bed in solely for engagement reasons.

Here is an example, I have a Gentleman named Joe that used the website in order to change his clutch. I drove down to him set the clutch up in a way to help bed it in. However, as soon as he followed the steps I asked him to follow to bed the clutch in, it began to stall out. This was normal, and I reset the KISS point again for a post bed in clutch. I might add he had one of the best engaging F1 systems I had tested in a while when I reset it.

Closing

In closing, let me offer my advice. Maybe we should again think of this, and understand the circumstances correctly. You just paid $2000 in parts, and you are concerned about protecting that with a $300 bill? Penny wise, pound foolish much? After all that work, you need someone with the proper education and back ground to protect it. It’s what’s best for the vehicle and the investment that you just put into it. Sure I am certain you will hear glory stories of people who have beat the odds, and  come out on top. But you will also hear stories tomorrow of who won the lottery, yet you did not. This advice is free, do whatever you feel is in your best interest. The article was merely mean’t to inform you. Chances are we’ll probably never meet, and  whether you used it or not is truly inconsequential to me.

 

 

How to Change a Clutch in a F1 Maserati

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I think one of the longest threads I’ve ever posted on Maseratilife.com or SportsMaseratiuk.com had to do with changing a clutch in a F1 Maserati. It’s another reason why I think a separate website is so much better to host this information. Most of the time it just bleeds into the rest of the other forum topics and isn’t found again until a specific Google search is performed.

So you are either a DIYer and want to try this on your own, or you’re a shop trying to expand your experience with these automobiles.  Before I get into this subject however, I must warn you. This is not for the faint of heart. You will still need to bring the car to someone who can set the PIS on the car, and also re-write the clutch configuration data so the vehicle knows it has a new clutch in it. This can only be done with an SD2/3 tool or an aftermarket tool like the Leonardo system.

Additionally, be warned, you always need to bed a new clutch in. You should not be taking off like you are in a F1 race as soon as you are finished. No, much rather for the first 500-700 miles your shifts and take offs should be nice and smooth. You will not be going over 55 mph. Your driving should be akin to your grandmother driving a car. I assure you, you will not be happy if you glaze over the brand new friction discs in the car or hot spot the newly re-finished flywheel. If you do so you will have terrible engagement, or you will be taking the car apart.

I want to add here as well, there are really two ways to take these cars apart to do a clutch job, and depending on whether you are doing this yourself or in a shop would probably determine which way you should go. If you are in a shop I would more than likely drop the entire sub-frame with tires and all, you will have the lift to raise the vehicle. Keep the sub-frame/torque tube as one unit, take the torque tube from the bell housing.

If you are attempting this by yourself or with a friend I would leave the sub frame. Loosen it for clearance, and remove the torque tube and gear box from the sub frame but leave it in the car. Either way it is totally up to you. If you are removing the sub-frame with the gearbox and all, don’t take the trunk apart unless you are having clearance issues. You shouldn’t. The sub-frame, gearbox, and torque tube can be removed as a unit if you have the correct tools to do so.

I will be showing here, more of a private setting to take it apart though I do have the car on a lift.  My first F1 Maserati I did with cradling, in a small garage years ago, so it is possible. Contrary to what people may think you don’t need a huge garage with a lift to service these cars. If you are a mechanic, or mechanically inclined the tools don’t give you experience or skill you must have that already. If you have that you could do this in a driveway if you wanted to. I once replaced an F1 pump in the driveway of a Client’s car that was a few hours away from me. I laid on cardboard as a make shift creeper. He needed the help, and I didn’t mind doing it.

Take the Trunk Apart

 First things first, lets get the trunk apart so you can have enough clearance to slide the gear box back away from the torque tube.

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As you can see by the photos above,  you simply first need to remove the plastic trim piece around the trunk latch before you can pull the carpeted piece up that sits in the trunk well.  You will need a Philips screw driver or a motorized tool of your choosing. You’ll also need this to remove the well itself. This is assuming if you keep stuff in your trunk you have removed it, including a spare tire if you have one.

Next is the actual trunk well itself, again a Philips but you’ll also need an 8mm because there are some studs that come through with nuts on them.  The studs should come up at the bottom of the well closest to the latch.

In the last photo above you can see exactly four holes (those are the 8mm studs) at the bottom and two on the side. On the sides its philips and sometimes you need to pull the insulation away to get to them like this:

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When you are finished you pull the well out and set it aside. You should see this heat shield next:

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In order to take the heat shield out of the way. You have to get under the car. Now I’m assuming if you are at home or have your own garage you should already have the entire car about 2′-3′ in the air. Whether cradling or jack stands, you’ll want to be able to put a creeper under the car and slide back and forth. You’ll also want to be able to drop the entire exhaust to slide it out. So you need to get the car in a position that makes it easiest on you.

When you get under the car you should remove the rear valance, it’s the one below.  It will be easier after removing the valance, which is basically torx head bolts, to then remove the exhaust before we remove the heat shield.  The 4200 is a bit different how it detaches as there are other bolts inside of the valance on either side. Whereas the pic below just shows torx heads on the outside parameter and sides.

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Front Sway Bar and Exhaust

Next we need to remove the front cross member and sway bar in order to drop the entire exhaust out of the way. 20160323_17210920160323_17210720160323_172138 20160323_172705 20160323_172940

The first two photos above show the support cross member that has to be dropped. It’s two, 13mm bolts, on either side that needs to be removed. After doing so, pry it down and remove it. It should be concave and must be put back the same way.

Next you are looking at detaching the front sway bar. You don’t need to remove it, you can just let it hang out of the way. Both caps are easy to spot in the next photos above. I cannot remember but I think they are 14-15 mm. Remove these and drop the sway bar down.

Here is another photo with the cross member and sway bar dropped:

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Next we need to drop the exhaust:

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Unfortunately, this photo is blurred. But you can basically see that each manifold just before the secondary cats have two bolts. They are hex head bolts and need to be removed.

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Here in this photo above on the top right hand side you will see a metal bracket attached by the secondary cat. It’s 13 mm and is holding each cat in the same area. They need to be loosened to drop the exhaust down.

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There’s brackets attaching the rear part of the exhaust manifold to the gear box like above. Those also need to be detached. There’s one on either side.

Lastly, you’ll need to remove the pipes from the rear boxes like so, it’s 15mm on each box. Just rock and twist them out:

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Removed and out of the way it will look like this:

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Okay, now lets get that heat shield out of the way:

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8mm nuts on these studs, the front ones are easy, the ones toward the rear of the car will be a bit more difficult. Use a wobble socket with wobble/swivel extensions it will help out. Then fold up the heat shield a bit to get it out of the way. Remove it from the car being careful not to scratch the paint on the rest of the rear valance.

Torque Tube and Gearbox

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So you are looking at 8 15mm nuts on each side to the torque tube. In order to reach the 15mm nuts on the top part of the torque tube toward the gear box you need an “S” wrench like this one.  However, toward the front you can just use a couple of long extensions with swivel/wobbles like these photos below. Obviously, the impact is optional. You can also get to the top bolts on the other side with an “S” wrench as well:

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What you’ll want to do is detach the torque tube closest to the gear box first.  You’re not dropping it yet. You will just be detaching it in order to get the gear box ready to slide back out of the sub-frame cradling. Additionally, since you are close to the floor already you can get a jack stand to support the torq tube so it doesn’t hit the floor when you remove it from the gearbox.

Next before we separate the gearbox we need to remove the mounting bolts to the Emergency brake. In order to do so, if you are under the car, you should have it in the air anyway. You can not have the emergency brake engaged to loosen the hardware. It will create too much stress on the cable if it’s engaged.

Here are some photos of what you will need to be loosening:

20160324_124835 20160324_124841 20160324_124855If you have a 4200’s series car, the E brake will be attached to the Torque Tube. You’ll have to reach around on top, and you’ll also have it bolted into the slot of the side of the torque tube. The GS you only need to disconnect the hangers and brackets. The last picture is the hanger above the gearbox. You need to make sure and detach it or you’ll have a heck of a time getting the gear box out.  Here’s a photo of the one above the gear box that was bent when it was done not realizing it was still there:

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Next, you’ll go around to reach up into the trunk area. You will see the connecting harness to the gearbox on the left side of the car like so:

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Now, you will also see the rear cross member in this photo. But before you loosen those you’ll need to detach the half shafts on either side of the gear box going out to your rear wheels. Unfortunately I don’t have photos for that specifically, but it’s okay because you’ll clearly see where they attach. You’ll need a 13mm socket or wrench. If your car is in neutral it will make it that much easier. Just spin the rear tires to rotate around to the next bolt.  Once you are finished push the half shafts out of the way. You don’t have to worry about removing them.

Next is the rear cross member, four 13 mm bolts on either side, but also remember to detach the heat shield on the right side that folds around it. You should have a jack under the gear box. Once you complete this you’ll pry apart where the torque tube is in front of the gear box. This will push the gear box rear-ward in order to separate it. The cradling will support the gear box as you continue to pull it rear-ward and pivot it out of the cradling. If you feel you need a little more space you can un-bolt the sub-frame bolts, 3 on either side to give you more. You don’t need to completely remove them. Here’s what you’ll have when done:

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Again you should have already had the jack stand holding the back of the torque tube up. You can just slide the gear box out of the way as a unit.

You will see the hydraulic line running down the torque tube. I don’t think I mentioned disconnecting this from right under the gear box above but it’s a quick disconnect similar to what you’d see on an air compressor. Just push it back and it will detach.  Running down the torque tube is 10mm nuts holding the hydraulic line that need to be unbolted before you can take the torque tube down.

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 Once you’ve done so, you can detach the other bolts on the torque tube. Place a jack to support the front part.  Pry it apart from the bell housing and lower it down. Remember this is heavy!

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 Bell Housing and Clutch Removal

Next up you’ll need to unplug the F1 position sensor wire on the right hand side of the bell housing. I usually just wind the hydraulic line up and wire tie it together to get it out-of-the-way. F1 position sensor wire below.

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Next you’ll need to get that swivel/wobble end ready again for the top bell housing bolts.  Work your way around until you have them all.

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Once you get them all out, just make sure the heat shield is out of the way above the bell housing when you start prying it apart, it will take some persuasion to get it apart. The heat shield begins to sag down a little over time. Just take the end of a hammer and press up.  It bends fairly easy.

When you are done this is what you should have:

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Next you will have the pressure plate and clutch still on the flywheel:

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You should notice nine (9) different hex head bolts around the outside diameter of the pressure plate. DO NOT try and take those out one at a time. You will strip the last couple of bolt holes with the remaining bolts as you take them out. Since you’ll want to resurface the flywheel this would be a terrible situation when you go to reinstall the new pressure plate and flywheel.

What you will do is take your 5mm or 5.5 mm hex head socket, and go clockwise. or counterclockwise. Slowly loosen each bolt about a half a turn. Walk it around just like this to slightly release the tension of the pressure plate to remove it.  When it’s off you will have the flywheel like below.

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No special tricks for this. Take a socket and take the bolts off, and tap the flywheel off. Be careful as well, it has a bit of weight to it like the pressure plate and friction discs do.

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The final step will be your spigot bearing- in the U.S. we usually call it the Pilot bearing. If you don’t have a pilot bearing puller, don’t fret, let me teach you an alternative method.

Basically this method is a way to apply a kind of hydraulic pressure to the back of the Spigot bearing to press it out of the crank shaft. Some guys like to use grease which is going to be really messy. I like to use bread because it’s less messy and you don’t need an air tight seal so the grease doesn’t blow back on you.

So here’s how you’ll do it. Take black electrician’s tape, or a good holding tape like this. Wrap it around your 3/8″ socket extension until it barely fits into the hole in the middle of the spigot bearing.

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Next shove bread into the center of the spigot bearing hole until you cannot get anymore in:

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Next take a hammer and put the extension right into the hole, and hammer the bread into it. Take the extension out, and put more bread in. Repeat over and over again until the Spigot pops out like this:

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Then just clean all of the bread out of the hole. If you’d like, take your new spigot bearing that you have and get a socket that covers the outside edge of the bearing. Now flip the socket around where the rachet would normally go, and hammer the new one into place.  It’s supposed to be really snug, so don’t lubricate this at all, in order to get it into the crank.

F1 Position Sensor and Thrust Bearing Removal

When you flip the bell housing up, the first thing you are going to see is the center shaft coming through the middle, the thrust bearing sitting on the sleeve, and the F1 position sensor with the wiring coming out.

The earlier model 4200’s don’t have the star set up like this where there are 5 hex bolts at each point to release. This one is from a GS so it does have it like this. A Quattroporte should also look like this. If it’s a GranTurismo S F1 car, the F1 position sensor will be off to the side a bit.  Let me show you the difference- this photo is the GS/Facelift/Quat bell housing:

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This one below is the really early model 4200’s assembly:

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 Before loosening up the hex bolts at the five points you will need to detach the hydraulic lines going to the slave cylinder of the thrust bearing. Additionally loosen the bolts holding the F1 position sensor wire in place.

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After you pull the lines out you can remove the 5 bolts that are at each point of the star in the bell housing. Then remove that assembly, it will look like this:

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The photo above is how you will do the later models, however, if you have the earlier model without the star mounting, this is what you’ll need to do:

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Take the two opposing bolts out on either side of the base of the thrust/slave cylinder sleeve.

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Then the thrust bearing mounting bolts:
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Please again note you will not have to go through this with the star mounting in the later models.

After you loosen these, you will be able to slightly clock the slave cylinder sleeve in order to get to the hex head mounting bolt underneath it. This older design was a bit of a hassle as you can see. But when you’re done this is what you’ll have:

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Now that you have this apart, you can remove the F1 position sensor and it’s mounting base from the bottom of the assembly:

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Tips for Installation

The magnet protruding from the bottom of the slave cylinder is a very important piece. This is what the F1 position sensor slides over in order to make the hall effect sensor work. Additionally, do not forget, this is what tells the NCR what position the thrust bearing is in. It transmits the data for clutch wear, PIS, and a host of other functions.

The pin must be pressed out, or you can remove it with a hammer and pin of like size. When you put this back on the new thrust bearing, that screw head ALWAYS faces forward, regardless if it’s a Ferrari or Maserati.

A small digression on this topic. Not long ago I helped a gentleman with his GTS F1 car. The car wasn’t shifting correctly, and throwing F1 position sensor codes. He took it apart and thankfully he sent pictures to me. The clutch had been replaced not long ago. At first, my thoughts centered around the F1 position sensor being faulty. When I received the photos I could tell right away, they had installed this magnet backwards. That, we believe, was the actual culprit though he replaced the sensor anyway. Magnets do have poles, don’t reverse them by placing the magnet backwards. Here are some photos showing what I am explaining:

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I normally do not use the OEM thrust bearing from Maserati. They had various issues to begin with, and I feel Hill Engineering makes a more trustworthy component.

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When you get ready to put this back together, I am kind of hoping you paid attention to how it came apart. If not here are a couple of pics to help out.

This photo is how the springs should sit in the back of the thrust bearing. Because they can fall out if you’re not careful, it’s best to post these:

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Flywheel Resurfacing

Most people think they have to purchase a new flywheel in these cars in order to complete the full service. I know mechanics that merely clean off the old one and re-install. That’s one extreme. The other is to purchase a new flywheel.

You can get away with not doing anything to the flywheel at all. I don’t recommend it.  These flywheels develop hot spots because of the F1 system and how it engages. This is especially true when the PIS point is high and it slips more off the line. Maybe some pictures would be better to show you. Here are two flywheels from two different F1 Maseratis:

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Hot spots in flywheels will cause the friction discs not to engage the full surface of the flywheel face. It’s basically hardened metal in those areas where increased heat was created.

When flywheels are resurfaced minute amounts of metal are taken from the face, and run out is checked. This positively removes any hot spots and additionally removes any micro cracking on the surface as well. This will affect where the PIS of the car will be set but any tech that knows how to set the PIS, will be unconcerned about this. Before I forget most machine shops will already see where the pressure plate mounts around the outside edge and will take the same amount off here to make sure it’s all done uniformly. If you’re concerned, make sure you mention this to them when you bring it in.

Here are those same flywheels after being machined, hot tanked, and checked for run out:

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Please notice the difference in thickness of the top flywheel from the one just below it.  The top flywheel is from an early Spyder. The flywheel weighs about twice as much as the one below it. The one below it is from a later model GS. Flywheel resurfacing will only cost about $100.

Clutch balancing comes up from time to time. Here’s my recommendation. If you have the heavy flywheel get the clutch and flywheel dynamically balanced together at a machine shop. If you have the smaller flywheel don’t worry about it and follow the service manual and clock the factory balancing marks 180 degrees apart from each other.  Below is picture of a dynamically balanced flywheel. I don’t want to draw this out by talking about tolerance stacking and why it would be beneficial for one and not necessarily the other. I can state I’ve had both tested at machine shops. The thicker ones tolerances were a bit more than the thinner one. I was specifically told not to waste money on the thinner flywheels, but the thicker ones benefitted more from being balanced together with the clutch assembly. I bring all this up because they sell kits to balance the flywheel in the car. I can say with certainty they are not necessary, and I’ve seen people charged for them when the dealership knew they would not use them.

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I mentioned clocking the factory marks 180 degrees from each other. When you take the flywheel in make sure they score it so it’s not hot tanked off . But here are the marks on both the flywheel and the pressure plate. It’s the yellow and white lines. When you open the new box of the clutch/pp you will see the factory mark right on the front face of the pressure plate.

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As you can imagine, this has been a very long post and I’ve been waiting to say this. The rest of installation, is the reverse of how it was removed. I think I’ve covered everything I could to help out.

Please feel free to contact me if you have a special situation or need consultation on a specific issue.

Maserati F1 Clutches

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Another subject you will hear a lot about with F1 cars, is of course F1 clutches.

F1 clutches in Maserati F1 cars are not like standard three pedal car clutches, nor were they ever designed to be. Generally they last about 30,000 miles in these cars. The older these Maserati cars have become the more Techs are learning about how to set up the clutches so that longer shelf lives of the clutches are documented. This includes using mods such as Formula Dynamics Drive-by-Wire system in these cars.

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Above is an F1 double disc Maserati clutch.  They are manufactured by Valeo.  Many times, by many different people, different types of clutches have been tried in Maserati F1 cars, usually the hot topic is Kevlar. All todate have been unsuccessful. You can get them in the car, and initially get them to work but not for long periods of time. The engagement is usually too harsh stalling out the car or too soft constantly slipping the clutch.

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Above is a brand new stock F1 friction disc set up. Brand new you can see the mm measurements are approximately 6.34/6.21mm. Fully worn these disc will measure respectively right at 5.34/5.21. There is a manufacturer variance, so not every clutch will have exactly this mm size but it will be close. Here is another brand new clutch measured to show you the variance:

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Clutch Wear Reading Algorithm 

Clutch wear readings are done using a Maserati specific scan tool, or aftermarket scan tool like Leonardo that can access the gear box computer known as the “NCR” in these cars. When a new clutch is installed in the car, the new clutch parameters are written into the NCR by the Technician doing the install. The NCR of the car measures the friction disc material through the F1 position sensor from this starting parameter.

That data will read like this on a scan tool.

New Closed Clutch Position (This literally means the closed clutch position when a new clutch was put into the car, and the Technician re-wrote those parameters).

I will use a previous car’s parameters: 18.281mm

Closed Clutch Position (This is the current closed clutch position in the vehicle and cannot be changed)

In this instance it was: 18.423mm

Much has been made about the algorithm the scan tool uses to calculate the clutch wear percentage, usually by people who don’t understand that computers don’t use snake oil, they use hard numbers. It is accurate, but isn’t the final say on whether a clutch needs to be replaced. For instance, if you have a high KISS point, or PIS set up (Explained in another article) it causes a lot more slippage of the clutch. You can have 50% clutch wear left, and yet need to replace the clutch because they are glazed over, or you have hot spots all over the flywheel affecting engagement.  Additionally, depending on where the car has come from you can also get an unsavory character to go in and change the New clutch settings to give you a lower wear reading for a clutch than it should have.  (Also discussed later).

Here are the hard input numbers of the algorithm the Scan tool bases the F1 clutch wear reading on from the example numbers above.

Closed Clutch Position: 18.423mm

Subtract this number from: New Closed Clutch Position:  18.281mm

this equals, 0 .142,

then it will be divided by 5.56*.

We now have, 0.025. This number is finally multiplied by 100. So the clutch is worn 2.55% in this Maserati.

The scan tool always shows how much it’s worn, not how much is left. I usually invert the number for the client. In this case, that would mean it’s 97.45% remaining.  The Maserati Scan tool does not show the Tech this Algorithm, it merely gives him the parameters of where the clutch is from New, Current, and calculates those figures with all of these number to give him/her the clutch wear percentage. So it’s very possible for him not to even know this.

I usually take those numbers myself, with my phone calculator and calculate every clutch wear reading  from the scan tool. I don’t base my clutch wear percentage off of the scan tool’s inputted algorithm. I base it off of the new/current clutch position numbers themselves.  I do this mainly because I’ve had a problem with a scan tool calculating these number correctly.

Again, the scan tool does this automatically, the NCR is merely providing the scan tool those New/Current clutch parameters. The NCR itself doesn’t calculate that algorithm, it provides in millimeters the distance worn through the F1 position sensor.

[*This number is ostensibly the actual thickness of the friction disc material on one plate, minus the metal in-between it. As you can imagine since there is a manufacturer’s variance in friction disc thickness this would also slightly throw off the actual wear reading itself.]

Physically Checking the Friction Discs

Many times I’ve been asked is it physically possible to check the friction discs of these cars. The answer is yes, with a little bit of trouble on your part you can.

There are two cut-outs around the bell housing itself not specifically designed for this but can be used to measure the actual physical thickness of the friction disc material.

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The photo above shows a cut-out basically  at the 11-11:30 o’clock position, and another at basically the 7-7:30 o’clock position.

Another view:

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The trick is to spin the motor so the clutch friction discs can be seen through these cut-outs. Either from the top passenger side under the hood, or under the car at the other position. If you look you could also remove the exhaust hanger from the bottom of the bell housing (the black bracket in the photo above), to check as well.

You basically are trying to line up the cut-outs of the bell housing with the cut outs showing you the friction disc of the pressure plate like below:

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You’ll only get a good look and measure the outer most disc which is okay because they wear evenly. If you bump the key in the ignition you can look from the top and see when that one is lined up.  Photo below

The only thing left to do now is to get a measuring tool. You already know the dimensions from above of a fully worn, and brand new clutch. You can stack long feeler gauges together, or use a long  “T” handle hex key tool to do this. For instance, a 5.5mm or 6mm “T” handle hex key stuck down between the two metal plates would give you a fairly good idea of how much actual clutch life is left. (See photo below.)

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I have to add this caveat here though, it’s going to be very difficult to see fractions from 5.5 to 6mms, with T handles. But, either way, there you have it.  If it’s truly a brand new clutch a 6mm should fit right down to the friction disc without forcing it.