[flash]

Over the years I have run into a number of problems with the Fidanza flywheels. As it turns out, I am not alone. I am sure some others will pop on and comment, but a couple of things have been discovered, which are not comforting, and are very likely to happen in any car subjected to track conditions or extreme heat (like on a dyno).



There are plenty of guys out there running these flywheels who have not "had a problem", or at least, that's what they think. The real problem is that you cannot tell if you have a problem without taking things apart. By that time, it could be too late.



Here is an explanation, as well as a fix for the problems.

Fixing the Fidanza-2s.doc.pdf Size: 560.74 KB  Downloads: 142

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[Ab54666]

Interesting read as I have an 18lb one fitted from RS Barn.....

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[DaveN]

I have my engine out at the moment and will be definitely doing this fix.

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[Fox944]

I was running a PowerHaus Billet Flywheel on my car with zero issues. It would be very difficult to source this flywheel today as PowerHaus is all but shut down. It is actually 1LBS lighter then the Fidanza Flywheel @ 12.5LBS vs 13.5LBS (Fidanza). The biggest negative of this flywheel is the Price. $1,300.00..or about $1,000 more for 1LBS less weight.

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[Cloud9...68]

Out of curiosity, what's the purpose of the nose piece? Couldn't the bushing simply have been pressed into a single-piece flywheel? Purely hypothetical, of course, since it is what it is...

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[flash]

i'm not sure that powerhouse did not sell the fidanza (by the way, my light fidanza really only weighed 12.5# - they just list it at 13) - based on the picture on lindsey's site, i think maybe the spec unit is actually made by fidanza. the one shown in their catalog sure looks exactly like mine did. autoatlanta shows a different pic though, so i'm not sure about what is what there.



anyway...



i thought mine had zero issues too, until i pulled it out. like i said, you can't tell without removing it. so far, every single one i have seen has had at least one of the problems.



but, the issues are fairly easily remedied, albeit at a bit of a hassle.



the nose piece is separate to save cost by using a smaller piece of aluminum. there are a number of ways they could have done that, but the bearing sits out a bit, so they needed to handle it one way or another

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[Cloud9...68]

The issue of the gouging of the aluminum around the bolt holes is definitely of major concern. Not sure if I took any pictures, but I did nothing but torque my 18 lb flywheel, and then removed it when Flash alerted me to the issue. I put zero miles on it, in other words. Just the act of torquing the bolts (and I'm positive I didn't over-torque them) gouged the aluminum quite deeply.



When I recently took the flywheel to the machinist to address issue #2, he commented that he's recently been seeing more and more aluminum flywheels with the steel ring insert used to address isssue #1, so this isn't something relegated to just this flywheel.

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[Fox944]

The Powerhaus Flywheel was def. not the same unit as the Fidanza..and was lighter. I had both side by side 5 years ago. I took extensive photos of the Powerhaus flywheel and may have even sent you some several years ago. If I ever get geek squad over to save all the files/pics off my old PC, I will re post them. Too scared of losing more files by restarting that pc.

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[flash]

no worries. it's probably just them using the wrong photo. i know for sure that the fidanza i had came in under 13, but for the life of me, i can't remember exactly how much. it doesn't really matter much. the mass isn't the issue. the torque loss/galling issue would happen regardless of mass. that's just steel torquing down on aluminum.



the one pic i can find of the spec shows a different construction, but the same lack of a steel ring at the bolt circle, so it would suffer the same problems. i don't know about their nose cone design though, so i can't comment on that. again though, you'd have to take it apart to see it.



it's a bit scary to think that i was banging gears at high rpms, all the while the bolts were not torqued to spec anymore. those of us with an engineering background can tell you what happens with aluminum when it starts wobbling under stress. it's not pretty.

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[Eric_K]

Hmm, never had a problem racing with a Fidanza flywheel.

Did 6 years with one on the 968 engine, sprint races, 4,8,12 hours endurance races, multiple different drivers, days over 105F, etc.

I have 4 years with the same Fidanza on 3 different 951 engines, again no issues.

Never a bolt that wasn't torqued or an issue with the pilot bearing. I've had plenty of things to worry about, but the Fidanza flywheel isn't on the list.

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[kwikt]

Hmmmm, got one on my 911 and one on the 968. Only annoying problem so far is the buzzing sound on the 968 but none on the 911. Both have been on for at least 3 years. Although after reading this, I'm debating swapping the Fidanza back to the oem maybe this weekend unless someone talks me out of it.

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[flash]

i knew there would be plenty of people who said they did not have a problem. that doesn't mean a thing. millions of people walk across the street every day without getting hit by a bus too. i'm willing to bet nobody checked the torque on the bolts later on down the road. why would they? if you pull them off though, you'll find the galling.



that's the real danger. there is no telling what is going on, or when it will let go.



even the owner of fidanza knows about the issues. there haven't been any tragic accidents yet, but is it logical to roll the dice when the fix is relatively easy?



i've personally seen too many with problems to let one be in one of my cars without the modifications. in just the past year i've come across 2 cars have had problems with 2 different flywheels, and 3 others i know of that have seen similar issues. that's not a lot, but i don't see a large percentage of the cars either. but i've seen those, and that's a pretty big sample, relative to how many cars i know running the flywheels, and in a relatively short time. thinking back though, all but one are the 18lb units, so maybe it's mostly those. frankly, the sampling isn't big enough though to know if it is limited to one model, or really affects both. when people start doing clutch jobs, we'll know a lot more.



the big issue to me is that i've seen what happens when a flywheel shatters, and i rather prefer my legs where they are.



again though, the mods are relatively easy, and once done, there won't be a problem.



the entire purpose of this thread was to make people aware of a situation, and to provide a solution. they are free to do what they want. i'm not selling parts or have any interest in any of it.

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[Cloud9...68]

There seems to be a lot of variation in the tolerances, at least with regard to the nose piece. My machinist told me mine popped out after a light tap with a plastic hammer, while I know of someone else who said his was in very tight. So, as Flash says, it's a bit of a crap shoot. But I can definitely vouch for the gouging of the aluminum under the bolt heads, which seems to be a universal problem, and one not exclusive to this flywheel, as I stated above.



After having R & R'd the clutch and flywheel once, I was surprised how easy the job was the second time around. Tedious, yes, but not very difficult.

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[kwikt]

Yep , I purchased all the parts a while ago. Knowing that one day I'd be re installing the oe flywheel again.

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[Ab54666]

I can't quite picture where this fits with the flywheel I have?

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[flash]

please look closely at the pics in the advisory. you should be able to see where things go from there.



the plate goes on top of the first shot, but first you have to counterbore down for its thickness.



the nose cone is the protrusion in the first shot. from there you have options as to what to do about it. the simplest is to tack weld it on the back side, assuming your balancer can fit in the hole without having to remove the nose cone. the best solution is to make a new one, complete with a groove for a snap ring to retain the pilot bearing, and make it larger diameter, so as to have the new plate retain it from the front side.

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[Rob in Oz]

Sorry if this sounds a bit basic, but with respect to the gouging problem, why couldn't you put flat washers under the flywheel bolts?



Regards



Rob

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[Ab54666]

[quote name='Rob in Oz' timestamp='1356036568' post='136443']

Sorry if this sounds a bit basic, but with respect to the gouging problem, why couldn't you put flat washers under the flywheel bolts?



Regards



Rob

[/quote]



Thats what i've since found out a lot of the UK people have done.

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[DaveN]

This is only a guess but you probably could. The problems that occur to me are 1) the washers could shift ans throw out the balance whereas a solid ring would not. 2) you would have to countersink all the washers individually? 3) With basic store washers you may not be able to balance properly (too much offset?) and every time you remove the flywheel you would have to re-balance; with the ring you would only do this once if you marked the ring on a re-re.

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[flash]

2 problems with washers:



1. the washers need to be pretty thick (at least .06") so, you still need to counterbore the flywheel, because you need every one of those threads to stand any chance of retaining torque.



2. using a plate eliminates any variance in surface tension, and spreads the load across more surface area. this makes for much more even torque, and less hub flex.

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