13 replies to this topic

[968cabx2]

Finally got around to my "other" project 968. I am ready to start building it and putting it back together, I left a message with Pete from RS Barn and never heard back him. so I am looking to buy a RS Barn motorsports flywheel if anyone has one lying around. I decided to go with the RSB 18 lb unit and not the 12 lb Fidanza because of the vibration issue. I welcome any thoughts or suggestions. Thanks Guys,

[flash]

be sure to read this:

http://www.968forums...__fromsearch__1

[968cabx2]

Just so I'm clear, does that apply to the RS Barn 18lb unit as well or just to the 12 lb Fidanza unit.
I've pretty much ruled out the fidanza unit long ago because of the vibration issue which seems to be much greater than the 18 lb unit which is of course greater than the DMF. I figured that the 18 lb unit was a "happy medium."
If I can't find an rs barn then I will have to go with the DMF. Just was hoping to get a little mor performance out of this one with the 18 lb unit. Not sure what I want to do now but I'm still leaning to the RSB flywheel. I figure that with the lighter flywheel and flash's NA package, this car will have a bit of an increased smile factor.

[94SilverCab]

Try e-mail rather than phone.

JMO,

Jay

[flash]

it applies to both units. they are both made by fidanza.

the "vibrations" are not really all that different between the units. i've had both. the only thing that seemed to help at all was installing an S2 harmonic balancer pulley. it cut down the noise and such by about 50%. of course it also added back 4lbs, so the performance suffered.

be sure to do the mod to whichever one. it's pretty ugly to see the bolts back off.

in the end, i went back to the DMF.

[968cabx2]

Flash,
So in the I'm getting that you think the DMF is the best option, is that correct?

My thought was that if I had to replace the flywheel (I'm pretty sure the DMF I just removed was original with 80k on it) then I would opt for the lighter more permanent RSB unit and put up with a bit of a vibration at 2.3k rpm's. Little better performance and no worries about the eventual "wear" of the DMF unit.

So my questions are:
1 With a correctly "fixed" lightened flywheel to eliminate the design flaws, do you still feel like the DMF is a better option?
2 Is the performance gain with the lighter flywheel in a "play" cab worth the vibration increase?
3 is the lighter flywheel if corrected for its design deficiencies a "permanent" replacement for the DMF which eventually has to be replaced or is that an inconsequential consideration?

Thanks for weighing in on this.

[Lear35A]

For what it's worth, I've had an RSBarn 18# unit in my coupe with D1R SC for over 6,000 miles. I do have an S2 balancer pulley on the front. I do have the "fix" for the bolt holes installed. I do not notice any vibration, and I consider this flywheel very much permanent. I have no idea what the performance gain is or isn't. I consider my car quite peppy.

[flash]

the vibration is still there, as is the noise. you have likely become numb to it. i did to some extent too. the noise was what bugged me. it really made the car seem like a bucket of bolts. people would turn their heads when i was driving past them in parking lots. i was even stopped and asked what the rattle was. not something one would expect from a porsche.

the other issue that i discovered, though i have not verified it with another situation yet, is that the vibration and rattle associated with the solid flywheel, resulted in a worn shaft in the transmission. i conclude that this was the case, as i only had 25k miles on this transmission. i had it rebuilt, with every shaft and bearing changed at about 25k. at 50k i had it taken apart in an attempt to change some gear ratios (it turns out that the audi gears do not work in the 968 box). in taking it apart we discovered a worn shaft. it looks like the things on it were what was rattling, and that rattle wore the shaft. like i said, i have not had a second one apart yet to see if it also has the same problem, and there isn't justification yet to take one apart.

as for what is "better", it really depends on the individual. i did not find the performance increase enough to justify putting up with the noise. others might not feel the same way.

with the modification, and the S2 harmonic balancer, the setup can be considered permanent, assuming that the transaxle issue turns out to be an isolated incident.

[968cabx2]

Looks like I'm saving this decision for as long as I can. Guess I'll do the head gasket, cam pads and chain and motor reseal and then hope I get a divine inspiration as to what to go with for a flywheel. The possibility of wearing transmission shafts does not give me a warm fuzzy feeling.

Best price I've seen on a DMF was $745. Have not priced one out from Sunset. Does that seem like about the right price?

[flash]

keep in mind that i had the 12lb unit in there for the first few years, and then the 18 for a few after that. all in all, i ran for about 8 years with a light flywheel. i had the chance over those years to see what things resulted in what changes, and really try everything i could think of. i spent a few thousand dollars trying to come up with a solution to the noise, including a number of various clutch disks with damping mechanisms. nothing worked.

the noise bugged me so much that i stopped driving the car, long before i started the supercharger project. it just made the car sound like some kid's half baked project car. shifting was more herky jerky (worse with the 12lb unit), and the occasional cold stall was a drag. yes, there was a small improvement in acceleration (not nearly like the 12lb unit though), and gear matching was easier. however, by the time i added the S2 dampener (which is no longer available) the benefits were just not there enough to justify it to me. like i said, in the end, i went back to the DMF. in my opinion the solid flywheels are not well suited to a street car.

from what i hear though, if you can get your hands on the steel unit, it does not exhibit the issues. it seems that it is the nature of the aluminum that causes the problem.

[Racebannon13]

Flash, do you have any further details on the steel unit you mentioned ? Weight, manufacturer etc?

I have the sneaking suspicion the car I just purchased has a light weight flywheel. Around 3k rpm there is a sound somewhere between a buzz and resonance. How " zingy" do these flywheels make the big 3 liter? By Blipping the throttle in neutral does the tach spin up pretty high ?

[flash]

it's the OEM unit for the turbo rs. 18lbs. uber rare.

how zingy depends on which unit is in there. the 12lb unit was pretty quick to rev. the 18 not so much.

the sound associated with the flywheels is a rattle, very much located in the transaxle. the vibration is in the shifter. if you have a buzz or resonance, particularly at 3k rpm, it is more likely exhaust related.

[speedysprocket]

My car has a vibration at 1800 and 2200 RPM under load with a light flywheel, which is consistant with what I've read from other light weight flywheel users...

[flash]

yup - it's very subjective. it bugs some people. it doesn't bug others.

as i said, my concern now is that the rattle might actually be doing damage in the transaxle. i've only seen what happened to mine. i have no proof that it was the rattling that caused it. it's just hard to imagine that a box, which was rebuilt at 25k, and only had another 25k on it, showed that much wear. more data required.

may not be a problem in a track car in either event, as the transaxle should be torn down at least every other season, and had the bearings changed, whereupon an inspection could be done and any worn parts replaced.