Rev happy Flywheel / clutch choices for street use.

[JMortensen]

The 16# unit was aluminum. My recollection is from 10+ years ago, but I was really shocked at how heavy it was and that stuck in my mind. If it were 13 lbs I would have bought it. I'm definitely not going to say that I'm right and you're wrong, but it would be nice if someone had a real number in a catalog or something as opposed to either of our recollections...

[cygnusx1]

Another option is Chromoly.

 

How's this for taking out weight where it counts!

 

http://www.upgrademotoring.com/performance/jun/ltflywheel.htm

 

or

 

http://www.upgrademotoring.com/performance/jun/ultflywheel.htm

[Tony D]

The Kameari is Chrome Moly, and has more holes on the outside for morewindage cooling of the clutch assembly...(tic)

[Tony D]

"It would be nice if someone had a real number in a catalog or something as opposed to either of our recollections..."

 

Ask and you shall receive:

 

CF Steel SFI Rated Flywheel is 25.4#-Part Number 700800

CF Aluminum SFI Rated Flywheel is 12.5#-Part Number 800800

 

From the 2009 Midway Industries Online Catalog, though it claims not to be for a "2+2" but I know people who have gotten both 240 and 225mm Flywheels from them, and since the only difference is bolt patterns for the cover and friction surface, I don't see that adding up to a 16# wheel under any circumstances. MSA has always advertized them as 13#, which follows to the 12.5# number in ther factory documentation.

 

http://www.centerforce.com/clutches.tpl?cart=123974506814732304&subsection=clutchselector&searchStr=fsearchStr2&fstep1=step1&fstep2=step2&flymake=NISSAN-DATSUN&flyapp=2.4L%20240%2C%202.6L%20260%2C%202.8L%20280%20%26%20ZX&option=flywheels&avail=no

[rejracer]

Per the Fidanza application guide their steel flywheels weigh as much as the stock units. I spoke with no limits and they indicated the steel flywheel was only 10.5 lbs, I believe they had their numbers mixed up.

 

I called up Taylor Race, and for the application they did not suggest a 5.5 or 7.25" dual disk setup.. I learned a lot though. They were not comfortable estimating miles as this is very subjetive to the use. Also the initial cost was around 1300.00 depending on the configuration, and the fidanza/act setup I have decided on is around 800.

 

 

As far as why Tony's lightened stocker... I agree that it's where the mass is removed from. I don't think it's a valid comparision to compare flywheels of the same (or different) weight that are of different design and materials. I understand how a heavier flywheel could have less MOI. Until we measure the MOI, it's just so much subjective (and relative) opinion. If we wanted to be objective abou this we would need to measure the moi on the same test for each flywheel. There's no "well I think" mine's better with a scientific test.

 

While speaking with Doug at Tayor Race, he mentioned that the 7.25" clutch has a MOI of 75lbs. While a 5.5" clutch has a MOI of 35lbs. I asked "It's possible to MEASURE MOI?"

 

"Yes" was his response. Thinking about this some more it would be possible to rig up a fixture to rotate the flywheel on. Then with a low power motor, spin the flywheel and time how long it takes to get to terminal velocity. Another similar test is to spin it up to a known RPM and then put a known load on it and time how long it takes to stop. I assume the longer it takes the higher the MOI.

 

I've read a number of threads on the aluminum flywheels and the only concerns I have are around proper fitment. I believe I should have considered it a bit more before mentally writing them off. I am going to go this route for the time being. I just bought one off of Ebay. The fidanza Aluminum unit appears to be the best bang for the buck, and is servicable.

 

I still suspect the Kameari or the Jun units are more responsive units, but the serviceability is what has my eye now, knowing that the act disk I have is aggressive.

[Tony D]

It is absolutely possible to measure MOI!

 

Yeah, unless you are making mongo hp and torque, multiple discs are difficult to live with on the street. We have a triple disc clutch in our B-Car and it's 7.5" with a total flywheel, clutch, cover weight of 15#! Look at the pedal and it changes 2000rpms! LOL

 

"Serviceable" is a relative term. Mr. P is not happy with F-Wheel at this point in time...but what can you do? Make your own?

[cygnusx1]

It's really easy to calculate MOI if you have a cross section and material specs. I designed a machine to cut slats, from a wood-like material, with 32 skill-saw blades spaced 1" apart on a common shaft. There was no way that just the blades and motor were going to do it. I ended up calculating the required MOI to cut through each slat of material and added flywheels in between each blade that had enough energy to make the cuts without killing the motor and gear drives. The power required was to bring the blades back up to speed before the next slat.

 

MOI is a basic calculation. Of course I would still need to go dig out one of my old, dusty textbooks to prove it.

[hughdogz]

Hi Guys, I wasn't kidding when I mentioned a non-destructive way of measuring the polar moment of inertia using a "tribulum". It is like a pendulum, but instead of just a mass on a string, it is three strings.

 

Imagine you have a circular piece of plywood. Then mount three eyes 120 degrees apart near the outside. Then take three pieces of wire to hang the plate to a ceiling, keeping the wires vertical. Then place the flywheel / clutch exactly in the center. Now you have a tribulum.

 

Twist the tribulum say ten degrees. The amount of time it would take to return to a standstill would indicate the polar moment of inertia (integral of R^2 dM) For a circular plate / uniform disk, it would be (mass * radius^2)/2.

 

There may be a better way to do it, and I might be able to come up with the energy equation to actually get a number in kg*mm^2 or pound_mass*in^2 from the angle of twist and time.

[cygnusx1]

If you had all the flywheels handy you could just hang a weight off of a string wrapped around the OD of the ring gear. Then mount them on a free spinning spindle, let go of the weight and see which one unwinds the fastest. The fastest to unwind has the lowest MOI.

[hughdogz]

^^ that sounds more like "real-life" loading. That's thinking with your dip-stick Cygnus!! (of course hehe!)

 

I came up with a refinement to a PMOI inspection fixture design, to better measure the time it takes to return to a standstill.

 

Mount a laser underneath the tribulum disk at zero degrees (horizontally). With it at a standstill, mark the wall where the laser is pointing at zero degrees. If it stays within a certain range (distance) of the mark as it winds down, stop the time. Of course, the laser measurement would be more accurate the further away from the wall you have the 'trib! Measure the angle of twist by mounting another laser (vertically) at either the floor or ceiling at ten degrees...

 

Now I'm thinking of making one, to measure the difference between a stock 240mm flywheel versus a SPEC. And the stock clutch versus a Centerforce DF. I have quite a few to experiment with.

 

I'd need a baseline using a circular disk (Iron, steel or Aluminum) to get good number to start with. It would be great to get another piece (of equal mass) that is a ring-shape. The PMOI can be determined for each by known theory. We can find the PMOI's of the flywheels / clutches by interpolating (or extrapolating) the times of the known one(s).

 

If it works, we could share the results by shipping or sharing the plans for the simple fixture...just a thought

[rejracer]

Hugh, if you test it, let me know how you built it. I'll be getting my flywheel (Fidanza 10.5lb aluminum) and would be willing to measure it.

 

From what I understand, we would have to measure this with the same diameter and length wire/string. We would also need to mount it using the same distance from centerline of the flywheel.

 

Thanks,

Robert

[rsicard]

Tony D: Just for my education what is a sprung hub versus a solid disk? I refer to the sentences: "You Datsun Guys and your sprung hubs. I swear. Drive a solid disc like the VW guys do and you don't have to worry about your springs compressing...and if you have any competence with your left foot control and clutch release, it drives just as nice as a sprung hub, with less to go wrong!"

[jintei]

Talking about lightening drivetrain components for rev-happiness , has anyone tried the aluminum driveshafts? do they help revving too?

 

What do you know about it? http://www.thezstore.com/page/TZS/CTGY/PRC02F

[Tony D]

In the center of the clutch hub there are (on an older VW) simply rivets and a solid center. Many 'racing' clutches incorporate this.

 

On most Domestic stuff, as well as all the 240/60/80 and 510 stuff I've worked on they all have clutch hubs like the newer VW's used: they have a series of springs and a thicker center hub that allows the friction facing part to compress these springs somewhat before transmitting motive force to the center hub with the tranny input shaft spline.

 

Solid Hub:

Sprung Hub:

 

I used a Sprung-Hub disc at the insistence of my engine builder, after having nothing but solid discs in my bus for 15+ years and I don't know how many miles.

 

I can tell you those springs popped out of the hub and locked up the works at 65,430 miles though! And a trouble free solid disc went back in...and my wife didn't know the difference!

 

The springs are supposed to soften engagement, and 'prevent chatter'...some of the higher end clutches use elastomeric dampers, or a combination of springs and elastomer. If you have a disciplined foot, a solid hub is just as easy to engage as a spring hub, and without a failure point.

 

What JeffP found in his hub was the springs compressed to a point where the hub had inertia, and was knocking against the rivets as a stop---and then driving the car. Bad Mojo! His new clutch doesn't do that by design and the disc is somewhat different in the spring configuration (dampers inside the spring). You can see the piece in the second photo that will 'knock' against the rivets. Compare the rivets holding disc to splined hub in the solid, versus the sprung hub and see what you decide about which is likely to hold up long term?

 

I'm thinking I suffered more clutch wear with a solid hub, but I NEVER had a solid hub fail like the Sprung-Hub did. More parts, more failures...that's what I see.

 

Make sense now? Gracias Amigo! ;^P

[Tony D]

driveshafts and wheels/tires were discussed earlier...

[hughdogz]

I'm not sure if my verbal description was enough, so I tried making a model first. Since we usually have 8 foot ceilings, I think 7 ft would be a good number. I'm also trying a Dynamic Simulation to see if I can actually get some decent results / numbers to see if it will work.

 

 

 

 

I know, those hanging "eyes" are overkill, but I had them handy.

 

I was thinking in order to calibrate it, or to calculate a know PMOI, I could simply get a five-gallon bucket and fill it with sand. Knowing the dimensions and mass, I can calculate the PMOI. Then I can record the time it takes to come to a standstill. Then record the time 1/4 full of sand, and probably be able to interpolate the PMOI for the flywheels / clutches.

 

I think Tony D might be referring to the springs shown here in a typical clutch friction disk:

 

{Edit: Doh! Tony, beat me to it. LOL!}

 

{Edit_2: Now that I think about it, if we made the base big enough, we could measure the PMOI of rims too! }

[JMortensen]

"It would be nice if someone had a real number in a catalog or something as opposed to either of our recollections..."

 

Ask and you shall receive:

 

CF Steel SFI Rated Flywheel is 25.4#-Part Number 700800

CF Aluminum SFI Rated Flywheel is 12.5#-Part Number 800800

Thanks for that. I'm right with you on the sprung hub puck disks too. Never understood why anyone would buy a sprung puck clutch, the puck clutches are so grabby they're just going to annihilate those springs...

[rossman]

I read somewhere that sprung centers reduce wear to the splines on the gearbox input shaft. Has anybody experienced accelerated wear using solid hub disks?

[woldson]

Thanks for that. I'm right with you on the sprung hub puck disks too. Never understood why anyone would buy a sprung puck clutch, the puck clutches are so grabby they're just going to annihilate those springs...

 

 

 

DANG both you GUYS!!

That is what has fail on several clutch jobs in the past.

No I did not know about unsprung disks, so my new one is sprung, six if I remember correctly......Live and learn....

[rsicard]

Tony D: Sure makes a hell of a lot of sense what you have experienced. The springs are just another failure point. Thanks ever so much for the explanation. Did not know about solid hubs but they make a LOT OF SENSE. Now I want a solid hub clutch disk!