John P Aluminum Flywheel, Steel Insert Question

I have a John P Aluminum Street flywheel, bought it used and would like to replace the steel insert. It's an 18 bolt, 215mm insert. Does anyone know if one of the Fidanza Steel inserts will fit? I know some are 18 Bolt and they do come in 215mm, but having trouble finding the correct one and was wondering if the bolt pattern would even be the same. I tried contacting John P himself, haven't got a response yet.

Thanks.

One question, cause I have been doing some work with a guy who makes NHRA Top Fuel flywheels and clutches: does the steel insert have slits all thru so the thing an move around as it heats up? It should but the Duratec thing we were sizing up didn't and he was all tsk tsk tsk---

As for the patter being the same, how can that be detirmined without knowing what yours is?

Here are some pictures.

Damn, that's rough deal. The steel face is always so thin there's no stability in the thing itself, andits screwed onto a hunk of aluminum that heats up faster and moves so much more than the steel does, bad recipe and you see the scalloped localised blueing showing localised overheating... is the thing slipping or chattering???
have you considered just surfacing it? It'll make it flat but then being thinner the threshold for warping is lower and lower..

I just bought it (used), I would like to replace the insert, it is pretty close to the screw heads that hold in the insert. Also the previous user had a metallic 6 puck clutch being used on it and we all know those eat metal for breakfast. I was just hoping to replace the insert before i installed it so it would be fresh.

might want to have it magnafluxed before you try and find a replacemnt insert , personally i like my legs.

fidel said:

might want to have it magnafluxed before you try and find a replacemnt insert , personally i like my legs.

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Good idea! Will do!

You can't magnuflux an aluminum flywheel, the "mag" in magnaflux is short for magnet and we all know aluminum is not magnetic. The only way to check aluminum is with a flashlight and a magnifying glass of find a machine shop with a big money x-ray machine, good luck with that. I usually just give them a good inspection and I have never had an aluminum flywheel come apart. Besides, the aluminum will not do the damage steel will do when it comes apart.

red740t said:

You can't magnuflux an aluminum flywheel, the "mag" in magnaflux is short for magnet and we all know aluminum is not magnetic. The only way to check aluminum is with a flashlight and a magnifying glass of find a machine shop with a big money x-ray machine, good luck with that. I usually just give them a good inspection and I have never had an aluminum flywheel come apart. Besides, the aluminum will not do the damage steel will do when it comes apart.

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doh, brain fart, there are die test that can be done though.

red740t said:

You can't magnuflux an aluminum flywheel, the "mag" in magnaflux is short for magnet and we all know aluminum is not magnetic. The only way to check aluminum is with a flashlight and a magnifying glass of find a machine shop with a big money x-ray machine, good luck with that. I usually just give them a good inspection and I have never had an aluminum flywheel come apart. Besides, the aluminum will not do the damage steel will do when it comes apart.

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The thin steel face--without slits---certain can---and clearly this one has---be subjected to tons of heat and shock--- it could be checked with a little creativity. Aluminum is conductive, the face is magnetic.

And as for aluminum not being as destructive---well how is a hunk of aluminum weighing x, slung out with a speed of z any less potentially destructive than a hunk of iron weighing the same x slung out at speed of z?

As for not coming apart, maybe just luck. Ever consider the strength of aluminum at 800F?
And yeah clutches, flywheels etc do get up there in heat...Notice the blue on the steel? That's 500F at least.

I'm thinking about what John is saying here and tend to agree.

My only issue is the difference in the density of the iron vs. aluminum when it tries to come through a firewall or floor. Aluminum will tend to deform more than iron, and it would be a larger piece of aluminum to have the same mass as the hypothetical piece of iron. So in this marginalized argument I would consider that the aluminum would be safer in the instance of catastrophic flywheel destruction.

I have used aluminum flywheels in high powered street applications and have experienced heat related problems much like what i see in your pictures. Heavy street cars that see more clutch slip from starting from a stop would like a steel flywheel better in my opinion. One like JohnV builds, don't bother trying to get one from that other John as we all know that story.

badvlvo said:

I'm thinking about what John is saying here and tend to agree.

My only issue is the difference in the density of the iron vs. aluminum when it tries to come through a firewall or floor. Aluminum will tend to deform more than iron, and it would be a larger piece of aluminum to have the same mass as the hypothetical piece of iron. So in this marginalized argument I would consider that the aluminum would be safer in the instance of catastrophic flywheel destruction.

I have used aluminum flywheels in high powered street applications and have experienced heat related problems much like what i see in your pictures. Heavy street cars that see more clutch slip from starting from a stop would like a steel flywheel better in my opinion. One like JohnV builds, don't bother trying to get one from that other John as we all know that story.

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Yeah the part would have to be 3 times the volume for the same weight...
And yeah heat is the big deal in all clutch systems.

Years ago when making these things (CV adaptors for mounting Toyota Supra MkIII IRS diff into Xratty/Sierras)
the guy who re-did the bolt circles and correctly cut the timing 60-2 things builds NHRA Top Fuel clutches for cars and bikes.. he said when I was asking about "why do i feel so squeamish about aluminum flywheels with steel faces screwed in, cause I really am squeamish" that was his answer "ever think of the hardness of aluminum at 800F?"

Nuff said
It was he who said when i showed him a brand new aluminum flywheel for a Duratec "Hmmm no slits in the steel face, this thing will bow up like a cup" and grabbed one of his Top Fuel flywheels (made in stainless---for the heat properties) and showed me the slits..

On steel bodied production based cars heat is a big deal...that is on reason I made the bowl in the flywheels I made a smaller diameter than OEM Volvo: more mass for heat absorbtion where the mass won't be a big deal...the other reason was to allow use of 2 or 3 disc 7.25 Tilton or AP where the disc ID is smaller---thinking ahead to the day people here begin to think about really good clutches with acceptable pedal weight, the flywheel is ready...already.

Steel is real..

(This is a disguised BUMP for the ad)

John V said:

the other reason was to allow use of 2 or 3 disc 7.25 Tilton or AP where the disc ID is smaller---thinking ahead to the day people here begin to think about really good clutches with acceptable pedal weight, the flywheel is ready...already.

Steel is real..

(This is a disguised BUMP for the ad)

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Good looking ahead! The Mcleod RXT twin disc on my cobra is awesome, nice and light but still holds all of the power I can throw at it.

I have a Fidanza aluminum/steel insert flywheel, 7.5lbs, in my fwd Toyota Matrix XRS which holds 188 crank hp, not so much torque 135 ft lbs though. I just track attacked, time trialed it both days this weekend, running in the engines sweet spot of 6200-8200 rpms most of the time. I have no qualms about this setup at all. This has about 80,000 miles on the clutch and flywheel, here's a video...

http://www.youtube.com/watch?v=2qjJi-nXbDY

I have one of these flywheels in my car. Was very low mileage and looked almost new when I got it. I haven't put many miles on my car with it, but in the couple years it's been in, no issues to report.

Mine had a clutch bolted to it when I bought it, some marking from the disc, nothing more:
http://www.pbase.com/towerymt/image/117244111.jpg
http://www.pbase.com/towerymt/image/117244112.jpg
http://www.pbase.com/towerymt/image/117244104.jpg
http://www.pbase.com/towerymt/image/117244109.jpg

Rob had/has one in his (former) 242 "drift" car for years. Much torque/rpm/heat thrown at it including the time he drove it on the trailer in 4th gear smoking the clutch after breaking the trans at the drag strip.