Rb25 Cast Iron Flywheel - Machinist Wants To Replace It

[The Mafia]

Hi Everyone

I'm halfway through a Rb25\30 build, and I have taken my flywheel to the machinist. He said that I shouldn't use the flywheel because its an older cast iron flywheel, and they are dangerous. It does have some blue colouring in the center.

He wants to replace it with a Steel flywheel. (The Machinist is family so he's not just trying to make money).

Anyway, what should I do? I have RB30 flywheel that doesn't have hot spots, can I use that, or should I buy a new steel flywheel?

The Clutch is an Excedy 3200pound clutch.

Thanks

Jono

[Craig SLO33]

hey Jono, since your rebuilding the lot why not get an aftermarket LIGHTENED FLYWHEEL,far better for engine response......just a thought....craig

[The Dan]

DO NOT USE THE RB30 FLYWHEEL!!!

It is made from the bad cast iron. If anything, the RB25 flywheel would be the pick of the two as it is made of nodular cast iron so is less likely to shatter.

If you are making over 400hp at the wheels then DO NOT USE A CAST FLYWHEEL!

[The Mafia]

DO NOT USE THE RB30 FLYWHEEL!!!

It is made from the bad cast iron. If anything, the RB25 flywheel would be the pick of the two as it is made of nodular cast iron so is less likely to shatter.

If you are making over 400hp at the wheels then DO NOT USE A CAST FLYWHEEL!

Glad I asked.

I'm making about 430rwhp. So, thats probably 480hp at the flywheel?

Definately get the steel flywheel then?

[The Dan]

Glad I asked.

I'm making about 430rwhp. So, thats probably 480hp at the flywheel?

Definately get the steel flywheel then?

There is probably an 80% chance you would never have a problem but if you put slicks on and went to the drags, it's a fine line between taking your leg off or driving away unharmed.

[The Dan]

Definitely get a steel one.

Exedy, X-clutches and NPC all do good flywheels. I always recommend the NPC ones of course as they are not over light. 6kgs compared to the 10kg factory unit

[Tony de Wonderful]

How is power relevent? The flywheel 'feels' max centrifugal force (trying to tear it apart) at red-line regardless of whether you make 200 or 400 KW.

[Tony de Wonderful]

6kgs compared to the 10kg factory unit

Can you notice that? Just wondered?

[MrStabby]

How is power relevent? The flywheel 'feels' max centrifugal force (trying to tear it apart) at red-line regardless of whether you make 200 or 400 KW.

Typically you make more power at higher rpm and thats not the only force - think about torque, and hence Elites mention of slicks.

[The Dan]

Yeah it's not centrifugal force that tears it apart. Peak torque is before peak power and it is torque that smashes them. The only reason why I mentioned power is because it's easier for people to relate to. Everyone knows how many hp or kw they have so it's easier to put a figure on it.

torque and hp usually go hand in hand so it's roughly the 450-500nm of torque that tends to be their breaking limit. But once again, it's really only when you load the absolute crap out of them.

For the $400-$450 it's not worth the risk.

And yes, you can feel the difference between the 6kg and 10kg flywheel. throttle response improves and the car revs more freely. There is no rpm 'drop off' due to being too light.

[The Mafia]

So what size do you recommend for a RB25\30? Would a 6.5kgs be good for a daily driver?

[The Mafia]

ok so I spoke to Jim Berry on the phone.

Very surpised at what he said.

here it is in point form:

- Unles it is cracked, Do not change the standard Flywheel.

- Do not change the weight of the Flywheel. The japs got it right and we will not like it at all, for the 20,25 or 30. (Knows about the 30 Hybrid.

- The Standard nissan item is very strong and the talk about blowing them to pieces is a load of shit. He said only holdens and fords do that. Mr Nissan got it right apparently. Unless the guy that bolts it on removes the dowel, or doesn't bolt it up right. They are made out of good cast iron.

- Chrome Moly Flywheels are shit and are too hard

- Excedy have crap Centers and pressure plates on quite a few models (my model is one for example)

Edited February 9, 2010 by The Mafia

[Mr. Untouchable]

Interesting.

[The Dan]

lol