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Discussion Starter · #1 ·
Have any of you lightened your flywheel? I was thinking about lightening my flywheel because of how long the rev is on it stock... my autocross buddies (non-IS owners though) said that it would help after they drove my car in an instructional run.

Thoughts? Suggestions?

I searched on it, but I'd like feedback from you tracksters since the only reason I'd want to do this is to help me on the track.

Thanks. 8)
 

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I have not lightened the flywheel on the car but I can try and give some insight.

As you may already know the idea behind flywheel lightening is to reduce the amount of weight your engine uses power to move. For street, it's recommended to shave off about 5 lbs. For racing, you may consider removing even more. Advantages are increase in acceleration and deceleration. The negative effect of lightening your flywheel is the loss of rotational mass inertia when accelerating from a stop. Without careful clutch and throttle work you may stall the engine more often.

Here's a scenerio, say your entering a corner when road racing, and do a heel-and-toe downshift. Since you're matching transmission rpm to engine rpm, the flywheel weight would have no braking effect (with a lightened flywheel). Yet if you have a big heavy flywheel, it will want to keep spinning, which means as you slow down, your brakes have to slow down the flywheel as well. Result is increase in brake use.

That may be what your friends were thinking. Hope that answers your questions. Take this FWIW.
 

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Discussion Starter · #3 ·
Thank you for your input. It is much appreciated.

So I take it that this should significantly enhance my times on the track then?

Its too bad that from what I've foung the cheapest light flywheel made for the IS300 is like $550, and you also need to buy an upgraded clutch kit due to the way the stock one is designed... apparently they don't mesh.

Expensive! It better be worth it! :)
 

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Dela - whoa!!! I wouldn't jump on a lightweight flywheel just yet. First of all it would place you in the Street Prepared class where you need serious $$$ to be competitive. You will lose much of the driveability on the street.

I have an aluminum flywheel and heavy duty clutch on my race IS. There is no way I would drive this thing on the street unless I had a ton of horsepower to make it worthwhile. Plus it costs a bunch plus labor. Probably $1k in parts alone.

The reason you need to change the clutch also is because the stock clutch uses a solid hub disc and a dual mass flywheel.

To use the aluminum flywheel you need to use a sprung-hub clutch disc.

We also changed the underdrive pulleys with aluminum ones from UR racing at the same time. Reducing weight on both ends of the crank allows the engine to rev up quicker but it's not a huge change versus stock.

-Derek
 

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I just noticed your mods put you in Street Prepared already. Plus labor should be cheap because you work for a Lexus dealership.

-Derek
 

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Discussion Starter · #6 ·
Derek,
Thank you. It seems that you have quite a bit of knowledge in this area.
I'm new to the sport and have been doing surprisingly well. I've only entered 2 comps yet and the first one I took 15th out of 38, and the second I took 5th out of 31. A fellow Lexus salesperson and another mechanic here all are seasoned autocrossers and drivers and introduced me to it. Now, we are known as Team Lexus of Brookfield by the other members... just to be funny of course. (Because before the IS no one considered Lexus to be a company to build a great AutoX competitor). HA!

You are right though. Unlike you I still need to drive this car on the street. So if this is the case do you suggest that I NOT do this to my car?

Also, right now my local chapter has agreed to start me out out (with a few other newbs from our region) in "Rear Wheel Drive Street Tires" with a DS index... which is why with my mods I must be doing quite well.

They are considering these first few events for me to be "prepation" for a full season next year in the correct index.

So, I guess this is why I'm here asking about all of this... I have a feeling I'm gonna need all the help I can get next season in the more competitive class.

So... I ask you... what (with the mods you see that I have) can I also do to make my car competitive in the correct class without doing anything to hinder its regular street use? I just don't want to be eaten alive out there!! ;)

GOD I'M ADDICTED THOUGH!! (I can already feel the shakes in my hands!) hahaha
 

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Discussion Starter · #7 ·
...oh, and YES, labor is really cheap, but Parts (especially aftermarket) can still be costly! :-?
 

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Dela,

If you car has the factory LSD you may want to consider running STX if your local region has it. It runs on street tires an allows up to a 17x8 rim w/ 245 width tires.


Here's the rulebook:

http://www.moutons.org/sccasolo/Rules/index.html

If your hands are shaking after a run that's good....

I would advise against changing the flywheel/clutch just yet. Get some more experience under your belt.

Put the money into a nice set of light wheels and some Falken Azenis tires for STX.

-Derek
 

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Discussion Starter · #9 ·
WoW! Thanks Derek!

We do have STX and I do have the factory LSD... so I'll look into your input.

I already have lightweight weight wheels. 17 x 7's. They just came in yesterday and I will be putting the Falkans everybody is running on them.
So far I have already been doing everything you suggested, so it looks like I'm on the right track (no pun intended.)

Thanks again!
 

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Dela

If it's not too late see if you can get those wheels in 17x8 instead. You'll have a hard time fitting the 245 falkens on a 7 inch rim. If you can't you'll have to get the 225 falkens.

-Derek
 

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Discussion Starter · #11 ·
Derek,
Is there any drawback to going with the 225's?? (other than the obvious "wider is better" rhetoric?)

-dela
 

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Discussion Starter · #12 ·
...also, what class would normally be more competitive STX/STS or Street Prepared and why?

What is the true difference between the three?

I guess I don't really know what class I'm truly supposed to be in next season. Right now I have a DS index which is awesome... one of the lowest on the track... will this change if I enter another class as well?

(Excuse my naivity and I apologize for the question and answer session ;) )
 

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Dela,

With your mods you are way beyond DS. STX/STS are street tire classes and should be close to DS in index. DSP is much faster and usually needs a dedicated car to be nationally competitive.

STX is a fun, well populated class in many parts of the country. I'd stay there for a while until you really get addicted.

Derek
 

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I'd agree w/ Derek to stay in the STX class. They allow most all popular mods and there are usually a ton of cars in that class locally. It's fast becoming one of the larger classes and is a lot of fun. I think the only mod you have that takes you out of STX is the race pipe.

take a look at the link that derek posted for the mods allowed in each class. It's very good and comprehensive. http://www.moutons.org/sccasolo/

The STX class is in here.
http://www.moutons.org/sccasolo/Rules/street_touring.html
 

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not too light now. a common misconception is that lighter-everything will make everything else faster.

lightened fly wheels feel nice 'round the corners - rev matching and downshifting blend together smoother. One thing that did suprize me when i installed a lighter flywheel was how much more braking I had to do. :D
 
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