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Dogdish Flywheel Pros & Cons

tintintin

Member
Joined
Sep 11, 2012
What are the pros & cons for the dog dish flywheel?

What are the symptoms if the spec distance between the two surfaces is not maintained?
 
I would like to ask also, what is the point of a lighter flywheel? In motorcycles, it's common to add a heavier flywheel, to smooth the powerband and make the engine more tractable.

Why is this not desirable with cars? The lower weight of the flywheel doesn't add power.
 
I would like to ask also, what is the point of a lighter flywheel? In motorcycles, it's common to add a heavier flywheel, to smooth the powerband and make the engine more tractable.

Why is this not desirable with cars? The lower weight of the flywheel doesn't add power.

It does add power though. Removing weight from the rotating assembly is relatively cheap horsepower.

Motorcycles have an inherently light rotating assembly so they can be peaky, and particular about shift points due to how quickly they can change RPMs, up or down. One of the benefits of a heavier flywheel is when you push in the clutch the engine speed falls slower so you're more likely stay in the engine's powerband while shifting without needing catlike reflexes. Lightening the flywheel allows the engine to spin up faster, but it's all a balancing act.

Issues with lightweight flywheels are usually related to clutch chatter, but one of the bigger problems is heat. Part of the job of the flywheel's mass is to dissipate the heat created by the friction disk. It's not uncommon for even stock flywheels to exhibit heat damage and cracking after prolonged use or abuse. If you go too light this can cause damage to your clutch, or cause catastrophic flywheel failure.
 
I think every exploded flywheel I can remember was a dogdish. Almost always modified in some way.

The heavier flywheel makes the engine's throttle response in neutral much slower, which can be an issue depending n how you drive, how quickly you want to shift gears.

And as you accelerate, it's additional mass that the motor has to spin up, and back down, and back up, for every gear. While the effect is mot noticeable in neutral (up or downshifting - how quickly the motor changes rpm), it also shows up in the car's acceleration as a whole.

If it's really light, it can make idle tuning (if you're mixing your own tune) a bit trickier, since it reacts much more quickly to idle air changes. And it can make it a little harder to drive for a n00b, since it's a bit more likely to stall - less energy stored up in the flywheel to move the car if you let the clutch out more abruptly.

I have/had lightened flywheels on both my Volvos (on the PV, and when the 245 still had a Volvo motor). In both cases, it makes the engine feel much more responsive, a bit less tractor-like, more eager to rev, sharper throttle response, no downside really.
 
Upside for the dog dish flywheels:
Almost impossible to stall the car when taking off. It’s not exciting to drive, but it’s totally fine for a stock setup.
Larger clutch diameter, so you can get more torque capacify without having a heavy pedal.
It already has a 60-2 trigger wheel.
 
I would like to ask also, what is the point of a lighter flywheel? In motorcycles, it's common to add a heavier flywheel, to smooth the powerband and make the engine more tractable.

Why is this not desirable with cars? The lower weight of the flywheel doesn't add power.

Motorcycles tend to have a) way high power output relative to weight and b) in all but ideal surfaces a "problem" of finding grip for both acceleration and braking.
Only place I've seen flywheel weight added is on loose surfaces, like mud, or rockier surfaces.

And there it is wonderful...or more accurately the lack of enough "schwungmass" is a real pain.
Cars TEND not to have excess power and they tend to have lots of grip.

Again except on loose surfaces--where the real fun is---like gravel roads..Now there some "reasonable" flywheel weight is desirable, especially iif the motor has some 'reasonable" powerz...
But EVERYTHINg that rotates counts..from front pulley, crank, flywheel, pressure plate, disc, gears and shafts n the box, prop shaft, diff, halfshafts wheel tire package...

And then there's the question of "what's Light?" and "what's 'heavy'?"

At 30.7 or 31.4 lbs the dog dish thing is, for a 2,3 engine in a car fawkin heavy
Flywheels in the 8-9 lb range are ridiculously light...
14lbs like the steel ones I made are light but not silly...

Another thing which comes into the equation is what are the gearbox ratios?

Got super wide ratios, you want more swung mass...
Got real close like 2.25:1 first and 1:1 top, you want somewhat lighter...

I still say its all a little wanky since the flywheel always is rotating in the same direction...so it picks up some percentage of rpm but its not like the thing starts and stops 4 times every complete 720* cycle....some things do..And slowing a piston and half of rod weight at TDC then starting it down, then stopping it at BDC again and then starting it again now that costs power..How much? Guys with more math skills can tell you that but just thinking...and looking at every modern motor after say 1988 says there's somehting there cause evrybody has made great efforts reducing reciprocating weight.

But in the end my main gripe is I ain't a fan of cast iron flywheels, light or heavy..

Steel.. nuff said.
 
We'll if you really wanna tell em how great they are you gotta make a video, here's mine. I call it The DAmage!


<iframe width="560" height="315" src="https://www.youtube.com/embed/45X58bJYLP0" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
 
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