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Offline railmania

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what are the Advantages/Disadvantages to a light weight flywheel
« on: February 06, 2015, 08:24:58 PM »
I have a 76 Pinto Sedan.  It is getting a fresh 2.3L with a 4 speed manual tranny.  I got a lightweight flywheel for cheap. It weighs 10 lbs.  I think the standard flywheel weighs about 20lbs.  What are the advantages and disadvantages to a lightweight flywheel.

I stand a little confuse on this matter.

Thanks all.

Kevin

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #1 on: February 06, 2015, 09:00:29 PM »
Kevin,
 A lightweight flywheel will cause the motor to rev quicker, but that comes at a price if your gear ratios aren't ideal. It will be more difficult to lug the motor at slow speeds and could really mess up your starts from a stop , (especially from a hill slope)
 My 72 2.0l had a near stock clutch / flywheel ( weight near 30 lbs)  I was only going to use the car for racing so I purchased a twin disc clutch/ aluminum flywheel (Total weight 15 lbs) And boy did it wake up the Throttle response! But the price was a clutch that was all in or out, and much harder to engage easily. The other consequence has to do with the flywheel/ crankshaft balance and harmonics, and what will happen to when the vibrations get to the nuts and bolts. I literally had my alternator unscrew the small bolts that held the two halves together, and that was with a smaller (underdriven ) crank pulley. That never happened before, same motor, same performance mods. It really needs to have the Crank rebalanced with the Flywheel or a harmonic balancer added to the front of the crank. Racing mods can cost you down the road, and seldom offer a great benefit without consequences.

 Pintosopher,  Stuck on revs..
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Offline amc49

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #2 on: February 08, 2015, 11:20:14 PM »
Smaller engines like and hate them worse than big ones. The flywheel weight is what propels the car forward from a full stop with a relatively heavy car with a very small engine, not like a bigger V-8 with much more torque from a dead stop. Expect to kill the motor a few times till you get the knack of it.  The clutch will be harder to modulate to get a smooth takeoff until you master the somewhat different technique to do it. More slipping will be needed. The flipside is the low weight lets the engine rev up through the range much quicker. The gear ratio issue becomes more important with smaller engines, they cannot power through a lug point like bigger ones can when trans ratios are not closely matched to each other.

Offline railmania

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #3 on: February 09, 2015, 10:32:16 PM »
Sounds like I should keep/use the original flywheel.  This light weight "racing" flywheel may need to be sold. 

I have an 8" rear end with 3.00:1 gear ratio.  Pretty high gears.  Probably will have trouble starting from a stop with light weight flywheel.

Thanks for the help.

Kevin

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #4 on: February 10, 2015, 05:30:02 AM »
Sounds like I should keep/use the original flywheel.  This light weight "racing" flywheel may need to be sold. 

I have an 8" rear end with 3.00:1 gear ratio.  Pretty high gears.  Probably will have trouble starting from a stop with light weight flywheel.

Thanks for the help.

Kevin
Kevin ,
 That 3:00 rear end gear won't cut it with a manual trans and 4 cylinder. You'll need a minimum of 3:40 to make it happen off the line with a 4 speed. My 2.0L has nearly 165 HP and a 4 speed and with 20" diameter road racing slicks , it does get going quick. But with the average 23 to 25 inch diameter radials you'll be wishing for that elusive 4 speed with the close 1st to 2nd ratios. Unless you go with a T5 trans to solve all the drivability issues. I also suggest a L/S Diff to keep it moving around corners.
 Pintosopher :)
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Offline 76hotrodpinto

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #5 on: February 10, 2015, 10:20:07 AM »
I have one in my daily. It's not exactly street friendly. I won't be putting in my turbo setup. The few people who have had the nads to ride with me, think I just take off like that cause I want to race everything. Nope. Just trying to not kill it at take off.
1976 half hatch 2.3 turbo w/t5.

Offline amc49

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #6 on: February 10, 2015, 09:26:48 PM »
As said, a 3.0 rear gear is too much highway gear for a small four, most run like 3.40+, the newer ones with OD use around 3.90.......... .............. .............. ....not enough engine torque, that gear is for a V-8.

Offline railmania

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Re: what are the Advantages/Disadvantages to a light weight flywheel
« Reply #7 on: February 12, 2015, 07:33:32 AM »
I have found 8" pumpkin from a late 60's falcon.  There are no tags on it but when I do the test the gears are 3.75-3.80.  That would work with a T5.  That would be a decent highway car and still be ok at the stop lights.

How easily does a T5 go into these pintos.  who has done that and what were the concerns.
Thanks