Flywheel lightening and balancing...

conceptrat · Post by **conceptrat** » Thu Sep 25, 2008 3:51 pm

Howdy all,

I've just had a very expensive mechanical bill for replacing a broken cambelt (engine was fine though b6 is non interference on all but wild cams). While getting this sorted out I decided to get the aftermarket paddle clutch installed and seeing as that was going to mean cleaning up the flywheel I decided to get that sent off and lightened and balanced instead.

Now I did a reasonable amount of research on the web to see how much to remove for a street setup and decided on reducing the flywheel weight down to around 10-11lbs (4.5-5kg). The research showed that this should provide a more responsive feel to the acceleration and deceleration but with a possible disadvantage of slightly more chance of stalling.

Not a problem. Only when I get the car back from the mechanics, after a 3 week wait, the cars performance is flat and it's no more responsive throttle wise than previously.

Has anyone else been through this process and had better / different results?

madandy · Post by **madandy** » Thu Sep 25, 2008 7:17 pm

A flywheel as light as yours should make a noticeable improvement to your throttle response and acceleration.
I'd suggest an issue exists with your engine or engine management post repairs.

Growler · Post by **Growler** » Thu Sep 25, 2008 9:41 pm

I lightened the standard flywheel by just a tad over 2lb. I didn't want to take much more off being cast steel. (Take too much meat off and you can run the risk of the flywheel shattering). And I didn't want to loose too much torque either.
I then bolted a new clutch (And associated bits) to the flywheel and had the whole assembly balanced.
I did notice a difference. Especially in the upper rev range when say you knock it down a gear and pass someone.

The only trouble I have had was my own doing.
About 5 years ago I was doing an autocross type event on tarseal. As I when round a cone I stood on the accelerator to light up the rears but instead the cltuch decided to slip. The car runs fine but I think I glazed the clutch lining.
When I get enthusiastic and pull the engine out again I will replace it with something better (The clutch that is!!)

SLYDIT · Post by **SLYDIT** » Thu Sep 25, 2008 9:46 pm

when i had my lightened 1600 flywheel i noticed the difference straight away. theres obviously something not right since the engine was put back together.

i would check first:
The throttle position switch is set up correctly.
The timing is set correctly to 14 degrees (not the 10* defalt)
check that your oxygen sensor hasnt failed due to being contaminated from the engine failure. ( a bad o2 sensor can still read ok but it will be SLOW to react to change, thats the dead giveaway)

conceptrat · Post by **conceptrat** » Sun Sep 28, 2008 1:28 am

Hey Slydit,

Do you think that when the cambelt broke that the cam timing couldn've been upset. I would've thought so but the mechanics said they just put everything back together and it worked fine.
I'm of the mind that the cam timing could be out by one tooth.

poison · Post by **poison** » Sun Sep 28, 2008 3:03 am

Quite possible to be a tooth out, garages certainly make their fair share of screw up's. From my own DIY screw up's on my Celica, I was a tooth out and it ran smooth enough but just didn't perform.

It shouldn't be too hard to check without any fancy tools, just a workshop manual to show where the timing marks on all the pulleys are. Then turning the engine over until the main pulley timing marks are lined up then looking at the cam pulleys, but you would need to remove the cover.

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