Living with a lightened flywheel on a 3.6

Living with a lightened flywheel on a 3.6

Author
Discussion

ChrisPap

Original Poster:

395 posts

153 months

Tuesday 12th January 2016
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Hi all,

I found a few threads on lightened flywheels and everyone agrees engine response is improved. But what I'd really like to know is if there's any downsides.

I need a new clutch and I'm wondering about getting a lightweight flywheel too. I just want to know if I should expect any aspects to be worse. This is a street car with a 3.6 and I assume TVR set the flywheel mass for a reason, so has anyone found problems with:
  • lumpy idle (with or without A/C on)
  • difficulty pulling away
  • any other dramas?
Thanks in advance for any experiences shared.


Don1

15,936 posts

207 months

Tuesday 12th January 2016
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With a 4.0 I had a re-learn pulling away... not much 'feel' in a lightened flywheel.

Sagi Badger

589 posts

192 months

Tuesday 12th January 2016
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See my garage and posts relating to clutch. Always thought the gear change was slow so set about reducing the inertia in both the flywheel/cover, for response etc., and the clutch plates to save the syncros from working so hard and speed up the gear change.

I have superlight flywheels on both my cars with 7 1/4 clutches on both, one is a triple the other a twin. Both are without transmission springs and on both I have reduced the pedal travel. Pretty extreme but very drivable.

Upside is it a much better throttle response
Downside is pulling away with the engine that has a cast crank and a 3.46 diff, the other has a billet which is heavier, it is "on/off" but I get on with it now. Best was at the MOT station where the tester insisted on driving it onto the ramp, 7 stalls later he got and said "you'd better do that", which I did with the tiniest touch of throttle. Felt good with the audience that had gathered.

If you are using a lightweight, not a super light, and 8 1/2 clutch you will not have a problem pulling away or with the idle.

J

ShiDevil

2,292 posts

173 months

Tuesday 12th January 2016
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Some good insights here smile. I wondered what your thoughts are on a 4.3 with a lightweight flywheel? Characteristics, pro and cons etc. My Sagaris is having its engine rebuilt at TVR Power at the moment. Long story, don't you just love private sales!

s6boy

1,613 posts

224 months

Wednesday 13th January 2016
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Sagi Badger said:
See my garage and posts relating to clutch. Always thought the gear change was slow so set about reducing the inertia in both the flywheel/cover, for response etc., and the clutch plates to save the syncros from working so hard and speed up the gear change.
Naively this is a side of a lightened fly wheel I had never considered before. I love the mechanical feel and input you need to change gear, probably one of the highlights of the car, but fourth to fifth at high revs has always meant either a graunch or needed a pause before slotting home. All other gears are pretty much as quick as I can move the lever. So in your experience and with no other changes to the car does the fly wheel make that much difference?
Personally I would have to drive a lightened/non lightened back to back because as far as I am concerned the response to the throttle IS instant and I can't believe much else other than a n/a direct throttle lightweight Caterham/Atom etc could give that response.
Any feed back could be useful as I am still on the original clutch at 65k miles so this may be useful in deciding which route to take in the not too distant.

Sagi Badger

589 posts

192 months

Wednesday 13th January 2016
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s6boy said:
Sagi Badger said:
See my garage and posts relating to clutch. Always thought the gear change was slow so set about reducing the inertia in both the flywheel/cover, for response etc., and the clutch plates to save the syncros from working so hard and speed up the gear change.
Naively this is a side of a lightened fly wheel I had never considered before. I love the mechanical feel and input you need to change gear, probably one of the highlights of the car, but fourth to fifth at high revs has always meant either a graunch or needed a pause before slotting home. All other gears are pretty much as quick as I can move the lever. So in your experience and with no other changes to the car does the fly wheel make that much difference?
Personally I would have to drive a lightened/non lightened back to back because as far as I am concerned the response to the throttle IS instant and I can't believe much else other than a n/a direct throttle lightweight Caterham/Atom etc could give that response.
Any feed back could be useful as I am still on the original clutch at 65k miles so this may be useful in deciding which route to take in the not too distant.
There are two parts to this, both relate to inertia.

Firstly the simple mod is the lightweight flywheel with standard 8 1/2 clutch. Slightly crisper throttle response/pick up in first, second and third gear, beyond this I doubt the benefit would be noticed.

The more complex mod is to reduce the inertia further with a superlight flywheel and use a smaller clutch, 7 1/4, so the plates have less inertia which means on gear change up they slow down quicker and save the syncro's from a hard life. If you drive a Cosi it will change gear quicker than a SP6, unless you hammer it in and don't care. Well I do and I also notice a difference. What you get in addition is less mass/inertia so better still in the lower gears.

The best bit is when you start up and they bark as soon as they fire up.

J

s6boy

1,613 posts

224 months

Thursday 14th January 2016
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Thanks for that Sagi B, a good insight and interesting option.

ninetynine

535 posts

241 months

Friday 15th January 2016
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when i fitted a lightweight fly wheel to mine i did notice the engine to pick uo revs a little quicker
but after a few drives i dont notice it any more

but i do notice having to give it a few more revs to pull away when in traffic or not being a hooligan

imho if your flywheel worn do it if not save your money