Lets Talk Flywheels

Lets Talk Flywheels

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Discussion

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
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Hi all,

I'd like to start a discussion on flywheels.

'Ol Gasbag' is getting a new clutch soon as it's time to say goodbye to my unnecessarily heavy Helix unit, so with the box coming out and a new clutch going in now's the tine to fit a lighter flywheel.

Actually I've already done this very thing when the Helix was fitted a few years ago and was delighted with the results. I simply went to Rob Robertson of V8 Developments, he supplied me a machined down original cast iron SD1 flywheel, for those that don't know the 4.0 Chimaera is fitted with a completely stock 32lb SD1 flywheel which is in my opinion way too heavy for a car that only weighs around 1100kg.

The SD1 weighs around 1440kg and was designed to be a flexible family saloon so a 32lb flywheel makes perfect sense, the far lighter Chimaera on the other hand simply doesn't need all this flywheel mass and it also fair to say the car is likely to be driven in a very different way to the Rover.

Anyone with a 4.0 Chimaera who is having their clutch replaced should therefore give serious consideration to lightening their standard flywheel, my 32lb original had a full 7lbs taken out of it to give me a 25lb flywheel and I can say with 100% conviction there were absolutely to downsides, only benefits.

TVR clearly new all this back in the day as they also machined these cast SD1 flywheels but only on the 5.0 litre cars taking it down even further than mine to 22lbs, when I bought it from Rob Robertson he explained stopping the machining at the 25lbs mark was a safer limit to work to than TVR's 22lbs.

With my new clutch being installed soon I've now started to look at the flywheel again, I've concluded that I can remove a further 5-7lbs without any downsides, a flywheel weighing between 18-20lbs should in theory be ideal. Obviously with TVR stopping at 22lbs and V8 Developments setting their limit at 25lbs it seems pretty conclusive I would be ill advised to try and get my SD1 type cast flywheel down to my target 18-20lbs.

So that leaves me searching for new made lightweight flywheel of which there are quite few options, the problem is I can find nothing on offer in my 18-20lbs target weight.

The nearest thing available is the 15lb unit from V8 Tuner, but I'm a little concerned 15lbs may just be fraction too light as I do like a reasonable idle and good drivbility.

http://www.v8tuner.co.uk/product.php?id=773



Can people using this V8 Tuner 15lb flywheel give me their honest appraisal of it and how it affected the way your TVR drives, it may also be helpful to include your power & torque outputs as what might be fine in something making 300ft/lbs plus may not suit 'Ol Gasbag' with her 260ft/lbs of torque.

Please also educate me if an "off the shelf" flywheel in my 18-20lbs target weight is available.

Thanks in advance, Dave.



Edited by ChimpOnGas on Friday 9th October 09:54

ClassiChimi

12,424 posts

148 months

Friday 9th October 2015
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I'll be watching this with some interest scratchchin

DangerousDerek

8,655 posts

219 months

Friday 9th October 2015
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Just a short reply from me.
Mine was reskimmed after suffering damage from a paddle clutch (never again).
The work was done at a small machine shop just outside Portsmouth naval base when i worked there a few years ago.
They took about 3 lb off the rear and it now weighs 22 lb.

Lots of heavy abuse with an AP racing pressure plate and JE cerametallic plate and its still looking and working fine.

I do fancy going lighter but at the moment i think if it aint broke.....
I will look to getting a light steel fly when the time comes to upgrade (ie when this clutch gives up). I will probably go for the RST.

ClassiChimi

12,424 posts

148 months

Friday 9th October 2015
quotequote all
When you think about it that 3lb is a lot of weight to lug around!
Even at 25 that's still way lighter than standard,,
Food for thought!

ClassiChimi

12,424 posts

148 months

Friday 9th October 2015
quotequote all
If you go to light with the flywheel doesn't that start to cause engine balance issues especially with the Rv8 ?

Pupp

12,206 posts

271 months

Friday 9th October 2015
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I've a couple of TVR 500 flywheels, including the one on the car. They were both under 22Lb and neither was a machined SD1 unit... bespoke castings I think.

I would have no hesitation going lighter still with a steel unit

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
quotequote all
ClassiChimi said:
When you think about it that 3lb is a lot of weight to lug around!
Even at 25 that's still way lighter than standard,,
Food for thought!
I know, I know.

But lets face it a 32lbs flywheel is nuts in a car like this, so anyone with a 4.0 litre Chimaera would do well to get their flywheel shaved. Take it down to a safe 25lbs and they will notice a big difference just as I did.

So I'm now at 25lbs and it's working really well, no issues with low speed tractability and a super rock solid idle as well, best of all the engine picks up revs so much better.

But the question I'm trying to answer is could it be lighter still scratchchin

My gut feeling is I could reduce it's weight by another 5lbs and it'll still keep the stable idle and good low speed driving manners, so to me a 20lb flywheel seems the ideal and I'm certaily fearful of going any lower than 18lbs.

The truth of course is I'm guessing really and the closest flywheel on offer is 15lbs anyway, so perhaps it'll be just fine confused

That's why I'm on here asking for feedback from anyone who's fitted this 15lb flywheel from V8 Tuner. I'm sure there's a few of you out there with it so it would be great to hear your honest feedback.

The issue I'm trying to avoid is discovering I don't like it after it's all bolted in, I know the whole thing is subjective as one man's fantastic is another man's undrivable but some real world feedback would help a lot.

Personally I feel it could go either way, I may love it or I may just find I've taken a step too far. The only real way to find out is to pay the £400 and try it, but before I do I'd love to hear from anyone with this V8 Tuner 15lb flywheel.

http://www.v8tuner.co.uk/product.php?id=773



Anyone ears

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
quotequote all
Pupp said:
I've a couple of TVR 500 flywheels, including the one on the car. They were both under 22Lb and neither was a machined SD1 unit... bespoke castings I think.

I would have no hesitation going lighter still with a steel unit
Thanks Gary that's really helpful, so the 22lbs 5.0 litre flywheel was a bespoke casting for TVR, I never knew that scratchchin

Perhaps that supports why Rob Robertson didn't want to take my standard SD1/4.0 Chimaera flywheel any lighter than 25lbs and the 5.0 litre ones are safe at 22lbs scratchchin

Anyway, I'm in no doubt I can go lighter than my current 25lbs one without issues, but can I take it as low as 15lbs and still have a nice driving TVR?

It's a hard one to callscratchchin

I guess I could source a 5.0 litre flywheel but it hardly seems worth it for the 3lbs advantage over my current one.

Feedback from anyone with real world experience of the 15lbs V8 Tuner flywheel would be much appreciated yes

Pupp

12,206 posts

271 months

Friday 9th October 2015
quotequote all
As it happens, I have an unused one sat in the house currently. I'll photo it later and post up for comparison but, from memory, the TVR ones are quite obvious as being a different component from the Rover ones (that's not to say modified Rover ones were never fitted, can well see that happening). Dom would know for sure

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
quotequote all
Sardonicus said:
Dave my flywheel is 6.5 kg and and I would give you an opinion on what its like but seeing as opinions are like arse holes and everyone as one it would be just that scratchchin (thats not having a pop at Gary etc) however I will say dont go too mad you want to retain some FW inertia with that FI build you plan otherwise you will end up with an on/off switch frown not being awkward but without you experiencing it its going to be hard for you to gauge wink I have no regrets with my choice it compliments my spec perfectly and I certainly would not change it I can go from tickling along in 1st at idle to flooring the gas with no clutch action to instantly breaking rubber it really spins up nicely with thanks to that FW biggrin oh yeh 500 fly is def bespoke like Pupp states I have a pic





Edited by Sardonicus on Friday 9th October 14:26
Thanks for that Simon and you're quite right, as I've already said the whole thing is subject to personal taste and expectations so it's impossible to make my choice over a forum.

One half of me says I should play it safe and stick with my current 25lbs one, but there's also a devil on my shoulder telling be to grow some balls and buy the 15lbs unit.

It's a shame there isn't something in the 18-20lbs bracket because if there was I wouldn't think twice about fitting it.

I guess I'm going to have to make a choice at some point, and with the fantastically smooth way 'Ol Gasbag' is driving after our recent round of improvements I'm super tempted to think she'll be just fine on the 15lbs one from V8 Tuner.

Only time will tell if I've gone too light, the problem is it'll be an expensive mistake if I end up not liking it rolleyes

NB: Simon, You Have Mail

Edited by ChimpOnGas on Friday 9th October 14:47

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
quotequote all
Sardonicus said:
trangely enough Dave my brother was over on saturday and we fitted a 19 pounder FW he is surprised at the difference its made he will be wanting the other set of DIY heads fitted next I'm sure rolleyes I know he will be reading this whistle NO mail Dave scratchchin
Check your junk mail Simon..

I also sent you a response to your S-10 tail housing query the other day and wondered why you didn't acknowledge it confused

That 19lb flywheel you fitted to your bother's car sounds ideal, can you PM me with where it came from?

Thanks, Dave.

Sardonicus

18,928 posts

220 months

Friday 9th October 2015
quotequote all
ChimpOnGas said:
Check your junk mail Simon..

I also sent you a response to your S-10 tail housing query the other day and wondered why you didn't acknowledge it confused

That 19lb flywheel you fitted to your bother's car sounds ideal, can you PM me with where it came from?

Thanks, Dave.
Thanks Dave will do, it was a machined JE FW he wont go lighter with cast

domV8

1,375 posts

180 months

Friday 9th October 2015
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ClassiChimi said:
If you go to light with the flywheel doesn't that start to cause engine balance issues especially with the Rv8 ?
^^^ I have been thinking about this exact mod for the last year - but this is what I want to get a conclusive answer on...

Surely if you change the flywheel, the crank assembly will need to be rebalanced..?

If this was the case, would you not require the crank etc out of the block and balanced to get a proper job done for high rpm reliability - turning it into quite a major job..?

ChilliWhizz

11,990 posts

160 months

Friday 9th October 2015
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So, er, this probably won't be any help at all, but thought I'd post as this is personal experience of having a lightened flywheel on a Ford 1600 xflow... My first ever car, a series 2 Lotus 7 with a knackered Cosworth 1340 lump in it, bought a xflow from Caterham out of a well crunched S4 Lotus 7 (the plastic one if anyone remembers..) and rebuilt it in my bedroom (Much to Mothers disgust). So, before I get carried away with the fascinating story of rebuilding a Lotus 7, had all the rotating parts lightened and balanced..

Long story short, engine spun up at light speed, car weighed slightly more than a box of Kleenex tissues, but, and this is the point I'm getting at, the engine braking with a really light flywheel in a really light car was vicious... lift quickly off at WOT and I was regularly head butting the windscreen... deceleration and weight transfer to the front of the car lifting off at 6k rpm was very interesting...

So, so just saying really.... smile

phazed

21,844 posts

203 months

Friday 9th October 2015
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I just found the receipt for my forged aluminium flywheel that came from Abbey sports cars Ltd Which is V8 tuner.

My invoice is for £400 but I see they are actually £530 now!

I noticed they state that they are 11lbs in weight.

As a few people who have driven my car will confirm, the engine acceleration is extremely rapid and spins up instantly but it is still a pussycat to drive.
There is a very minor amount of shunting at about 1500 to 1700 rpm If you really look for it, which may or may not be caused by the light flywheel, apart from that you would never know that the flywheel is so light.

ClassiChimi

12,424 posts

148 months

Friday 9th October 2015
quotequote all
^^^^^^ that's remarkable and quite true, but your engine spec is rather different to ours isn't it Peter?
It's a rocket ship I know that much smile

ChimpOnGas

Original Poster:

9,637 posts

178 months

Friday 9th October 2015
quotequote all
phazed said:
I just found the receipt for my forged aluminium flywheel that came from Abbey sports cars Ltd Which is V8 tuner.

My invoice is for £400 but I see they are actually £530 now!

I noticed they state that they are 11lbs in weight.

As a few people who have driven my car will confirm, the engine acceleration is extremely rapid and spins up instantly but it is still a pussycat to drive.
There is a very minor amount of shunting at about 1500 to 1700 rpm If you really look for it, which may or may not be caused by the light flywheel, apart from that you would never know that the flywheel is so light.
Thanks Peter, I guess it's fair to say you've got a significant slug more torque than me so that may well be helping.

But it has to be said 11lbs is one very light flywheel, so if you're still getting a nice drive maybe I could get away with the 15lbs one on mine?

I had a good chat with Simon an hour or two ago and he says stick with my 25 pounder, there's a lot to be said for this actually.... because.

A. It's proven

B. I'm not taking any risks I may not like it

c. It's free

To throw £400 at something only to find I don't like it and then have to pull the whole thing down again would be an expensive mistake.

The problem with all this is if I don't do it I'll always be wondering "What If?"

For sure if I don't fit the 15lb flywheel and stay with what I have I'll spend the next however many years torturing myself about all that crisp throttle response and eagerness to rev I could have had.

This is proving trickier than I'd thought, what we really need is someone with a 4.0 litre Chimera who's fitted one of these 15lbs flywheels and can be honest about how it changed things both good & bad.

Anyone ears

Edited by ChimpOnGas on Friday 9th October 18:30

TV8

3,118 posts

174 months

Friday 9th October 2015
quotequote all
Hi Dave, some info here. Lots of other cars use the RV8 so the info could be out there somewhere re the 4lt with light flywheel
http://www.britishv8.org/Articles/Introduction-to-...

I would go for it personally.

MPoxon

5,329 posts

172 months

Friday 9th October 2015
quotequote all
I will also be watching this with interest. I enjoy reading your epic threads Dave, always a lot of research backed up by facts and normally a spreadsheet thrown in somewhere. wink

Good to meet you at the Garner day as well. thumbup

Boosted LS1

21,167 posts

259 months

Friday 9th October 2015
quotequote all
domV8 said:
^^^ I have been thinking about this exact mod for the last year - but this is what I want to get a conclusive answer on...

Surely if you change the flywheel, the crank assembly will need to be rebalanced..?
Wouldn't that depend on if the engine was balanced without the flywheel and clutch pack originally as some engines are. This allows for a change of flywheel or clutch pack, damper etc.