TR2 Flywheel Weight

[PeteT]

Hi sage ones, whilst I'm having the bottom end balanced I was thinking of having a bit taken off the flywheel. I've read elsewhere that 22lds is about the safe minimum. I've just weighed my original one and it weights exactly 22lds! Is that a coincidence or has it already been reduced I wonder! I know the early ones were the lightest but we're they that light?

 

Regards Pete

[stuart]

Yes they were the lightest of all. Leave it as it is just get everything balanced.

Stuart.

[Dick]

My 3a has an early 2 flywheel. I did weigh it many years ago but have forgotten what it was.

If anyone has one off the car it would be interesting to know what the weight is compared with a later 3 - 4 one.

Remember if you want to change to the earlier type you will need the starter motor to go with it. Early ones used the 'bomb' type with a different number of teeth on the pinion.

[ianc]

Kastner says of the TR4 that the standard, cast iron, flywheel is about 31 lbs. He recommends an aluminium flywheel for SCCA racing in the USA.

 

Vizard ("Tuning Standard Triumphs over 1300cc") writes of saving 6-8 lbs, and has drawings to show how it's done on TR4 and TR4A (and the 6-pots, too).

 

Ian Cornish

[BlueTR3A-5EKT]

My spare TR2/3 flywheel assy which is standard weighs 22.8 lbs

The Borg & Beck spring clutch cover and plate, that goes on it, weighs a further 16.5 lbs. (That's a total of nearly 20 bags of sugar or 160 Mcdonald's 1/4 pounders whapping around on the back of the crank)

 

As Ian C has stated - Kastner wrote that a competition flywheel was available that saved 11 lbs on a standard TR4 unit, which starts life at about 31 lbs. - So a comp flywheel was 20 lbs.ish. I 've seen and touched aluminium flywheels with steel inserts for clutch friction face which were even lighter, I felt my pocket was not prepared though.

 

I did spend an amount of money getting my currently in use TR2/3 flywheel lightened by Oselli, it is certainly lighter. I also had it redrilled to accept the smaller diaphragm clutch from the TR4A-5-6. Later clutch being smaller and lighter. My tickover is a fairly smooth 8-900 rpm warm.

 

Conclusion - As Stuart has stated get it all balanced. Individual parts first then as assemblies. Other hint - Get a spare clutch cover done at the same time to go with the flywheel assy if you intend to keep the car.

 

Cheers

Peter W

Edited April 4, 2015 by BlueTR3A-5EKT

[Graze]

When you are quoting 22lbs are you including the ring gear weight?

 

The Ali flywheel I've got for my 4 is about 15 lbs no ring gear attached

 

Not sure what the ring gear weighs in at

 

Graze

[BlueTR3A-5EKT]

When you are quoting 22lbs are you including the ring gear weight?

 

The Ali flywheel I've got for my 4 is about 15 lbs no ring gear attached

 

Not sure what the ring gear weighs in at

 

Graze

 

My original weight was for the flywheel and ring gear assy (shrink on type - remember you can fit a TR5/6 shrink-on ring gear to a TR2/3 flywheel, opening up other starter motor & bendix gear options)

 

The shrink-on ring gear alone weighs 1.9 lbs. - I do not have a bolt on ring gear, but would say it is heavier.

 

David Manners sales parts lists quotes weights: http://www.jagspares.co.uk/home.asp

So

TR2/3 shrink-on 201454 as 0.82 kg

TR4/4A bolt-on ring gear 202834 as 1.45 kg

TR5/6 shrink-on 201350 as 1.145 kg

Cheers

Peter W

[BlueTR3A-5EKT]

Here is who did my balance and lightening work - with prices.

http://www.oselli.com/service/engineering/balancing

 

Peter W

[PeteT]

Thanks guys, my fly wheel is 22lds including the ring gear so it is already pretty light. I intend to leave it at that and just have the whole thing balanced. I always thought the engine picked up quickly so this must be why. Can't wait to see what it's like with the 87mm displacement. I will have the engine rolling road tuned when it's run in. Anyone hazard a guess at the power (torque I suspect) increase from the original (84 I think) to the new 87mm?

 

Regards Pete

[Ashley James]

I wonder if they aren't smoother with a heavier flywheel because I had a couple of engines fully balanced and although they were smoother overall, they had a rough patch at a bit over 3000. I believe the TR4A had the heaviest flywheel and wonder if it helped with the rough patch.

[Alec Pringle]

"aluminium flywheels with steel inserts"

 

I've seen a few of those, usually en route to the scrap metal stillage after a relatively few thousand miles working life . . . . .

 

22lbs with ring gear is quite light enough for sensible road use, and given that the era of free lunches faded away with the Industrial Revolution it's reasonable to expect that a lighter flywheel will result in at least some loss of smoothness, as Ash suggests, and require more frequent gear changing under load.

 

Cheers

 

Alec

[Tr4Tony]

Hi

 

Much lighter than 22lbs on a standard steel flywheel means taking a lot of metal out of it (at considerable cost) and if it's not done well can weaken the whole thing considerably - it's easy to mill out the back and keep going, making the main disc very thin. This is very bad news as they tend to shatter. You also absolutely must must must use a minimum of four bolts and four dowels. Lightest I've gone is 21lbs and that started to crack, so be aware.

 

If you want to go lighter (ie under 10lbs) the 'doily' flywheels are they way to go but they also crack under severe load. Additionally your revs drop off very quickly the lighter the reciprocating weight is, so your gear changes tend to be lumpy if you're not quick and light on the clutch.

 

My experience of the aluminium flywheels with steel faces is that they are very poor and tend to detach / debond if the get hot ... Ie on a performance engine.

 

Hope this is useful.

 

Regards

 

Tony

[TriumphV8]

For many years I have a Fidanza Aluminium flywheel for the Porsche 964 Carrera RS clutch in use.

It was even lighter than the already quite light 964 RS flywheel.

 

From that good results I bought another for the TR6 from Fidanza 4 years ago.

It is bolted with the 4 bolts like original but uses ARP bolts from Chevrolet.

 

Can not say anything bad about Fidanza......

What motorsports does to the flywheels may be a different point

but I took my cars for some quick rounds around Nürburgring with no bad effects.

 

I personally would like a flywheel as light as possible because

the TR6 crank is so heavy and TR3 is not better.

 

At all steps of lighting or fixing I would keep in mind that the flywheel rotates with a lot of energy

at our feeds and if it fails the result may be really bad.

Edited April 6, 2015 by TriumphV8

[Dick]

Just weighed a 'bolt on ring gear' flywheel and it was 29.8 lbs. With ring gear and bolts.

 

Re Ashley's comment, I wonder if a 4a flywheel is heavier to compensate for the lighter diaphram clutch.

 

I wonder why ST changed the weight post TR2s. You would think that there was a good reason or were the heavier flywheels Vanguard and it was just a cost cutting excercise to get away form the lighter 2 flywheel which might have been a 'special'.

[stuart]

I suspect the heavier weight was to do with the higher output engines and to make them more civilised in traffic.

Stuart.