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Triumph TR6 - Lightened Flywheels

Curious for those who have used a lightened flywheel, which "brand" was used? What are the differences between the aluminum ones that are out there and the steel ones and having the origional turned down. I have heard turning the origional cast one down is a risky business. Any experiences would be greatly appreciated.

Ken Jackson

Me too...:)
Doug Baker

I had my (1975)stock flywheel lightened from approx 31 pounds to 22-23 pounds cost -$125. All material was taken from engine side and the shop that did the lightening has never experienced problems with this lightening process over the last 25 years. (Autosport in Seattle, Wa.) A good shop in your area could do it easily. Aluminum flywheels range from a low of 8 pounds to a "normal" 11-12 pounds - available from TSI and other good TR sources, cost-low of around $300 and up. As with all modifications that you explore on the net , there will be 20 people "who haven't done it actually, but who heard about a guy who's had problems" with whatever mod you consider. If you listen to these guys you'll never do anything but keep it stock. A lot depends on how you plan to drive your car, if high revs are your thing- over 5000 to 6500 maybe it'd be better to go aluminum. I built my engine to be a low rev , torque monster. I use a 5000rpm redline. (Supercharged) One thing to remember, there is no free lunch. You're not going to "gain" horsepower, rather you're going to achieve "it" in a different way. My driving style often has me at low rpms at relatively low speeds. I was concerned about a loss of very low speed tractability, as well as cost. I have 4000 miles on engine and am very happy.
David Johnston

Thanks, David. That's a very good explaination. Next go-round I'll likely get the stock FW lightened a bit. So tell us more about the supercharging....I'm licking my chops about it.

Brent B

I have an aluminum flywheel and an otherwise stock driveline. It made a huge difference in the personality of the car. It revs up much faster of course, but the acceleration through 1st and 2nd is much improved. It really freed up the motor.

Definetly the biggest bang for the buck IMO.


Tim Brand

I prefer going the aluminum route myself. Ted at TSI sells Firenza flywheels and I have have one of those in the "normal" weight. A friend has one that he got from Tilton many years ago, don't know if they still supply that flywheel, weight is about the same as the Firenza. The Firenza unit has a replaceable drive surface and the machining of the aluminum is very nice. Excellent surface finish and mismatch, easily up to ANSI Type I/Type III quality. PAECO lists an aluminum flywheel, but unless they have changed it considerably, I would pass on theirs. I have one of those too from many years ago. The surface finish on it is rather "cobby" and it turns out that it is machined from 2024-T351. From a finish and mismatch standpoint, it is one ugly piece of work. While the engine heat would help it to age up to a -T851 condition eventually, having bare 2024 and especially in a non-fully aged condition isn't a good idea to me given the susceptibility to stress corrosion cracking in 2024-T3x, especilly in the short transverse grain direction (fortunately, most of the load would be in the long transverse and logitudinal direction). The Firenza units are 6061-T651 material. You give up a little strength, so to make up for that, they get a little beefier but the 6061 is rather corrosion resisitant making it a more than fair trade off in my eyes.

How are they in use? It is a bit more difficult to launch since you don't have all that momentum of the spinning boat anchor, but still not difficult given the nature of the TR6 engine. The engine does spin up quicker with the light flywheel. If you are going to use the car as a daily driver and you have to slog it out in pure stop and go at what seems like 10' intervals, maybe you're better off with the boat anchor. Otherwise, the primary down side is that you have to part with some cash.

I run an aluminum flywheel manufactured by Fidanza and really like the effect on the engine which, in terms of seat-of-the-pants feels like a faster reving motor.

Before mounting the Fidanza wheel I had the machine shop lighten my stock wheel and found no seat of the pants change - very dissapointing.

But overall, I think you have to have a basic strategy for what you are doing with your engine.

You are either in the pressurized camp or the normally aspirated carb-cam-header group.

If you are going to force feed your motor, forget about the fidanza. The seat of the pants will not notice any change.

I you are going the normally aspirated route, go for the lightened rotating mass.

By the way mouting that aluminum wheel on your steel drive shaft is a major pain in the ass.

The wheel is designed as an interference fit. I heated mine on a red hot stove element and then torqued it down on the motor.

Then removed the wheel to determine if the thing when on properly.

Do that about three times and you get it seated.

If you pay your shop to do it better find out if they really know what the heck they are doing.


John Parfitt

I meant "Crank Shaft".
John Parfitt

John How did you get from Calgary to Vancouver in five minutes. Does your six have the "beam me up Scotty option" or is it just that fast?.....
B. Towne

David, I tried your e-mail but it failed. Could you e-mail me so that I could ask you something pretty important about surercharging my engine. I have a engine at the shop as we speak.
Gene Holtzclaw

It was a freudian slip as I was posting from a hotel room in Vancouver....the Westjet Teleporter service....
John Parfitt

Hi again - I'm not a frequent or consistent contributor to the list but have really enjoyed all the varied comments/opinions in a mostly lurking mode and keep "sort of up to date" on most discussions over the last 3 years or so. I made my comments about lightening the stock flywheel because that's what I know. I wasn't in any way saying it's the best way, just why I chose that pathway for my car. A question for Tim,Steve and John: Does having the aluminum flywheel change anything else about the character of the engine or the driving experience ?
Is it easier shifting ? Is engine vibration changed ? -- those kinds of things.
And Brent - I'm using an Eaton supercharger
like the own used in the Mini and in some Toyota applications. Mounting kit made by Sal Vespertino in NY. Relatively clean looking, gives great all around drivability,average 19 mpg, with a great sound. Generates enough power to make the chassis actually twist as I engage the clutch. I don't race it. It's far from completely dialed in - this spring/summer-I'm installing a wide band O2 sensor, with guage , have vacuum advance set-up that I'll be able to manually control. I'm going to an electric fuel pump. Lot's of fun. But this thread is about flywheels. Looking to hear more from John,Steve,Tim,others?
David Johnston

This thread was discussed between 08/06/2005 and 13/06/2005

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