Lightened Stock Flywheel

[davidk]

I'm about to begin the HDVA conversion, and someone, somewhere, recently posted that they lightened their stock flywheel per Kastner's recommendations. I have one of his books, but it's not covered in detail. Does anyone know the specifics on lightening a TR-6 stock flywheel? Thanks for your help!

 

[prb51]

David,
I've just taken them to an auto machinest and told them what weight I desired and balance them. They remove the metal from the thickest outside rotating mass area and there is plenty of that on TR3 flywheels. 17 lbs is a good middle of the road weight for a TR3, not sure on your six.

 

[trfourtune]

be very careful. Serch the web for the David Vizard book on tuning triumphs and download it. There is a picture and description. You don't want to take more that 5lbs off, total. It's unsafe. If you want to do something better/lighter go to ts imported automotive and get the aluminum flywheel and put a tr4a/tr6 clutch on it.
Regards
Rob

 

[PeterK]

Joe Alexander https://www.the-vintage-racer.com/Products/default.asp offers lightening of the stock flywheel. Contact Joe for details.

 

[tdskip]

www.141.com/triumphs/vizard.pdf

 

[DougF]

For competition, Kas lightened the clutch and flywheel to a total weight of 13 lbs. But along with this lightening and other mods, they were consistently running revs around 7,500 rpm on the track.
I can't find the info at this time, but from what I referenced before, I plan to remove 3-4 lbs. from my flywheel. I seem to remember this being middle of the road for a street car. TR6/250 flywheels are considerably lighter than TR2-4A.
Just remember that a lighter flywheel allows the engine to rev freer, but it also reduces the ease of starting motion when taking off from a standing stop.

 

[prb51]

Doug,All
I've seen 17 lbs. quoted as a good comp. for a street TR3 (How to Improve Tr2-Tr4).
Who has done this and with what drivability results?

 

[tomshobby]

I think the original flywheel is 24-25 lbs. My aluminum flywheel is 9 lbs and drives very well. The only differences I have noticed is at idle where the sound of the cam is more pronounced and at initial take off where there is not as much stored energy. However I left my idle at the same 950rpm which works fine. And even with the very initial start difference the light flywheel's much quicker acceleration far more than makes up for it.

 

[TR3driver]

It's not just the weight, it's where the weight is located. Weight near the hub makes a much less effective flywheel than weight near the rim.

On my deceased TR3A, I was running an alloy flywheel (same thing Fidanza sells, I believe, tho I got mine from Jim Donato) on a relatively stock motor (except 87mm liners). ISTR it weighed about 10 pounds without the pressure plate (which was the lighter 4A style) and stock bolt-on ring gear. Oh yeah, I also had a TR6 gearbox which has a taller 1st gear (2.99 vs 3.38).

The change in drivability was considerable; I definitely had to relearn how to drive the car. Simply got to keep the rpm up higher while launching, and the rpm drops much easier with the alloy wheel. Usually hard launches were not the problem for me, it was just loafing around town or in the parking lot where I would forget and kill it. But even after several years of driving it to work every day, I did still kill it on occasion. Perhaps that's a statement about old dogs and new tricks, I don't know.

But I have to say that the result was worth it to me. The car accelerated much quicker (if launched properly) and in general seemed far more 'nimble'. Throttle response was much better, especially when downshifting the OD at the same time. I'll be moving that flywheel and gearbox to the project TR3, when the time comes.

 

[davidk]

Thanks for the responses. The Vizard link above looks like a lot of good information.

 

[davidk]

Got the lightened flywheel back from Joe Alexander https://www.the-vintage-racer.com/ today (thanks for the lead PeterK). Very fast turnaround (he received it last Tuesday, I got it back today (Monday)!. Looks great. Highly recommend him.

Now I hope to get it installed and the HDVA conversion finished in time for the VTR Regionals in Austin.

 

[PeterK]

Looks like a good machining job. That ought to make a big diff with the HVDA. Enjoy!

 

[prb51]

Looks really good...what weight did he machine it to?

 

[davidk]

From 28 to 18 pounds.

 

[prb51]

About the same weight many recommend for the TR3...lighter yet heavy enough to maintain 'normal' rpm level driving.

 

[trfourtune]

I'd put in a scatter shield just in case, i like my feet and ankles just fine thank you. I've also heard or the tr6 pressure plates losing parts.
R

 

[prb51]

What is the tunnel made of in a TR6?

 

[DNK]

Original, cardboard.
Now, plastic

 

[prb51]

I'd put in a scatter shield just in case, i like my feet and ankles just fine thank you. I've also heard or the tr6 pressure plates losing parts.
R

Interesting comment. This plate wasn't lightened too much as compared to the lighter alloy ones available.
I understand there is more crank/flywheel flex etc. in the 6 vs the 3/4's but are you refering to racing stress or street use?

 

[trfourtune]

the original flywheel material is not that strong.
tr6's are known for crankshaft issues which translate to the flywheel. I would do it in a street car if it was lightened. I plan to "fiberglass" my "plastic" cover with kevlar cloth to about 3/8" thick for my tr4 with an aluminum flywheel (overkill i know)
R