MGB & GT Forum

I've heard of several lightened flywheels on MGB's destroying an engine and clutch this year.

The reason for the heavy flywheel is to stop excessive vibration on the crankshaft.

Has anyone on this site experienced any alloy flywheel failures?

I've seen a couple on race cars and it's not pretty. When the steel ring gear comes off of the aluminum flywheel, it's like a big sawblade inside (and even through) the bellhousing. Take a stock flywheel to a good machinist and have it lightened to around 15 pounds and you'll be fine. The cost of an alloy flywheel for the street doesn't give any return. Basil 707.762.0974 basiladams@yahoo.com

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Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains



Edited 1 time(s). Last edit at 2012-08-15 01:24 PM by Basil Adams.

I have an AL flywheel on my motor and have experienced zero problems over 4 years. In the most recent rebuild I did a through visual inspection for any fretting on the mateing surface, at the locating pins or at the bolt holes... nada.

The failures you reference, were they street cars, race cars... and were they using new ARP fasteners or were they running used bolts.

I've seen a few people have flywheel come loose in racng, but it had little to do with flywheel, aluminum, or not, but more so with thier reuse of the flywheel bolts, even ARP flywheel bolts have a torque cycle of 12, and racers would reuse them too many times, and they would fail. Most all currently produced aluminm flyhweels have the ring gears pinned to the flywheel these days, and Fidanza, the most common producer of our aluminum flywheels, does this, and Spec, the latest aluminum flywheel prodcucer of our flywheels does the same.

Aluminum flywheels are dynamicly balanced alot better than your stock flywheel, and in no way should contribute to clutch wear. I think anyone who ever had a small engine sport car that would freely rev, knows a MGB doesn't do this very well, and aluminum flywheel greatly improves the slow revving nature of the MGB engine. Being a 30 year user of aluminum flywheels on these engine, I highly doubt an aluminum flywheel damaged any one's engine, or clutch, so I cry fubar to those who say differently.

Bottom line reducing rotating mass in an engine assembly increases acceleration rate of a given engine, and there is nothing you can do that will do this any better than a aluminuim flywheel, for the net results in mass reduction, or for the fairly small amount of money an aluminum flywheel cost vs the results it gives. A Aluminum flywheel is great bang for the buck in the "seat of the pants" performance difference it gives.

From my experience, it's pretty much all pros, and no cons.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

x2 what Hap said. He helped me source and assemble the parts for my engine rebuild last year, including a Fidanza flywheel. I am delighted with the result and the rapid throttle response and acceleration in 1st & 2nd gear. I have no clutch issues, no "off the stoplight" issues as I had read scare stories about. I did add the PowerPro Harmonic Balancer to the front just as insurance against any excess vibration but the pulley/blancer needed to be replaced anyway. I also use the larger Triumph clutch plate to add just a bit more surface area to the clutch/flywheel interface. Happy to endorse the Fidanza. Great new "spirit" to my B.

David

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David J. Kinsey
Virginia Beach
Tidewater MG Classics
1980 MGB "Runaway"

It was an alloy one with new bolts etc., on a street MGB. What I don't know, is, if they used ARP flywheel bolts or new stock ones. Or, how long ago the flywheel was installed.

The stock bolts have extremely thin heads on them, for what reason, I'm really sure of, and they have tab washer ring behind them, again kinda unnecessary. The ARP bolt have 12 point heads on them,and will say ARP on the bolt head, and actually are not listed as MGB application, but rather small block Chevy/Ford flywheel bolts part #200-2801, they end up being like 1/4" shorter than the stock MGB flywheel bolts, but this is not a issue, people have been using them for decades in MGBs. Also ignore ARP torque recommendation, and stick with the factory's torque for the flywheel bolts, I do torque them with wet red loctite (very important, no washers), I don't know if the loctite deal is really necessary for street engines, but I tend to carry over my race engine reliablity things I do to them, to my street engines, figuiring better safe than sorry.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

I've run both lightened steel and alloy, the latter a 40 year old aluminum wheel from a 3 main engine (they were homologated for the TVR for some reason, and mentioned in the SCCA papers for that car, but not the MGs....) No problems whatsoever.

I agree with Basil - don't bother with one for the street, spend the money on head work or a good balance job instead.

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Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (375 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

I really appreciate everyone's responses. A Newbie like me is hungry for proven history on updated MGB parts and experiences.

Peace of mind and reliability is important to me, as everyone who is restoring their pride and joy B's!

What if you HAVE done the head work and had a good balance job Bill?

Tally-Ho!
Simon

An alloy flywheel is aboiut the last thing I'd spend money on for the street. Lots of other improvements that can be made.

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Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (375 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

Bill... the reason I ask was also touched on by Hap... the soft lock tab is a guaranteed way to have a flywheel loosen and wreak havoc... especially is you build a performance motor and extend the rev range.

As far as adding one to a performance build; I would recommend it. It's not a be all end all addition, but as part of a well-designed build which includes improved induction, exhaust and ignition... lightening both the rotating mass and the overall assembly produces a significant improvement in performance.

I never use locktabs any more. Modern thread locking compounds have taken their place and eliminated the 'soft tab' syndrome. In fact the last few engines I've built don't even have lockwashers in most places.

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Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (375 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

Bills... I figured you didn't use the locktabs any longer, the comment was directed to the OP who is also Bill!!!

Well, I still don't like aluminum but I have...

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Basil C. Adams
1956 MGA Coupe (Show Car)
1957 MGA Roadster (Driver)
1958 MGA Coupe (Racecar)
1959 MGA Coupe (unrestored)
1960 MGA Coupe (unrestored)
1960 MGA Roadster (Driver)
MKIII Elva Courier (E1056)
1967 427 Cobra
1972 Alfa Romeo Montreal
A coupla late MGBs
1960 Austin Healy BN7
More Cars than Brains