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MG MGF Technical - Warning: MGF Flywheels are made from crap steel

Warning: MGF Flywheels are made from crap steel (well at least the batch I got)

MGF VVC built Jan 99

Pictures can be found:

I've had 3 mechanics say "I've never seen that happen", "Must be crap steel" & "The fault has most likely been there from day 1"

Other then being pissed off and out of pocket, I'm concerned the "fault" may effect a "batch" of them (If the flywheel did break completely there could have been a nasty accident)

Is there any way to let MG in the UK know ? (I'm going to write to MG Australia)

It's now been replaced by a billeted steel flywheel (I'm surprised it wasn't billeted steel in the first place)

Matthew Minion

So it didn't actually break up then Matt.

What were the symptoms?

I'd guess it's most likely a stress fracture and easilly confirmed by examination of the inner surfaces of the fractured parts.

As your mechanics say it should never happen unless perhaps there's an a tremendous amount of imbalance, which I'd expect someone to have noticed.

I'd want it raised with Longbridge pdq.

John Thomas

Well actually the flywheel is made of grey cast iron. Its generally lowly stressed. I have never seen a failure like this one before. I have also never seen the amount of embedding under the boltheads or the brusing on the crank palm. Are you sure the right flange headed screws have been used and the right torque. From what I can see in the pictures the initiation seems to be from the area of the washer face. If your engine has never been apart then I would definitly contact MGR.
Paul Hollingworth

Remarkable. Depends on how these things are manufactured. Are they cast then have those centres with the sleeved holes inserted? Maybe these centres with the sleeved mounting bolt and dowel holes are a separate item and the rest of the flywheel cast around it. Uncertain, but, on the evidence of the photos, the latter process would appear to be used here. Maybe there was some contamination when the flywheel was cast around the centre(s) which lead to future failure.

Be very interesting to know which process applies here and what feedback you get from the manufacturer - who may not actually be MG-R.

John McFeely

Crikey - those cracks look scarey. Not heard of anyone complaining of problems with the flywheel before - but perhaps it is too soon?
Rob Bell

There are no inserts, its just one iron casting.I can't think of anything that could have caused any dynamic loading that would have resulted in this failure. If the clutch cover was that out of balance surely it would have felt dog rough.
Paul Hollingworth


What were the symptoms?

Out of gear, foot on Clutch = Sounded like normal
Out of gear, foot off Clutch = Sounded like a tractor
In gear, foot off clutch driving around = Sometimes sounded like tractor, sometimes sounded normal

No indication of a problem, Car was fine, went for a Sunday Drive down the coast, stopped for lunch, drove back home and while parking first heard the sound.

"Are you sure the right flange headed screws have been used and the right torque" Upto that point in time, only MGR Australia have touched the car (so I don't really know)
Contamination in the iron, is what I'm thinking.... A friend works at the airport using airport transfers tonbridge I'm trying to see if I can run this thru a x-ray machine.
"Not heard of anyone complaining of problems with the flywheel before - but perhaps it is too soon?"
It would be interesting to find someone with another "F" (VVC) made Jan 99 with around 50,000Km on the flywheel (I don't think it's issue effecting all "F's" maybe just that batch)
On the BBS, there's the odd couple of stories on ruff engines.... it would be interesting to find out if the flywheel was involved.

Is right, There are no inserts, its just one iron casting. Once the car felt "dog rough" it was parked (then driven to the mechanics)

Matthew Minion

I am pretty sure the flywheel design on the 1.8 K series hasn't changed since it started production. It is alone in K series because it mates to the PG1 gearbox, untill the 1.6 MGF came along and a new flywheel was designed for that. The 1.6 usually takes the R65 gearbox or did until last month when Rover decided to sell 300 midland car workers down the swanney by switching to a German Getrag gearbox. The explanation was that they had fell out with BMW who still owned the plant at Longbridge that made it. Now BMW will switch to Getrag also for the MINI and the plant will close.
Paul Hollingworth

wow, looks scarry. Looks more like the flywheel was a victim of some abuse while fiting or removing it. Can't imagine it is caused by just spinning around...

Any chance you could put the original flywheel on a scale so we know the weight ?


That damage was caused by just spinning around. There is no way you can cause that damage during the fitting or removal... it solid iron (you could drop it from 20 floors up and it wouldn't bend) That crack has grown only over time (a long time)

Even if the flange headed screws where over torqued you couldn't cause this level of damage.. under torqued and it would have been dog ruff for a long time

I've seen a number of flywheels in my day (including MGF's) and that one is stock standard.. so I don't see what weighing it will achieve.

Steve Myers


If BMW own the plant how can Rover be held responsible for the closure?

And as a BTW Getrag make superb gear boxes so whilst that may not help the poor bastards that have lost their jobs it may well help MGR to sell more cars and therefore keep other jobs in the UK.

Ted Newman

>>I've seen a number of flywheels in my day (including MGF's) and that one is stock standard.. so I don't see what weighing it will achieve<<

Steve, I think that Erik was asking for information purposes only - and so it is possible to conceptualise how much lighter a 'light weight' flywheel is... certainly I'd be interested to know this! :o)

You're right though, the total rotational mass is unlikely to have caused these stress fractures, unless the distribution was uneven (but that should have resulted in a significant vibration?)
Rob Bell

>>> I've seen a number of flywheels in my day (including MGF's) and that one is stock standard.. so I don't see what weighing it will achieve. <<<

Just like Rob posted, just to know how much it weights.



Two things;
Racing flywheels are about 1/4 - 1/5 the normal weight (they are made out of Billeted steel and not iron)

There was no significant vibration at anytime... in that if I was deaf I wouldn't have known there was a problem.

Matthew Minion

I have seen damage like this once before on a car I owned, it was caused by incorrectly torqued bolts and "enthusiastic" use of the clutch, in my case the bolts were not fully tightened and dumping the clutch at the lights one day resulted in the centre of flywheel tearing out. One point to note is that the locating dowel on mine was also badly worn by the time the flywheel failed, that was caused by the flywheel moving around, if your mechanic mentioned that your locating dowel was worn then this is nost likely the cause.

The Wiz

This thread was discussed between 06/06/2003 and 11/06/2003

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