Do i need to spend 300+ on a flywheel?

020s are a special case because the pressure plate bolts to the crankshaft, and the flywheel is just a ring that contains the clutch disk.  It also has some pretty decent sized circumferential ribs there specifically to add mass that are easily removed.

It's to the point that I can't find images of non-lightened flywheels for comparison.

I bought a used FM Fidanza for my NB1 and put a new friction disc on for like $250 total.  Do this!  If you have to, sell blood, borrow from your children, rob a liquor store.....

Back in the day this question wouldn't even have been asked.  Very few after market alloy flywheels were available and everyone just took their stock flywheel to a knowledgeable machine/racing shop and had it cut down and balanced.

The advent of alloy wheels added a wear issue - they normally have a steel friction surface attached to the ally framework and resurfacing is thus limited and the attachment of steel to alloy is an additional possible problem area.

Here is a Spridget steel flywheel fairly radically lightened:

This is a windowed MGB wheel

In reply to wspohn :

My favorite old timey racer device was using a clutch from a Porsche 356 (160-180mm diameter?) and bunging a friction surface onto an automatic's flexplate.  I never did find how what they were using for that, if it was a cut up Porsche flywheel, or if it was the plate of another pressure plate.

This was before you could just ring up any supplier in the country and get a 7.25" or 5.5" multidisk clutch and move on with your life.

(Actually my FAVORITE was TIG welding AN fittings onto a junkyarded pre-downsize GM B body air conditioning evaporator core.  Instant large capacity, high efficiency oil cooler.)

I'd never heard of the flex plate idea!

We used TR7 clutch discs in our racing MG engines (a bit more friction surface but otherwise interchangeable) and I had a very special alloy flywheel that had been available in the Elva Couriers for SCCA (sadly, I sold it on my TVR Grantura race car - if it had been easy to swap I'd have hung it on the garage wall).

I don't think alloy flywheels added a wear issue. Both the steel surface bolted to an alloy flywheel and the steel surface of a steel flywheel will wear the same way. They can both be resurfaced. The difference is that you can bolt a new friction surface on to an alloy flywheel but you cannot do that to a steel one.

wspohn said:

This is a windowed MGB wheel

Why are the windows not symmetrically cut? Is the bolt pattern for the pressure plate not regular, or did the machinist just eyeball the work?

In reply to Keith Tanner :

Could there be dowels next to three of the bolts?

Good call. Pictures of the other side of an MGB flywheel show that to be the case.

Pete. (l33t FS) said:

In reply to wspohn :

My favorite old timey racer device was using a clutch from a Porsche 356 (160-180mm diameter?) and bunging a friction surface onto an automatic's flexplate.  I never did find how what they were using for that, if it was a cut up Porsche flywheel, or if it was the plate of another pressure plate.

 

This was before you could just ring up any supplier in the country and get a 7.25" or 5.5" multidisk clutch and move on with your life.

 

(Actually my FAVORITE was TIG welding AN fittings onto a junkyarded pre-downsize GM B body air conditioning evaporator core.  Instant large capacity, high efficiency oil cooler.)

I always used those for oil coolers. TIG weld an AN fitting and you're good to go. 

Keith Tanner said:

I'm always worried about stuff like stress risers and inadvertent weak spots with a modified stock unit. Basically, every time is the first time. 

I think it depends on the fw design. I have probably lightened 75 vr6 flywheels over the years. You can just make one cut to the back side where it bulges and take off a few lbs. Goes from 15lbs to 11lbs that way.

Paul_VR6 (Forum Supporter) said:

Keith Tanner said:

I'm always worried about stuff like stress risers and inadvertent weak spots with a modified stock unit. Basically, every time is the first time. 

I think it depends on the fw design. I have probably lightened 75 vr6 flywheels over the years. You can just make one cut to the back side where it bulges and take off a few lbs. Goes from 15lbs to 11lbs that way.

I am probably going to attempt this for my Quantum's flywheel, since nobody makes aluminum flywheels for 016 trans setups anymore.  But every sharp edge is a place for a crack to start, so I am trying to figure how to do it without making a frag grenade.

The quantum one like to 020 design where the flywheel is on the outside, or more traditional?

In reply to Paul_VR6 (Forum Supporter) :

Traditional.  From what I understand I could just use a flywheel for a five cylinder 01A or 01E (all are same ring gear diameter) with the appropriate clutch, since 016 flywheels mount the clutch inside a deeply recessed ring, but I'd have to machine the flywheel's pilot bearing boss away.  Which doesn't make sense if I'm using a clutch made for the flywheel, but it may be an input shaft length thing.

Either way, not something I want to spend a lot of money on and then possibly modify to uselessness.

Pete. (l33t FS) said:

In reply to wspohn :

(Actually my FAVORITE was TIG welding AN fittings onto a junkyarded pre-downsize GM B body air conditioning evaporator core.  Instant large capacity, high efficiency oil cooler.)

When i swapped a th400 into my trail rig jeep I was concerned about trans heat because I would spend all day putting around at idle, almost never getting the torque converter up to stall speed and not having any ground speed to help move air through the cooler. I used an ac condenser from a 79 cherokee as the trans cooler. It was as big as my radiator. It worked great.