Cracks in my flywheel

[67gt]

I started taking apart my engine and noticed that my flywheel has hairline cracks about an inch long all over the face. What would have caused these cracks? I would figure that the flywheel is no longer usable, does anyone have a recommendation for a flywheel clutch assembly for the 390.

Thank you

 

[65ShelbyClone]

Localized overheating caused the cracks. With an engine bigger than a 302, I would lean toward an aluminum flywheel.

 

[rbohm]

what you are describing is actually heat checking. before tossing the flywheel, have it resurfaced at a good machine shop. if the checking is deep(not usual), then replace the flywheel with one of similar weight. i prefer billit steel wheels, but a good aluminum wheel will work also, as long as it has a steel or bronze insert to handle the load.

 

[MustangMatt1966]

what you are describing is actually heat checking. before tossing the flywheel, have it resurfaced at a good machine shop. if the checking is deep(not usual), then replace the flywheel with one of similar weight. i prefer billit steel wheels, but a good aluminum wheel will work also, as long as it has a steel or bronze insert to handle the load.

like rbohm said, check to see if it can be resurfaced, mine had heat spots and cracks on it, i got an aluminum one and went to put it in and realized my old flywheel was balanced with the engine, so i couldnt use it. So i got the old flywheel resurfaced, and its good as new. Moral of the story, if it aint broke, dont fix it

 

[67gt]

I will look into resurfacing. I’m not sure how deep they are but I can feel most of them with my finger nail. If it can’t be machined I need a 0 balance flywheel.

 

[allcarfan]

i do not suggest a light weight aluminum flywheel.

 

[65ShelbyClone]

I will look into resurfacing. I’m not sure how deep they are but I can feel most of them with my finger nail. If it can’t be machined I need a 0 balance flywheel.

I know Fidanza aluminum flywheels have removable counterweights so you can use them in 0, 28, and 50oz applications (for smallblocks at least). I don't know if all FEs are internally/0 balanced or if it was just the pre-70s.

i do not suggest a light weight aluminum flywheel.

Mmmkay, details? The biggest downside I know of is costing more to resurface them(usualy means replacing the stel friction plate). I'll concede that for a stock street car, even a Mustang, a steel one will be the most drivable.

 

[67gt]

Ok I found a place that is only 10 minutes or so from my school, Advanced Engine Rebuilding Inc. They quoted me $40. Has anyone in the Cape area heard of them? Here is a picture of the flywheel.

 

[1320stang]

One point to make, 429/460's have the same bolt pattern and diameter as the FE's. For some reason, it seems if it says 'FE' on it the price gets bumped a bit. There's a lot more 429/460 stuff out there, both new and used that will tend to be cheaper.

BTW, are you a member of FordFE.com? Someone on there may have one for sale, just post in the classified section, but you can ask questions in the general forum.

 

[allcarfan]

When I had my turbo car, both of my engine builders from two different shops said that switching to an aluminum flywheel would hinder performance. They both said that it will rev faster, but because of its lightweight, that Id lose a good bit of torque. Just going by what they told me. I was buying parts through one of them and he could have sold me a $600 aluminum flywheel and made a good chunk of $$ off of it, but sold me a much, much cheaper one that was steel.

 

[67gt]

Would there be any real advantage to switching to a steel flywheel instead of having my cast piece resurfaced? Does it grip any better and will be more resistant to cracks? The car only has 50,000 miles on it. My clutch disk also needs to be replaced. It is fraying on the edges. Should I replace the pressure plate too? How is the stock diaphragm spring? At this point should I just replace it too? Does anyone have a recommendation on brands that won’t break the bank but will hold up to the occasional trip to the track.


Thank you

 

[1320stang]

Well, I've got an aluminum flywheel for my '63 Fairlane, but it's N/A and it will be FE powered, much like 67GT's car and big blocks have torque, so I'm not sure your concern is valid in this instance. Totally different application, totally different car with totally different suspension.

My Fairlane will be a drag only car, 67GT's might be a street car with occasional 1320 jaunts. If that is the case, I'd likely go with a steel flywheel. Also, there is a difference between a steel flywheel and a cast iron flywheel. Steel ones are usually SFI approved whereas no cast iron one is. Cast iron has a tendancy to explode with a lot of shrapnel, so a scattershield is usually warrented if you're going to be making 'sprited' clutch dumps, but I'd get one in any case, piece of mind if nothing else.

390/427 are 0 balance whereas 428's are not. I believe that the 429/460 is 0 balance, but don't go off my word.

 

[1320stang]

Any flywheel can be resurfaced. The cracks are a result of heat and are pretty common. At what point you need to worry about them is up for debate, usually depending on your wallet and whether or not it's a daily driver. You can look at old pictures of where a flywheel explosion has sawed a front engine dragster in half, Big Daddy almost lost his foot because of one, hence he developed the modern rear engine dragster.

I'm a big fan of the 3 fingered pressure plates, many will disagree. The diaphram has a much more 'modern' feel to it. I like McLeod for the 3 fingered variety, but then again, I've not driven or dealt with any performance diaphram applications.