There is an interesting thread running on 460ford.com about a flywheel explosion on a 800hp Boss headed big block. The video and photos are a must see.


http://www.460ford.com/forum/showthread.php?t=138991

http://s732.photobucket.com/albums/w...t=100_6747.flv

I think its telling about a housing that lacks the lower containment bolts

Jason

I think it's ONE thread about ONE very stressed race engine and ONE flywheel explosion. :)

Fact is, flywheel explosions are very rare with the advancements in design from the 60's, when they were considerably more common. Show me ONE thread here on Club Cobra that has a specific example of a typical street Cobra and a flywheel explosion. You MIGHT see a reference to something like an 800 horse monster or a 9 second drag race only car. But even then, flywheel/clutch explosiongs are incredibly rare.

Then again, you could get hit by a bus crossing the street at any given moment in time... :)

It should also be noted this 800 horse monster was running a STOCK flywheel. Myself, I run an SFI approved Hays wheel, as they should have done!

That flywheel had no business on that motor.
But that’s not what this is about,
This is about cutting the lower bolt holes of a scatter shield off. And while you don’t want to talk about the consequences, we should advise about them.
The fact of this failure is that the flywheel let go @ 5000rpm, significantly less than the SFI standard requires, and well under what many owners spin on the street, “just playing around”
It destroyed the housing and the block. It went across the room, thru a wall and damaged a cabinet.
As I said in the 460ford.com thread, I can’t imagine if that had been in a Cobra.
Yes we all “should” all use SFI certified flywheels.
and
Yes flywheel failures are rare.
But some don’t and “stuff” happens, that’s why we buy scatter shields in the first place.
Just something to think of before you cut 30% of the containment strength away.

By the way, if you read the post, and follow the build you will see is not a “very stressed racing engine”, it’s a very healthy street motor on pump gas. 557 CI, Boss headed, 10.4 to 1, solid roller, single carb.

I know, boring, nothing to look at here....

…..Jason

K brothers have a good pic of the mod. I think the grinder with cutoff wheels is easier to handle and keep a straight line. I use the Pferd wheels, good balance between wear and cut. I just had one here that looks like it was done by a drunk guy. One of the nicest I've seen cut is Anthony's http://www.clubcobra.com/forums/fe-talk/100006-low-profile-oil-pan-kudos-nick-acton.html
They did a straight cut either side and a nice following of the belly underneath.
http://img199.imageshack.us/img199/7357/antbell.jpg
If I'm going to blow a bellhousing I want it weak on the bottom to blow out there. That way I can still stand up to push the broom and clean up the debris..........

I used an electric grinder with a cutting wheel. I cut just above the two bolts and removed about 3/4 of an inch. I then painted the cut edge with clear fingernail polish to prevent corrosion.
On the safety aspect. That flange if ever it caught a manhole cover at 30 MPH in the dark, which had better odds of happening than an exploded flywheel, could cause a very serious situation.
I never entered the housing either, both plates on the bell still come together.
For me...a safer situation, and peace of mind.
Lou

I have a McLeod scatter shield and didn't cut outside the bolts. I used s Sawzall and it took about five minutes to cut (on the bench) and another 20 minutes to clean up and paint.
Bill Stradtner

Ok Here are the choices I have to cut the Bellhousing

Sawzall
http://www.harborfreight.com/cpi/cta...temnumber=4095


4" Grinder
http://www.harborfreight.com/cpi/cta...emnumber=91222


Handheld bandsaw
http://www.harborfreight.com/cpi/cta...emnumber=47840


What do you guys recommend. I will have to purchase any of these tools


I figured a 3" cutting wheel would probably take forever. Rememeber ther the bellhousing is out of the car.

Of what you listed, I'd use the portaband. Then come back with an angle grinder and clean up the cut.

I just used my sawsall and a good metal blade worked fine then touched up the rough edge with a mini grinder..Bill

the 4" grinder with thin cut off blades will work. You will have sparks to content with. Gloves & face shield a must, lots of light, mark your cut with Sharpie. The grinder and saw take about the same time. If you have to buy one buy the grinder. The SawZall would be the hardest to use in my opinion. I have all three tools but have never used the SawZall for cutting the bellhousing. But we always cut them on the car.
After you make the cut you can clean it up with the grinder. You might want to buy a pack 4" 60 Grit Flap Discs, Harbor Freight has them for $8.

Touch up with paint.

Dwight

I was dreading using the grinder to do the job, thinking it would take forever or not work at all. I was surprised how quick it did the job. Time wise, no problem.

ok its lunch time, I think I will pick up the 4 " grinder as many of you have mentioned.

Thanks Excaliber for your post, I was thinking the same thing that the grinder would not be able to cut thru. I guess it will work.

I have to paint the bellhousing anyway so I could paint it when done.

Here's another pic of mine. I did it on a stand-up bandsaw (out of the car of course)

Anthony


http://www.clubcobra.com/photopost/d...4_Medium_1.JPG

Very clean, acmjg. My McLeod scattershield looks similar and I don't feel the least bit compromised by this simple mod. As others have said, bottoming out at speed is an outcome that has considerably higher odds (and ramifications) than torching a modern flywheel.

-Dean

Just cut the flange and the least number of bolts to gain the clearance you want. Do not cut into the round part of the shield over the clutch itself. That part of it is the main containment, if anyting should happen the weak part is on the bottom.

Lee

I too was bothered by how low the Lakewood flange hung, but in my opinion, the fasteners holding the scattershield are there for a purpose. Removing material below the bottom fasteners is a good idea (about 1/2"). Nothing has touched the lowest area of my shield after over five years of driving, but then I do tend to avoid rough roads. A modern clutch and flywheel is also a good idea. But I don't want to be the first guy on my block to have anything blow out through the bottom of my shield (and then back up). But if I were to take it apart again, I'd seriously consider one of them newfangled units with even more ground clearance. :p Rich

acmjg,

Thanks for the detailed Photo.

I just picked up a Sawzall with (5)18 tooth blade. I picked up a angle grinder for finishing touches.

I guess this will do it.

Don't forget the face shield and ventilate the garage before you start showering sparks. :eek:

What he said. I once had a name-brand cut-off wheel explode on me and leave a 3" slice in my face shield. Without the shield I would be typing this in Braille.
Bill Stradtner

don't do it
 

Priobe Don't do it. If the car doesn't have to pass a state inspection where the lowest part must be higher that the rims on the wheel, leave it. I have not cut mine and run and raced it for 12 years. I run 17" 335/35 pilot wheels. I have not hit the bell once. My clearance is 4.5" front and rear at the corners of the frame where your behind an in front of the tires. Stance on the car is fine. You are talking 3.0" clearance under the bell housing NJ roads are not the best in the world. Next town over has speed bumps to slow down people in a park area with kids. I have not hit the bottom of the car yet. I do go 5mph over the bumps.
The other question is if there is a failure of the clutch or flywheel, it is easy to bend the block plate without having the bolts and bottom lip to help keep are parts in the bell. I race and drive hard. If you want to trim the botom of the bell leave 1/2" around the bolt holes to bolt the plates together. The minute you trim the bell housing your bell if void of the warranty.%/ The odds of your clutch or flywheel blowing up are small, but the amount of damage to your car COULD cut the car in half. This I have seen 2 times at the racetrack for 1/4 mile.
If you go to the FE forum and look at the Boss motor that blew up in the dyno cell, this might give you a good idea about the amount of force and damage that a flywheel can do. I have 4 lakewood bellhousing on all my cars and and jeeps. I like walking with my own legs, even if they are old and in poor shape. If you are worried about clearance under the car, than go to a Quicktime bell housing and sell the lakewood. I don't know how bad the roads are in your part of the country, but might are poor.:o Rick L.