Exploding Clutch

What actually happens when a clutch explodes? I assume the plate comes apart.

There can be several "levels" of decomposition, some are just bad, some are deadly. Looking at least toxic, the most common (experience) is the failure of the friction material. It can come off of the rivets (or glue) and spray out into the housing. This leaves nothing to drive the disk, and the vehicle just doesn't move or slows to a stop. The splines driving the clutch shaft can also fail making noise but little forward progress. The springs in the hub, or the spring containment can fail letting the springs jam into the pressure plate this can cause the vehicle to keep driving making the only choice to be shutting it off, or moving the trans out of gear. The third possible failure involves the pressure plate or components of the plate. If the speeds are low (normal farm tractor) the failure is usually not a catastrophic event, but it can be really dangerous if running at high speeds in a puller, or a hotrod/race car. Failure can take the flywheel with it making a grenade out of the middle of the vehicle. A student in my AS Automotive program lost both feet when the clutch and flywheel exploded at about 7500rpm in a 57 Chevy drag car in 1970. He missed a shift into 2nd and the components blew the tunnel and dash through the windshield, and embedded flywheel parts into the pavement. His feet were forward of the clutch, and both were destroyed. Jim

MANY things can happen and none of them are good..!!

Much depends on just what the engine was doing and just WHAT came apart..

A Clutch-Plate can loose chunks of friction materiel at about any RPM and make a real Racket and cause much vibration ( unless the clutch is disengaged to stop the clutch-plate from rotating..
There IS the possibility the friction materiel folds and jams..causing the Clutch to be unable to disengage and that is dangerous also..

Then, there is the type of "Explosion" we would all not care to have experience with.. The Presure Plate letting go ( comes apart) at high RPM, breaking the flywheel along with it and the pieces Exploding OUT of the Clutch compartment..

I have a friend who is about the luckiest one I know... back in the early 1960's, he believed A Small Block Chevy was not ready to "Run" until it carried 5 lbs of oil pressure at 6,000 RPM...

He regularly shifted that '58 Chevy/ 327 at 8,000 RPM..( Back when that was un-heard of)..

Now, when the Clutches would explode (Lucky every time), they went DOWN out of the bell-housing...

He carried a large Mallet all the time, to knock the flywheel/Pressure Plate Pieces out of the Asphalt after they blew... a TRUE Motor-Head..!!

Yep, he is very much alive and has Both feet to this day...!!

In today's world, most Sane competitors have Forged Scatter-Shields in place to keep the shrapnel to a minimum.. !!

Generally a clutch "exploding" doesn't do much damage unless it takes the flywheel with it. Then it can be catastrophic. Here in this vid a diesel engine runs away and the flywheel lets go breaking a Farmall 1206 in half. The 1206 is a 112 HP 10,000 pound tractor.

https://www.youtube.com/watch?v=y7gKbk0jyyM

As you can see the results can be dangerous. If your head got in the way of a chunk of pressure plate or flywheel it could easily kill you!

Rick

I destroyed a clutch on a 1010 massey 4 wheel drive with loader ,.. it was tuf little buger for 18 hp , and I workt it to the point of abuse ,.. ,. and a very good cold weather starter ,.and i got my money back when I sold it . anyway ,, I had a load of dirt in the bucket and a heavy grader blade on the back for ballast and balance,,. I was in low range 2 going up a 25 degree bank backfilling and banking my garage,. I was going straight up the hill and was constantly aware of the possibility of the nose slipping either left or right and then having a rollover ,.. after about 50 trips up the hill depositing dirt and rock trash , it nosed over and I punched the clutch , I rolled back plenty fast nd the tranny was screamin , I dumped the clutch and all I heard was a lot of racket like throwing gravel in a feed grinder ,. there was nuthin left of the clutch except aa plate of flimsy steel

A fella in the tractor pulling circle got lucky when the bolts holding the flywheel to the crankshaft broke at about 2800 rpm on a 900 Case. Flywheel at that speed cut thru the cast bellhousing cutting the tractor in half. Fuel and electrical everywhere it never caught fire and he got off without any major injuries.

Sanctioned drag races require an explosion-proof shroud around the clutch/flywheel.

Not good quality but shows what can happen. Starts at 40 seconds.

https://www.youtube.com/watch?v=J1a8ZQxq8EE

Ive seen damage of the pressure plate exploding on a 69 road runner with 383 4 speed. A 5 inch piece of pressure plate went through the heater and fell on the floor on the inside.

I shattered a pressure plate in a 55 chevy which the stamped metal housing around the actual plate kept it bolted to the flywheel and I drove the car home. Lucky me.

My daddy bought a new 1971 chevy truck with a 3 speed transmission. I was telling my buddies at school how the fully syronize transmission was nice, how you could easily shift to low without coming to a full stop. Which led to a bet that it couldn't be done. We were going to settle this bet later that week. So on my way home I decided to perform this feat at least once and why not at top speed, 85 mph. There wasn't nothing but the hub of the clutch disc left on the pilot shaft.

Yep, I was that kind of teenager.

You have never lived till ya blow a clutch at around 7 grand and have it come thru the scatter shield of the time and have pieces of it remove the master cylinder off the fire wall and slice the steering shaft in half like a hot knife thru butter and put big dents in the floor boards clean back to the back seat and make big lumps in the hood . Yep that happened to me . And two weeks later a young guy with a vett had his clutch blow while showing off for the lady's at a local beach and lost both feet . I was at a pull many years back and a guy had a W 9 with twin 462 Lincolns hooked together and the flywheel broke off the ft engine crank and went thru the 1/4 inch steel he had over it and cleared the top of the grandstands and went thru a couple cars out in the parking lot .

That is what is required today , but back when i started drag racing the best bell housing was a NASCAR cast steel bell and not a cast iron like stock . And guess what when a dual disc clutch blows at over 7 grand it will come thru BTDT . Don't want to do that again.

We ran steel safety bell housings on stock cars. The theory was in case the clutch let go, the steel would deform and contain shrapnel instead of shattering. I never actually saw a clutch let go, though, even though we turned up to 8,000 rpm. But, the pressure plate seems to hold things together at that rpm as long as you don't release the clutch.