This Ain't Good..

[Nial McCabe]

During ~My Recent Adventure~ at the Thompson Vintage Festival last weekend, my Spridget turned the inside of it's gearbox into spaghetti.
As a consequence, the engine stopped. Suddenly.

To be honest, I'm not sure if it was the engine or the gearbox that failed first. No matter...it was all a mess.

The crank broke in two pieces at the rear counterweight.

I was able to throw the gearbox into neutral and the engine was actually still running when I shut it off after coasting to a halt. I'm not sure 5 Minute Epoxy will fix this one.

I put together a useable trans from three junk units a few days ago (one filled with mud and one filled with acorns). Seems to be OK.

And I had a semi-rebuilt 1275 engine I quickly finished up yesterday.

Powertrain is now back the car and even sounds pretty good for being built
out of mostly crap. I'll find out at the Pittsburgh Vintage Grand Prix in less than two weeks.

Anyway, here's the crank from the engine I pulled out......

[Heightswitch]

I don't think you need to circle the damage Nial

On the plus side at least it held together..That would have parted company from the block at a fair old lick if it had completely fractured at that point!!!

N.

[GORDON STREETER]

Actually this isn't that unusual as I've seen several A and B series engines with broken cranks over the years with the engines still running.
Sometimes it's caused by not leaving a radius on the side of the journal when it's reground leaving a stress riser .
It could have been cracking for a while and the sudden stop finished it off.

[Normal Bloke]

Bravo Sir!

[midgetman]

When my Midget crank broke it was where a journal met the Web. I drove it back to the pits thinking the exhaust was knocking on the bodywork! One big clue was that the front pulley/damper wasn't there when we flipped the bonnet

[Nial McCabe]

Originally Posted by Heightswitch

I don't think you need to circle the damage Nial

Hahaha! Very true!

Originally Posted by midgetman

When my Midget crank broke it was where a journal met the Web......

To some degree it's almost impossible to eliminate stress riser areas on a reground crank. Mine was reground and the radii looked good but it's really hard to tell. Even the standard-size ones will snap so it may just be the nature of the beast. Only 3 main bearings, less-than-perfect balance and 7000 RPM can be a bad combination.

One of my students races with our club in a vintage 1600 Formula Ford. Last year the flywheel and rear main bearing sheared cleanly from the rest of the engine. I wish I could find the picture of it. Engine kept running but he thought he'd ruined the clutch. Until he turned it off and tried to restart it. Flywheel turned.....and nothing else.
So even Fords can do this.

Luckily, my block seems to be OK and damage seems to be limited to the crank. So eventually I may be able to rebuild this 1275.
Right now I'm still amazed the engine I just slapped together to replace it sounds so good!

[GORDON STREETER]

FF engines normally break the back off the crank because of grounding out the bell-housing and flywheel on the track, apart from that it's unusual for one to break (apart from the 3 bearing 1340 cc one) I've seen a fair number of them in the last 50 years of racing and never personally had one break even in massive blow ups !

[Nial McCabe]

You are probably right about the bottoming, Gordon. I did not really look at the FF in question (but I'll see it in 10 days at the PVGP and I'll ask the owner).

One of the most spectacular explosions I've ever seen was the 1600 MGA engine in my friend, John's car. John is a Brit and he raced on your side years ago.

Anyway, we were racing and he had just passed me out of the The Boot at Watkins Glen (normally we are good racing partners but my regular engine was out and I was running a bog-standard 948).

Rods and bits flew every which way from his MGA and the force blew out both sides of his engine. After we pulled it out you could look straight through the left side to the right. We found a 5 lb piece of the block on the track.
These photos don't do it justice but you can see some of the damage.





If you are still reading and would like to see what it looked like from the driver's view, I have a video from my car and John's on this auspicious occasion (you can even see John waving at me just before it happened). He dumped 6 quarts on the track and I recall the cleanup fee was a lot.

Click on the link below and slide to 1:20 to see what it looked like:

~John Faulkner's Car Exploding at Watkins Glen~