Magneto self destruct

[Newtexaz]

I read a few older posts on this and I see where the exact cause is unknown as to why this happens. Possibly a cracked magnet or a failed brass screw. In the case of my 27 Fordor, I heard a ping almost as if a rock had kicked up and hit the exhaust pipe and then it felt as if I was having a fuel starve issue or the ignition was cutting out. I pulled over and the car died. It started right back up but was running rough. I revved it up only slightly to try and determine what was going on with it when everything broke loose sending shrapnel through the hogs head, floor boards and oil pan. At this time the engine locked up and grey and black smoke filled the inside of the car. I'm lucky enough that none of the pieces hit me when they entered the car. I have taken the engine out and apart this weekend and the pictures show what was found. One piece I am trying to figure out....the u-joint came out when I pulled the engine and I found the u-joint pin broken with both peened ends still in each side of the square end of the u-joint. Not entirely sure how that would happen unless its totally unrelated. I would think that would take forward or backward thrust. Again, I wasn't moving when the mag let loose. Does anyone have any thoughts on this?

I am hoping that this is the extent of the damage after I check the block real good for cracks and put a dial indicator on the flywheel and then the crank output flange. This will go back together with Oil slingers and no magneto.

Randy / Fort Worth

[Henry K. Lee]

Randy,

Welcome to the self destruction club! It really does not take much for this to happen. I would suspect a combination of a cracked magnet with a loose retaining screw on the plate. It only takes one and the chain reaction begins. I hate it for you!

All the Best,

Hank

[Henry K. Lee]

I would say your broken u joint pin is unrelated and more than likely caused by fatigue over time from being possibly a loose fitting on the square shaft and oscillation.

[R.V.Anderson]

This is precisely why I have never recommended the in-car magnet recharge procedure. Not removing and recharging the magnets individually doesn't allow you to find and remove cracked magnets or other parts of the magneto such as broken magnet screws, all of which, as can be seen here, are time bombs in an engine. Cracked magnets are a major cause of a weak magneto, in any case. I'm not saying that an in-car procedure was involved here, just that it's an opportune time to remind everyone about it. The procedure was popular 80-odd years ago but the magnets and other parts were 80-odd years younger then. There's no need to do away with a magneto. Just be absolutely certain that all parts are known beyond doubt to be good before you re-assemble things.

So glad that neither you nor anyone else was hurt.

[Newtexaz]

Thanks everyone. I’m glad to hear that this issue wouldn’t cause the u-joint pin issue. Couldn’t think of how it would but it concerned me. Hopefully this week I can make time to clean up and inspect the engine and other parts for any damage. I will post any pics of issues I find. Hopefully it will help anyone else that runs into this issue.

[John.Zibell]

Please consider keeping a functioning magneto. The engine runs so much better on magneto than battery.

[RustyFords]

My car runs a lot smoother on mag, so I'd encourage you to keep the magneto function.

When I freshened up my engine, I removed every magnet for inspection and replaced all the retaining screws. Then when Ross Lilleker did the final part of the rebuild and inspected all my work, he inspected the magneto once again.

[Henry K. Lee]

Randy I have cleaned, recharge magnets, rebuilt coil ring if needed. Give me an email if interested. This is my last one.

[D Stroud]

Oil slingers are not without problems either. They have a reputation of breaking off. Dave

[RajoRacer]

Depends who's slingers you purchase !

[Henry K. Lee]

I agree Steve!

[Newtexaz]

Update: I have the engine/transmission put together and back in the car after the magneto had come apart sending parts and pieces through the hogs head. Once back together the bands were all adjusted but I have been having issues with the linkage between the low pedal and the main clutch shaft. On one drive, it felt like it was adjusted to short, I found that was truly the case, I adjusted it correctly and after the next drive it would feel as if it was adjusted too long and upon inspection that was also the case. Earlier on in this thread I had written that I found the U-joint pin broken. Is it possible that the drive shaft is moving enough forward and backward that it is pushing everything forward enough - effecting the clutch shaft position? I just took the car for a another test drive and I am getting heavy chatter in high and it doesn't fully engage into high until I let off on the gas and reduce speed (Low pedal is returning as far back as it will go). Possible that the pinion is skipping over the ring gear due to the drive shaft movement?

[Henry K. Lee]

Randy,

Were you able to set the clevis shaft to the free neutra as the book states. Also if your hand brake lever is not fully forward it will cause a slipping action to occur. Hope this Helps. Nothing worst than going for an ice cream run in a modern car!

Hank

[Newtexaz]

Hank, I was able to get neutral but how good of a neutral it is changes every time I take it for a drive. Seems to be a moving target..... I do need to cut a little bit more floor board out but the handbrake is nearly all the way forward. The ramp is definitely not touching the adjustment bolt.

[Newtexaz]

I have also found one of the rear hubs loose and the shim was ground up. The car will rock forward and back when parked. Possibly the trust washers worn away allowing the drive shaft to move?

[Scott_Conger]

this is no guess as to what you do or don't have going on, but only to say that some rocking while in place is a perfectly normal occurence. It is the magnatude of it which points to trouble, or not...

[Norman Kling]

Seeing the condition of your hogs head, I'm sure that you had to replace it. Did you use the low pedal as is in the replacement hogs head, or did you replace the low cam and notch? If those are not in good condition, you will find that you can't get the low to work properly. In that case you would need the low band too tight in order to get it to work. If it is too tight, you will not achieve a free neutral. And to get it to work properly you would need to loosen the low band so it would only work in low with the pedal below the floorboard. Another possible cause of a problem would be the clutch lever. The yoke might not be engaging properly with the clutch.
Anyway, check all of the above and also what I posted here. I question whether you have a problem with the ring and pinion unless they were bad before. But if the car came to an abrupt stop when the magneto collapsed, perhaps the jolt could have affected the rear axle gears.
Norm

[Newtexaz]

Norm, Scott, Hank,

Thank you for the info. When I replaced the Hogs Head, I replace all of the cams/notches and all new pedal shafts. I was not moving when the magneto let loose so there was no sudden stop.

Randy

[Newtexaz]

Thank you everyone for your assistance. I figured out why finding neutral was a moving target, the clutch spring is weak and not returning to the same place each time. Had to add an external spring for now. All is working correctly between low and high now.

New issue - reverse pedal seems to be in the right place (Plenty of power in reverse and the pedal does not go to the floor) but when the engine reaches operating temperature, I have no reverse. I just don't want to get the reverse band too tight. Other than adjusting it tighter, does anyone have any other ideas why this would be happening?

[Henry K. Lee]

Randy sounds like you did a great job!

Your reverse not working as well as you want is more than likely caused by springing action in the steel band not seating in a tight circle. Let it break in a bit and slowly tighten up as required. Glad to be of assistance.

All the Best,

Hank

[Newtexaz]

Sounds good Hank. I hope that does it. You are always helpful, thank you