O.d.
The countershaft always turns. Period.
The difference is, the 4 speed OD is not really a 4 speed OD but it is a 4 speed that Chrysler modified the shift rods so that when the shifter HANDLE is put into the 3rd gear position, the gear box is actually in 4th gear, which is direct. All that means is the disc, input and main shaft are all turning in the same speed. That would be crank speed.
To get it to overdrive, you put the handle in the 4th gear position, but the gear box is actually now in 3rd gear. And since you can never turn something overdrive that is directly driven, the engineers made 3rd gear overdriven. That's how they have an overdrive.
Does NOT matter what the trans is, the counter gear is always turning. Is power moving through the counter gear? In every gear but the direct gear, which is 4th in a standard box, and what they call 3rd gear in the overdrive box (which, as I said is really 4th gear, but you flip the 3-4 lever down instead of up and it changes what gear you are in, relative to shifter handle position).
Is the OD really any weaker? Depends on who you ask. I have only used one on the street, and that was 1980 on accident. We tried to break it, but never did. Didn't have much HP, but we would get blind drunk and beat the snot out of it. We finally gave up. Obviously, more HP and bite, or a bad clutch and I could have destroyed it.
I was told the counter gears are what are weak. They have a different bearing arrangement or something. Use one with caution.
One last thing. It is beyond silly and cheap to run a stick and NOT use a scatter shield. In fact, I would call it downright IGNORANT and STUPID. You don't need to fail a flywheel, or a disc or the pressure plate to need a scatter shield. Doo doo occurs. We are all human and make mistakes. It is arrogance that breeds perfection in our own minds. Why am I anal about this?
I bought my first scatter shield in the summer of 1981 and all my friends (who were mainly stick guys) thought I was stupid. And arrogant. The rules didn't call for it, so they thought I just wanted to be overkill. I had never seen a clutch failure, but I damn sure figured that at some point, they had issues, or why make certain cars use them? And I was very abusive on parts back in the day.
The weekend before Labor Day (and incidentally, one week before the big GO) there was an AHRA National event at my local track. I had waited for it all year. All the hot dogs were gonna be there, but most didn't show, because they were focused on Indy. Saw my first mountain motor Pro Stocks that weekend. Yuill brothers showed up. Pretty cool. Anyway, there happened to be a goodly amount of stick cars there, and as the faster cars came up, my buddy and I walked up to the starting line. I will NEVER FORGET what happened next.
A Pontiac pulled up, and he was a stick. It was about 10:15 so the track was tight. He was in the tower lane, not 50 feet from me and my buddy, if that. They stage the cars and the Pontiac goes to the mat. I don't think he got his foot off the clutch and there was a VIOLENT EXPLOSION. As the car in the other lane left and things got relatively quiet, I realized my ears were ringing, and I could still hear the sounds of metallic parts hitting each other and the ground. Everyone was stunned. Finally, the driver got out, and we could see him limping, and his right foot was bloodied up. He went to the ambulance and they drug the car back to the pits.
We made it over to the car, right after the driver and his brother, who owned the car got there. The damage was almost unbelievable. It shredded the tunnel. Blew the dash up in the center. The cab was peppered with shrapnel. The engine, transmission and shifter were JUNK! The driver not only had some serious foot issues, his fruit salad was hit by flying debris and he said that was hurt worse than his foot (I would think so).
We talked for a bit, and then they wrote "for sale" on the back window. The brothers decided they were done. To my knowledge, they never raced again. You can say they were pussies, or they were cowards. Maybe they were. But we heard the explosion. We felt the concussion. Our ears were ringing. And the damage was almost unexplainable. From a single clutch explosion. So what happened? Was it junk parts? Was it driver abuse?
Nope, it was FATIGUE. In 1981 a mid 11 second car was pretty damned fast and he was in the mid 11's. On Friday, they tore up a disc on the last run. Probably about 9 PM. Being the racers they were, they had spare parts at home. They pulled it apart at the track, and left with the flywheel. They called their engine builder who met them at 6 the next morning and surfaced the FW for them. Back to the track and they slapped it back together. It was their first run of the day, and as far as I ever knew, the last one they ever made. In a hurry, tired from breaking their asses just to get there, running their first National Event and then killing a clutch Friday night, they just were too tired to rely on their own ability to function with out sleep and operate on motor function alone. Neither one torqued the flywheel bolts. One ASSUMED the other had done it. The results were spectacular, horrifying and devastating. The driver could have been killed. The car was pretty much junk.
The moral of the story is simple. The thing we love to do it inherently extremely dangerous. It needn't be a parts failure that gets you. It could be a simple routine, mundane task that gets overlooked. The results are, never the less, paid in money, blood and possibly, a life. I take this crap very serious. I don't care who you are, if you are using a stick, and you are going to go out and treat it like you stole it, then don't be a cheap *** and buy a SCATTER SHIELD. Anything else is dumb. It don't matter if the rules don't say you need it, you MUST have it, you MUST have it. Take a 30 pound flywheel, add a 10-12 pound disc, and a 30 or so pound pressure plate and bolt them up. You now have 70 pounds of ballistic projectile. Now, add RPM to that mass and you get the ability to kill, very easily.
My apologies to the OP. I did not intend to jack this thread. When someone is ridiculed for wanting safety equipment, that is complete and utter stupidity. Any car with bite SHOULD have a scatter shield on it. PERIOD. I appreciate that an apology was made. That was right and good. But the fact remains that very few people have seen a clutch failure, for any reason. If you did, you would only ridicule the fool who doesn't want one.
I hope my long ramble just may change on mind.
