Originally Posted by rhjames
does this occur only in high gear, or when you reach max rpm in each gear?
GOOD QUESTION. I'LL HAVE TO TAKE IT OUT REAL QUICK AND SEE IF IT DOES IT AT HIGH RPM IN ALL GEARS OR JUST 5TH.
some vibrations with tires/wheels don't show up until high speed (revolutions). again, is this at one particular speed, or at a particular rpm in each gear?
DEFINITELY NOT THE TIRES OR A BALANCING ISSUE
a bent wheel will show up immediately (vibration), and continue to high speed, so this should not be the cause.
NOT A BENT WHEEL
Torque tube vibrations (bad bearings, bent shaft, and the like) will show up immediately as well, so probably not the cause. Same thing for axle shafts.
I ACTUALLY FEAR THAT IT'S ONE OF THESE. IT HAS ALWAYS FELT TO ME LIKE SOMETHING WAS BENT OR OUT OF BALANCE IN THE DRIVESHAFT. I KNOW ABSOLUTELY ZILCH ABOUT MECHANICALS, BUT I DO KNOW IMPROPERLY BALANCED TIRES VS. A BENT DRIVESHAFT OR SOMETHING OF THE LIKE....
CV joints will make noise when going bad, lots more noise at higher speed. could this be what you're dealing with? (it's usually not just a high speed problem)
I DO KNOW BAD CV JOINTS, AND THIS IS DEFINITELY NOT A BAD CV. NO VIBRATION IN THE WHEELS WHILE DRIVING ETC. IN FACT, IT DRIVES LIKE A BRAND NEW CAR UNTIL YOU DUMP IT AND IT REACHES 1000 RPM'S SHORT OF REDLINE...
clutch/flywheel/crank balance, would also show up immediately, but would be more noticeable when the engine is under load.
THEREAGAIN, THIS WOULD SOUND MORE LIKE WHAT WE'RE TALKIN' ABOUT HERE. HOWEVER, I DID JUST HAVE MOST OF THE INTERNAL CLUTCH COMPONENTS REPLACED, MINUS THE DISC AND PRESSURE PLATE, AND IT WAS ALREADY BAD BEFORE THEY REPLACED THE CLUTCH COMPONENTS AND STILL IS AFTERWARDS....
engine misfire is another item, but ask yourself why it only does it at high speed (rpm's)? If this is the cause, it is probably not spark related, but fuel related. The fuel pump(s) may not be putting enough fuel volume to the engine for it to keep up with the rpm/load requirement. Another fuel issue could be filter, tank, pick up or line restrictions. G-forces can also come into play with this.
NOW WAIT A MINUTE. IT RUNS A LITTLE ROUGH AT IDLE, HAS 3/4TH'S THE POWER OF YOUR AVERAGE GT DURING THE ENTIRE WAY UP TO REDLINE. IT ONLY RUMBLES REALLY BAD AT HIGH RPM'S, BUT STILL RUNS LIKE CRAP BEFORE HITTING THERE....
I have run many drag race cars that exhibited no vibrations or engine stumbles while revving/sitting still, but when you put a load on it (running it down the track) the fuel starvation becomes apparent.
IT COULD BE A FUEL PROBLEM, OR LACK THEREOF, I GUESS. IF THE MOST FUEL IS BEING DUMPED WHILE UNDER THE MOST SERIOUS LOAD, THEN THIS WOULD MAKE SENSE.
HOW ABOUT BAD PLUGS AND/OR PLUG WIRES? WOULD THEY CAUSE A SLIGHTLY ROUGH RUNNING AT LOW RPM'S AND THEN BE CAPABLE OF CAUSING THAT SERIOUS RUMBLE AT HIGH RPM'S?
these are just suggestions and are in no way a complete list of things to go through, but you can start with them.
I CERTAINLY APPRECIATE ALL OF YOUR SUGGESTIONS. BOTH YOU AND DANGLERB'S. I'LL BE PASSING ALL OF THEM ALONG TO MY TECH UPON HIS RETURN NEXT MONDAY. AND I'LL CERTAINLY LET EVERYONE KNOW WHAT THE ACTUAL PROBLEM WAS ONCE IT'S FINALLY BEEN SOLVED. MAYBE THAT WILL SAVE SOMEONE ELSE THE TRAIL AND ERROR LATER ON...
good luck---
--Russ
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