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So my 73 F100 body/ 75 F100 4x4 chassis truck was extremely loud(not the exhaust) when I bought it last fall. The rear end was shot. I just finished a total over haul, new ring and pinion, clutch plates for the limited slip, new axles, bearings, brakes and brake hardware. This eliminated 95% of the noise. It now made a vibration in the engine/ transmission area surface/ more noticeable. It occurs and gets worse when the engine revs. It does it in neutral, clutch pushed in, in all gears moving down the road and sitting still. It seems to deminish slightly at about 65mph but still prevalent. Any help would be greatly appreciated.
If it does it sitting still it' is in the engine. only other possibility would be a clutch out of balance issue and that's unlikely. So that can be quite a few things. making sure it's firing on all 8 is the starting point . a miss can feel like a vibration.
You might check and make sure your throw out isn't riding the pressure plate.
I’ll start with the checking the plugs and wires. The carb is running a little rich I will get that adjusted as well. The power steering pump pulley is not aligned with the other pulleys and the belt is squealing. I just ordered new parts for the bracket that are missing and will get it straightened out. This may be causing some vibration?
notice the washers and spacers on the bracket along with pulley rubbing the high pressure hose.
So I dug into the carb, found 2 vacuum ports with no caps or hoses attached. Connected the PCV up( had oil blowing out of the opposite valve cover intake. Checked the choke, it was working as it should. Hooked up the vacuum guage, went to turn the throttle screws in so I could back out about 2.25 turns to get a starting point. The screw on the right was turned all the way in so I was not getting all the needed fuel. Got the carb responding well now. Found one motor mount perch missing one bolt and the other was loose. Tightened it up, getting a new bolt today. Vibration is way better. I think the rest of it is in the front bearings. Making progress. Thanks for the pointer Sixpack 440.
Beside all the above, and universal joints,... Check your transfer case mounts. Check both ends of driveshaft to see if transfer case slip yoke, and rear pinion are loose. Look for any obvious misalignment. My truck would develop a slight vibration above 60 mph within a few months of changing rear universal joint. I replaced the transmission several months ago (T18), and all vibration ceased. So that said, it could be the transmission also.
