Inconsistent vibration from 1500-2500 RPM ???
10-30-2007, 12:03 AM
#1
Inconsistent vibration from 1500-2500 RPM ??? Hey guys. I have a weird problem. I have an inconsistent vibration that varies with engine RPM but only between 1500 to 2500 rpm.
It does it randomly when just driving, and it will do it in all gears. I can induce the condition you could say though. If I am at 2000 rpm in any given gear and its in a good mood and not vibrating then I push the clutch, rev to 2500 then dump the clutch it will rocket back down to 2000 rpm and begin to vibrate pretty bad, like a bent driveshaft bad. Then usually within a shift or 2 it goes away all together or is BARRELY noticable. I can rev the motor up and dump it or downshift and dump it and it will begin to vibrate. But only if it ends up being between 1500 and 2500 rpm once its dumped, if I dump the clutch at 4k while moving say from a steady 3500 it wont vibrate, but if I slowly let it decelerate by itself it will vibrate from 2500 down to 1500 then stop once it's below 1500. I have never been able to get it to vibrate at any rpm with the clutch dissengaged. Sometimes it wont vibrate a bit through all the gears. The vibration isn't as severe as it is sometimes either.
I have a resurfaced spec flywheel, new spec 3 disc, new hydraulics, new mainshaft and tailshaft bushing. Ford 9 inch with new gears, pinnion bearings, and axle bearings. I inspected the LCAs, sway bar, torque arm and panhard bar, etc etc. Motor mounts and Trany mount look good. New driveshaft (but theres a catch, read on...)
When all the above work was completed it felt like there was a ever so slight vibration in those rpms then as the miles got racked up it got worse...
I had a local place build me the driveshaft. It know it needs balanced. The shop just built it for me and I was to have it balanced elsewhere as they don't do it in house. I installed it and it vibrated at 60MPH, I flipped it around 180 deg and it vibrates around 100 mph now. I installed a greaseless 1350 u joint in the back and a 1350 to stock gm conversion u joint up front. Could I have messed up the U joint(s) on install, or could the out of balance shaft cause the random vibration?
As soon as I can afford it Im getting a 1350 slip yoke and getting it balanced. I'm hoping that will cure it but I know I am not that lucky.
Does anyone have ANY ideas?
It does it randomly when just driving, and it will do it in all gears. I can induce the condition you could say though. If I am at 2000 rpm in any given gear and its in a good mood and not vibrating then I push the clutch, rev to 2500 then dump the clutch it will rocket back down to 2000 rpm and begin to vibrate pretty bad, like a bent driveshaft bad. Then usually within a shift or 2 it goes away all together or is BARRELY noticable. I can rev the motor up and dump it or downshift and dump it and it will begin to vibrate. But only if it ends up being between 1500 and 2500 rpm once its dumped, if I dump the clutch at 4k while moving say from a steady 3500 it wont vibrate, but if I slowly let it decelerate by itself it will vibrate from 2500 down to 1500 then stop once it's below 1500. I have never been able to get it to vibrate at any rpm with the clutch dissengaged. Sometimes it wont vibrate a bit through all the gears. The vibration isn't as severe as it is sometimes either.
I have a resurfaced spec flywheel, new spec 3 disc, new hydraulics, new mainshaft and tailshaft bushing. Ford 9 inch with new gears, pinnion bearings, and axle bearings. I inspected the LCAs, sway bar, torque arm and panhard bar, etc etc. Motor mounts and Trany mount look good. New driveshaft (but theres a catch, read on...)
When all the above work was completed it felt like there was a ever so slight vibration in those rpms then as the miles got racked up it got worse...
I had a local place build me the driveshaft. It know it needs balanced. The shop just built it for me and I was to have it balanced elsewhere as they don't do it in house. I installed it and it vibrated at 60MPH, I flipped it around 180 deg and it vibrates around 100 mph now. I installed a greaseless 1350 u joint in the back and a 1350 to stock gm conversion u joint up front. Could I have messed up the U joint(s) on install, or could the out of balance shaft cause the random vibration?
As soon as I can afford it Im getting a 1350 slip yoke and getting it balanced. I'm hoping that will cure it but I know I am not that lucky.
Does anyone have ANY ideas?
