Damper Plate

Need some information on damper plates, How can you tell if it is bad and needs replacing?

351W in a '84 MasterCraft, I am currently rebuilding the motor and the machine shop said that someone drilled the weights out of the flywheel and it was 24 grams out of balance. I always had a little bit of vibration and noise when running in reverse.

John,
From a recent post:

8122pbrainard wrote: jellison wrote: My question is... Does the plate have to look broken to actually be broken? Also when i wiggle the spline on the transmission where it attaches to the flywheel I can hear a small amount of slop/movement in the transmission. IS THIS NORMAL????!!!! Jason, The damper center hub should be preloaded with the springs so there should not be any movement. The slop on the trans, is it radial? If so, you may have a bearing problem. The best way to check for radial play is with a dial indicator.

John,
As mentioned, put a new one in. Also, flywheels do not use weights for balance. Like any cylindrical rotating object, weight is REMOVED by spot drilling near the outer diameter.

Pete, small block Fords do use an external weight,351 and early 302's are 28oz imbalance late 302's use a 50 oz. some aftermarket flywheels have bolt on weights so they can be used on any engine

Come to think of it dad's does too but it's the lower step on the ladder vibrating. Guessing not too many have the ladder though.

They still drill them as an assembly when balancing though . It only becomes s concern when your mixing or matching parts. If you pull your engine apart for a rebuild no problem, need a replacement part you have to know what you have. I don't think Chevys are that way, we need to ask Steve.

mamigacz wrote: jpage wrote: I always had a little bit of vibration and noise when running in reverse. I’ve had the same reverse vibration issue on two of my ski boats. On both boats, I replaced the prop with an acme prop, replaced the damper plate, replacing the strut bushings and adjusted shaft alignment to spec. The issue never went away. I think it’s from cavitation, not imbalance. In forward, both boats had no vibration issues. Does anyone else have this vibration issue in reverse?

You could have transmission problems with reverse - I have pulled them apart and rear clutches in real bad shape that were working but could not have been happy about it. I have seen boats with the controls not quite correctly adjusted that operate lower rpms in reverse at idle and that sometimes makes the damper plate angry. Also the exhaust on some boats can be a bit more rumbly when in reverse pushing water into the pipes... it would really depend on the specific type of vibration.

mamigacz wrote: jpage wrote: I always had a little bit of vibration and noise when running in reverse. I’ve had the same reverse vibration issue on two of my ski boats. On both boats, I replaced the prop with an acme prop, replaced the damper plate, replacing the strut bushings and adjusted shaft alignment to spec. The issue never went away. I think it’s from cavitation, not imbalance. Does anyone else have this vibration issue in reverse?

Since reverse uses the planetary gearset, there are always extra harmonics.