I ran my boat yesterday ran it up to 90 or so when I let off the gas (quickly) the drive made a nasty clunk . I think it's the water pushing the prop backwards witch can't be good. This can't be the only boat that does this so does any body no what to do?

I don't know ,,,,but if u hear a noise @ 90 ????? u got something major wrong or fery good ears !!!???

If its realy the drive ??? What drive is it ?

The drive is a bravo 1 on a Eliminator Daytona 650hp. You can feel and hear the noise it's like the water slams the prop backwards it makes one big clunk then it's fine . If I bring the speed down slower witch is what I try to do it just fine . Last year it did the same thing I thought it was slop in the steering but I just but on full hydraulic. With a nose cone there is so much water pushing on the prop thats what it's got to be .

How can water push the prop backwards ??????? if u go forward ????!!!!!!

Think about it.

Its maybe the drive, Gimbal or something, but i don't know .

I am guessing major problems in the drive. At this point have it looked at or torn down before it is totaly destroyed.

Forgive me for jumping in.
Bravo's "overrun" when you back off hard on the throttle. The prop will try to spin at close to boat speed while the engine rpm is lower, but I don't think the clutch would cause a noticeable noise. Sudden decel of the engine combined with water reentry at high speed "could" pull hard enough on the drive trim to cause the drive to pop off the trim relief pistons. Then when you throttle back up, it can slam back to the original position causing what could be a very noticeable noise. But this still does not sound like what you describe because you say it is when you decel, not throttle back up.

What the heck is a trim relief piston ???? Are u talking Outboard or Bravo ??!!

Bravo's have relief pistons in the trim cylinders too. It has a special 2 part piston that can let the drive trim out with enough impact, then it can return to the same position after the impact (memory piston). Doubt it is the issue described here.

I did not know that ,,,sorry, never pushed a bravo boat that far i guess !! LOL

Thanks

Is everything on the transom tight? You can get a side to side motion when accel/decel if there is something loose??
Is the propshaft tight? No end play, rotates with some preload on the bearings that it rides on?
Does it do it at medium speeds?? Like 50-70mph range or just at 90mph??
Anyone else in the boat that can try and locate the noise as it happens?? Have the wife ride on the swim platform and see if she can feel or see it?? (sorry couldnt resist)..

Just thinking out loud here..