Anyone ever had to replace a drive coupler on their Sonic? Just wondering if it can be done without pulling the engine. I experienced slippage in my port drive and I think the coupler is going bad.

plum, doubt that will change that without pulling the motor....usual signs are burnt rubber.

Try running only one drive at a time and see how each one acts

I did one on my 31. Not a bad job. You have to pull the engine. I just raised it about 1.5 feet and changed the coupler in the air. You need to check your engine alignment, its frequently the root cause. I think it took me an hour and a half.

could it be a prop hub ?

have you tried switching prop hubs to see if it follows ?

Well, I don't think my coupler is bad, after all. I layed on both engines and the couplers look fine. I also checked both prop hubs, which are solid hubs, and they're both fine, too. I did check my engine alignment over the winter when I pulled the drives to service the u-joints and both were perfect.

I experienced a very strange over-rev moment on the port engine at WOT. I was running along with both engines turning just under 5000 RPM and the port engine suddenly went right up to the rev limiter, sounding the alarm. I backed down to 3500 RPM and had to give the SB engine more throttle to keep the engines in sync. I went back to the launch about 3 miles away without issue. Forward and reverse work perfectly on both drives and there were no unusual sounds or readings. I checked the lower magnetic plug on the port drive and it's clean. I also checked the trim throughout the range to ensure the drives are even. I'm stumped. I've decided to switch back to my stock 28's and go out again to see if the problem will reproduce.

Its possible some debris in the water got caught on your outdrive which could make the prop slip.

I'm thinking the port drive popped out of gear. That would explain why I had to give the sb engine more throttle to keep the drives in sync. It was under load and the port engine wasn't. However, the port engine shifted fine in and out of gear at the dock. I'm going out this weekend to see if it happens again.

Took the boat out yesterday. I was on and off plane at least a dozen times and ran lots of WOT. The slip issue did not reproduce. I did remove my labbed props and install my stock 28's. Now, I'm wondering if the blades flattened out causing the prop to blow-out. I'm sending the labbed props to Bblades for a check-up.

Sometimes you can suck air down your drive shower and blow a prop out.

The thing is that it continued to act strange even when I brought the drives back to neutral and slowed to about 50. Even if Bblades doesn't find anything wrong with the props, I wanted to tweak them to gain 100 RPM. I can only spin them to about 4950 when it's 80+ degrees.