The universal joints are huge. They are the size of grapefruits. They are new boxes with less than 15 hours on them and the drive line is straight as an arrow and I used an alignment tool. The problem is the Stellings bolts direct where as the IMCO goes thru the original rubber mount. The metal to metal direct drive creates enought vibration to make knock sensors get up to 85 hertz - the Mercury scan tool picked it up and we traced it to the Stellings universals. We are in the process of both backing off the knock sensors with a reprogram and tring to find a rubber mount that goes in between the Stellings yolk and the flywheel.

I havn't read the whole thread, but what about working the propr to increase bow lift? Maybe even go back to old school 3 blade prop.

One of my customers had BBLADES re work some B1's that wouldn't trim at all, and now they trim the nose up and he picked up 5mph GPS.

Still only a 70mph boat, but better than 65.

3 blade Mirage actually picked up 1 mph on top of that, but it might have been a fluke.

The B1 is a lot better all around.

Forgive me if this is a repeat of someone else's post.

I understand the arguement, but to date I haven't had any problems/failures with connecting the driveline/shaft to the coupler that Stellings provides and connecting it directly to the flywheel, BUT.....I will agree with BenPerfected concerning the U-joints/Shims set-up. I have found (the hard way) in my boat, that the U-joints will begin to fail right around the 200hours mark---at least in this reference. And I put my drives thru U-joint hell before that---so, they may even last a little longer. And these are the "greasable" U-joints. I have replaced all U-joints in the driveline/shaft with non-greasable U-joints which are actually supposed to be a little stronger----not really sure if the non-greasable U-joints are the better way to go or not.

We were unable to get the angle on being able to get the grease hose on the ZERTS fitting of the U-joints that are/were closest to the flywheel/coupler and (obviously) I believe this is why they failed---while we were still able to successfully grease the other ZERTS fittings in the other U-joints each year.

ben perfected knows what's up...if your angles are not correct in the boat, on that drive shaft. no matter how small the angle, the two u-joints will not cancel(vibration) each other as they are designed to do...boat manufactures and suppliers make this mistake WAY too often...

that aside...at the speed your running, the boxes are going to slow you down. the engine and drivetrain need to come way up. the water is way too clean back there and a very small change in the boat will net you large load changes.

Kieth.....keep us posted on your drive trials this year. thanx

BTW, I have had to learn to live with my own Stellings box/drive heigth/prop testing woes too. You must greese those U-joints at least once every year---at least that is what I do. Is it enough???---who knows, but I plan on replacing ALL the U-joints every 200 hours. I am currently running blue printed XR drives w/IMCO -2" shorties, and 5-bladed Hydromotive props with naturally aspirated 600+hp/680 lbs of torque per side. I have busted a lot of stuff back there....but for now everything seems to be okay. I know every situation is different, but I have several stories I had to live and learn/trial and error on that I could tell you about that may help you.

Pull the connector off of the knock sensor for a blast or two and see what gives before you reprogram. Let us know!!! We've all spent money only to slow down so be patient and act like nothing's wrong around your wife!!! :evilb: