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  1. #1
    Join Date
    May 2015
    Location
    Novi
    Posts
    55

    Default Flex/Damper Plate Replacement after engine ticking

    First off thanks to everyone for the information on this site, it's helped me more than a few times and I thought it was time to give back. There are a few threads out there about damper or flex plates and I thought I'd share my experience with my 05 Mobius LS. Towards the end of last summer I started hearing a tick coming from the rear of the engine (only at idle speed), it was not very loud however when I put my hand on the top of the motor mount I could feel something coming through the mount along with the tick. I looked around on this site and some others and read a lot about flex or damper plate failures preceded by a ticking noise. I at first decided I didn't really want to tackle this myself but a call to the local ski boat shops changed my mind, being springtime I was told they might be able to look at the boat in about 6 weeks, I also suggested it might be a flex plate issue to the local moomba dealer and was told they could almost guarantee that wasn't the issue as they only replace about one of those a year. Solid reasoning. So I decided to bite the bullet and ordered a new flex plate from skidim (around $100, item 1516). It was not the first thing I did however for those of you who are hearing a ticking noise and wondering if it's the flex plate you may want to remove your starter first, have a look and run a stick magnet around the starter hole...here is what I saw:
    flex_plate_1.jpg

    A pile of broken flex plate springs. So yes there is the smoking gun, I was lucky as there are some other posts out there where the broken springs had shot through the bell housing. My boat was still driving perfectly fine other than the ticking noise but probably wasn't far away from all of the springs failing.

    Ok so time to replace the flex plate.

    Tools you will definitely need: 15/16 box end wrench and socket, 9/16 box end and socket, 1/2 and 3/8 drive ratchet and extensions, torque wrench, big pry bar, ratchet straps, 2x4's, clymer manual

    Step 1. Remove the rear seat and center floor panel.
    Step 2. Disconnect transmission shift linkage and wiring. Take some pictures so you don't forget what goes where.
    Step 3. Get a $10 hand pump and pump what transmission fluid out through the dipstick hole that you are able to. Then remove the fluid lines going from the transmission to the transmission cooler. Put paint dots on one of the fittings/lines so you know which is which later.
    Step 4. Remove the propeller shaft hub from the transmission hub. Be sure to put something over the prop so if you are able to reach the rudder when you separate the two you don't ding the prop.
    Attachment 22149
    Step 5. Now it's time to support the engine. I took the hook on the front of the left bank cylinder head and put it at the rear so I had two hooks equally spaced. I'll probably take a beating for my hoist but it worked just fine. I also put a couple pieces of wood under the engine as secondary supports. The transmission was supported in the same way, it's not that heavy and this is just an interim step while you loosen the bolts.
    hillbilly_hoist.jpg
    Step 6. Remove the flywheel shield bolts. These are a bit tricky (even to find). You need to be behind the drivers seat and looking towards the back of the boat at the flywheel , there are two bolts holding the shield on, on either side of the engine. I used a flex and some long extensions to loosen these. One of these locations is shown in the empty bolt hole next to the starter hole in picture #1.
    Step 7. Ok now with the engine and transmission supported it's time to remove the vertical motor mount bolts, you will also want to loosen the horizontal wedge bolts (which control the side to side position of the engine/transmission. Before loosening anything put paint dots on the vertical bolt threads right above the transmission crossbar and on the crossbar where the wedge bolt is, this is just to get you close when you put it back together, you will still need to do an alignment. After you mark the current postion, loosen the wedge bolts and remove the vertical mount bolts . For the vertical mount bolts you will need to loosen the locking nut above the cross bar and then get a 15/16 box end on the nut on the very bottom. You'll need to move the locking nut down as you loosen the mount bolt. I read some other posts for older boats where they removed the mount right off the transmission, there is not enough room on the 05's.
    zf_mount_bolts.jpg
    Step 8. Remove the flywheel housing bolts. You may want to leave one hand tight until you're ready to remove the transmission but the transmission is doweled as well so it's not going to just slide down, I had to rock it pretty good and slip a pry bar in to separate it from the engine. Once it's loose have a buddy help you lift it onto some 2x4 behind the engine.
    Flex_plate_trans.jpg
    Step 9. Remove old flex plate and install the new plate, torque to 35 ft lbs or whatever your clymer manual states for your boat.
    Flex_plate.jpg
    Step 10. Reinstall transmission. This is atleast a 2 man job but 3 is better, 2 to lift and maneuver the transmission back to the dowels and a third to rotate the transmission hub at the rear to get the splines on the transmission and drive plate to line up. I also cut some course 3/8 threaded rod to make some guide rods. Reinstall transmission housing bolts and torque to 30 Ft lbs.
    Step 11. Reinstall engine mount bolts and align according to the paint dots you put on in step 7. For the horizontal alignment you will need to get a big pry bar or spreader to move the engine/transmission, it takes a good bit of force.
    Step 12. Alignment #1.. You will need to recheck it in the water. Get a set of feeler gauges and pick a gauge, slide the hubs together with the gauge in between at either top or 90 degrees from then check it 180 degrees from your first position by seeing what gauge you are able to slide in. Try to get both the horizontal and vertical gaps within 0.003" of each other. The clymer manual covers this in pretty good detail, worth the $20 or $30. Tighten the hub bolts to 50 ft lbs. Be sure to check the alignment again in the water mine was quite a bit different then when I did it on the trailer.
    Step 13. The easy stuff, reinstall the shift linkage, cooler lines and transmission wiring. Leave the floor and seat out or loose until you check the alignment in the water. Add transmission fluid back to the full mark.

    Done. Go have fun.

    This is a solid day of work or maybe two, it is a pain in the... but I saved myself a lot of money and downtime.
    Last edited by BT_48170; 05-29-2015 at 10:27 AM.

  2. #2
    Join Date
    May 2009
    Location
    North End Lake Lanier GA
    Posts
    8,089

    Default

    Welcome to the Forum BT_48170

    Excellent 1st post lol. Great write up. I have not seen this issue before but this still something that can happen to older boats.
    Malo <--- Means--Evil or Mean One. This explains a lot.
    2013 Mojo 2.5 Skylon Tower. Bestia < Beast >

    https://vimeo.com/59208513?from=outro-local

  3. #3
    Join Date
    Jul 2008
    Location
    Des Moines, IA
    Posts
    3,237

    Default Flex/Damper Plate Replacement after engine ticking

    Great work! I made this a sticky for now so it will stay at the top of this forum.

  4. #4
    Join Date
    Jul 2015
    Location
    TEXAS
    Posts
    2

    Default

    Thank you very much for this write up. I think my Damper Plate may be broken as well. I would love any help in diagnosing and repairing my situation.

    05 Mobius XLV,
    Indmar Assault 5.7L,
    Hurth ZF 45 CW Transmission

    It has not been ran too much in the past couple of years. Starts up fine every time. When barely put into gear it runs rough, like the idle is too low and you can hear a clicking noise even with the hatch down. The noise disappears and the engine runs much smoother when you get it up to about 800 rpm. So I increased the idle with the idle adjustment screw next to the carburetor so that it idles at the higher 800 rpm.

    Since then the boat has run great, with no clicking or noise in the higher idle for the past couple of trips (15 hours). Yesterday evening on the way back to the boat ramp (2500 rpm) it somehow slipped into neutral and was no longer spinning the prop shaft. There was NO loud or unusual noises when this happened... Boat still running great, but could not get it into gear, forward or reverse. It simply acted as if it was STUCK IN NEUTRAL. The neutral button on the throttle was working properly. Jumped in, prop is there, and can spin as normal with my hand. Decided to check my throttle cables, both to carb, and to transmission, and both functioning properly. Checked prop shaft coupling bolts, and everything seemed fine. Fluids were all full. Transmission fluid is slightly brown compared to its normal pink. It was getting dark, and someone else heading to the boat ramp was nice enough to tow us back. While being towed the prop and shaft spun smoothly, so no issues there.

    If the damper plate is the issue could I completely lose the ability to put the boat in gear and turn the shaft?

    Is there anything else I should check before pulling transmission and motor and checking the damper plate?

    Thank you for any input!!

  5. #5
    Join Date
    May 2015
    Location
    Novi
    Posts
    55

    Default

    Yes if the damper plate completely failed it would decouple the transmission from the engine. I am kind of surprised you didn't hear something worse than you did though. I would say start with the starter, remove it and see if you find any broken springs in the starter cavity or the bottom of the bell housing. If you don't see anything you could try to snake a cheap bore scope in there and get a closer look.
    2011 Mobius LSV
    2005 Mobius LS (sold)

  6. #6
    Join Date
    Jul 2015
    Location
    Angola
    Posts
    13

    Default

    I just had to do mine in my 05 Mobius LS right before selling it. It took maybe 4 hours tops with a lot of maneuvering things around to take off as little connections as possible. Overall fairly easy if you're patient and work it through with a buddy.

  7. #7
    Join Date
    Jul 2015
    Location
    TEXAS
    Posts
    2

    Default

    Well ya'll I have an update. I did what you suggested BT and found this...

    image.jpg
    image.jpg

    Hopefully these pics upload correctly from my phone. My damper plate is definitely shot...
    Do you guys have a link or skidim part # for the correct Damper plate?
    While I am at it, is there anything else I should be replacing?

    Thank you guys for all of your help. You are making my life much easier, and my checkbook thanks you as well!!

  8. #8
    Join Date
    May 2015
    Location
    Novi
    Posts
    55

    Default

    Wow...looks like the 05 damper plates were not quite up to snuff. The aftermarket part looks to be quite a bit more robust, this is the correct one for your engine/transmission http://www.skidim.com/DAMPER-DRIVE-P...uctinfo/97596/ (item 1516). Shouldn't need anything besides the plate, new transmission fluid and some grease for the splined transmission shaft/new springs. Good luck, let me know how it goes.
    2011 Mobius LSV
    2005 Mobius LS (sold)

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