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HOW TO: Aligning the powertrain

CrankyGypsy

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(referencing 2005 AR230HO)

had some repairs and mods that required me to pull the engines, the grates, and the pumps. i'm suspicious the engines have been pulled before, so i decided i had better take the time to ensure a proper alignment. i had my engines out and didn't install them until after i had the rest of the system aligned, and i wrote this with that in mind.

there are three possible shim points along the powertrain. they are: the flat pump plate that the impeller housing bolts to; the bearing housing (with the coupler shaft); the four feet of the engines. there is also a "stopper" under the case near the magneto that could require shimming as well. you may also find shims between the case and the feet (one bolt per), but i opted to not unbolt the feet from the cases. i would highly advise against ever messing with these as the bottom-most bolts (two bolts per foot) will maintain alignment much better and allow you to slide the engine easily. there are three types of shims: small, very thin horseshoe-shaped shims for the pump plate and bearing housing; large plate shims about 3/32" thick for under the feet; medium, nearly-square ~3/32" plates for under the stopper. i suppose stainless steel fender washers would be a good alternative to the horseshoe shims in a pinch.

not knowing what to expect going in, i ordered four spare horseshoe shims but only one each of the foot and stopper plates. i instead ordered some aluminum plate in 3/32" and 3/16" so i could cut some of my own if i needed to ...and i ended up cutting a bunch.

THE PUMP PLATE:
i would advise not attempting to align the pump plate or the bearing housing with the rubber hose still attached to the back of the bearing housing that allows the impeller shaft to pass through the hull - it can throw off alignment if it isn't on there perfectly. once you figure out the shims on the bearing housing, re-attach the hose and then do the final bolt-down before moving on to the engine.
the coupler shaft needs to be inline with the impeller shaft with no deflection, so we'll use the bearing housing as our gauge to get the pump plate square. install and torque the pump plate (i torqued these to 18ft-lbs), the impeller housing, and impeller shaft assembly. you're going to need a helper reaching inside to hold a box wrench onto the nuts so you can tighten the bolts from the outside (especially when you seal this and the silicone has a 5-10min working time). slide the bearing housing with the coupler shaft onto the impeller shaft. fully engage the bearing housing into the splines of the impeller shaft, press it against the engine wall and let go. if the bolt holes in the bearing housing line up with the holes on the engine wall, the pump plate is correct and you can move on to aligning the bearing housing. if you have to adjust/push the bearing housing with one hand so you can get the bolts to pass with the other hand, the pump plate needs to be shimmed. unbolt, shim, re-torque and check again. having the engines out so you can look directly at the holes will make knowing which corner(s) of the pump plate will need shims easier. use the horseshoe-shaped shims placed between the plate and the gelcoat. do not add silicone yet - sealing this is the last step.


THE BEARING HOUSING:
if the bolts pass easily (nuts are not added yet) through the engine wall AND all three corners are flush to the wall without you touching the assembly, the bearing housing is aligned with the pump plate. if there are gaps at one or two corners, they will need to be shimmed with the horseshoe-shaped shims. press on the corner making contact and start sliding in shim(s) to fill the gaps. if you've got it lined up, pull it and add the rubber hose that joins it to the hull fitting then bolt the housing in - i think i torqued these to 10ft-lbs. don't forget to re-attach the hose that covers the pump shaft within the bilge before final torque.


THE ENGINE:
this is easily the most time-consuming/tedious part of the project. i ended up spending a lot of time getting one engine aligned, moved onto the next one only to realize the first one could've been better ...so i did one of them twice to make them both perfect. you're going to need some way to relieve the weight on the feet so you can get the bolts in and out easily (they need to be removed a few times). you can do this by using an engine leveler on a pulley above the boat, connected to a winch like i did. or you can simply attach ropes/chains to the engine hangers and have a partner pull on them to alleviate the tension on the bolts. i made it even easier on myself by running the bolts through a die and re-tapping the holes prior to install. i also had the engine hatch off, which made taking measurements at the coupler easy.

aligning the engine comes down to aligning the engine-side coupler to the impeller-side coupler. you will need to leave the rubber coupler damper out for now. if you leave the damper in, it will bind and give you incorrect measurements, plus add stress to the bearing housing mount points.

my starting point was with the old shims back where they were before i had pulled the engine. then i threaded the eight bolts about halfway on all four feet. again, relieving the weight will make it easier to get them in/out and you'll avoid cross-threading, which will cause a nightmare i would not want to experience. the bolts have to be in (they don't need to be tight) to take the measurements, otherwise the weight will cause the feet to splay out and alignment will be off when you do your final bolt-in. you're going to be adding/removing shims and rechecking the tolerance at the coupler repeatedly.

i used one of the stopper shims as my straight edge to check the coupler alignment. basically, place a straight edge on one coupler half and use a feeler gauge to measure the gap from that edge to the other coupler half. it should be no more than 0.50mm. i measured the gaps at about 12, 3, and 9 o'clock around the coupler each time. if any one is greater than 0.50mm, shims need to be added (or removed) somewhere. i'd say you really want to aim for under 0.35mm to get it perfect.

finding the right combination of shims can quickly become frustrating. after a while, i started making it a little easier on myself by using the smaller stopper shims i had. i would relieve tension with the bolts still halfway threaded and slide the stopper shim(s) in, which would give me a fairly accurate reading. once i found what worked, i would then swap in the proper foot shim and double-check the tolerance - saved my fingers some pain.

the truly frustrating aspect (aside from hurting your self as you lean your skeleton over sharp corners to see the measurements) comes with trying to figure out in your head which foot needs shimmed to accomplish a specific direction at the coupler. what worked for me was to shim the aft feet to raise/lower the coupler and use the bow feet to get it to move left/right. this got me in the ballpark quickly, then i could fine tune it by adding a shim here or there until it finally got within tolerance. i think a lot of it was dumb luck and patience. the gap between the two coupler halves is 2-4mm. i used two of the stopper shims as a feeler gauge for this: if they didn't fit, i was good to go.

once the coupler is aligned with the correct combination of shims, you'll have to remove all the bolts and slide the engine towards the bow so you can slide the damper in. once in, slide the engine back into place and thread the bolts back in about halfway. re-check your measurement one last time. and here is when you know you've gotten it perfect: the damper inside the coupler very easily moves around inside the two halves. you can't get any better than zero binding! when i got this on the second engine, i just had to go back and redo the first. wait to tighten the bolts until the stopper is shimmed.

THE STOPPER:
the stopper doesn't actually make contact. it seems to be there to allow the engine to bounce, but not bounce too far. andyak had his engine out so i asked him take a measurement for me since there is no spec in the manual. his stopper had a gap of 0.35" ...so somewhere around 8-9mm between the stopper rubber and the bottom of the case seemed right. to find the measurement, i placed the stopper where it needed to be and inserted a stack of shims into the gap. i measured the thickness of the stack and removed shims until i got 8-9mm total thickness. however many shims i removed gave me the number i needed to add under the stopper (if any). and yes, you need to have additional joints in your forearm to get these bolts in - they are tough! add some loctite. i used a short 10mm box wrench to make quarter turns to eventually get them down. if you can't bend your arm around a corner, you might have to lift the engine up.

FINALLY:
if everything is lined up, do a final bolt-in on the feet. do one foot at a time by removing the bolts, adding some loctite, and snugging them down good. i didn't find a torque spec anywhere, but i would guess it's got to be around 18-25ft-lbs. these bolts have lock washers on them, so it shouldn't need to be that crucial to get an accurate/high torque. now go back and remove the pump and the pump plate. add gobs of silicone and re-bolt to specs.
 
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Julian

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tdonoughue

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Thank you! Nice write up.
 
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