Fixing an Ultrex lower unit- my latest project

hi all,

At some point last year, I rammed a rock with the trolling motor which turned the nose cone 30 degrees or so. No biggie- got out of the water, turned it back, and no issues since. Fast forward to two weekends ago. I was trolling across the lake on a long troll (30 minutes or so electric only lake) and part way across it started to make noise. It was clearly happening as the shaft turned as the pitch would go up as the speed went up. It would still do all the normal speeds, just with more noise. I thought I had killed the bearing somehow, so I fished it slow all day and got it home safety. I pulled it apart this past week and first the through bolts were bent. One only a little, the other a LOT. Looking at the rest of it though, nothing seemed out of place. So I ordered a set of through bolts and today I installed them. This is the old bolt against a straight edge. The gap between the corkboard is almost a full bolt width and you can see the kink towards the threads.

Put it all back together and… still clicked. While I needed new bolts, that wasn’t the problem. So pull it all back apart, this time all the way to pulling out the armature and brushes. I had done this before on the autopilot so was familiar with all the bits. These were just much bigger.

Everything looked alright. I was at my wits end so I called minn kota service. I told him what it was doing, what I had checked, etc. He was at a loss as well. I was using a flashlight to light up the insides and telling him how clean it looked when I saw this. What you’re looking at is the main body of the lower unit with the nose and prop sides removed. The black cable is the transducer cable.

The silver piece is a guard for the cables. That thick black ‘liner’ is a magnet inside of which the armature spins. I asked him if the guard is supposed to be crimped at one end. The answer was a definitive no. Remember when i hit that rock last year? It turned the through bolt enough that it pinched the guard. In the full resolution picture you can see the threads from the bolt impressed in the aluminum guard. I pulled the entire guard out and used a combination of flat screwdrivers, pliers, and some round metal stock to get it back to a close enough shape. A quick reassembly (including greasing up the bearing and seals) and all works as normal now.