Transmission Woes!

Well it’s been a long few days work with the transmission and even longer since we have updated the blog due to lack of internet! For those that don’t want the details – it’s fixed, no need to read further…….if you are curious and don’t mind technical stuff, here is the info:

The mechanic that I had talked to last weekend was not going to do the work for 2 reasons, one – he could not fit down the lazerette to work on it, not that he was that large, but it is a tight fit and two, he said it was not that hard and I had recently replaced the coupler, shaft and stuffing box, so how much harder could it be?

My 35 year old transmission was a Hurth HBW10 (Hurth is out of business and ZF makes replacements). The HBW10 seems to have been replaced with the HBW100 before going out of business. The mechanic got on the phone on Monday first thing to ZF to call for the replacement unit model – they said the ZF10 which sounded reasonable enough. I had asked him about upgrading to the ZF12 or ZF15 as they seemed to be more robust units. He checked with ZF who said the ZF12 and ZF15 were ½” higher and ½” longer. The longer size I thought I could fit in (might have to get a diver to pull the shaft back a bit to get the coupler on) but the ½” more vertical from the coupling would mean that I would have to raise the engine mounts by ½” and didn’t feel I would have enough thread left, so he ordered me the ZF10. I had also decided to add a transmission cooler (bolts on the transmission and raw water goes thru it to keep the transmission cooler) as it could not hurt and we will be doing lots of motoring on the ICW). As it turns out the mechanic had a new Volvo one that he thought would fit and would give me a good deal on – sold! Hope it fits….

I took the old transmission out which was quite simple. The new ZF10 arrived on Tuesday noon and the mechanic brought it to me with a bottle of ATF. The adapter plate (which goes between the transmission and engine) did not quite fit on but was very close so I took out the dremel tool and we trimmed a 1/16” of an inch or so off of some tabs on the plate, which fixed it. When I went to put the transmission in I noticed it was 1/2” shorter and 1/2” less vertical height from the coupler! Eek. We figured it was just changes after 35 years so I needed to drop the engine mount adjustments by 1/2” or so. The problem was that one of my engine mounts had 2 nuts on the bottom of the thread, which meant I would not be able to lower it enough unless I took off this second nut. I borrowed a jack to support one corner and proceeded to raise the engine enough by adjusting all the mounts so that I could take this one mount off and then the extra nut – whew that took a few hours! After that I did the best alignment I could and proceeded to put it all together, the 1/2'” less length was not issue as I had enough room around the zincs and prop. The cooler I did not hook up yet but decided to leave it for now. When it was hooked up the reverse and forward was opposite of the old one, I could have reversed the lever on the transmission but it was tending to bind a bit so I decided to just leave it reversed. It seemed that the transmission would stick when going from reverse to neutral; it had nothing to do with the cable as I was switching it at the transmission with the cable off. I did not do this when the engine was not running. The feathering prop we have has tons of torque in reverse even at idle, maybe it was overwhelming the new transmission? The mechanic was stumped and would call ZF in the morning. We did a quick sea trail with it also but the sticking was evident.

In the morning the mechanic talked to ZF – they said the proper replacement was supposed to be the ZF12 and not the ZF10 as he was told the first time!!!  He was not amused nor was I!!! ZF agreed to ship a new ZF12 out with no charge for the bigger unit or for the shipping. Back out the ZF10 came. Also the engine had to be raised back up the ½” again.  During that day I spent 3 trips to Hamilton marine (really close) to get all the hoses, barbs etc for the cooler. My biggest concern was that I was running out of room to put the coupler back in without pushing the shaft further out of the boat. There happened to be a diver around, he went down and looped a rope over the end of the prop and we brought it to the side of the boat so that hopefully the prop would not fall out of the boat!

The second new transmission arrived on Thursday noon, the adapter plate fit on great and with the coupler out of the way it bolted on fine. I had to push the shaft further out of the boat however to put the coupling on. This should not have been an issue as this transmission was the same fit as my old one – but they changed the design of the “fingers” that attached to the coupling – it was now a solid flange and this meant that I lost on inch or so to play with! I finally got the coupler on but try as I might I could not get the shaft back further into the boat. I grabbed my “spare air” (small emergency scuba tank) and mask and went down to investigate. Man that water is cold without a wetsuit! I did 3 dives all together, not fun. As it was the shaft need to go forward an inch or so, try as I might it would not go in (yes the stuffing box was loosened). I was finally able to coax it ahead about 3/16” of an inch at a time buy putting the coupling together, then loosen everything again, tighten up and repeat, it took a few hours to do this but I got it to within 1/8” of an inch or so of the original. Finally I hooked up the cooler, checked for leaks and tried the transmission. Hey – the reverse and forward were back to the old way and there was no binding! A sea trial followed and all worked fine. It was a long few days stuck in the lazerette, Heather was my “gopher” and understands many different types of tools a lot more now! Speaking of which, am I ever glad I brought a lot of tools, even my 16” channel lock pliers got used. Attached is the new transmission with oil cooler.