Shift Interrupt Switch Help
05-10-2026 | 09:17 PM
#12
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Joined: Nov 2008
Posts: 49
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From: Lake Isabella, Michigan
Hi Jt, if you're doing a bellows job install a new shift cable (8m0176523) and cable bellows (74639a2) while you're at it. The cable in pic looks fairly aged. A new cable will help the butteryness. Todd
05-10-2026 | 10:22 PM
#13
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Joined: Oct 2000
Posts: 20,285
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From: Omaha/LOTO
Hard shifting could also be due a bad detent/ball or the shift assembly inside the drive. As long as its shifted below 1000 rpms, the drive should live, but the lower the better. I've had a few boats that idled around 850rpms in neutral and the drives were fine.
05-13-2026 | 10:59 AM
#14
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Joined: Jun 2021
Posts: 3,554
Likes: 2,153
From: SW Ohio
Took my 26’ Firehawk cat out yesterday for the first time. I posted another thread about my steering issue. On top of my steering issue, I’ll be replacing bellows within the next week or so and my drive shifts hard. It’s a blower motor with a big cam so I tried to time my shifting when the RPMs dropped the best I could. Short run to see what issues I needed to address.
So I need help with understanding the shift interrupt switch.
Should I have a switch where the shift cable engages the short drive cable in the bilge(because I do not)? Or can this switch be tied into the shifter (gaffing) at the helm?
At the helm, I looked at the wiring and was able to figure out which wires were for the trim. 3 wires remain, blue, red, and black. Are all 3 of these for the neutral safety? The neutral safety does work.
Anyways, is this as simple as buying a switch and putting it here?
It has a digital 6AL MSD ignition. Not the marine version so it does not have a timing retard wire. So will wiring this switch inline with the coil ground wire be okay? Thanks for the help.
So I need help with understanding the shift interrupt switch.
Should I have a switch where the shift cable engages the short drive cable in the bilge(because I do not)? Or can this switch be tied into the shifter (gaffing) at the helm?
At the helm, I looked at the wiring and was able to figure out which wires were for the trim. 3 wires remain, blue, red, and black. Are all 3 of these for the neutral safety? The neutral safety does work.
Anyways, is this as simple as buying a switch and putting it here?
It has a digital 6AL MSD ignition. Not the marine version so it does not have a timing retard wire. So will wiring this switch inline with the coil ground wire be okay? Thanks for the help.
During my rebuild last winter, while the drive was off, I noticed a weird "jam plate" that was installed on the trim ram pivot pin under my transom assembly (It has "Do Not Remove" laser engraved on it. Anybody familiar?). I guess it's supposed to work as a physical stop for "down" trim. But mine has gotten bent over the years to the point it could pivot out of place far enough that the drive hit the edges of the sheet metal instead of the face that it was supposed to make contact with. As a result, it kinda chewed up that spot on my drive a little. I removed it, straightened it out, and had my welder buddy add some build-up material to it to both reinforce it and add back in what had been lost from my drive. It now rides how it's supposed to, but I think the drive still doesn't make contact with it in the full "down" position like it's supposed to, because, new since the rebuild, it have a noticeable "clunk" when I shift into forward, and it feels like it's the drive taking up that little bit of gap when the load hits. I've also noticed that, if I trim up just the slightest little bit, the clunk goes away. Check and see if you have this plate. Even if you don't, make sure your drive is fully engaged with whatever stop may be there. You also might try trimming up just a bit and see if the shifting quiets down a bit.
Also.... Shameless plug
.... While you're redoing your bellows, why don't you replace your Drive Oil Bulkhead Fitting, and leave that maintenance issue behind you?Thanks. Brad.
05-13-2026 | 06:14 PM
#15
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Joined: Sep 2013
Posts: 696
Likes: 111
From: KY
JBooten,
During my rebuild last winter, while the drive was off, I noticed a weird "jam plate" that was installed on the trim ram pivot pin under my transom assembly (It has "Do Not Remove" laser engraved on it. Anybody familiar?). I guess it's supposed to work as a physical stop for "down" trim. But mine has gotten bent over the years to the point it could pivot out of place far enough that the drive hit the edges of the sheet metal instead of the face that it was supposed to make contact with. As a result, it kinda chewed up that spot on my drive a little. I removed it, straightened it out, and had my welder buddy add some build-up material to it to both reinforce it and add back in what had been lost from my drive. It now rides how it's supposed to, but I think the drive still doesn't make contact with it in the full "down" position like it's supposed to, because, new since the rebuild, it have a noticeable "clunk" when I shift into forward, and it feels like it's the drive taking up that little bit of gap when the load hits. I've also noticed that, if I trim up just the slightest little bit, the clunk goes away. Check and see if you have this plate. Even if you don't, make sure your drive is fully engaged with whatever stop may be there. You also might try trimming up just a bit and see if the shifting quiets down a bit.
Also.... Shameless plug.... While you're redoing your bellows, why don't you replace your Drive Oil Bulkhead Fitting, and leave that maintenance issue behind you?
Thanks. Brad.
During my rebuild last winter, while the drive was off, I noticed a weird "jam plate" that was installed on the trim ram pivot pin under my transom assembly (It has "Do Not Remove" laser engraved on it. Anybody familiar?). I guess it's supposed to work as a physical stop for "down" trim. But mine has gotten bent over the years to the point it could pivot out of place far enough that the drive hit the edges of the sheet metal instead of the face that it was supposed to make contact with. As a result, it kinda chewed up that spot on my drive a little. I removed it, straightened it out, and had my welder buddy add some build-up material to it to both reinforce it and add back in what had been lost from my drive. It now rides how it's supposed to, but I think the drive still doesn't make contact with it in the full "down" position like it's supposed to, because, new since the rebuild, it have a noticeable "clunk" when I shift into forward, and it feels like it's the drive taking up that little bit of gap when the load hits. I've also noticed that, if I trim up just the slightest little bit, the clunk goes away. Check and see if you have this plate. Even if you don't, make sure your drive is fully engaged with whatever stop may be there. You also might try trimming up just a bit and see if the shifting quiets down a bit.
Also.... Shameless plug
.... While you're redoing your bellows, why don't you replace your Drive Oil Bulkhead Fitting, and leave that maintenance issue behind you?Thanks. Brad.
I appreciate the fitting info but I’m changing bellows Saturday so I can have it ready for the holiday.
05-13-2026 | 06:59 PM
#16
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Joined: Jun 2021
Posts: 3,554
Likes: 2,153
From: SW Ohio
So maybe I misunderstood…. Is it physically difficult to move the lever or is it hammering going into gear?
Thanks. Brad.
