Shift Interrupt System. Can one be added?

[Jim Marshall]

My Volv0 270 vintage '74 was always shifted rough and tended to hang into forward or reverse gear when going to neutral.

I like the idea of a shift interrupt system. Can one be added on an older Volvo 270?

Jim

 

[Don S]

Re: Shift Interrupt System. Can one be added?

No, the shift interrupt is used to release a dog clutch in the lower unit. Volvo's don't have dog clutches.
Maybe you should consider fixing yor problem instead of reengineering it. What you probably have is a worn or out of adjustment shift mechanism on the back of the upper gear box. Or even a faulty cable from the control to the drive could cause your problem.

 

[Jim Marshall]

Re: Shift Interrupt System. Can one be added?

I pulled everything apart in the Volvo and it looks like it is in great condition. Bearings are nice, gear wear is slight with a nice pattern. The clutch system looks like new. I replaced all seals and o-rings and put it back together.

I replaced the control cable. It needed it. I made the adjustments according to the manual. I have yet to put it in the water but since everything looked like it was in good shape and since I have had it since new I have no reason to believe it will not be the hard shifting situation all over again.

The engine always idled down nicely from the start so I don't feel that is a problem. Volvo was supposed to have that cone clutch feature that was supposed to be smooth shifting.

Jim

 

[Sparkinator]

Re: Shift Interrupt System. Can one be added?

Hopefully the new shift cable will fix it. When I installed a new one on mine (SX) it fixed my shifting problems.

 

[Don S]

Re: Shift Interrupt System. Can one be added?

The shift mechanism has 2 ramps (yellow arrows) that the pin (red arrow) rides on to shift it out of gear, those 2 ramps can become worn and won't be steep enough to pull the drive out of gear easily. The pin can also be pushed up and can cause the brass spool to have a high spot on it. (Green arrow). If it's not flat, then that is part of your problem.

All of the above can throw the adjustment out. If all is ok, it may just be out of adjustment, and with the upper gear box off, you can check it like this.

 

[Jim Marshall]

Re: Shift Interrupt System. Can one be added?

Don,

Thanks for the pix. I had to pull the retaining pin and the pin out to replace the seal and everything looked fine and seemed to function well. Like I was saying, everything looked almost new with little detectable wear and that included the shift mechanism.

I changed the oil yearly and never found any indication of metal particles or anything in it. It always came out looking like new.

I will get the boat running, put it in the water and try it to see if maybe it was the cable. Since it has been that way since it was new, I wonder why?

Jim

 

[Don S]

Re: Shift Interrupt System. Can one be added?

Since it has been that way since it was new, I wonder why?

It may be that the shift mechanism adjustment was never done properly from the factory. Wouldn't be the first thing that was bad from the beginning.

 

[Jim Marshall]

Re: Shift Interrupt System. Can one be added?

Don,

That could be, too. I adjusted the lockouts as well. The Volvo is a bullet-proof drive. The shifting is my only complaint.

Jim

 

[Don S]

Re: Shift Interrupt System. Can one be added?

I had a 280 that I converted to a DP, it has the same shift setup, and even with dual controls on it, it went into and outof gear with no effort at all.

 

[Jim Marshall]

Re: Shift Interrupt System. Can one be added?

It has been a mystery.

Jim