35hp Bigtwin; con you swap gears?

ryendube · Jul 7, 2009

K so mtor started to slip out of forward gear after a weekend of stupid shifting due to a saturated float. (wouldnt idle was shifting at high rpm)

so tore LU apart and found what I expected, chipped clutch dog and gears a lil rounded, so just flipping the clutch around doesnt seem like a feasable option. Now after looking closely at gears they look identical except for differnt bushings.

question, if i press out the bushings can i just swap the gears around? use rev for fwd, fwd for rev?

Joe Reeves · Jul 7, 2009

Re: 35hp Bigtwin; con you swap gears?

Yes, swap the gears. Press out the forward bushing and install it into the reverse gear thustly converting the gears, BUT do install a new clutch dog.

ryendube · Jul 7, 2009

Re: 35hp Bigtwin; con you swap gears?

thanks man. now i just need to source out a clutch....

Joe Reeves · Jul 7, 2009

Re: 35hp Bigtwin; con you swap gears?

What year is that 35hp Evinrude? Model Number? I'll check my remaining stock.

ryendube · Jul 8, 2009

Re: 35hp Bigtwin; con you swap gears?

Joe Reeves said:
What year is that 35hp Evinrude? Model Number? I'll check my remaining stock.

has patent year of 56 and serial number of 25930 50775

Joe Reeves · Jul 8, 2009

Re: 35hp Bigtwin; con you swap gears?

Model number 25930 is a 1957 35hp Evinrude. Sorry, don't have a book on that one where I can look up part numbers.

F_R · Jul 8, 2009

Re: 35hp Bigtwin; con you swap gears?

Joe Reeves said:
Model number 25930 is a 1957 35hp Evinrude. Sorry, don't have a book on that one where I can look up part numbers.

375783 clutch dog
25hp, 1951-55
30hp, 1956
35hp, 1957

1958-up is different

ryendube · Jul 8, 2009

Re: 35hp Bigtwin; con you swap gears?

F_R said:
375783 clutch dog
25hp, 1951-55
30hp, 1956
35hp, 1957

1958-up is different

thanks for this.

every dealer around here said its not avaliable until I gave them the above part number.

coolguy147 · Jul 8, 2009

Re: 35hp Bigtwin; con you swap gears?

ryendube said:
K so mtor started to slip out of forward gear after a weekend of stupid shifting due to a saturated float. (wouldnt idle was shifting at high rpm)

so tore LU apart and found what I expected, chipped clutch dog and gears a lil rounded, so just flipping the clutch around doesnt seem like a feasable option. Now after looking closely at gears they look identical except for differnt bushings.

question, if i press out the bushings can i just swap the gears around? use rev for fwd, fwd for rev?

make sure u shift brisk and at idle. plus u could have always started in gear ?

ryendube · Jul 13, 2009

Re: 35hp Bigtwin; con you swap gears?

swapped bushings out, the front gear bushing needed to be pressed out and the rev just fell out, now its reversed. went to put it all back together and the whole assembly isnt lining up. Anyone have a exploded view of the lower unit I could take a gander at?

ryendube · Jul 13, 2009

Re: 35hp Bigtwin; con you swap gears?

k think I figured it out i guess it just didnt spin as freely/clean as I expected it to. back of gear rubs against spacer. Looks like it always did though judging by the wear marks. One thing id love is some instruction on adjusting the shift. ie over comp a lil in forward to ensure full engangment.

Willyclay · Jul 13, 2009

Re: 35hp Bigtwin; con you swap gears?

I have a service manual that covers your motor. It contains an exploded view of the gearcase. Send me a Private Message with your email address and I will reply to you with a scanned copy as an attachment. Good luck!

jay_merrill · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

If you ever have to do this again, don't forget that you can have the gears cut.

gbeardmore · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

jay_merrill said:
If you ever have to do this again, don't forget that you can have the gears cut.

Jay,
Above you mention having the gears cut. I'll be tackling this project soon on a "fix-er-upper". Can you elaborate on what "cutting" involves? THANKS!

ryendube · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

gbeardmore said:
Jay,
Above you mention having the gears cut. I'll be tackling this project soon on a "fix-er-upper". Can you elaborate on what "cutting" involves? THANKS!

would assume he means getting them machined.

would you just flatten the groove like newer style set up or redo the same contour?

jay_merrill · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

When a clutch dog goes bad, it usually causes some amount of wear on the matiing surface on the "non-geared" face of the forward or reverse gear. The tabs on the clutch dog have a tendancy to wear more easily, so sometimes all you have to do is to replace the dog. Sometimes, however, the wear on the gear is too severe and replacing a dog without fixing the gear, will just result in premature wear of the new dog, as well as further damage to the mating surface on the gear.

One way to deal with this, is to "cut" that mating surface, It is done by removing the gear and placing it in a drill press. An offset pass down into the mating surface is made in such a way that only half of the drillbit is cutting into the material. This removes the rounded off edge and creates a fresh surface for the new clutch dog to mate with.

I've never tried to do this myself and I don't recommend that anyone else try to either. I had the procedure expalined to me, but its important to have the proper drill press. Obviously, trying to drill "half a hole" will make it very easy to end up with a drill bit that wants to wander. For this reason, having a professional machine shop do the work is usually best. Most outboard motor dealers with repair facilities, will know of someone who can do the work.

MushCreek · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

I don't think that would work on a drill press. A milling machine (and milling cutter) maybe. It depends on how hard the material is. But a drill bit trying to drill 'half a hole' will just walk off, regardless of the machine it's in. I'm thinking about trying this with my '83 Johnson; it jumps out of gear in forward. I'd like to try re-machining the clutch dog and gear to see if I can get another life out of them. I'm a tool maker by trade, and have an entire shop at my disposal, though. If I do it, I'll report back, with pics.

jay_merrill · Jul 14, 2009

Re: 35hp Bigtwin; con you swap gears?

MushCreek said:
I don't think that would work on a drill press. A milling machine (and milling cutter) maybe. It depends on how hard the material is. But a drill bit trying to drill 'half a hole' will just walk off, regardless of the machine it's in. I'm thinking about trying this with my '83 Johnson; it jumps out of gear in forward. I'd like to try re-machining the clutch dog and gear to see if I can get another life out of them. I'm a tool maker by trade, and have an entire shop at my disposal, though. If I do it, I'll report back, with pics.

You may well be right. I've sent several sets of gears off to be cut, through my local BRP/OMC dealer. What you are saying makes sense, and is exactly why I would never try to do the job myself.

If the job is done on a drill press, I would think that you would have to block the gear up to a very high position and use a very short bit. You would also have to be able to lock the gear into position with no ability to move at all. Otherwise, as you say, the bit would wander as soon as it began to cut.

wbeaton · Jul 15, 2009

Re: 35hp Bigtwin; con you swap gears?

jay_merrill said:
You may well be right. I've sent several sets of gears off to be cut, through my local BRP/OMC dealer. What you are saying makes sense, and is exactly why I would never try to do the job myself.

If the job is done on a drill press, I would think that you would have to block the gear up to a very high position and use a very short bit. You would also have to be able to lock the gear into position with no ability to move at all. Otherwise, as you say, the bit would wander as soon as it began to cut.

I've tried it with a drill press, but you need a de-burring tool as a drill bit won't work even if you only have a small amount sticking out of the chuck. A milling machine would be better suited to this.

samo_ott · Jul 15, 2009

Re: 35hp Bigtwin; con you swap gears?

MushCreek said:
I don't think that would work on a drill press. A milling machine (and milling cutter) maybe. It depends on how hard the material is. But a drill bit trying to drill 'half a hole' will just walk off, regardless of the machine it's in. I'm thinking about trying this with my '83 Johnson; it jumps out of gear in forward. I'd like to try re-machining the clutch dog and gear to see if I can get another life out of them. I'm a tool maker by trade, and have an entire shop at my disposal, though. If I do it, I'll report back, with pics.

I'd like to see/hear about this update when you've done it.... Post pics when you do it...

35hp Bigtwin; con you swap gears?

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