Replacement Onan Governor Ball Spacer

[TC10284 111]

So, I searched high and low to find someone that could mill out a replacement Onan governor ball spacer. I got lucky enough to find one locally that would do it. He has made me a few of these things.  He said he is happy to make more for you guys if interested. Can provide cost details if anyone is interested. 

I haven't posted a classified yet, because I wasn't sure of the interest. So I'm asking here first. 

 

My contact has professionally milled out a governor ball spacer for the Onan P220g/P218g/P216g based off an original. The only difference is that it has an extended tab like the plastic ones to make certain it doesn't ever slip on the cam shaft. It's made out of aircraft grade aluminum. I've tested one in my P220g and it has been working great. 

 

 

Thoughts or interest? 

 

 

 

 

[seuadr 488]

nice!

 

i would think it relatively rare that someone needs one, but when they do need it, they need it bad - and i imagine that this would be the last one that particular motor would ever need!

[TC10284 111]

43 minutes ago, seuadr said:

nice!

 

i would think it relatively rare that someone needs one, but when they do need it, they need it bad - and i imagine that this would be the last one that particular motor would ever need!

 

I've ran into it a lot on many of the 520's I've got. And so I sought out someone who could and would machine them. So yep, I'm hoping this is the end-all for those with the issue! 

 

[seuadr 488]

Got an idea of cost per? 

[TC10284 111]

1 minute ago, seuadr said:

Got an idea of cost per? 

 

Yes. $100 per spacer (same price I've paid). He says if he got a lot more to make, he could use the CNC which would reduce cost.

[lynnmor 7,361]

There is a demand, @onanparts.com is working on supplying them and another member has made one and possibly will make more.  The one concern for me is that aluminum will expand faster than the steel it is pressed on, so it better have a tight fit.  Do the math on coefficient of expansion and get it right.

[TC10284 111]

2 minutes ago, lynnmor said:

There is a demand, @onanparts.com is working on supplying them and another member has made one and possibly will make more.  The one concern for me is that aluminum will expand faster than the steel it is pressed on, so it better have a tight fit.  Do the math on coefficient of expansion and get it right.

 

Right! It's a tight fit already, and I had him add the extended tab to help prevent any slipping in case that does happen. And I also used red threadlocker on the one I've tested, just as an extra measure. 

[lynnmor 7,361]

13 minutes ago, TC10284 said:

 

Right! It's a tight fit already, and I had him add the extended tab to help prevent any slipping in case that does happen. And I also used red threadlocker on the one I've tested, just as an extra measure. 

 

Keep in mind that the tab only drives the spacer if need be and does nothing to keep it located laterally.   I made a tool to drive the spacer on to the correct location while keeping it straight.  I did look at manufacturing the spacers as I have a shop with CNC, but decided against it for now.

[Bill D 1,992]

1 hour ago, lynnmor said:

 

Keep in mind that the tab only drives the spacer if need be and does nothing to keep it located laterally.   I made a tool to drive the spacer on to the correct location while keeping it straight.  I did look at manufacturing the spacers as I have a shop with CNC, but decided against it for now.

Do you have any pictures of the installation tool you made?

[Bill D 1,992]

12 hours ago, TC10284 said:

So, I searched high and low to find someone that could mill out a replacement Onan governor ball spacer. I got lucky enough to find one locally that would do it. He has made me a few of these things.  He said he is happy to make more for you guys if interested. Can provide cost details if anyone is interested. 

I haven't posted a classified yet, because I wasn't sure of the interest. So I'm asking here first. 

 

My contact has professionally milled out a governor ball spacer for the Onan P220g/P218g/P216g based off an original. The only difference is that it has an extended tab like the plastic ones to make certain it doesn't ever slip on the cam shaft. It's made out of aircraft grade aluminum. I've tested one in my P220g and it has been working great. 

 

 

Thoughts or interest? 

 

 

 

 

If they can be made on a CNC machine in mass quantity, could they be made out of steel instead?  How much would the cost go up?  Also, why are there drilled and tapped holes in each finger of the spacer, they were not there in the originals?    Bill

Edited April 2, 2021 by Bill D

[lynnmor 7,361]

15 minutes ago, Bill D said:

If they can be made on a CNC machine in mass quantity, could they be made out of steel instead?  How much would the cost go up?  Also, why are there drilled and tapped holes in each finger of the spacer, they were not there in the originals?    Bill

 

He obviously cut blanks then drilled and tapped the holes so he could hold them on a lathe fixture and then the milling machine fixture.   This part would be hard to hold without the tapped holes.   Steel would add machining time and cut the material cost a nominal amount.  Which material would perform the best is anybodies guess, the aluminum would protect the balls but might wear more, but then plastic worked OK.

[TC10284 111]

3 minutes ago, lynnmor said:

 

He obviously cut blanks then drilled and tapped the holes so he could hold them on a lathe fixture and then the milling machine fixture.   This part would be hard to hold without the tapped holes.   Steel would add machining time and cut the material cost a nominal amount.  Which material would perform the best is anybodies guess, the aluminum would protect the balls but might wear more, but then plastic worked OK.

 

Bingo, sir. 

[lynnmor 7,361]

50 minutes ago, Bill D said:

Do you have any pictures of the installation tool you made?

 

Here is a photo, the outboard end is drilled and tapped in case the thing gets stuck.  The center hole needed extra clearance because the Onan parts are not very concentric.  The hammer end is deliberately made small to keep it driving straight.

 

[Handy Don 12,578]

55 minutes ago, lynnmor said:

 

Here is a photo, the outboard end is drilled and tapped in case the thing gets stuck.  The center hole needed extra clearance because the Onan parts are not very concentric.  The hammer end is deliberately made small to keep it driving straight.

 

Nice having a machine shop at your back when you need a special tool! Makes me wonder how you label and keep track of these gadgets!

[Handy Don 12,578]

Questions back to @lynnmor and @onanparts.com and any other Onan gurus:

What causes these to fail?

How practical is it to "stock" a spare?

Other Onan parts, though pricey, seem pretty available--but these aren't.

My engine is only about 410 hours, but I expect to take normal care of it and run it for years and years. Or is it more likely to fail in some other way than this?

[TC10284 111]

14 minutes ago, Handy Don said:

Questions back to @lynnmor and @onanparts.com and any other Onan gurus:

What causes these to fail?

How practical is it to "stock" a spare?

Other Onan parts, though pricey, seem pretty available--but these aren't.

My engine is only about 410 hours, but I expect to take normal care of it and run it for years and years. Or is it more likely to fail in some other way than this?

 

If I recall, the "glue" on the plastic ones eventually breaks down and comes loose. And after, when the engine heats up about 15-20min of use, the plastic spacer will start spinning freely on the cam shaft. Thus the governor losing control. RPM starts spiking slowly and continues. Eventually, you can hit a solid 4000+ RPM at WOT (WAY too high). Then that can obviously lead to catastrophic failure of other engine parts.

Someone correct me if I'm off on that.   

 

As mentioned, I've ran into this problem on the majority of the 520s I bought. A few I haven't. When I get one, I automatically look to see if it's one of the plastic ones without tabs when I have it down for adjusting valves. And I've got ahold of one with plastic version with extended tab that was broken. I have tried gluing the plastic ones with JB Weld and it lasted a few runs, but eventually broke loose again. And finding a metal replacement can be difficult. So the tractor sits while I'm hunting a metal one. So it's a useless engine during that time. And so that lead me to search out different machine shops that could do it. Finally found the really nice guy I've been working with on this. 

Edited April 2, 2021 by TC10284

[Bill D 1,992]

2 hours ago, lynnmor said:

 

He obviously cut blanks then drilled and tapped the holes so he could hold them on a lathe fixture and then the milling machine fixture.   This part would be hard to hold without the tapped holes.   Steel would add machining time and cut the material cost a nominal amount.  Which material would perform the best is anybodies guess, the aluminum would protect the balls but might wear more, but then plastic worked OK.

Thanks for the info.  I'm not a machinist.  Any idea how the original metal ones were held for machining?  Just curious.  Bill

 

[bc.gold 3,403]

49 minutes ago, Bill D said:

Thanks for the info.  I'm not a machinist.  Any idea how the original metal ones were held for machining?  Just curious.  Bill

 

 

EDM you can see the rough edges from the electrical discharge.

 

 

 

 

 

[lynnmor 7,361]

3 hours ago, Bill D said:

Thanks for the info.  I'm not a machinist.  Any idea how the original metal ones were held for machining?  Just curious.  Bill

 

The plastic ones were molded, I haven't examined a metal one closely but I suspect they were die cast which is similar to plastic molding.  One thing I am sure of is that  EDM would be too slow and too expensive for this part.  The burrs on the edges may have come from the imperfect edges on the die used for casting the part.  If machining was used I am sure that expensive special holding fixtures would have been utilized.

 

The plastic parts gain size in the hole over time due to the plastic relaxing.  Plastics can have a high co-efficient of expansion and that is why the slippage only shows with the engine warmed up.  That constant changing of size is what causes the relaxing.

[Bill D 1,992]

5 hours ago, lynnmor said:

The plastic ones were molded, I haven't examined a metal one closely but I suspect they were die cast which is similar to plastic molding.  One thing I am sure of is that  EDM would be too slow and too expensive for this part.  The burrs on the edges may have come from the imperfect edges on the die used for casting the part.  If machining was used I am sure that expensive special holding fixtures would have been utilized.

 

The plastic parts gain size in the hole over time due to the plastic relaxing.  Plastics can have a high co-efficient of expansion and that is why the slippage only shows with the engine warmed up.  That constant changing of size is what causes the relaxing.

I have seen the metal ones shatter.  Being a die cast part would explain that.  

[tom2p 2,394]

Dumb question(s):

 

I have two Onan powered 416-H.

 

How do you know if the governor ball spacer is slipping or failing ?

 

Does the problem only surface when the engine is run at full throttle ?

 

I never run the 416s at full throttle (and rarely if ever run 312 at full throttle).

 

Edited April 3, 2021 by tom2p

[TC10284 111]

8 hours ago, tom2p said:

Dumb question(s):

 

I have two Onan powered 416-H.

 

How do you know if the governor ball spacer is slipping or failing ?

 

Does the problem only surface when the engine is run at full throttle ?

 

I never run the 416s at full throttle (and rarely if ever run 312 at full throttle).

 

 

If I recall, the "glue" on the plastic ones eventually breaks down and comes loose. And after, when the engine heats up about 15-20min of use, the plastic spacer will start spinning freely on the cam shaft. Thus the governor losing control. RPM starts spiking slowly and continues. Eventually, you can hit a solid 4000+ RPM at WOT (WAY too high). Then that can obviously lead to catastrophic failure of other engine parts.

In the past I've tried to control it by dropping throttle to keep the RPM where it should be, but it doesn't work like it should since the governor can't control the load anymore. I forget exactly what happened when I dropped throttle, but I remember it just didn't perform right. 

Thus far, I have not had to do this repair on a P216g, but that does not mean it can't/won't be a problem. 

[lynnmor 7,361]

9 hours ago, tom2p said:

Dumb question(s):

 

I have two Onan powered 416-H.

 

How do you know if the governor ball spacer is slipping or failing ?

 

Does the problem only surface when the engine is run at full throttle ?

 

I never run the 416s at full throttle (and rarely if ever run 312 at full throttle).

 

 

When the spacer slips the set speed will not be controlled and will run faster.

I always run an engine at its designed speed of 3600 RPM when it is worked.  See your manual.

[bc.gold 3,403]

On 4/3/2021 at 12:00 AM, tom2p said:

Dumb question(s):

 

I have two Onan powered 416-H.

 

How do you know if the governor ball spacer is slipping or failing ?

 

Does the problem only surface when the engine is run at full throttle ?

 

I never run the 416s at full throttle (and rarely if ever run 312 at full throttle).

 

 

Engine rpm runs away.

[bc.gold 3,403]

 Wheel Horse 3D, will you printer print wax filament.

 

I have not given up on reproducing the governor spider. within the next couple of days blow the dust off of my Induction furnace for another project hopefully it still works.

 

Aiming for a shrink fit some useful data.

 

Edited May 26, 2021 by bc.gold