48" mower deck shell

[TimJr]

So, my dad picked up a used 48" deck for the shell.  He has been trying to explain to me some assembly problems he has been having with it.  He found it on Craigslist or something and I didn't see it until today.  Long story short.  The 48" deck that was under his 17GTH is a 1690502 and was fine mechanically, but the shell was shot - cracked and welded a lot, rusted.  So he picks up this other deck with a pretty good shell, but mechanicals shot.  The new deck didn't have a tag anymore.  The cover tins were worn through above the outer arbors, which we thought was weird, until he began reassembling it with the parts from the 1690502.  The pockets where the arbors bolt in are different depths. The bolts that hold the pullies onto the arbor shafts were contacting the covers.   I know I have seen/heard discussions of the differences between early and later decks, but haven't personally been involved in any parts swapping.  I am guessing it is a 1970's deck that originally had the early arbors and the PO mixed and matched stuff by installing the later arbors and then wrecking the covers with the contact.

When I say early, I guess I mean any deck with the old style round tubing arbor housing.

When I say later style, I mean decks with the 2 piece cone shaped arbors.

I am aware of the aluminum spacer rings from the 1980's that were used to adapt from one to the other, but for the life of me I can't find the service bulletin that explains them - I know I have seen it in my literature somewhere.  I actually have some of the rings, just never used them or seen them installed.

The orange 1690502 deck shell has the deeper pockets and is correct with the 2 piece cone style arbors.

The other black deck shell has noticeably shallower pockets where the arbors mount.  Never mind how the arbors are bolted in now - he was just trying different spacing.

Were the shallow pocket decks originally equipped with the old style round tubing arbors?

Which way did the aluminum rings allow you to mix and match -

Old deck, new style arbors?

Or, new deck with old style arbors?

I haven't measured the new style arbors, but the early ones measure about 4.25" from the mounting flange down to the face where the blade attaches.

Right now, the plan is to just space up the covers to keep the arbor shaft bolts from contacting the sheetmetal. 

Edited February 23, 2018 by TimJr
Added pics.

[PhanDad]

The rings are used under the deck when replacing a deck shell with a new deck shell that has shallow pockets.  Here's the Mower Housing Kit Installation Instructions:

 

Mounting the arbor under the deck keeps the blade at the same distance from the main shell surface. 

The rings are also used for new arbors to be used on old decks with deep pockets (and I assume this means the old style one piece tube arbors).  

When you use a new style arbor (two piece) on an old deck with shallow pocket, the arbor is mounted under the deck with one spacer ring between the top of the arbor and the bottom of the shell.  

 

I'll put the full Arbor Replacement Kit Installation Instructions in the "Download" Forum later, but here's the "Cover Pic":

 

Edited February 23, 2018 by PhanDad
Added detail and pics

[TimJr]

Thank you for posting that.  I couldn't find info anywhere, but I see I was searching for the wrong part number.  I had a number on the rings I have, but it must be the wrong number.  I have had my hands on lots of Simplicity decks over the years, but in all honestly never really did any mixing and matching.  It was always by the model number using the correct parts.  I don't think I ever replaced a deck shell, so I never experienced this situation.  I was aware of the rings and they allowed an upfit/back fit but didn't know for sure the details.

Maybe I am missing something -  Why did Simpicity make shells with 2 different depth pockets for the 2 piece cone style arbors?  Am I misreading - it seems like that is what is being said.

I completely understand that the old welded round tubing style arbor and the 2 piece cone style are likely different heights and would require the rings to allow for the same overall blade height.

Based on your info, the black deck shell my dad picked up is likely a replacement shell from the 90's??  (He painted it black.......he had some paint laying around.....)

However, with the way the arbors will be lowered down with the rings if installed as above, it appears it will cause a belt alignment issue on this deck in regards to the idler pulley.  I am going to have to go back over there with my rings and spend some time swapping things around to get this figured out for myself and hopefully have some good info to share with everyone once done.

[Chris727]

Tim, 

The old style tube arbors with flange were not used on decks with pockets. I do believe I have seen two different depths of pockets on the 2 piece arbor decks. I think the change may have occurred sometime during the 7100 Series.  

[Chris727]

The old single housing arbors sure were easier to rebuild! 

[PhanDad]

Tim,

Thanks for clearing up a deck housing part number mystery for me. 

If I read your first post correctly, the orange deck is a confirmed mfg #1690502.  It appears to have deep pockets, like my 42" 1690271 deck:

Mfg #1690272 is the 48" version of the above deck.  It has flat blades and the 2 piece cone arbors.  I believe this was the first deck series to have that style arbor.

And a pic of a #1691219 deck that came with my 17GTH-L showing shallow pockets:

I was always suspicious that the housing part number (1685282) listed for the #1690502 deck was wrong because it was the same as for the #1691219 deck.  I suspected Simplicity updated the part number for the part that was available at the time of printing (Part numbers from the "Sovereign, GTH-L , 900 Series, 2800 Series, 7100 Series Attachments and Accessories" Parts Manual ).  I didn't understand how the same housing could be used for both mfg #s since the #1690502 has flat blades and the #1691219 has gull wing blades and the 2 piece arbors and stoneguard are the same.  Since your orange deck is a confirmed #1690502, the housing part number must be different, probably part #1685105, the same as the housing for deck #1690272.  Mystery solved. 

2 hours ago, TimJr said:

Maybe I am missing something -  Why did Simplicity make shells with 2 different depth pockets for the 2 piece cone style arbors?  Am I misreading - it seems like that is what is being said.

You are not misreading.

I believe the reason Simplicity changed the depth of the pockets was 2-fold: easier stamping and elimination of the arbor shaft spline wear problem on the blade end.  The first 2 piece cone arbor shafts had full length machined splines.  If you've ever tried to get the blade adapter (piece above the blade, common to both the deep pocket and shallow pocket decks) off the shaft, it's a chore since the splines where the blades rest are always messed up:

This condition also makes centering the blade impossible and contributes to blade vibration. 

 The first fix was to grind the splines flat where the blade sits and use a collar to center the blade.  The improved arbor shaft looked like this:

The ground shaft arbors were first used on the #1690501 & 502 decks.  An improvement, but a little collar part to keep track of.  (Another Simplicity oddity is for the change to IPLs for the inclusion of this collar part, the collar is shown in the "Housing & Arbor Group" rather than the "Cover, Drive, & Bail Group" where the blade and other mounting parts are shown.  Most folks don't even know a collar should be used.)

When Simplicity switched the deck housing to shallow pockets, the gull wing blade came with it to compensate for the less deep pocket and keep the blade cutting line at the same depth for both decks.  The gull wing blade has a different bottom spline washer (gull wing on left, flat on right):

With the gull wing spline washer, the blade no longer contacts the arbor shaft, hence no spline wear (the blade mounting hole is obviously bigger).

And finally an overview of the flat vs gull wing blade mounting parts:

         

[PhanDad]

13 hours ago, TimJr said:

However, with the way the arbors will be lowered down with the rings if installed as above, it appears it will cause a belt alignment issue on this deck in regards to the idler pulley.

Since the "new" deck shell has a shallower pocket, if you mount the arbor assembly on top, the drive pulley will be higher by the difference in the pocket depth and will not be in the same plane as the idler pulley (and hit the deck cover). 

When the arbor assembly is mounted underneath with a spacer ring, the drive pulley will be lowered by the difference in the pocket depth and should be in the same plane as the idler pulley (and won't hit the deck cover).  

I'm thinking you will have to move the idler pulley assembly from the #1690502 deck to the "new" shallow pocket deck for all the pulleys to be in the same plane.  (That's what the housing replacement instructions assume - moving all parts from the old deck to new).

The above was a bad late night thought.

I decided to measure.  On a deep pocket arbor assembly (flat blade deck), the distance from the top arbor housing plate to the top of the pulley is about 2".  The corresponding measurement for the shallow pocket arbor assembly (gull wing deck) is about 1-1/2".  The difference appears to be in the pulley.  They are different part numbers. 

Here are pics of the top and bottom sides of the side arbor pulley for the shallow pocket (gull wing deck): 

On the deep pocket deck, the "downside" pulley hub is longer and has 2 diameters.  I don't have a pic of it (yet).    

Let us know what you find.

Edited February 24, 2018 by PhanDad
"deleted" thought & added measurement info

[PhanDad]

Some more pics to complete the story.

This is a pic of the deep pocket side arbor pulley, part #1655867:

The above pulley is about 4-1/16" in diameter, the same diameter as all newer decks with the OEM two piece cone arbors.

This pulley comes with the arbor replacement kit #1685082 (First page of the this kit install instructions are above):

 

The above pulley is part #1657182 and is only 3-9/16" in diameter, the same diameter as the old cast pulleys on FDT decks.  Also note the Kit Install Instructions are for "Deep Deck Mowers" not deep pocket decks (that came with the 2 piece cone arbors).  I learned about this replacement arbor kit because one was installed on an early deep pocket deck that came with a tractor I bought.  The kit number was written on the pulley as can be seen in the pic.  With the smaller pulley, that blade spins faster.  

There is similar Arbor Replacement Kit #1685078 to replace the tube arbors on the AC 300/400 and AC Built Homelite shallow right discharge decks.  It comes with the larger diameter deep pocket pulley (#1655867) to match the diameter of the original pulleys.  

 

[TimJr]

Hopefully in the next week or so I will have a chance to look into the mower deck in question.  My main concern now is getting proper belt alignment to the idler arm.

I knew about the differences in arbor shafts in regards to the splines.  I did not know about the different pulley hub heights.

I thought about the whole gull wing vs. flat blades yesterday and figured that must have been when the depth of the pocket changed.  Makes sense now.  I also noticed in the instructions for the arbor kits with the spacer rings, it clearly shows an old flat top style mower deck.

Another question got answered above before I had a chance to ask about it.  I noticed that old 48" decks with tube style arbors used a belt that was 85.2" long and had pullies listed as 3.5" OD.  The later decks with cone style arbors use a secondary belt that is 93.1" long.  Simplicity does not list the diameter, but above it is pointed out as being a little over 4".  That would likely explain the need for the longer belt - has to go around a bigger pulley.

I  think the idler arms are different part numbers between the shallow and deep pocket decks.

But yes, the orange deck in my pics still has the original serial tag on it to confirm the 1690502 number.

So now my question is, do the blades on the gull wing blade deck sit at the same height relative to the front lip of the deck the same way a deck with flat blades sits?

I have a 1691219 under my 18hp Sovereign.  I needed more cutting height, so the easy thing to do was get rid of the gull wing blades and converted the blades and hardware to 1690502 flat blades.  I got my cutting height, but may have altered my quality of cut without really thinking about it back when I did it.  I have since seen someone who gained the cutting height by making some Delrin rollers that were larger OD than factory rollers to raise the deck up to gain cutting height.  I suppose I could be down an easy 1/4" just due to wear on the ID and OD of the rollers, plus any wear on the roller shaft.  Maybe more.

Thanks for the input on this.  What initially seemed like such a messed up situation is turning out to be fairly uncomplicated with a little knowledge.

 

Edited February 26, 2018 by TimJr

[PhanDad]

12 hours ago, TimJr said:

So now my question is, do the blades on the gull wing blade deck sit at the same height relative to the front lip of the deck the same way a deck with flat blades sits?

I believe they do, the decrease in pocket depth = increase of gull wing down bend.

12 hours ago, TimJr said:

I have a 1691219 under my 18hp Sovereign.  I needed more cutting height, so the easy thing to do was get rid of the gull wing blades and converted the blades and hardware to 1690502 flat blades.

I did the same thing.  What I didn't like especially was the plane of the blade was higher than the stone guard.  My deck has the smaller diameter round bar that the turbo blower mounts.  The angled, square tube stone guard would probably be OK.

Since my Homelite T-12 has the right discharge shallow deck that can adjust to about a 4" cut, I decided to use it for the heart of summer duty and I switched the 1691219 deck back to the gull wing blades.  I thought I noticed better performance with the gull wing blades in leaf duty, but it might be the fact I'm running gator gull wing blades now. 

[ShaunE]

1 hour ago, PhanDad said:

I have a 1691219 under my 18hp Sovereign.  I needed more cutting height, so the easy thing to do was get rid of the gull wing blades and converted the blades and hardware to 1690502 flat blades.

To me the easiest thing to do is mill out the hole in the straight blades so they fit on the newer style arbors.  I understand the blade plane is higher but I've noticed no complications in doing this.  However I'm running the old style stone guard as well.