1277 weak hydro

[Greentored 3,201]

The 1277 I picked up last week got to see some much needed TLC. Been running it around and even pulled a disc to test it out. Noticed it doesn’t have much oomph in reverse. I drove it up the trailer ramp when loading, so forward motion is there, but it does struggle- need to get a head start to get it up the 3-4” concrete step into the shop. 

Fluid was atf and looked ok, was replaced with same and correct wix filter, new drive belt, not slipping. Motion control has full range. Axle keys good. 

  It’s a Sundstrand, that’s all I know, and appears to be the early one. Anything I can check? Hoping it’s just got a valve hung up or a chunk of crap in it as it sat for years. 

Thanks in advance! 

[daveoman1966 3,745]

Well, at 63 years old, the 1277 is nearing retirement.  There is, no doubt, significant internal wear causing the pump to loose pressure.

These aren't so bad to work on...if you're wrench-wise, that is.  The pump overhaul precedure is very like the Sundstrand Hydro-gear and I can provide a narrative on what/how to do steps.

 

 

[Greentored 3,201]

Wrench wise, no problem. My main concern was whether parts are available. 

I pulled the acceleration valves out, one was missing the spring behind the Allen screw in the center of the big 1 3/16 nut. The check ball was frozen on one side and had fallen through on the other. Now don’t laugh, I replaced the missing spring with a bic pen spring just to see if it’ll work. 

Not going to light it off this late, but there is much more ‘push’ effort just rolling it over with the starter, and actually loading the pump now. 

Sure do appreciate any insight you can give me to fix this correctly, not with pen springs 😆

[ebinmaine 67,268]

[Greentored 3,201]

Bic pen to the rescue- it works! Stay tuned for an evening update. 

[ebinmaine 67,268]

4 hours ago, Greentored said:

evening update

[Greentored 3,201]

@ebinmaine it’s killin me man! Up at my little a frame all weekend, reception sketchy at best. Text sometimes, pics doubtful, vids forget it,  Can’t even participate in the ‘let’s hear em!’ Thread I started. Phone is full of pics and vids, will be melting this forum down when I get to work in the am👍

  Worked the ol 1277 in the garden for a good hour dragging the disc, i doubt it’d turn the tires over if I butt it against something, but she pulled that disc and no longer gets stuck on a cat turd in reverse either 😆

[ebinmaine 67,268]

We'll let it slide..... This time.

 

Nice to hear it's goin good 👍

[daveoman1966 3,745]

5 hours ago, Greentored said:

@ebinmaine it.......st something, but she pulled that disc and no longer gets stuck on a cat turd in reverse either 😆

Cats are my favorites....  To disparage their dump in such an disrespectful manner isn't kind.    but I'm glad to know the beast is workin' for ya.   Did you replace one of these springs....  or the springs in the Fwd or Rev Valves? 

[953 nut 55,068]

                Glad you got it working well, You could probably improve it even more with a set of acceleration springs like Dave showed in his photos.

[Greentored 3,201]

@daveoman1966 The spring I replaced with the pen spring (haha) was located behind the allen plug that is in the end of that big 1 3/16 nut. There was a spring and a very short T shaped 'disc' in one valve, no spring, and the disc cocked sideways in the other.

Also, there was a 'check ball' which was jammed inside the hole in the center of that 1 3/16 nut, and on the other side the ball would would push through that hole with a little effort, by hand. Obviously not being familiar with the operation of these units, I made an educated guess that the check ball allows rapid pressure against the larger double springs, and slows the flow to return, so I carefully peened the holes, laid the check balls on top of the holes (where they would be to the inside toward the unit when assembled) and stuck it back together. Was my guess correct? haha

If these parts are available I would like to purchase them. Thanks bud!

[Greentored 3,201]

Ok fellas, the saga continues. I have fallen in love with this 1277 and REALLY want to save the ol Sundstrand and make it 100%. Shes been on a couple cruises, pulling the garden disc, etc... but once she warms up, I cant get it up the 3" step into the shop without a running start. I downloaded the Wheel a Matic manual found on this site (the wealth of information found on here is a HUGE help, thank you guys!) and pulled every single check valve, piston, spring, needle, etc... to make sure they are clean, free, needles seating correctly, and all looks good. I am not finding any metal shavings or 'sparkly' fluid or contaminates. I put a slight stretch on the charge relief and check valve springs which has helped, but once it gets to operating temp, its weak again.

One area I know for a fact is in question- the acceleration valve 'dampening valve'- the big 1 3/16 hex plug. In the pic below, there is a small allen plug in the end of this hex plug. Behind it is a small spring (this is where I used the bic pen spring), a small disc, and a check ball. The more I study this, the more I think this ball should be contained inside this large hex plug as part of the assembly and should not come out. It is not shown in the manual diagrams.

Can anyone shed some light on this? I would like to address these first before ordering a full overhaul kit and going through the entire unit.

Thanks!

[Greentored 3,201]

Just bringing this back up to the top. These dampening valves in previous pic- anyone? I have called LJ, Nova, BJ Hydraulics- nobody has heard of a Sundstrand 3100077. The ol girl is my primary tractor now and is doing the job, but the warmer it gets, she starts to get weak, I need the seals and am ready to overhaul, but theres not much sense in that if I cannot get these dampening valves sorted out or replaced.

I did find a Sundstrand part number for them- 6444, obviously NLA.

I am one step from slapping an 8 speed in her. 

[ebinmaine 67,268]

I know next to nothing about hydros but maybe one of these guys can lead you in a direction....

 

 

@953 nut

@daveoman1966

@pfrederi

[tom2p 2,394]

can't comment on that particular model - but Sundstrand has been around for a long time - many considered them to be the 'Cadillac' .. ( or current 'Lexus') 

most cement trucks for years and years used Sundstrand ... Sundstrand pump mounted in front of the radiator and motor mounted near the big drum 

 

the asphalt grinding machines ... 'roto-mills' or whatever they were called ... most were powered with Sundstrand pumps and motors ...

 

steel mills ... manufacturing facilities ... Sundstrand ... 

 

some amusement park rides ... Sundstrand ...

those pumps internally looked very similar to the pump on a Wheel Horse ... variable displacement pump -  swash plate with pistons - etc etc ... used a small charge pump ... (?) ... 

 

Edited May 13, 2020 by tom2p

[Greentored 3,201]

12 minutes ago, tom2p said:

can't comment on that particular model - but Sundstrand has been around for a long time - many considered them to be the 'Cadillac' .. ( or current 'Lexus') 

most cement trucks for years and years used Sundstrand ... Sundstrand pump mounted in front of the radiator and motor mounted near the big drum 

 

the asphalt grinding machines ... 'roto-mills' or whatever they were called ... most were powered with Sundstrand pumps and motors ...

 

I like the beefy eaton in the ole 520, but tell ya what- this Sundstrand, even being not 100%, is smoother than the eaton, and in the 1277 would flat out annihilate the 520 in a drag race haha.

[tom2p 2,394]

4 minutes ago, Greentored said:

I like the beefy eaton in the ole 520, but tell ya what- this Sundstrand, even being not 100%, is smoother than the eaton, and in the 1277 would flat out annihilate the 520 in a drag race haha.

I've seen the Eaton 1100's survive poor maintenance and keep on going for decades 

 

few if any fluid and filter changes - grass packed on top of the trans (under the console tunnel) - cooling fan blades damaged ...

 

Edited May 13, 2020 by tom2p

[daveoman1966 3,745]

Sindstrand 3100077 was used in automatics in 1965-67.  (875,1075,876,1076,1276,877,1077,1277).  In 1968 thru 1973 the design model was changed to 90-2046 (chargers & Bronco 14) or 90-2062 (for the GT-14 series). 

While the outer images look the same in the 3100077 and 90-2046 (62) look very similar, there are apparently internally different parts. 

I have to wonder if the DAMPENING VALVES and springs from the 90-2046 style will swap into the 3100077 of earlier vintage?  

 

[daveoman1966 3,745]

The automatic models of 65-67 MAY have been called the 'Wheel-a-Matic'   ...or  HYDROGEAR.  When contacting BJ Hydraulics, or others, ask them to lookup HYDROGEAR 3100077.  I thought that Hydrogear was a variant of Sundstrand, but maybe not.  

In any case, there is a Hydrogear Section in the Sundstrand manual and it starts on pages 47 - 56.  There is also a 1965- 1968 Service Bulletin listing on the HYDROGEAR that MAY open some doors.  This is a LONG .pdf file, but I can't see how to send just the pertinent pages of it...so, here goes... 

 

The manual I refer to is already in the MANUALS section....  65-72  Transmissions...Automatics...  Name of it is 

FREE

 Transmission Hydro Sundstrand SM #492-4206.pdf

  

 

 

Edited May 13, 2020 by daveoman1966

[R. L. Addison 299]

I would say that the power loss when warmed up is in the valve plate/cartridge in the rotating group. The valves are a cushion to eliminate shock load. I have a few parts for this transmission, but nothing that would cause your warmed up lack of power. I have scrapped a couple of these transmissions in the past because a foreign object went through the gear motor and damaged the gears and housing. The only way to get parts is to take them out of an identical unit or make them. A later model piston to piston unit is a direct interchange by changing one gear. Sometimes the later units (piston-piston) can be found if an engine blows on a unit. These are good units (hydrogears and piston-piston) but many times are neglected.

[Greentored 3,201]

@daveoman1966 @R. L. Addison  thanks fellas. I have no doubt she is just tired, Dave and I have spoken and emailed about this. I just dont want to go through an overhaul and chance trashing it again due to an issue with the dampening valves.

The fluid I drained looked decent, did not smell, and I have found very little if any debris/crap inside when checking springs, changing fluid, etc....

[Greentored 3,201]

2 hours ago, tom2p said:

I've seen the Eaton 1100's survive poor maintenance and keep on going for decades 

 

few if any fluid and filter changes - grass packed on top of the trans (under the console tunnel) - cooling fan blades damaged ...

 

When I bought my 520, it moved, but very very slow, and when I drained the fluid, about 1.5 quarts of muddy water and something similar to oil bubbled out. I thought 'shes done'. Changed the fluid and filter, adjusted the motion control and she has been perfect. .

Old mans (cough) 317 deere he bought brand new in 81-82- sundstrand unit. I serviced the tractor for him last fall and it had the original hydro filter on and was nearly rusted through. "Dad, did you EVER change the hydro fluid in this!!!???"  "Damn, I dunno. Probably not."

Same thing- 2 quarts of molasses in this one.  New fluid and filter- shes 100%.  Unreal.....

Both these tractors will turn the tires on dry pavement when butted against the shop dumpster.  

Actually- the 520 moved the dumpster, because thats a real tractor

[daveoman1966 3,745]

The automatic models of 65-67 MAY have been called the 'Wheel-a-Matic'   ...or  HYDROGEAR.  When contacting BJ Hydraulics, or others, ask them to lookup HYDROGEAR 3100077.  I thought that Hydrogear was a variant of Sundstrand, but maybe not.  

In any case, there is a Hydrogear Section in the Sundstrand manual and it starts on pages 47 - 56.  There is also a 1965- 1968 Service Bulletin listing on the HYDROGEAR that MAY open some doors.  

 

[WVHillbilly520H 10,373]

3 hours ago, Greentored said:

I like the beefy eaton in the ole 520, but tell ya what- this Sundstrand, even being not 100%, is smoother than the eaton, and in the 1277 would flat out annihilate the 520 in a drag race haha.

Obviously at the moment depends what they are dragging... 

[daveoman1966 3,745]

I'm still in the camp to pull the pump off and look at the 9 BRASS Piston slippers, the base of the piston cyulinder block, and the Thrust washer.  I gotta think they all need resurfacing... and the charge pump hosuing...and the gerotor set.  These all get worn over time...