1981 931B Transmission leak and confirmation help

[surferboy120]

GOAL: To verify I am on the right track for this repair I am about to make to my leaking trans.

Background...

I lost trans pressure due to low trans fluid resulting in the loader not wanting to move. Little did I know the small weep where the leak is got worse so shame on me for not taking care of sooner.

Below are some pics of the leak.






So it seems the leak is coming from the universal joint into the transmission.

Based off the parts listing shown below



It seems the problem has to do with the seal listed as "9" part # 3H1397. I am basing this off of my machines serial # of 29Y1109 and Transmission - 1AA01241

Would you guys agree I am on the right track here? Also do any of you have any experience with this repair? I can access it easy enough underneath and it appears to be about removing the universal joint and prying out the old seal and pressing in another. Could it be that simple?

Thank you in advance.

Thomas

 

[Nige]

I can access it easy enough underneath and it appears to be about removing the universal joint and prying out the old seal and pressing in another. Could it be that simple?

It may not be as simple as that, although hopefully it will be.

You should carefully inspect the surface of the 5G-2225 Yoke where the seal runs. It is not uncommon for the lip of the seal to wear a "groove" in the yoke. If that has happened in your case replacing the seal may not fix the problem long-term. Replacement or refurb of the sealing surface of the yoke may be called for.

Also you have to consider the possibility of play in a bearing or bearings (not shown) that support the shaft where the yoke #9 engages. Excessive play on that shaft could also cause a seal failure. When you remove the yoke and seal check the shaft carefully for any movement.

 

[surferboy120]

It may not be as simple as that, although hopefully it will be.

You should carefully inspect the surface of the 5G-2225 Yoke where the seal runs. It is not uncommon for the lip of the seal to wear a "groove" in the yoke. If that has happened in your case replacing the seal may not fix the problem long-term. Replacement or refurb of the sealing surface of the yoke may be called for.

Also you have to consider the possibility of play in a bearing or bearings (not shown) that support the shaft where the yoke #9 engages. Excessive play on that shaft could also cause a seal failure. When you remove the yoke and seal check the shaft carefully for any movement.

Thank you Nige I will post up some pics once I get it apart. I ordered the seal and all my fingers and toes are crossed that there isnt any grooves.... I will also really check for any play as well. Its been a great machine for the short time I have had it though. Only this issue (was a mild leak until now) and a now fixed tensioner seal leak for the tracks which was easy to fix as well.

 

[Welder Dave]

If the yoke is grooved a Speedi-sleeve might be an option.

 

[surferboy120]

If the yoke is grooved a Speedi-sleeve might be an option.

If it is the case I will have to get familiar with a speedi-sleeve so I can compare it as an option. Thank you for the info I am curious about this one.

 

[Welder Dave]

Speedi-sleeves are thin stainless steel bushings/spacers that fit fairly tight over a shaft that has become grooved and give the seal a new surface to ride on. They work good and can save a lot money over having to get new shafts or shafts repaired by welding. They can also make for less disassembly of components.

 

[surferboy120]

Speedi-sleeves are thin stainless steel bushings/spacers that fit fairly tight over a shaft that has become grooved and give the seal a new surface to ride on. They work good and can save a lot money over having to get new shafts or shafts repaired by welding. They can also make for less disassembly of components.

I love this as an option...I took a look at them online and wow could be a lifesaver depending on where this leak lands. I never knew about these. Thanks again for sharing.

 

[surferboy120]

I had time to take the Yoke and shaft going into the transmission side out.

It may not be as simple as that, although hopefully it will be.

You should carefully inspect the surface of the 5G-2225 Yoke where the seal runs. It is not uncommon for the lip of the seal to wear a "groove" in the yoke. If that has happened in your case replacing the seal may not fix the problem long-term. Replacement or refurb of the sealing surface of the yoke may be called for.

Also you have to consider the possibility of play in a bearing or bearings (not shown) that support the shaft where the yoke #9 engages. Excessive play on that shaft could also cause a seal failure. When you remove the yoke and seal check the shaft carefully for any movement.

On the bottom right is that the sealing surface you spoke of above? I pulled the yoke assembly but havent gotten the seal out yet as I only had limited time today but will get the rest pulled next weekend. You can see on the bottom the metal looks like it got hit. I suspect its because it was missing its inspection cover which I need to find or make. I wouldnt see this as a sealing surface per say. The rest so far looks fine. I have an additional o-ring to order for this shaft since its out but everything looks great other than the damage seen below which I will either grind\bend straight or if it does play into sealing things then I will try to find a replacement which I am sure will be tough.

 

[pittsburgh cat man]

I don't want to step on any ones toes but I've seen that yoke before it is part of 9p7243 transfer group not the 5g1818 that is pictured above

 

[Nige]

Attached is the parts breakdown of the 9P-7243. You are looking at items 15-17 for the Seal, O-Ring, and Yoke. The Part Number of the seal is different to the one in the 5G-1818 Group. Something about power takeoff in the title of the parts breakdown the OP posted above didn't sound right but I never bothered to check it.

On the bottom right is that the sealing surface you spoke of above?

The "sealing surface" of the yoke is the outside diameter of the shaft where the lip of the seal runs, shown arrowed below. If you look at it closely you may find a circumferential mark on the surface where the old seal was running.

 

[surferboy120]

I don't want to step on any ones toes but I've seen that yoke before it is part of 9p7243 transfer group not the 5g1818 that is pictured above

When I was researching seal part numbers online because I left my parts book at the workshop I noticed the yoke is used in a few groups so I am not surprised although to Nige's point you will see misc parts being different here and there.

 

[surferboy120]

Attached is the parts breakdown of the 9P-7243. You are looking at items 15-17 for the Seal, O-Ring, and Yoke. The Part Number of the seal is different to the one in the 5G-1818 Group. Something about power takeoff in the title of the parts breakdown the OP posted above didn't sound right but I never bothered to check it.


The "sealing surface" of the yoke is the outside diameter of the shaft where the lip of the seal runs, shown arrowed below. If you look at it closely you may find a circumferential mark on the surface where the old seal was running.

View attachment 325863

Thanks Nige I am in luck as I have no wear marks at all thankfully. I will double double check again of course but only the issues is related to the bends mentioned previously on the mounting surface itself. Once I actually pull the seal and check the internal bearings for movement I will start to feel better overall about the source of the leak. Hopefully its just being over 40 years old seal breakdown lol.....

 

[surferboy120]

Attached is the parts breakdown of the 9P-7243. You are looking at items 15-17 for the Seal, O-Ring, and Yoke. The Part Number of the seal is different to the one in the 5G-1818 Group. Something about power takeoff in the title of the parts breakdown the OP posted above didn't sound right but I never bothered to check it.


The "sealing surface" of the yoke is the outside diameter of the shaft where the lip of the seal runs, shown arrowed below. If you look at it closely you may find a circumferential mark on the surface where the old seal was running.

View attachment 325863

Question...... So without that one o-ring in itself the trans will leak? Sorry I know the question is somewhat silly but I am amazed that this "may" be a primary sealing surface? The reason I ask is this.......So after further inspection this week I found that the plate below only had 3 bolts. The two shown which were tight and one above which I could remove by hand of the 6. I got new bolts and tightened everything down and did the following before putting the yoke and drive shaft in....dont laugh at what I am about to say lol....ok just a little please lol.... I put trans fluid in to see if any fluid came out the side of the plate. The answer is no ....didnt before even with only two bolts but.....it did come out where the yoke goes which makes sense although I still cant believe that one seal can prevent leakage?


I make the above comment because I want to know of I need to remove that plate and go ahead and replace any other sealing surfaces while I am at it. The seal I bought when I posted originally I HAVE NOT replaced and to be honest cant find where it goes. Seal listed as "9" part # 3H1397. I suspect its right under that plate but didnt want to remove the plate until I see what you guys thought. This seal 3H1397 is smaller than the yoke or the of course where the yoke fits into the trans so I am having a hard time understanding where this seal goes and if removing that trans plate is going to create bigger problems for me.

I have the manual but it doesnt show much as far as this plate or whats behind it..

I appreciate any thoughts before I dig in.

 

[surferboy120]

Attached is the parts breakdown of the 9P-7243. You are looking at items 15-17 for the Seal, O-Ring, and Yoke. The Part Number of the seal is different to the one in the 5G-1818 Group. Something about power takeoff in the title of the parts breakdown the OP posted above didn't sound right but I never bothered to check it.


The "sealing surface" of the yoke is the outside diameter of the shaft where the lip of the seal runs, shown arrowed below. If you look at it closely you may find a circumferential mark on the surface where the old seal was running.

View attachment 325863

Your parts breakdown you attached is exactly what I needed actually....Not sure why my CAT manual doesnt seem to have that illustration. I also got the parts book so I will review the parts I got vs the what your schematic shows which visually appears spot on. This would explain why my seal I originally order is the wrong size....So maybe I answered my own question with your parts breakdown. Now to find the correct seals it seems.

 

[surferboy120]

@Nige so upon further inspection your parts listing is spot on......everything shown matches up.....time to order some parts and pull things apart..... I need to find your manual...I guess its online? Its way better than the books I bought.

 

[Nige]

Some of the knock-off parts manuals are not as good quality as we would like them to be, and certainly not as good quality as OEM. Been there, done that.....

SEBP1247 is the Parts Manual you need. It covers all 29Y-prefix 931B machines.
I don't see any used paper copies kicking around at the moment but that could change tomorrow.

The manual is available in either paper, Adobe pdf on a CD, or a pdf download from HERE. Simply enter as a guest, put SEBP1247 in the box and click Search. S&H charges would apply if you bought a paper or CD version. You could also investigate buying manuals from HERE. These are also genuine OEM documents and sometimes come out cheaper than buying direct from Cat.

 

[surferboy120]

Some of the knock-off parts manuals are not as good quality as we would like them to be, and certainly not as good quality as OEM. Been there, done that.....

SEBP1247 is the Parts Manual you need. It covers all 29Y-prefix 931B machines.
I don't see any used paper copies kicking around at the moment but that could change tomorrow.

The manual is available in either paper, Adobe pdf on a CD, or a pdf download from HERE. Simply enter as a guest, put SEBP1247 in the box and click Search. S&H charges would apply if you bought a paper or CD version. You could also investigate buying manuals from HERE. These are also genuine OEM documents and sometimes come out cheaper than buying direct from Cat.

View attachment 326743

Interesting.....I have the SEB1247 but after review mine was published in May 1979.... My unit seems to be from 1981...Vehicle Serial - 29Y1109 ,Engine - 45V31446, Transmission - 1AA01241

My parts book lists my serial as well......but your diagram from your parts book is way better. Even my Original CAT service manual published in Feb 1986 didnt have your type of schematic. Looks like I am going to buy some more manuals LOL........

I got my parts ordered (13, 15, 17) and feel 100% confident this should be fairly easy to complete now that I can see the parts. The plate was already pretty easy to pull as well.

 

[Nige]

Interesting.....I have the SEBP1247 but after review mine was published in May 1979.... My unit seems to be from 1981...Vehicle Serial - 29Y1109 ,

Take a look in the top RH corner of the front cover. It should say SEBP1247-xx. The latest one is SEBP1247-03 published in May 1989. Maybe the book you have is too "early" to cover your machine Serial Number.?

 

[surferboy120]

Take a look in the top RH corner of the front cover. It should say SEBP1247-xx. The latest one is SEBP1247-03 published in May 1989. Maybe the book you have is too "early" to cover your machine Serial Number.?

I think you are right Nige.... Mine doesnt have the (-xx) it is just SEBP1247. I am going to download the (-03).

 

[Nige]

I think you are right Nige.... Mine doesnt have the (-xx) it is just SEBP1247. I am going to download the (-03).

In that case your one is the original, aka -00, version. Not surprising that it doesn't have all the information related to a machine built in June 1981 considering that it was published in 1979.