C-120 Automatic - Parking pawl replacement

[Bar Nuthin 460]

The directions to replace the parking pawl seem pretty straight forward. I have the pawl, gasket and a new axle seal (if needed).

Does anyone have any tips they'd like to share before I attempt this?

[ebinmaine 68,205]

DO use a proper ROLL PIN PUNCH. 

 

Have new wheel seals handy. 

For that matter all 4 seals. 

 There might be a seal around the pawl shaft. I may have one here if needed.  

 

 

DON'T coat the case half gasket (or any other) with any silicone or other sealer. 

 

Install a magnetic drain plug.  

 

 

[Bar Nuthin 460]

@ebinmaine I hadn’t considered the pawl shaft seal(s). I’ll do a deeper dive in the manuals. 

[Bar Nuthin 460]

1 hour ago, ebinmaine said:

For that matter all 4 seals. 

There might be a seal around the pawl shaft. I may have one here if needed.  

 

@ebinmaine I'm only planning to pull the RH case.  I can only come up with the Axle Seal, the Brake Seal, and the housing gasket.

You reference 4 seals - what am I overlooking?

 

If you have a brake shaft seal, I will gladly buy it from you. Likewise, if you have an extra magnetic drain plug. 

 

Edited November 20 by Bar Nuthin

[ebinmaine 68,205]

6 hours ago, Bar Nuthin said:

 

@ebinmaine I'm only planning to pull the RH case.  I can only come up with the Axle Seal, the Brake Seal, and the housing gasket.

You reference 4 seals - what am I overlooking?

 

I was figuring:

2 axles seals. 

1 brake shaft seal. 

1 park shaft seal. 

 

 

6 hours ago, Bar Nuthin said:

If you have a brake shaft seal, I will gladly buy it from you. Likewise, if you have an extra magnetic drain plug. 

   

 

 

I have several New Old Stock CR 4911 seals. 

 

 

I have a few magnetic drain plugs but they stick DOWN from the case. 

I'll be buying some that set flush as stock ones do. 

You may be able to find one of them at a local store. 

Another option is to get some Rare Earth magnets and simply stick one the the bottom of the case.  

 

 

 

This is one of several ares of my not very well-organized Parts Department.  

 

 

 

PM me your address. 

I'd be glad to send a seal. I'll treat ya right.  

[953 nut 55,734]

9 hours ago, Bar Nuthin said:

any tips they'd like to share

Before you even think about going inside a transaxle be sure everything is spotlessly clean. 

[Bar Nuthin 460]

4 hours ago, ebinmaine said:

I was figuring:

2 axles seals. 

1 brake shaft seal. 

1 park shaft seal. 

I have several New Old Stock CR 4911 seals.

 

Very generous of you!

I guess I need to rethink this.  What is the difference between the brake shaft seal and the park shaft seal? To my limited knowledge, my C-120A doesn't have any brakes, Only the parking cog.

Since I'm only planning to pull the RH side off (leaving the internals intact) I can only identify

• 1-RH axle seal
• 1-parking shaft seal
• 1-RH case gasket

I have the gasket and axle seals, and I'll grab a drain plug locally.  I'll send you a message on the CR 4911 if you don't mind parting with one.

Thanks again!

Edited November 20 by Bar Nuthin

[Bar Nuthin 460]

3 hours ago, 953 nut said:

Before you even think about going inside a transaxle be sure everything is spotlessly clean. 

 

That will be more challenging than the actual repair! 

Edited November 20 by Bar Nuthin

[daveoman1966 3,758]

Your C-120 auto is roughly 50+ years old.  Inasmuch as you are replacing the Parking Pawl, I'd urge you ---if not already done so---  to pull the hydro pump AND the hyd motor for inspection.  There are many internal SOFT brass parts that are very like scored over the years  from the STEEL shavings of the worn-down parking pawl.  The first sign of internal damage is: AFter warmup, does the tractor seem to lose power?  If so, the only cure is to restore the surfaces of these internal brass parts.  This is not a difficult endeavor and gaskets kits are available for this Sundstrand Model 90-1136.  I have personally refurbished a dozen or more of this very model and have prepared a 'how-to' file to guide the process.  It is a free download...   here it is:   

SUNDSTRAND-Piston-Piston-PUMP-MOTOR-Refurb.pdf

[Bar Nuthin 460]

6 hours ago, daveoman1966 said:

Your C-120 auto is roughly 50+ years old.  Inasmuch as you are replacing the Parking Pawl, I'd urge you ---if not already done so---  to pull the hydro pump AND the hyd motor for inspection.  There are many internal SOFT brass parts that are very like scored over the years  from the STEEL shavings of the worn-down parking pawl.  The first sign of internal damage is: AFter warmup, does the tractor seem to lose power?  If so, the only cure is to restore the surfaces of these internal brass parts.  This is not a difficult endeavor and gaskets kits are available for this Sundstrand Model 90-1136.  I have personally refurbished a dozen or more of this very model and have prepared a 'how-to' file to guide the process.  It is a free download...   here it is:   

SUNDSTRAND-Piston-Piston-PUMP-MOTOR-Refurb.pdf 2.6 MB · 0 downloads

You may have psychic abilities. I made the decision last night to postpone replacing the parking pawl until next spring - and do a proper overhaul.  It doesn't currently show any symptoms, but like you say - it is damn near 50 years old.  Likewise with the engine at some point.

 

And - Thank you for the detailed guide!

Edited November 21 by Bar Nuthin

[Bar Nuthin 460]

17 hours ago, daveoman1966 said:

The first sign of internal damage is: After warmup, does the tractor seem to lose power?

 

@daveoman1966 When you say "lose power" do you mean losing torque at the wheels, or actually drawing the engine down?

[daveoman1966 3,758]

22 minutes ago, Bar Nuthin said:

 

@daveoman1966 When you say "lose power" do you mean losing torque at the wheels, or actually drawing the engine down?

Bt writing "lose power", I mean ...losing torque at the wheels.  

[Bar Nuthin 460]

1 hour ago, daveoman1966 said:

Bt writing "lose power", I mean ...losing torque at the wheels.  

Thank you. I haven't really put it through its paces yet - short of pulling my leaf vac around for a couple hours. Seemed to handle that well.

 

I bought it primarily for navigating my heavy gravel/dirt trailer around the yard. That's also the reason I want an operation brake pawl.

 

Edited November 22 by Bar Nuthin

[kpinnc 12,358]

3 hours ago, Bar Nuthin said:

That's also the reason I want an operation brake pawl

I don’t think I’d exert all that onto the brake pawl. That’s quite a bit for that tiny gear and paw…

 

Just my opinion. Maybe purchase a set of wheel chocks instead? 

[daveoman1966 3,758]

5 hours ago, Bar Nuthin said:

Thank you. I haven't really put it through its paces yet - short of pulling my leaf vac around for a couple hours. Seemed to handle that well.

 

I bought it primarily for navigating my heavy gravel/dirt trailer around the yard. That's also the reason I want an operation brake pawl.

 

Regardless of the load your tractor is moving from A to B...   NEVER pull up on the hydro engagement lever (Park) when the tractor is moving.  You MUST only use the Parking Pawl (Brake) when at a COMPLETE STOP! !  If you pull up the lever while in motion, tiny fragments of the parking pawn get sheared off and find their way to the soft brass parts I mentioned.