# Proto 2000 gear replacement



## tbdbitl (Dec 31, 2014)

OK, this is not a new problem, but I seem to have a slightly different outcome with the resolution.

I have several P2K GP7 and GP9 locos. They run well, but have binding issues, also clicking noises. I found the posts and YouTube videos on this problem, and they fit the issue to a T. I disassembled one of the units, and the axles are loose on the gears; I can see small cracks. I ordered the replacement parts from Athern - part 60024, and received them on Friday. I went to install them, but here is the rub. 


The videos all gloss over the step I'm having problems with - pressing the old axles into the gears. The parts look to be correct - the same size; the hole looks to be the same size; a 3/32 drill is a snug fit as I work it in on the new one, it's a little loose on the old one, but it is of course cracked. 

So how do I get them pressed on the axles? I tried to alligned them by hand, but they will not start; its as if the axles themselves are too big. What am I missing here?

1. Is there a tool to press the gears on the axles? I haven't found any reference to it so far. 

2. Is this the root of the problem with the P2K locos - the axles are too big, and were forced on at thte factory, causing the cracked gears. If so, is there a replacement wheel/bearing assembly I need to get? If so, does anyone have a part number. 

This is my first attempt at doing gear replacements - something I have avoided because most of my other locos are steam, and I haven't wanted to get into driver quartering issues. But this seemed so easy looking at the videos.....

Thanks in advance for your responses.


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## 3.8TransAM (Jan 13, 2016)

Strong hands 

You can use sockets on each side in a vice and slowly press them on. Make sure they are on straight and you want clearance on each wheelset between it and the axle.

Believe you want Athearn 60024 for the gears. Should show as being for the SD40-2 and comes in packages of 6 for $5-6 per package.

Do not replace just 1-2 axles if any are cracked, do all 4 in each loco.


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## J.C. (Dec 24, 2016)

try putting the wheels in you freezer and the gears in warm water, cold causes the wheel axles to shrink slightly the warm water causes the gears to grow slightly, I just put wheel in freezer here as the summers are very warm.


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## slammin (Mar 25, 2016)

Be sure you put the axle on a hard flat surface. A kitchen counter will work. You have to press the wheel holding it level. Then press the second wheel. It does take a lot of pressure. Wheels in the freezer should help, but handle then with a paper towel or thin clothe gloves. The heat from your fingers will heat them up very fast. I have done so many, I built a fixture to speed up the process. Once together, use you NMRA gauge to set the wheel spread. Make sure the wheels don't bind the square bearing on either end. As stated before, replace all 4 axles. When I buy another P2K GP, unless the seller tells me that gears are new, I replace them.


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## tbdbitl (Dec 31, 2014)

Success! I used the vise tip, although I didn't need the sockets; I used the recess for the screw mounts in the jaw of my Panavise to apply pressure without pressing on the end of the axle that protrudes from the face of the wheel itself. The biggest issue I had was keeping my fingers clear to keep them from getting caught without letting go of the parts too early. 

This worked well also from the unexpected side benefit of being able to see what was happening in terms of gaps between the bearings etc. I couldn't get the standards gage on the wheels in the vise, but some .010 plastic strips were good to use to measure the clearance. Once I thought they were good, I checked against the gauge and they were good to go.

I didn't have to use the freezer/warm water technique, but it's good to have an ace up my sleeve if I run into some other difficulties. 

So far I have only disassembled one truck - mostly to keep the number of loose parts to a minimum, but I will certainly replace all 4 axles.

Thanks again to all of you who took the time to reply, they were alll well appreciated. 

http://www.modeltrainforum.com/images/smilies/appl.gif


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## Lemonhawk (Sep 24, 2013)

The freezer trick will make it easier to get on. But you have a limited time, a minute or so and your back to the clearance you had at normal temperature. The freezer trick may also reduce the stress on the part also. The freezer technique is also used in real life. Putting new ware bands on old wheels you would heat the band up and cool the turned down wheel, you got one shot to get it right!


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## tbdbitl (Dec 31, 2014)

Not unlike the process of putting a new tire on a steam locomotive driver. There are some great pictures/movies of the old shops heating a tire with a gas burner apparatus, to make it expand enough to slide onto the wheel. I never heard of using a cold process to shrink the wheel - it was probably beyond the technology of the time. 

I think that they then used a water bath to cool the wheel, once the tread was in place; this quenching process might have also had the effect of further hardening the tire as well.

The good news from my basement was the fact that I completed the wheel/axle rebuild; lubricated the new gears, then reassembled the trucks and went for a test run. Nice smooth operation again. Thanks for all of the assistance.


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## 3.8TransAM (Jan 13, 2016)

tbdbitl said:


> Not unlike the process of putting a new tire on a steam locomotive driver. There are some great pictures/movies of the old shops heating a tire with a gas burner apparatus, to make it expand enough to slide onto the wheel. I never heard of using a cold process to shrink the wheel - it was probably beyond the technology of the time.
> 
> I think that they then used a water bath to cool the wheel, once the tread was in place; this quenching process might have also had the effect of further hardening the tire as well.
> 
> The good news from my basement was the fact that I completed the wheel/axle rebuild; lubricated the new gears, then reassembled the trucks and went for a test run. Nice smooth operation again. Thanks for all of the assistance.


I've put back together a lot of P2K's. Complete clean, axle gears and they are good to go. Nice engines you can get cheap.


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