# New Shay Trucks Drive Shaft Length



## chrisb (Jan 3, 2008)

I recently installed new power trucks from Bachmann. The Shay is of the vintage when the plastic wheel bushing crumbled. It seemest that the drive shaft on the front truck is a about 3/16 " too long. It it appears to bind on a right hand curve.
Has anyone esle experienced this?


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## Cap'nBill (Dec 27, 2008)

What radius track are you using?


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## Curmudgeon (Jan 11, 2008)

They're the same part. 
If you think it's so, swap out the driveshaft from the old truck. 

With the manufacturer in question, QC data allows virtually any non-compliant part to be "passed", it seems. 

Gear mesh okay? 
I am thinking mis-assembly on the shaft. 
Also, any chance they stuck a rear shaft in a front truck? 
Have to go look to see what the result would be.


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## Cap'nBill (Dec 27, 2008)

I replaced the plastic with the new metal trucks but don't remember binding, but using minimum 8' radius track. I used the old trucks to make a 4 truck shay with some square brass tubing. If necessary you could shorten in very small amounts...don't think I'd go for the whole 3/16th's at one time though.
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## Curmudgeon (Jan 11, 2008)

I went out and checked. Since I did a swap of plastic for metal on a customer's loco yesterday, I had both. 
The driveshafts are identical as is the motor, gears, wheels, axles, sideframes (except the sideshaft opening is square not roound...or is it the cover?) and measure (front) center op nearest journal to end, 2-9/16". 
The rears are exactly 3/16" longer, at 2-3/4". 
Look at the other end of the shaft. 
Rears have a plastic cap, fronts have a cross pin only. 
Bets are mis-assembly somewhere in PRC. 

If the rear one is right, just use your old shaft. 
If it's a rear shaft on the front, the crank and cylinders won't turn (unless by drag), as al BachShays run the monkey motion off #2 axle ONLY.


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## chrisb (Jan 3, 2008)

Thanks for the comments. It appears that this problem was caused by me. I had broke the U joint between the front truck and the crankshaft. More specifically the plastic Y part of the slip joint. To repair it I took the metal Y ouff the old front truck 
and glued it into the plastic square tube or female part of the slip joint. I suspect that I did not measure well enough. 
The binding happens with any turn to the right, 

If I could come up with a brass square tube with a square hole in it, I think I could solve this. Any suggestion? 
From Cap'n Bills Post it looks like you made these slip joints. How did you do it?


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## chrisb (Jan 3, 2008)

I just reread Cap'n Bill's post. So I see that you did make the slip joint. How do you deal with the square hole. 
I think I will another truck to my shay to make it a 3 truck.


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## Cap'nBill (Dec 27, 2008)

Just find a Hobby shop with the K &S metals....or online, and get 3 or 4 pieces of square tubing so that you have a 'telescoping' set. Just like round tubing. I may have soldered a couple pieces together to get the right appearance. Probably helps to have piece of radius track on the bench to get the length correct for inside and outside turns. Somewhere in the round sections, I drilled a small hole crosswise and put a pin in it so as to disassemble, if needed. Good Luck! Bill


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