Well darned, I cannot get the idler shaft lock pin to "move." Trying to drive it in with hammer and punch but it won 't move. The top of the pin was mushroomed over a bit so I used a dremel tool to remove the rounded edges and made it flush with the case. The slot in the end of the shaft appears to be in the correct orientation.
Anyone have any suggestions on what steps I should take? The BFH and punch didn't seem to move it one bit.
Lock pin is number 60 on the illustration.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Ron, it looks to me like you'll need to drill that pin out. It's possible that someone installed a pin that's too long and it's bottoming on the shaft, which per the illustration looks like a blind hole. The instructions say that you need to install a new pin in any case. If you can keep the hole centered in the pin, you can drill until its just a thin shell and drive the shaft out while collapsing the shell remnants of the pin. Good luck
Caveat: I have no direct experience with the SM420, but reviewed the overhaul instructions that you helped resurrect up in the tech tip section.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Is the shaft slot "horizontal"? There's a chance the last guy didn't have the pin and hole lined up and the pin is just smashed down on the surface of the shaft...can you turn the shaft with a big screwdriver?
Just a thought...
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
Is it supposed to be driven into the hollow tube? Drilling does seem like the way to go.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
The lock pin is supposed to fall into the blind hole as it's driven in. It looks like the pivot pin is 90 degrees out of position, but you have no way to figure out which way the shaft needs to turn. Try a little heat on the case to expand the hole, and move the pin a quarter turn with a big screwdriver and vise grips, or a ground down drag link socket. You'll either line up the hole or need to turn the pin another 180 degrees. That pin is hard enough to need a solid carbide drill bit to hope to cut it. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Is the shaft slot "horizontal"? There's a chance the last guy didn't have the pin and hole lined up and the pin is just smashed down on the surface of the shaft...can you turn the shaft with a big screwdriver?
Just a thought...
Mike B
Mike , the slot is vertical. I compared it to another SM420 I have and it looks correct. I have bumped the shaft and it does not move. Looks like some fun is about to happen.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
The lock pin is supposed to fall into the blind hole as it's driven in. It looks like the pivot pin is 90 degrees out of position, but you have no way to figure out which way the shaft needs to turn. Try a little heat on the case to expand the hole, and move the pin a quarter turn with a big screwdriver and vise grips, or a ground down drag link socket. You'll either line up the hole or need to turn the pin another 180 degrees. That pin is hard enough to need a solid carbide drill bit to hope to cut it. Jerry
Hey Jerry ! The slot appears to be parallel to the pin and looks to be the the exact same orientation to the "spare" SM420 I have in the shop. I noticed the top of the pin was mushroomed over so that makes me think someone "whaled" on it to get it installed. The top of the pin on the "spare" is nice and flat/square/crisp.
I'm going to try the heat method first and drilling last.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Can you not leave that in the case there shouldn’t be much you can do to when you take it out other than clean it up and you can clean around it when it is still in .
Can you not leave that in the case there shouldn’t be much you can do to when you take it out other than clean it up and you can clean around it when it is still in .
I don't know if I can get the countershaft out without removing the idler shaft. Plan was to replace all gears, shafts, bearings.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Hard steel pins can be annealed to soften them by getting the pin red hot and allowing it to cool slowly. Using a small heating tip on acetylene torch and concentrating the heat on the pin will heat it up without damaging the cast iron case. I'd suggest trying to do some annealing before you start drilling, if you choose to take that approach. Once the pin is out, you should consider threading that hole and retaining the shaft with a dog point setscrew instead of a pin when you do the reassembly. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Hard steel pins can be annealed to soften them by getting the pin red hot and allowing it to cool slowly. Using a small heating tip on acetylene torch and concentrating the heat on the pin will heat it up without damaging the cast iron case. I'd suggest trying to do some annealing before you start drilling, if you choose to take that approach. Once the pin is out, you should consider threading that hole and retaining the shaft with a dog point setscrew instead of a pin when you do the reassembly. Jerry
That's a very good idea Hotrod Lincoln. I'd considering threading that hole in case I somehow get the hole oversized when removing the pin.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I don't know why that pin would be hardened. It's only function is to keep the idler shaft from moving out of position, and a dead soft pin should be able to accomplish that. The fact that it's mushroomed seems to show that it's not hardened. But you'll find out once you try to drill it. Centerpunching it would tell the tale as well as to how hard it is. I'll bet it wouldn't take much of a tap on the punch to put a nice mark in it for drilling.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
I was able to use a file to start removing the "mushrooming" and ended up using the dremel to speed things up. So I don't think it's hardened. A bit of history, the pin GM# 590832 has been in use for various applications since 1939 and is described as 1/4" tapered x 11/16.
The lock pin in the SP250-50B Small parts kit is 11/16 long (.688 ) and measures .249" on the small end and .254" on the big end. So yes, its slightly tapered. I can "scratch" it with my old timer pocket knife blade so its not very hard.
I have close friend with a Bridgeport , along with a shop full of metalworking equipment, and I'll see if I can't talk him into getting the case squared up on an angle plate and get it drilled out with some level of precision.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Another place a threaded plug might be appropriate instead of a drift pin would be the full flow- - - -bypass selector pin on a late model 261 stovebolt engine block. I'm probably going to thread that hole when I build up one of the two late production 261s I have. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Mike , the slot is vertical. I compared it to another SM420 I have and it looks correct. I have bumped the shaft and it does not move. Looks like some fun is about to happen.
The shop manual says "Horizontal", which would put the slot in line with the pin.
I just went out and checked (4) different SM-420's I have and none of them have a slot in the shaft, so I have no idea how they lined it up when new...
Here's a picture of one of them.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
Have you considered welding a nut or a rod to the pin????
No guarantee but I would do some easy filling on the casting where the pin is located....just enough to see the outline/crack of the pin from the cast body of the transmission.....find myself a bunch of 5/16 nuts and weld down the middle...onto the pin......just like a broken stud........ a few will stick and a few nuts will fall off....and heat will build up in the tranny casting....... when you have a nut that seems to be solid....use penetrating oil or beeswax on the parts.... tap\ a few times on the nut......try moving the nut with a wrench....slowly back and forth..... it may break loose...start again...eventually is should release......
....and according to the drawing in your first posting the big pin is accessible from both ends....... can you tap lightly from each end of the big pin alternating every 3 or 4 taps..... it might loosen up the pin......also drilling the pin with a 1/8 bit then trying to screw in a metal screw to see if the pin might turn or even pull out....... patience is a virtue........ Good Luck
RAC1812, No , I briefly considered it but decided against it, below is my "update".
Well, my attempt to "drill" failed when the bit "walked" so its off to the friend with a bridgeport mill ..... For fun, I started working on the 2nd SM420 I have and the lock pin drove in with no problem. Using a .250 (1/4" ) drill I was able to determine that the hole for the lock pin is parallel with the top of the case so that's a big plus.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Got the trans case over to my machine shop guy and helped him get it setup on the bridgeport. Ran an endmill down through the lock pin and was able to remove it. Found that the hole in the idler gear shaft was not lined up with the hole in the case whick explains why I couldn't drive the lock pin through. Now on with the reat of the rebuild.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
Was the hole parallel or perpendicular to the slot on the shaft?
Yes, parallel to the slot and the hole in the case is parallel to the top surface (transmission cover mounting surface)
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
