Glad to hear that you finally beat this gremlin. For a while, it sounded like it was getting worse every time. It is one of those things that would take 2 minutes to show someone how to do, but take 20 minutes to describe in words.
sm420 stuck in gear
- Thread starter mancinator
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I thought I would bring this back up. I just installed a known working SM420 and it drove fine about 30 miles. Went to put it in reverse and couldn’t get the sm420 in gear. Lots of slop in the shifter and I could either only get 1st (with lots of cussing and manhandling the shifter )or when I let off the clutch, the tranny would bind and lung the motor until the engine died. No neutral.
Does this sound like a similar problem as posted by the OP? I’m trying to eliminate any possible issues I can try before having to pull the tranny.
Does this sound like a similar problem as posted by the OP? I’m trying to eliminate any possible issues I can try before having to pull the tranny.
Yes, it sounds like a top cover shifter problem. If the tranny is bound up and won't budge, two gears are engaged at the same time. Start by taking out the shifter cane and peek inside the hole to see if the shift gates are all lined up in a row. The gates are the slots that the nose of the shifter cane fits in to. Take a flash picture if you can.
Appreciate the response. Had a full day with the wife and son and will take a look tomorrow. I'll let you know how it goes.
Edit: Posted pics.
Looks like I need to line up the slots. what caused this and how can I fix it so it won't happen in the future? Any other comments from the pics?
Edit: Posted pics.
Looks like I need to line up the slots. what caused this and how can I fix it so it won't happen in the future? Any other comments from the pics?
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The tranny is in gear as the top slot doesn't line up. Which gear isn't clear because I can't tell which direction is front. Move the top shift rail to the left so its slot lines up with the other two. You may need to put the transfer case in N to get it to move. Then put the cane back in.
Wear on the cane nose, the ball and the retainer can cause it to slip out of the slot and get stuck.
Wear on the cane nose, the ball and the retainer can cause it to slip out of the slot and get stuck.
Thanks for the response PinHead...FYI, the top is towards the front of the 40. Here are a few pics of the cane nose, what can you tell me about it? Can I weld on more material and grind it back into better shape? If so, how much material can I add?
Short of taking the top cover off, is there anyway to fix the ball and retainer so it doesn't do it again? If I do have to take the cover off, what is the proceedure to fix those two parts?
It rained nonstop here all day so we did chucky cheese and a movie with my son so family got in the way of the Cruiser again. Dogeared some time tomorrow evening to give it a try.
Short of taking the top cover off, is there anyway to fix the ball and retainer so it doesn't do it again? If I do have to take the cover off, what is the proceedure to fix those two parts?
It rained nonstop here all day so we did chucky cheese and a movie with my son so family got in the way of the Cruiser again. Dogeared some time tomorrow evening to give it a try.
To be honest, I am disoriented if the top of the pic is forward. I don't see the gates that the nose fits in to. There are 3 of them from L to R facing front: 3-4, 1-2 and R that has a spring you need to compress for the nose to go in.
Line them up by prying them so they are all in a straight line. This is N. then put the cane back in. The nose looks pretty good. It is not obvious why it got out. Try it and see if it works.
Line them up by prying them so they are all in a straight line. This is N. then put the cane back in. The nose looks pretty good. It is not obvious why it got out. Try it and see if it works.
That is better. It appears to be stuck in reverse gear then. Pry the top slot over until it lines up with the other two and you should be good. Use a big screw driver or the shifter cane. The problem is the nose got out of the slot somehow.
OK. I got them all push forward and lined up. Learned what that plastic part is at the top of the pics above with the pin sticking to it. When they are all aligned in neutral, that pin pushes forward covering the top rail in the pic. I would suppose this is so the tranny can't be put in reverse or first while running at high RPMS. Once they were in neutral, I could only see the two bottom rails (pic) because the plastic piece covered the top one.
I started the rig without the clutch and it was in neutral, so this is promising. Marlin mentioned that he thinks my top cover is warn out so I would assume I either need rebuild or replace.
Thanks for the help Pin_Head. I wasn't able to drive it. It must have rained 1" in about 30 minutes last night so I didn't feel like taking a shower while driving the rig.
I started the rig without the clutch and it was in neutral, so this is promising. Marlin mentioned that he thinks my top cover is warn out so I would assume I either need rebuild or replace.
Thanks for the help Pin_Head. I wasn't able to drive it. It must have rained 1" in about 30 minutes last night so I didn't feel like taking a shower while driving the rig.
The little pin that fits in to the right slot is the spring that you have to compress to get it in to reverse. It should work fine now, but if it happens again, it is time to dig into the top cover or replace it. If it can go into two gears at the same time it will bind up and this should never happen. The top cover is designed to prevent this, so if it happens, it is worn out and needs replacement. If you replace it get the same one. There are two different ones and they are not interchangeable.
Pin_head,
Can you help me figure out the production date of my 420?
Casting numbers look like this:
K295
GM
3837334
Edit: I also included the top cover identifying numbers: On the driver side: 591568
On the passenger side top cover: K2362 (does that stand for 11th month/November 23 1962?)
Problem is Novak's website states side markings beginning with 38 would be a 1964-67 build date, but the top cover markings indicated by Advanced Adapters is a 1962 build date.
Maybe top cover was replaced in the past?
Can you read the date out of that? That's every external identifying mark on the tranny.
Do you happen to know what the cut off dates are between the two types of top covers (which years are compatible with which cover and which will work for mine)? My shift interlock plate is plastic.
Thanks, Dan
Can you help me figure out the production date of my 420?
Casting numbers look like this:
K295
GM
3837334
Edit: I also included the top cover identifying numbers: On the driver side: 591568
On the passenger side top cover: K2362 (does that stand for 11th month/November 23 1962?)
Problem is Novak's website states side markings beginning with 38 would be a 1964-67 build date, but the top cover markings indicated by Advanced Adapters is a 1962 build date.
Maybe top cover was replaced in the past?Can you read the date out of that? That's every external identifying mark on the tranny.
Do you happen to know what the cut off dates are between the two types of top covers (which years are compatible with which cover and which will work for mine)? My shift interlock plate is plastic.
Thanks, Dan
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What is vague about it Dan?
Your casting number(according to you) is 3837334 which falls into the 1964-1967 list.
If you want your transmission to shift properly, find a top cover from that same era/casting number run. The top covers have casting numbers on them just as the cases do.
I have mixed covers prior to 1964 onto 1964 and later transmissions and they will stick in gear and not shift properly.
The top cover date is what you suggest.
K295 might be Nov. 29, 1965, but the few I have seen have always been a 2 digit number for the year.
I don't know the cut off dates for the changes. When I bought my rebuild kit, they asked me for the date code because they told me that there were 3 basic variants with slight differences in the input seals, synchro rings and top cover. There are also differences in the low gear and a few things that are specific for heavy trucks.
I would call tourist auto or Anaheim gear and ask them.
K295 might be Nov. 29, 1965, but the few I have seen have always been a 2 digit number for the year.
I don't know the cut off dates for the changes. When I bought my rebuild kit, they asked me for the date code because they told me that there were 3 basic variants with slight differences in the input seals, synchro rings and top cover. There are also differences in the low gear and a few things that are specific for heavy trucks.
I would call tourist auto or Anaheim gear and ask them.
Thanks guys. I'll give Anaheim gear a call Monday.
Poser, the confusion is in the different dates between the tranny and the top cover. They do not match up or even fall into the same build date separation categories that Novak and Advanced indicate. 1947-63 are different than the 64-67 when it comes to some of the parts for rebuild.
My tranny is 1964-67 (38XXXXXX) and the top cover is 1962 (k2362) so that suggests the two were not originally paired together and thus the confusion. Since I know little about these, and Pin_head knows much more about them, I wanted confirmation that the two were indeed different build dates. So when I track down a compatible cover, it will work the first time.
Poser, the confusion is in the different dates between the tranny and the top cover. They do not match up or even fall into the same build date separation categories that Novak and Advanced indicate. 1947-63 are different than the 64-67 when it comes to some of the parts for rebuild.
My tranny is 1964-67 (38XXXXXX) and the top cover is 1962 (k2362) so that suggests the two were not originally paired together and thus the confusion. Since I know little about these, and Pin_head knows much more about them, I wanted confirmation that the two were indeed different build dates. So when I track down a compatible cover, it will work the first time.
OK guys. I removed the top cover and found the problem (after it still got stuck in two gears at once). The shifter interlock plate (plastic) cracked and broke apart (see pic one). Lots of little pieces in the tranny, but luckily it is plastic so the metal gearing broke it up without damage to the gears. I think I can just pull the bottom cover or drain plug and flush out all the pieces. So all I need is to track down a new shifter interlock plate.
I need to figure out how to take apart the top cover to put a new plate in. The speed shifter rails need to be removed to get the U shaped shifter yokes out of the way. It looks like I need to punch out the expansion plugs that cap the rails in place. (pic 2) Do you have any words of advice on doing that since I don’t think I can find replacements for them. It also looks like I am missing 2 interlock pins. Hopefully they are at the bottom of the tranny and not destroyed.
Last pic is of the internals (pic 3). Everything look right?
I need to figure out how to take apart the top cover to put a new plate in. The speed shifter rails need to be removed to get the U shaped shifter yokes out of the way. It looks like I need to punch out the expansion plugs that cap the rails in place. (pic 2) Do you have any words of advice on doing that since I don’t think I can find replacements for them. It also looks like I am missing 2 interlock pins. Hopefully they are at the bottom of the tranny and not destroyed.
Last pic is of the internals (pic 3). Everything look right?
I haven't spent too much time looking at the top cover of a sm420, so I didn't notice the plastic piece or know that it does. The things that prevent the shift forks from being in two gears at once are the interlock pins that are in holes between the shift rods. Maybe the plastic gizmo prevents the R fork from moving unless the other two rods are in N?
The disassembly usually involves removing the spring loaded detent balls retained by a screw cap, then driving out the roll pin that holds the fork on the rod and then sliding the rod out through the back and pushing out the plug. You have to remember to get the interlock pins and detent balls back in the right holes and note that the forks and rods are not interchangeable, so make sure they go back in the right hole.
Sure looks shiny in there.
Hope it works out for you.
The disassembly usually involves removing the spring loaded detent balls retained by a screw cap, then driving out the roll pin that holds the fork on the rod and then sliding the rod out through the back and pushing out the plug. You have to remember to get the interlock pins and detent balls back in the right holes and note that the forks and rods are not interchangeable, so make sure they go back in the right hole.
Sure looks shiny in there.
Hope it works out for you.
I found a new top cover. It has the metal shifter interlock plate so I just swapped out the whole top cover. Seems to work, but pops out of reverse, but the engine is off so it may just need to go through the gears with the engine running. I had to drain and remove the side cover of the tranny to get out all the plastic pieces. I am sure the gears would just chew them up, but they would probably start to wear down the gears with the particles so I couldn't run the engine until I get some new RTV.
Hopefully the new top cover will work. The forks were the exact same size and deminisions of the old one.
Hopefully the new top cover will work. The forks were the exact same size and deminisions of the old one.