Jump to content

Compound Shifter Stuck


leversole
 Share

Recommended Posts

I searched the forum and found nothing, but I read about this somewhere?!?

Anyway, on the first drive I got the compound shifter hung up...dont know what gear it is in, but I cannot change it. How do I "unjam"?

Other than that, I realize I got lucky last night, shifting this thing at speed is going to take some serious practice!

Thanks

Link to comment
Share on other sites

I searched the forum and found nothing, but I read about this somewhere?!?

Anyway, on the first drive I got the compound shifter hung up...dont know what gear it is in, but I cannot change it. How do I "unjam"?

Other than that, I realize I got lucky last night, shifting this thing at speed is going to take some serious practice!

Thanks

Sounds like you may have a shifting fork problem, or wear in the transmission. With the compound stuck, place the main in low or reverse, and using on and off power via the accelerator pedal, try to work the compound back to neutral. Keep moderate pressure on the stick when you apply, and release pressure on the accelerator but leave the main in low gear so you don't move very fast when you're not paying 100% attention to your driving. Triplex transmissions are a very easy shifting beast and I'm surprised to hear of one stuck.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

Link to comment
Share on other sites

I'd say the bottom end of the stick is worn to the point that it can jump out of one rail and get caught in between the rails when not shifted carefully. Back in the good ol days we used to carry a small pry bar in the truck for just such occasions. You have to stick the pry bar thru those 2 clevises that connect the compound shifter rails to the compound box and pry them into neutral, then the stick will be "unjammed"

To cure the problem, we used to build up the bottom of the stick with a welder, then grind it off to the approximate original shape & dimensions so it cannot jump out of the rails.

Until then you can also prevent it from jamming by shifting it "square", slide the stick straight out of gear, then across, then straight into the next slot. Don't push sideways on the stick when coming out of or going into gear.

Hope this helps.

  • Like 1

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

Link to comment
Share on other sites

I'd say the bottom end of the stick is worn to the point that it can jump out of one rail and get caught in between the rails when not shifted carefully. Back in the good ol days we used to carry a small pry bar in the truck for just such occasions. You have to stick the pry bar thru those 2 clevises that connect the compound shifter rails to the compound box and pry them into neutral, then the stick will be "unjammed"

To cure the problem, we used to build up the bottom of the stick with a welder, then grind it off to the approximate original shape & dimensions so it cannot jump out of the rails.

Until then you can also prevent it from jamming by shifting it "square", slide the stick straight out of gear, then across, then straight into the next slot. Don't push sideways on the stick when coming out of or going into gear.

Hope this helps.

Thanks! THat must of been it. I just moved one of the rails slightly and all is well. I was porbabably going fron lo to direct in a circular motion instead of up and over...lesson learned!

Link to comment
Share on other sites

I'd say the bottom end of the stick is worn to the point that it can jump out of one rail and get caught in between the rails when not shifted carefully. Back in the good ol days we used to carry a small pry bar in the truck for just such occasions. You have to stick the pry bar thru those 2 clevises that connect the compound shifter rails to the compound box and pry them into neutral, then the stick will be "unjammed"

To cure the problem, we used to build up the bottom of the stick with a welder, then grind it off to the approximate original shape & dimensions so it cannot jump out of the rails.

Until then you can also prevent it from jamming by shifting it "square", slide the stick straight out of gear, then across, then straight into the next slot. Don't push sideways on the stick when coming out of or going into gear.

Hope this helps.

AAAHH the good ol days! this is EXACTLY the fix my grandad used on the same problem! he was also a big proponent of "square" shift patterns! sometimes,he would (seemingly) let the RPM'S drop so low,you would think he was going to scratch gears! but i dont ever remember him doing so,this is the same way i learned to drive a duplex,triplex,etc.and always had good results....a lot can be learned just by paying attention!........Mark

Mack Truck literate. Computer illiterate.

Link to comment
Share on other sites

  • 1 year later...
  • 6 years later...

I have a 64 B61T with a triplex TRTL72 with a "stuck" compound shifter.  I'll use the suggestions on this thread to troubleshoot.  I think the "out of rail" problem will be the problem in this case because that stick feels like it is locked into a bad position.

Reverse, 1st and 2nd on the primary shifter work well.  I'll look for grease zerks too.

 

Thanks for the suggestions.

Link to comment
Share on other sites

5 hours ago, HugeHugh said:

I have a 64 B61T with a triplex TRTL72 with a "stuck" compound shifter.  I'll use the suggestions on this thread to troubleshoot.  I think the "out of rail" problem will be the problem in this case because that stick feels like it is locked into a bad position.

Reverse, 1st and 2nd on the primary shifter work well.  I'll look for grease zerks too.

 

Thanks for the suggestions.

H K trucking post has the best idea, I have done that many times to the aux. linkage many times.    terry:thumb:

Link to comment
Share on other sites

8 minutes ago, terry said:

H K trucking post has the best idea, I have done that many times to the aux. linkage many times.    terry:thumb:

Also bushings in the rail housing are probably worn out,might have to have some made..

  • Like 1
Link to comment
Share on other sites

I finally got to the compound shifter.  I removed the 4 cap screws holding the shifter.  The shifter, once removed, is stiff but does move.  I used a small vacuum to get out some of the dirt. 

The rails look like the compound drive is in Lo-Split.

I greased the zerk fitting and applied cleaner to the rails.  The left hand rail, for the Hi-Split and Direct, seems free and will move.  The right hand rail, for the Lo-Split, is firmly set and hasn't budged.  

My next step is to remove the floor panel so I can get better access to the top of the transmission.

I have a PTO drive to service with a drive chain that needs to soak in diesel for a couple of days so I'm going to do that while I see what advice comes my way.  :)

Thanks 

Compound_Shifter1.JPG

Compound_Shifter2.JPG

Shifter_Before.JPG

Link to comment
Share on other sites

On 4/8/2018 at 6:31 PM, Freightrain said:

Definitely see if it is the shifter or linkage that is frozen and not the box.  Pull the pin on the clevis and see if handle moves.

Where is the pin on the clevis or will I see that when I pull the floor plate?

Link to comment
Share on other sites

Might be a little easier on you if you get some silicon carbide sandpaper, rip it into about a 3/4" wide strip, get it around the shaft(s) so you can grab each end of the sandpaper with each hand, spray a little lubricant onto the rails and work the sandpaper back and forth working the rust off the shaft(s). Wouldn't be really good to drag that rust through the bushings if they are still serviceable.  

  • Like 2

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

Link to comment
Share on other sites

Just make sure the HI split is in neutral position before trying to move the other rail.  I'm sure the detents would lock the LO split side from moving if the HI split side is not in neutral.

Sure is one dusty, dry transmission.   Mine looks like it has soaked in a sludge pit with all the fluids that seep from it LOL!!   I clean mine off occasionally, but after a summer of driving it is coated with crap.  It's just done plum wore out.

IMG-20180116-202556-655.jpg

Larry

1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"

 

Link to comment
Share on other sites

23 minutes ago, 1965 said:

I’d fill that dude up to the rim with some diesel & let er soak for awhile 

That area doesn't retain any liquid. You could dam it up with modeling clay but really scrubbing rust with fine grit sandpaper is what is needed. The plating is worn away the shafts originally had which kept them from corroding. If they are kept lubricated they will do fine. Setting for long spells without movement usually renders this result.

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

Link to comment
Share on other sites

I appreciate the advice. I took the seat out this evening. It weighs a bit more than I expected. I removed all but two of the floorboard bolts. A storm came through and I lost my light. I can see the compound rails surrounded by dirt through the series-parallel switch opening.  I will get in there and learn more tomorrow. 

Link to comment
Share on other sites

I have a tri-plex trans out of a truck setting on my woodpile inside the shop I can photograph if you like. Been setting there for years and is my spare. It would show you the area unencumbered by a truck.....

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...