Manual Transmission Differences

[TomC]

In reading some of the threads posted about manual transmission, I see there are misconceptions on how they work.  There are basically two different types of transmission-synchronized and unsynchronized or what is called a crash box. 
Currently there are synchronized transmissions-is what is in your car and available on big trucks up to 6 speeds and 860lb/ft of torque.  They shift by pushing in the clutch, moving the gearshift to the next gear without gear crunching-using cone clutches that synchronize the gear speed before allowing the shift to be completed.
When you get above 860lb/ft of torque, you get into double counter shaft transmission (use two opposing counter shafts to counter act any torque bending of the main shaft) 7 speed (no splitters); 9, 10 speeds with a high/low range selector; 13, 18 speeds with a high/low range selector and a gear knob mounted direct/overdrive splitter; 15 speed with a high/low range selector and a dash mounted creeper range selector; 10 and 11 speed double lows that have a high/low range selector and a shifting knob mounted creeper gear selector.  All the transmissions above 7 speed (in the U.S.A.) are non synchronized transmissions.  What I see as a misconception is that many think these have sliding gears that crunch into engagement.  The ONLY gear that slides into engagement is reverse.  ALL other gears are constantly meshed together and are all spinning together all the time.  The only difference between a synchronized transmission and a non synchronized transmission is that a synchronized transmission has the cone clutches that spin the gears to the correct speed for you to allow a smooth shift.  In the non synchronized transmission, you have a sliding square cog that has to get to the correct speed before it will slide into the square hole of the next gear.  This is what makes for the feel of the gear crunching into the next-when in actuality the gears are always engages and it is the cogged slider that is making the gear crunching noise.
I know-way to much information.  Just trying to clear up a minor misconception.  Good Luck, TomC

[Dreamscape]

Tom C.,

As always your information if SO VALUABLE.

Thank You for taking the time to share with us that are so uninformed, and less experienced.

I always learn so much from your posts.

Paul

Dreamscape

[boogiethecat]

Tom, any idea why my FS6406A (supposedly brand new) is such a MONSTER to get into 3rd or 4th?  I have to push the shift lever up HARD and then a titch to the left to get it into 3rd from any other gear except 4th.  Once it's in the "pocket" it'll go easily from 3rd to 4th or back... just getting it in that gate is a total pain...

[TomC]

Gary- it sounds like the shifting gate on the top of the transmission is either worn or out of alignment.  I don't think it is the shifting fork in the transmission since you say that the transmission shifts fine once in the 3rd/4th slot.  I also assume that there are no shifting slots in the gear shift lever and linkage-meaning that when you had the linkage disconnected from the transmission did it just mover around freely, or did you feel some built in bumps or spring resistance in the linkage?  My best guess is you'll have to take the top plate off the transmission and inspect the 3rd/4th slot for being bent or worn, or even one of the other slots (1-2 or 5-6) also being bent causing an interference in letting you get into 4-5.  Since it goes into 5-6 and I assume alright into reverse, the general shape of the linkage should be good since those are the extremes side to side travel of the gear shift.  Let me know what you find.  Good Luck, TomC

[lloyd]

Just an addition/comment to Tom's discription of the manual transmissions, the 9,11,13,15,18 the reverse gear is a sliding collar not  a sliding gear, just like all the other gear selction in that transmission. In cause you needed to know that. The auto shift is basically a non synchornized transmission(manual gear box) with electric shift motors controlled by an ECM.
Lloyd