ZF5 S42 3-4 synchro snap ring and tons of shifter movement

[Flybyrotor]

So.........anyone know whats gonna happen if this snap ring completely unseats?

[Ford F834]

What is the context of this? Do you have one apart? Are you rebuilding it?

[Gary Lewis]

I don't know, but there's a ZF troubleshooting document here: Driveline/Transmissions/Manual Transmissions/ZF5.

[Flybyrotor]

I've got one in my truck, and recently theres been quite a bit of shift lever movement while heavy accelerating in 2nd and 3rd. The troubleshooting guide on this site indicates that for 3rd gear shifter movement, its the snap ring on the 3-4 synchro not being seated all the way. It doesn't indicate anything about a problem in 2nd, so I still need to check the trans and motor mounts, but the shifter does a figure 8 almost when in gear, so it doesn't seem like a mount issue.

I'm just curious what the end result will be if this snap ring completely dislodges while driving.

[Gary Lewis]

For the shifter to do a figure 8 it would seem like multiple mounts would have to be bad.  I suppose that's possible, but it seems unlikely.

And that leaves the tranny itself, and more specifically the snap ring.  But, I'd doubt that it just worked loose.  So has it been this way from the start, or did it start recently?

[grumpin]

I had to have a shop get into my ZF5 I had in a 1988 F250 with the 7.3 diesel.

One time my wife used my truck, I got in and drove towards work. Pulled up to a stop sign in second, checked traffic and reached over to put it in first. No shifter! Look down and it's laying on the floor!

The shift tower broke. Might want to check that.

Of course, I blamed my wife!

Another time, IIRC, it was a bent shift fork.

[Flybyrotor]

Gary, it was a recent/ immediate change. The second it did it, I just stopped and looked down at the shifter like "that the heck was that". The manual doesn't specify what type of movement there will be, it just says movement in 3rd. Its a new ZF, with maybe 7K on it now. Theres got to be a way for that snap ring to work loose though, otherwise they wouldn't put it in the troubleshooting section of the ZF manuals I wouldn't imagine. That would be a shops mistake, not a known issue with the trans.

I have had the shifter off recently, but it was after it started figure skating around the cab on me, so I'm pretty confident that its not loose. Both motor mounts and trans mounts are also new, so the odds of it being a mount issue, let alone a multiple mount issue seems slim to me.

[Gary Lewis]

Certainly seems like a tranny issue.  Is there a warranty?

[Flybyrotor]

unfortunately its only a 12 month warranty. The company was a nightmare to deal with, so I wouldn't rely on them for the warranty anyways. It'll take me 30 minutes to get the trans out, I'm sure a shop would be pretty reasonable to fix it. In the long run I was just curious what was gonna happen if I don't fix it asap.

[Flybyrotor]

So, a bit of an update;  trans mount is good, motor mounts are in excellent condition, bolts that hold motor mount to motor.... non existent. The more someone else works on this thing the more pieces come back not tightened Down. That being said, does anyone know offhand what size those two bolts are so I don’t have to pull one while at work tomorrow??

[Gary Lewis]

Looks like it is: 387811-S100 (BB—551—BT)—bolt (insulator to eng.)-7/l6"-14 x 1"

And, that's good news!

[Flybyrotor]

Awesome, thanks Gary!