A520 5th shift fork moves freely

[cout]

So I'm driving downtown and start to shift into 3rd, and all of a sudden I don't have any gears. Van is stuck in neutral and won't go anywhere. After removing the selector shaft housing from the top of the transmission, I was shocked to see that the selector shaft itself had sheared in half! I'll post pics soon.

I also notice that the 5th gear shift fork moves freely back and forth (there is still resistance on 1-2 and 3-4). 5th gear has always tended to grind but never really pops out of gear.

Is it likely that something else broke along with the selector shaft? Or could this be how it was all along? Is it drivable like this or do I need to swap the whole transmission?

What mechanism in the transmission makes the fork stay in place in the first place?

[a89mini]

It sounds like you sheared off a retainer bolt and or 5th gear dowel pin see pic

is it drivable=not unless you want more damage!


31833

[22mopar]

since you really need to pull the trans to fix it, why not just toss in another good used trans since they are cheap. heck might be a good time to update to a 555.

[cout]

I have another 520 I can put it. I like the 520 because of the final drive ratio (this is a daily driver for me, so I'd rather have good gas mileage). Also it was the only manual transmission I could find within a 150 mile radius of Charleston.

a89mini, I'm not sure what you mean by "retainer bolt" and "dowel pin". Closest thing I can find in the service manual is a "5th speed shifter guide pin" (#16 in your diagram), a "roll pin" (not shown in your diagram), and a "fifth fork set screw" (attaches to #14).

The service manual also says that the transmission is serviceable without removing it from the vehicle. Is this not correct?

[22mopar]

some parts are serviceable but really, why not just put another trans is. want to take a chance that some part is rattling around in the gear box and have it lockup in the middle of nowhere? It'll be a lot quicker and easier just to put another trans.

I have these vans with 520 trans and with 555 and 568 and even a 525. I have noticed no difference in fuel milage on any of them all with the same engine.

[cout]

I've never changed out a transmission before and was hoping to avoid it if possible. That's what I'll do if it's my only option though.

According to http://minimopar.knizefamily.net/transmanual.html and http://minimopar.knizefamily.net/perf/drivemanual.html, the final drive ratio in the A555 is 3.85:1 and in the A520 it's either 3.85:1 or 3:50:1. I had taken this as the gospel truth but I just checked the service manual and it says the A520 has a 3.81:1 FD ratio. I guess that lines up more with what you're saying. I haven't checked the stamp on my transmissions yet to see what I have.

[22mopar]

My 520 minivan trans has 3.85 and my 520 from a shadow has 3.50... I've put the shadow trans in the minivan 'hoping' for better fuel mileage. made no difference what so ever. all 555's are 3.85.

r&R the trans in a minivan is super easy. I did my very first one in just 2hrs... in the driveway.

[a89mini]

I have another 520 I can put it. I like the 520 because of the final drive ratio (this is a daily driver for me, so I'd rather have good gas mileage). Also it was the only manual transmission I could find within a 150 mile radius of Charleston.

a89mini, I'm not sure what you mean by "retainer bolt" and "dowel pin". Closest thing I can find in the service manual is a "5th speed shifter guide pin" (#16 in your diagram), a "roll pin" (not shown in your diagram), and a "fifth fork set screw" (attaches to #14).

The service manual also says that the transmission is serviceable without removing it from the vehicle. Is this not correct?


You say you have another 520 you might get away with borrowing parts from said 520 and using to repair van without changing trans completely!

diagram is kinda vague but breaks down as=

#2=Selector Shaft=======(YOU BROKE THIS?)=========
#14=5th gear shift fork
#16=1/2 shift fork
#17=3/4 shift fork
If you broke Selector Shaft it was probably due to engagement of two gears at once,
maybe 5th gear not releasing?there must have been a bang or clank at that moment!?

The key word is "pin" #14 in diagram is 5th gear fork which is held

by a "fifth fork set screw"(appears in diagram as roll pin/dowel pin/sping pin?)
just above # 14 this can only be seen w/side cover removed.

318465th gear fork w/set screw

Now if 5th gear Shift Fork Rail is moving freely without engaging Synchro than "set screw" could be broken?You must pull side cover to verify but can all be done in vehicle.
(I dont Believe theres a detent for 5th gear rail,detents are the ball and spring w/retainer bolt between #S 12 & 15 of diagram)should be part of selector housing.

GOOD LUCK-Richard

[135sohc]

The service manual also says that the transmission is serviceable without removing it from the vehicle. Is this not correct?

These 5 speeds are VERY serviceable IN the vehicle.

[cordes]

These 5 speeds are VERY serviceable IN the vehicle.

I would think that to be even more so in a turbo van.

[a89mini]

A complete "inframe" o/h is possible if you knew clutch and input shaft were still good!



=Richard=

[22mopar]

I wouldn't because getting things lined back up would be a PITA.

[cordes]

I wouldn't because getting things lined back up would be a PITA.

Way easier than pulling and reinstalling the trans though.