[416_Doka_82]

Hi, Looking for advice on a 416 gearbox. Having trouble down shifting into 4th & 3rd, i get grinding when trying to geting into these gear. why would this be? any help would be great.

cheers

 

[Tmax]

the common answer to this is that your synchroniers are worn out but there may be more to it. you may have the dreaded set screw failure that many seasond mog owners hate. what year is your mog and do you have any idea what trans it may have?

there are two varients. the f and the g trans. i used to have the f model with the same issue. not only did it not shift into these gears, but it would also not even stay in 1st or 2nd. i ended up tearing it apart and replacing a bunch of parts while i found the set screw at the bottom of the case.

in the past, it was mentioned that the set screw can be put back in by driling a hole in the case at the right spot. not sure if this applies to the f or g trans but just recently, in a G model, i did put it back in through the pan with no holes in the case. it was not that easy but doable.

so long story short, the set screw that holds the `1/2 gears may have come loose witch is a very common problem.

 

[hammogger]

Or you might have a dragging clutch. The lower gears don't shift very well if gears are still moving.

 

[MegaMog]

From my recollection the "Dreaded set screw failure" scenario usually resulted in a complete lockout of the gears, which doesn't appear to be the OP's problem. But since the set screw failure was brought up, I'm posting this story which was posted by Mike Hessling on the Mog List a few years back.

An interesting and informative read to say the least:

I had a similar experience with my 406 transmission and also was ready
to throw it to the junk pile. I was out for a drive and right in the
middle of an intersection it decided not to shift any more. It had run
perfect right up till that point. I shifted into neutral and took my
foot off the clutch to wait for some traffic to clear. Pushed in the
clutch and tried to put it into gear and had nothing. It was stuck in
neutral and all the coaxing in the world would not let a single gear
engage. Got out and with the help of a passing friend pushed it out of
the intersection. Towed it home and started trying to figure out what
went wrong.

First thing I did was drain the transmission and check the oil for
signs of destruction. Other than a little bit of fuzz on the magnetic drain
plug there was nothing. I removed the bottom inspection plate and
checked for more damage. Still everything looked just fine. No broken
teeth and no messed up gears. I pulled the top off with the shifter
and started checking the shifting plate. With it clamped in my vise I
was able to move it through all of the gears just fine so I pretty much
ruled out the shifter. I started messing with the gear clusters with a
large long handle screwdriver. I was able to engage and disengage all
the gear clusters except for one. Not knowing any better I assumed it
was because it just wasn't lined up correctly. Thinking that it might
have just been a burr on a slider I put it all back together, filled it
with oil, and fired up the motor. Quite the bummer when I tried to get
it into gear and nothing worked.

Again, drain all the brand new synthetic oil and take all the covers
off. At this point I am starting to think about where can I get a new
transmission and is it just the straight 6 speed part or is it
something to do with the cascade system or in the hi/lo range or in the reverse
section. In pure desperation I posted a plea for help here on the MOG
list. I got one lone reply from a person regretfully I can not name.
Not because I don't want to thank them again but because I don't
remember who it was. Shame on me for not saving the email. But I did
commit the answer to memory which is good because about 5 months later
it happened again because I chose to take the easy way out rather than
a more permanent fix. So here goes, I will try and describe this as best
as I can.

If you remove the top and bottom covers to the transmission it will
make this easier from my view. You will need a small inspection mirror and
a good drop light or strong flash light. Jack up the rear end of the
truck so you can spin the tires over easily. What I did was use my
foot to turn one of the rear wheels but a willing assistant will work good
to. When you spin the wheel one of the gear clusters will turn with
it. The cluster is toward the back of the inspection cover. It is
hard for me to describe which one. If you are laying on your back
under the truck with your feet towards the rear axle the gear cluster is on
the lower left of the inspection hole and disappears back into the rear
of the transmission housing. With the mirror you need to look back
toward the middle of the cluster. While slowly turning the wheel look
for a hole in the center of the cluster. Through this hole is a set
screw which I believe secures the shaft to the inner sleeve and holds
the cluster together. In any case, using a long handle allen wrench
(not sure the size but it is metric), check to see that the set screw
is tight. In my case it was loose and while it had not fallen out it
looked like it was ready to. Here is where I made my mistake. I
reasoned that since it had taken since 1973 for this set screw to
loosen up that if I just retightened it that it would probably take another
long time for it to loosen up again. Wrong answer. I tightened it up
and even put a little cheater bar on the allen wrench to get it extra
tight. Put it all back together, fired it up and everything worked
great. I actually put the top shifter plate back on first and tried
shifting it without the motor running. All worked well and I finished
the job and was off and running again. That lasted for about 5 months.
Then the same thing happened to me but this time I was in a parking
slot at work and when I tried to back up it was the same problem. No
gears.

Back to the house and back into the transmission again. This time I
took the advice of the person who I can't remember and drilled a hole
through the transmission case right under where the set screw is. You
can come pretty close using a ruler to take some measurements. As you
will see when you get under there, where that set screw is located is
way to tight to try and get the set screw out and back in again. At
least it appeared that way to me. By drilling the hole it allowed me
to get the set screw out. Clean the hole and the screw with some lacquer
thinner and then put it back in place with a good dose of red
Loctite. One thing to make sure of is that before you tighten the
set screw, try and ensure the cluster is in the middle of the shaft. Mine
actually looked like it had a dimple in the shaft either from the set
screw or one that was there from the factory. Try to center it as best
as you can before you measure for the hole. Either by good luck or
what ever mine worked out perfect. The hole ended up in the right spot.
After I was done with the set screw I taped out the hole for a 1/8th
inch pipe plug and sealed it up. Replaced the top cover and again
verified all the gears worked then put the bottom cover on and refilled
it with oil. That was 2 years ago and I have not had a problem with it
since.

One thing I did with mine and I know there has been a lot of discussion
about it on the list. I refilled my transmission with synthetic oil.
I know it is a matter of personal choice but I think it works better
than regular gear oil and is worth the money. There are many different
kinds available. I chose to use the Valvoline Synthetic Gear Lube because I
happen to like Valvoline and that's what my local Napa dealer had
available in a large enough quantity to refill the whole transmission.
Prior to changing out the oil I had troubles with it shifting hard
after a long high speed run. It almost seemed like it didn't want to go into
gear or that the syncro's were not working. Since changing to
synthetic I have had no problems with it no matter how long or how hard I run
it. Just my 2 cents worth.

I hope this helps you with your problem. Your description of what is
wrong sounds very similar to mine so it may be worth checking. To the
person who helped me out of the jam before if your still on the list I
say thank you again and if this fixes the problem all the credit goes
to you. If you need more information finding the set screw let me know .
I will try and help you as best as I can.

Mike Hessling
1973-406
Waterford, CT

 

[416_Doka_82]

Thanks for the info, i will get under the truck this weekend and find out about the type F or G. Year model is 1982, with 6 speed.

Last night took it for a drive and with the help of a bit of double clutching and ensuring the revs where low enough grinding is better.

With the story about the set screw and the drilling of the housing, have also heard about that before, would be good if someone had some pictures to show.

cheers and thanks agian.

 

[Spicergear]

MegaMog: GREAT POST!

 

[Tmax]

Thanks for the info, i will get under the truck this weekend and find out about the type F or G. Year model is 1982, with 6 speed.

Last night took it for a drive and with the help of a bit of double clutching and ensuring the revs where low enough grinding is better.

With the story about the set screw and the drilling of the housing, have also heard about that before, would be good if someone had some pictures to show.

cheers and thanks agian.

if its a 1982, then very likely you have the later trans. i assume its (G)

one thing to note is that although these two models look almost identical externally, the inside is quite a bit different. i think the G trans hast two set screws. one for the 1/2 gear and one for reverse gear. the F model has only one for the 1/2.

 

[MegaMog]

...one thing to note is that although these two models look almost identical externally, the inside is quite a bit different. i think the G trans hast two set screws. one for the 1/2 gear and one for reverse gear. the F model has only one for the 1/2.

I can't verify the following, but for what it's worth Jay Couch once told me that the the G Tranny can be identified externally by the presence of a raised casting on the passenger side of the tranny that looks like a pentagon with unequal sides. Based on that I've always assumed my '70 406 has the G Tranny, but I don't see anything on my Data Card to support this. I will say that when I replaced my front output seal I ordered one for a a G Tranny and it was the correct one, but for all I know the the F & G Tranny's may use the same output seal.

Here's some pics of my tranny:

 

[Tmax]

the way that i identify the two from each other is that the later trans, had a detent in the neutral position for reverse shifter with short throw where the earlier f tran has a long throw with no detends.

 

[esde]

the way that i identify the two from each other is that the later trans, had a detent in the neutral position for reverse shifter with short throw where the earlier f tran has a long throw with no detends.

Wouldn't that difference be in the shift cover, and not necessarily the trans case itself? As someone could install the cover from an early trans onto a later, or vise versa? The trans # is on the side facing flat under the top shifter cover, it will tell you F or G. Also, the f and g use the same side PTO bolt pattern, but the 2 locating dowels are in different locations, and the bolts may be different diameters (think they are but it's been a while...)

 

[Tmax]

Wouldn't that difference be in the shift cover, and not necessarily the trans case itself? As someone could install the cover from an early trans onto a later, or vise versa? The trans # is on the side facing flat under the top shifter cover, it will tell you F or G. Also, the f and g use the same side PTO bolt pattern, but the 2 locating dowels are in different locations, and the bolts may be different diameters (think they are but it's been a while...)

the shifting mechanism may be totally different as far as the location and the travel goes. the only way to tell is to have them side by side to compare. however, the revers does require more travel from one to the other so i would guess that part is different for sure.


i have seen the two different pto bolt sizes so that could be also one of the differences. i think one uses 6mm versus 8mm for the other.

ofcourse the tag is probably the best and most logical way to identify this.

 

[NevMog]

From my recollection the "Dreaded set screw failure" scenario usually resulted in a complete lockout of the gears, which doesn't appear to be the OP's problem. But since the set screw failure was brought up, I'm posting this story which was posted by Mike Hessling on the Mog List a few years back.

An interesting and informative read to say the least:

I think I have the same problem and my unit is a 1973 - wish you had pictures to go with the explanation...