Date registered: Dec 2002
Vehicle: 200D, 300TD, 230GE
Location: Flagstaff, AZ
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
460 Transfer Case "Play"
With Dave's (Hipine) permission, I thought I'd post an email I sent Dave and his email reply to me regarding a question that's been nagging me for some time. Perhaps it will help someone else. As you can all see, Dave's knowledge in this area is unsurpassed!
My email to Dave.........
Its Bruce in Flagstaff, AZ. I've got a question regarding my transfer case.
Since you recently rebuilt one, and had one explode, I just know you can answer
it for me.
Since I've owned the G (almost 3 years) I sometimes hear a "clunk" sound come
from the drivetrain when in real rough stuff or when going from coast to
throttle or vice/versa quickly. Like slack in the drivetrain. Mostly in low
range. A few months ago I heard the same noise under the same circumstances
from my buddy's brand new Jeep Rubicon. I asked him if he knew what it was and
he said "no".
Today while greasing the G, I decided to see if I could reproduce it when it
was lifted with all 4 wheels off the ground. I could. Here is what I found.
-In low range, the input shaft and the front drive shaft move together, that
is, there is no play between them. However, the rear driveshaft rotates with
about 12-14 degrees of freeplay before turning those two (or vice/versa). If
you move the rear driveshaft quickly back and forth past that play, you can
hear a clunk. I assume when the gears mesh.
-In 4-wheel high range, the input shaft and the rear driveshaft move together
(no play between them) and it is the front driveshaft that moves with about the
same 12-14 deg of play. Moving the front shaft quickly back and forth will
make a similar "clunk" at the ends of the travel, but not as loud.
- In neutral there is about 12-14 degrees of free play between the front and
rear driveshafts and of course the input shaft is not tied to them.
- In 2-wheel drive there is no play between the front and rear driveshafts.
There does not seem to be any up/down in any of the flanges. The truck does
not have any appreciable transfer case vibration as so many complain of.
SOOOO, my question is - is this normal or do I have a building problem?
Perhaps you could check the behavior of your spare transfer case to tell me if
this is what you find. If its not normal, would you hazard a guess as to what
is worn or loose?
Thanks so much,
And Dave's reply......
"Totally normal, Bruce.
The play has to do with a connection between gears on the front and rear
half of the front output shaft. The play is required to facilitate the
synchronized transfer case. The different direct/play connections you note
have to do with how the power travels through the case.
2wd hi - power goes straight through from input to rear shaft, the "play" on
the front output shaft isn't even in the picture, and it spins free
4wd hi - power is still straight through, so input and output turn together,
but now the front shaft is also driven, but it's driven by gears at the back
half of the case, so the "play" is preceptible at the front output.
4wd low - Power is transfered immediately from input to front output shaft
by gears at the front of the case, and the rear shaft is driven off the tail
end of the front output shaft (by the same gears that send ower out the
front in 4 hi), so the play is perceptible at the rear output.
Or, to put it a little more simply, there's ALWAYS play between the front
and rear output flanges. Which of the two is connected directly to the
input flange is determined by the hi/lo selector. In Hi, the rear flange is
connected directly to the input (by selector splines), in low, it's the
front flange that has the direct connection (by gears).
If the flanges are free of shake, and not leaking, you'de doing good!