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View Full Version : Course No. 101--Dana 44, Please Help



wagone
07-24-2006, 02:08 PM
I believe that I need to replace the axles or at the least repack the bearings in my Dana 44 Avanti differential. Since I am not familiar with the differential innards I thought it best to peruse the factory shop manual before beginning. A couple of things confuse me. The first is that my knowledge (limited though it may be) tells me that "clearance" and "end play" are basically interchangeable terms. And yet the Avanti shop manual says that in adjusting the end play by adding or removing shims to first "Bump the axle shaft with a heavy mallet to eliminate all clearances. Mount a dial indicator on the shaft and check end play". If all clearances are removed how can there be any end play to measure? What am I missing here? Also my shafts appear to have about .050" end play (hence a part of my reason for concern on the health of my bearings--apparently some clown has installed way too many shims) and hence the race would appear to ride too far out in the outer cup. Part of my confusion results from the fact that if I pull one drum and shaft out this .050" the other shaft appears to slide in that same amount. But this does not appear possible as the inner end of the shaft is merely splined to the side gear on that side and if moving one shaft causes the other shaft to move the opposite direction would appear to necessitate the side gear, the entire case, and the other shaft moving (which wouldn't seem possible since the shafts are just internally splined to the side gear). What gives here and what am I missing? Also, I would assume that a dial indicator is mandatory when adjusting this end play, or is another method available? It would also seem advisable to start the adjustment process with too many shims and ease up to the .006" end play figure, as starting with too few shims is going to drive the outer cup in too far necessitating starting all over again by first removing the shafts and cups. This would appear tricky and rather time consuming to accomplish, but then finding a Stude mechanic after 40 plus years could be rather time consuming also. HELP!!

wagone and the R2 Avanti

N8N
07-24-2006, 03:29 PM
A good rule of thumb if you do not have a dial indicator is "enough to feel but not enough to see." However if you have as much end play as you say, and you say that *both* axles move in and out, I wonder if you don't have side play in the differential itself- IOW time to take it apart and see what there is to see...

If this is a TT diff, is it possible that one of the axle shafts was removed and reinstalled without the person doing same noticing that the thrust block had fallen out? I'm not sure if that would cause the other axle to move, but it certainly would cause monster, sudden end play.

good luck,

nate

--
55 Commander Starlight
http://home.comcast.net/~njnagel

Mike
07-24-2006, 04:00 PM
The inboard ends of both axles bear against a "thrust piece" that transfers end play from one axle to the other. That limits how far one can go in, by how far the other can go out!
Most Avanti's came with limited slip rears; and the thrust piece in those is really three pieces. Two look like large rivets. Their heads are against the ends of the axles. The rivets are drilled hollow so a pin holds the small ends together. Often, when axles are removed, these fall out of place, into the axle housing tubes on either side. You can fish them out from the axle ends. They probably can't drop into the center section.
On my Avanti the "rivets" were drilled all the way through, just like really big pop rivets. The pin was a hollow roll pin. I ran a piece of kite string through the housing, from one side of the car to the other. I threaded the parts on the string, and pushed them into place with a piece of brake line.
A '57 Hawk limited slip I worked on had slightly different pieces. The "rivets" weren't drilled all the way through; and the roll pin was a tight fit in both. It had broken at some point.
I don't know if the Avanti version was a manufacturing change, or someone's modification. If I find one like the '57 again, I will drill all the way through and enlarge the hole so the rivets can turn on the pin. There is no loss of contact area at the axles, since they have a recess at the center, anyway. I think if the thrust pieces can't turn in relation to each other, they will break the pin.
Mike M.

wagone
07-24-2006, 07:04 PM
My apologies for not mentioning in my initial thread that this is NOT a Twin Traction. I have the build sheet and the TT is not mentioned and with the rear end in the air and one wheel blocked the other rotates easily by hand and the drive shaft then turns--I believe this indicates an "open differential" (i. e., not TT). So.......I'm at a loss to know what could be wrong in the pumpkin and still cannot fathom how moving one axle could cause the other to move (pulled towards the other axle if it is "pulled out" the approximately .050"). As it seems to me all that would happen is that the splines on the shaft would pull out the .050" from the side gear internal splines. Perhaps I can locate an "old timer" who understands the problem but almost always I find that I can make repairs (once I figure things out) better than someone I pay because they don't know anymore than I do and won't take the pains to
get "something right". Good mechanics are as hard to find as a good woman! Once found either is worth whatever it takes to keep them! Hopefully this entry will elict other comments as I'm really not interested in an axle shaft pulling out or breaking while I'm driving.....guaranteed to ruin an otherwise good afternoon, if not putting someone in an early grave. Thanks for any good suggestions. Oh, if one wheel is left on the ground and the other jacked up there is no end play (at least not enough to see or feel)--that seems a little confusing but perhaps there is a logical explanation.

wagone and the R2 Avanti:D:D

Dwain G.
07-24-2006, 08:41 PM
I'm too lazy to retype all this, so here is a copy of what I hope will answer your questions, from June 2002 Turning Wheels
_____________________________

Studebaker says the axle adjusting shims belong on the right side, but some people prefer to install an equal amount of shims left and right. In fact some of the aftermarket repair manuals recommend this practice. Where did the second reinforcing plate come from? Is there one on the right side? Of the 4 or 5 shims offered, the thickest is about .060” thick (1/16”). This may just be an extra unused shim. The wire apparently was someone’s attempt to eliminate what they saw as excessive end play. Do make sure the correct bearings are installed. The cup should have number 14276 on it, and the cone 14132T. The small end of the bearing cone (with rollers) and the thick side of the bearing cup both face out. When the axle is installed, the bearing cup should be about flush with the axle tube flange. It will be positioned later. When you install the shims, notice that the center hole in the shims is big enough to allow the bearing cup to fit through. When you install the backing plate, notice that it’s center hole is smaller and that it acts as a stop or retainer for the bearing cup.

When we talk about adjusting axle end play, we are really adjusting the wheel bearing clearance. The procedure is hard to understand because logic tells us the axles would have to be one solid piece left to right for this to work. Well, they are, sort of. If you push one axle in, it will push the opposite axle out because the inner ends of the axles butt up against a thrust block located inside the differential. With axles and bearings in place, install all of your shims on the right side (measure the thickness of this “test pack” with a micrometer or vernier caliper, some math comes later), then the backing plates, reinforcing plates, and outer seals, and tighten the bolts and nuts. At this point the shop manual says to bump the axle end with a heavy mallet to “eliminate all excess clearance”. Do this to both axles. This is an extremely important step and needs to be explained further. Heavy mallet means lead, brass, or big dead blow hammer. Hitting the end of an axle drives the opposite bearing cup outward until it seats against the back side of the backing plate. This is where it will stay, ready to absorb side thrust loads while cornering. If both axles are now pushed left and right, some movement should be felt. This is the clearance we need to measure and adjust. We only want a total of .002” to .006” total side-to-side movement, and this is hard to measure with anything other than a dial indicator. I suppose if one was to design a stout adjustable arm and bolt it to the left side backing plate, they might be able to get a reading using feeler gauges. If that clearance is too great, you must do the math, remove the determined amount of shim to bring end play into specification, then reassemble and retest. If the end play is still excessive with all shims removed, that probably means the thrust block is damaged or worn.

And yes, the brake drums, wheels, and tires also shift left and right along with the axles. But when the clearance is within spec., that is only about the thickness of one or two pages of Turning Wheels!



Dwain G.

wagone
07-24-2006, 09:16 PM
Thanks a bunch Dwain G. This helps answer my questions except the one (and maybe I'm wrong about this) where if I pull out on one shaft the other goes "in".......I can see how if you push one in the other would come out, but not the reverse. Guess I'll pull the shafts and see how many shims are in place (if any) and go from there. If no shims I'll take the pumpkin cover off and investigate there.......I'm sure the diff should be drained and checked for metal filings anyway. Thanks again and thanks to the others who answered and any who might still respond (can't have too much information I say....unless of course it is contradictory, and I just LOVE to be confused).:):):)

wagone and the R2 Avanti

garyash
07-30-2006, 01:35 PM
Ray Fitchthorn in the North Carolina SDC chapter has put the Dana axle adjustment process on line. See this page:
http://www.ncsdc.com/TechnicalPages/RearAxle/RearAxle.htm

There is also a bunch of other useful stuff at that chapter's web site: http://www.ncsdc.com

Thanks, Ray!

[img=left]http://www.studegarage.com/images/gary_ash_m5_sm.jpg[/img=left] Gary Ash
Dartmouth, Mass.
'48 M5
'65 Wagonaire Commander
'63 Wagonaire Standard
web site at http://www.studegarage.com