A833 Rebuild help needed.

[MD68]

So long story short, I have gone through the rebuild process and am to the point of reinstalling the main shaft/tailshaft assembly. When inserting main shaft, I can get the gap between tailshaft and main case to about 1/8 to 3/16 by hand. At that point, input and/or output shafts can be turned by hand. As soon as I start to tighten the bolts connecting tailshaft housing, everything locks up and won’t turn. I’ve inserted driveshaft and tried to turn with that with no luck. I have repeated this process several times with the same results. Here’s a few pictures to review and see if I’ve made an assembly mistake.

 

[AJ/FormS]

Ok first off, the snapring on the front bearing is not standard; you cannot use the one that comes on a new bearing, the retainer will not seal, and you may break it when you tighten the screws.. So you have to use the original factory snapring. But that has nothing to do with your problem.

Your problem is caused by one of three things.
1) one or more of the input rollers have fallen into the cavity. or
2) one of the two front brass rings is not indexed to the struts. or
3) the wrong tail, or tail-bearing is being used.
4) Edit by @inertia, see post #3
5) edit by AJ; see post #8; the 3-4 hub is on backwards.

looking at the pictures, my guess is the third gear brass is off the struts, but that is just a guess.

But there seems to be something else going on in the pics that I can't quite put my finger on; which is; the 3-4 slider seems to be offset towards the front, leaving the clutch-teeth on third gear way too far from the slider.

FYI
I never try to install the loaded rear end with the cluster pin installed.
Instead, I leave the cluster laying in the bottom as far down as it goes, then stand the case on end, with the input gear hanging down thru a hole in the bench, I made especially for it. and NO front retainer on it either.
Then with one hand,I drop the loaded rear end into the box clocked about 180 degrees out (see note 1), working the 3-4 slider around the cluster with the other hand. In my case I have the 4th gear brass already on the input gear, so I have to steer the struts into the proper slots.
With the rear end now sitting on the gasket, I rotate it slightly to expose the pin-hole, then slide the cluster into engagement, and drop the pin in. If the front washer has moved, and the pin will not drop through, then install one bolt into the only hole that lines up, and snug it down. Now you can lift the trans out of the hole in the bench, invert it, and align the washer, then finish sliding the pin in. Immediately I put the trans back in the hole, tail up, and finish installing the pin. Then remove the bolt ,rotate the tail into final position, and bolt it all together; finishing with the front retainer last.

Note 1
I have run into an occasional case where the clusterpin will not quite pass by the tail casting in the ~180* out clocking. So I always check before starting the assembly, and grind off the interfering casting.
Assembling the trans in this manner will take you only minutes, and with no stress.

If you still have issues;
Either; drop the input gear, or remove the rollers; AND remove the 4th gear brass; then test fit the rear. Your rear bearing install looks correct, assuming the rearmost snap ring is installed.
Easy-peasy Good luck

BTW-2
The rear bearing is not a standard bearing but is specific to this application. It is a wider bearing. So when you installed your rear bearing and fully seated it on the mainshaft, the rearmost snapring should have just barely fit,in the groove with ZERO space between it and the seated bearing..
If you had space, then you have the wrong bearing.
If you pushed the bearing back against the snapring, then the mainshaft would end up too far ahead.
If you left the too-narrow bearing seated, with space to the snapring, then there is only the press-fit between the bearing and the shaft to keep it seated. Once the trans gets up to temp, I cannot say if or how long the bearing will stay where you put it. Jus thought that was worth mentioning. You don't have to take it apart to look; the too-narrow bearing, together with the loaded mainshaft, will slide fore and aft in the tailhouse bore. And you might be able to see the error, thru the speed-O hole.

 

[Inertia]

4 -. You missed the groove for the rear snap ring,and won't let the tailshaft seat in the tailshaft housing .?

 

[MD68]

A couple more pictures of items mentioned above.

 

[MD68]

Do I have the 3-4 hub reversed?

 

[cawcislo]

I have my 71 A833 Torn apart currently and I took this quick pick of my 3/4 hub/slider and 3rd gear and how it looks compared to yours. Mind you this is an old worn synchro ring.

 

[mcodecuda]

You should get a copy of Jamie Passion’s book. It’s a great guide on rebuilding the 833.Books

 

[AJ/FormS]

Do I have the 3-4 hub reversed?

IDK, but there is something wrong there, that third gear will never shift right like that; I think the brass got under the strut, or out of the slot. Spin the brass around until you find a slot, then shove the strut into it and push the slider to the rear to keep them indexed.. OOps never mind I missed pic #1

Ok then grab third gear and pry it forward; if it moves more than a few thousands of an inch, then something is wrong. OOps never mind;
Yeah the more I study the very First posted pic, I think that hub is on backwards; slide the slider off and maybe I can tell more. Yeah that's it!. If you take the hub off and fit it into the input gear, you will see that the hub is clearanced to fit in there. If you reverse it ,the hub will hit the input before the loaded tail hits home. I will edit post number #2.

But there seems to be something else going on in the pics that I can't quite put my finger on; which is; the 3-4 slider seems to be offset towards the front, leaving the clutch-teeth on third gear way too far from the slider.

BTW-1;
if the teeth on your brass rings are less than about .030 away from the clutch teeth when lightly seated; then
1) your synchronization will be slow, and
2) it may grind going into gear, and
3) soon the struts may pop out on the adjacent gear, and leave you stranded in that gear, and
4) when you ram it into gear, you will overpower the brake action, and for sure get some grinding.
The brass needs to be up closer to .050/.060, or the struts need to be lengthened.
BTW-2
your braking cones are are glazed, and they will be slow to synchronize. I stick my gears in a lathe and run some 100/120g emery cloth over them, backed by the lathe-file, as the gears are spinning. Just a couple of swipes with the emery in full contact with the brake surface. I have learned to bias the swipes so that afterwards the brass screws itself onto the brake, during synchronization, and makes the trans shift like lightning. You can test this before assembly, by orienting the parts correctly and lightly pressing on the brass as you spin it in the correct direction; it should tighten up instantly. The 1 and 3 brakes are biased differently than 2 and 4, cuz they spin in opposite directions. I bias first for downshifting into.
Second gear is the most important, cuz that's the gear you will be going into and out of, the most.
Is it noticeable?
Well lemmee put it this way;
If you do it backwards, you will be pulling the trans out again real soon,lol, cuz it doesn't shift worth spit.
Did this happen to me?
Well duh, how do you think I learned this,lol.
If you take the mainshaft apart again to polish the brakes, you might as well do another trick I know. Which is; Take the strut energizer springs and stretch them out far enough to at least double the end-gaps. This will delay the slider to strut over-run and jam the struts into the brass keeping them working harder for longer. You won't feel it in the stick, but your clutch teeth will love you for it.
BTW-3
Trust me; forget full synthetic trans oil, it is just too slippery. Run a 50/50 of Dextron-II and 75/90 dyno EP oil, with NO SureGrip additive; make sure you read the label. The EP oil is for the cluster pin longevity, that is all I use it for. My cluster pins last for decades on this mix. The ATF squeezes out faster and the brass can get to work sooner, making your A833 shift like a toploader, fast and easy.
Yes I have heard some guys have got synthetic to work. But I gotta tell you, I once took that trans down three times in one week, to modify various things, in an effort to make it shift faster with synthetic. It failed my every attempt. So I took the rest of the week off, and the following week, took it down a fourth time, and washed all that slippery synthetic oil right outta there, and went back to my 50/50 mix. And after that I was rewarded with the fastest shifting A833 ever, maybe in the World! So either; I'm a dumbazz, or the the synthetic users are easier to please, or IDK, but I ain't ever gonna put synthetic trans oil in my A833 again.
Oh yeah, I better tell you; I street slick shifted second and third gears during this exercise too. This is done by grinding off every second clutch tooth, and every second spline in the sleeves; just the engagement area. You assemble it with the brass rings in it, and in everyday use, you never know that the trans has been modded. But this mod doubles the space where the slider meshes with the clutch, and when you get to ramming it in there, it shifts like lightning, so much so that it is easy to overpower the brass. Mine works to the highest rpms I have tested which is over 7200. BAM!!
When I was testing it, I walked the looong walks, the lengths of my blackies, and could not find any breaks in the stripes, while the clutch was disengaged between the shifts. That's fast. Well to be fair, the "junkie" 295/50-15s never stop spinning anyway, so they must be contributing their own flywheel effect during the momentary neutral. Yeah that must be it,lol.

 

[MD68]

That was it, the 3-4 hub was reversed. Flipped it around and it went together like it should. All is well now, thanks for the help!!!!

 

[AJ/FormS]

Yahoo!

 

[eekvonzipper]

That was it, the 3-4 hub was reversed. Flipped it around and it went together like it should. All is well now, thanks for the help!!!!

So, which way is Correct? With the Flat Side Forward (Above in Pic)
Or with the Protruded Side Forward (Below in Pic- as mine is installed?)

 

[Dan Brewer]

So, which way is Correct? With the Flat Side Forward (Above in Pic)
Or with the Protruded Side Forward (Below in Pic- as mine is installed?)

View attachment 1715725448

The hub installed on the mainshaft is correct.