Case 580B Transaxle / Differential Rebuild

Rebuilding my 1975 Case 580B Transaxle and Differential and could use some help / clarification during the process. I have the shop manual, I'm partially through the process, and I have some questions as I go along. Here's some back ground and pictures of the original damage. https://www.heavyequipmentforums.com/threads/case-580b-backhoe-transaxle-gear-destruction.124219/ Currently j have the Differential /ring gear out, I have the new parts, and I'm starting the "Adjustments" process. Based on the instructions I'm trying to set the side gear to spider gear backlash. It calls for "0.05" to 0.15" of backlash per the manual, is this supposed to be measured on each spider gear as I'm getting different backlash measurements on each spider gear VS side gear and it also changes as I rotate the spider gear around.. So I've labeled each spider gear 1, 2, & 3, and I've taken measurements from each 1/3 of the spider gear. So on the right side gear with a 2.66mm/0.104" (A39009) spacer washer I'm getting the following: Right side gear to spider gear backlash in thousandths with a 2.66mm/0.104" (A39009) steel shim. Spider #1) 18 -20- 22 thousandths as you Spider #2) 0-2-4 thousandths Spider #3) 15-18-25 thousandths Brand New Left side gear to spider gear backlash in thousandths with a 2.66mm steel shim. (Due to the spider gears being recessed it was harder to hold the spider so I only got I mesurement on each spider) Spider #1) 18 -20- thousandths Spider #2) 1-2 thousandths Spider #3) 25 thousandths Per the book if the measurements are different, your suppose togo off the smallest one, which would be spider #2. Based on this if I went up to the next thickest steel shim a 2.78mm/0.109 (A39010) it would give me 3.5 to 7.5 thousandths total backlash on the right side BUT it would push out spider #3 backlash to 28.5 thousandths on the high side. Is this an acceptable clearance or is it too large? If this is still not enough backlash on spider #2 the next size up is 3.04mm/0.119" (A39011) which would push it out a total of 10.5 thousandths for backlash on #2 of 10.5 to 14.5 thousandths BUT on spider #3 the backlash would be 25.5 to 35.5 thousandths. I'm thinking the 3.04mm/0.119" washer is too large and will push out the backlash too far on spider #3 at 25.5 to 35.5 thousandths? If the 3.04mm /0.119" washer is too big, what's the best option; going to the next thicker 2.77mm/0.109 steel shim even though the high side on spider #3 will be 28.5 thousandths ...OR is is better to keep #2 at 0-4 thousandths and #3 at 25 thousandths with the current 2.66mm/0.104" washer? Thanks

@alrman .....do you know whats the better way to set this up? Thanks

So to summarize my question: Is it better to use the current shim (2.66mm/ 0.104") and be at basically 0-3 thousandths lash on the tigest spider gear and 25 thousandths on the loosest spider gear. OR Is it better to go one shim thicker to 2.78mm / 0.109" and be 3.5 to 5.5 thousandths lash on the tigest spider gear and 28.5 thousandths lash on the loosest spider gear? Thanks

First thing I would do is find why there is a huge difference. Something is worn. Often the shafts that the spider gears run on are the cause, sometimes the gears are worn as well.

alrman said: First thing I would do is find why there is a huge difference. Something is worn. Often the shafts that the spider gears run on are the cause, sometimes the gears are worn as well. Click to expand... I measured the pinion widths and there all the same. 3 seems to be tighter on the shaft than 1, and 2 is the loosest on the shaft but there is no play in it on the shaft. The face wear pattern does not look bad to me (see pictures). Right side gear,, Pinion 1 is in the 18 to 20 thousandths range and pinion 3 is the 18 to 25 thousandths range. But #2 is in the 0 ro 5 thousandths range. Can I set it up like it is, with these variances in lash across the three pinions without it blowing itself apart? If so what is a safer way to set it up? Option 1) clearance on the tighter pinion with more lash on the looser one OR Option 2) Very little clearance on the tight pinion and less clearance on the looser pinion. Thanks

@alrman I Rememeasured and think I got it figured out. You are correct,, part of the problem is spider #2 has no play but its not tight on the shaft and I think it was sliding in to the side gear drive teeth allowing no lash. On the remeasure #2 is still tighter but I got the shims figured out to bring it closer in to spec range in both ends. Thanks for your help.

I would pull the shaft for each spider gear and inspect for wear. Then replace worn parts.

I’m kinda in the same situation. I’m getting about 8 to 10 thousandths on two spider gears and barely any on one. Unless I spin it around and maybe get one or two thousand . I can slightly push the final drive with a finger to one side and the backlash increases? This is on my work bench at the moment. Think I should get a shim to increase overall 5 thousand?? Mine currently only has one thick steel washer per side.

Bennettconstruction said: I’m kinda in the same situation. I’m getting about 8 to 10 thousandths on two spider gears and barely any on one. Unless I spin it around and maybe get one or two thousand . I can slightly push the final drive with a finger to one side and the backlash increases? This is on my work bench at the moment. Think I should get a shim to increase overall 5 thousand?? Mine currently only has one thick steel washer per side. Click to expand... I did replace all spider gears new.

alrman said: First thing I would do is find why there is a huge difference. Something is worn. Often the shafts that the spider gears run on are the cause, sometimes the gears are worn as well. Click to expand... What would be an acceptable difference in between all three? I’ve got one that’s about 8 or so thousandths from the other two?

@alrman I'm setting up the differential to pinion backlash. The bearing preload is 3.5 to 4 lbs and I've swapped the spacer plates around to set the backlash and I've taken measurements all the way around the ring, every two teeth. I have 3 teeth on the ring that are tight and the rest are varying degrees of loose, a couple at high end if spec and some .009 over spec. . I've swapped shims left and right and taken measurements and the tight area on the ring and pinion remains no matter the shim configuration. Ring and pinion backlash spec is 0.005 to 0.009 inches So here's my question, what's the best/safest way to set it up...

1. With the tight section at .005" backlash, setting a couple sections at .010 to .012" and the loosest section at .016 to .018" OR
2. Setting the tight section at .0035" ( under spec) and the looser sections .0085 to .0105" and the loosest section at .0145 to .0165" still almost double spec in the loosest section. Also can you confirm that setting the R/P back lash where there is zero lash on the tight section even though it's only3 teeth is a bad idea even if it brings the looser sections in to spec or just above spec? (I'm thinking this will eat the tight teeth under load and heat expansion?). Thanks

Anybody have good knowledge on this and can seer me on the right direction?

I have set up many rear differentials in my career. Never any heavy equipment but Ford dealer experience, my own shop and built many in my race cars over the years. The theory is the same with any of them. You do not want zero backlash. That will cause you way more trouble than too much backlash. Don't forget things heat up and expand. Set the backlash for the tightest teeth. You will be fine. If things are a bit loose you might hear some clunking but I doubt it. Gear oil provides a pretty good cushion. After you have done a bunch you develop a "feel" for backlash and don't bother with dial indicators. It is not that critical. I am sure you are nervous but don't overthink it. Same goes for preload. A bit loose is better, so you don't burn up bearings.

Is the cross-shaft loose in the crownwheel carrier housing? It may be the cause of the extreme difference. Ideally, you want the minimum & maximum backlash to be within spec.

Nine thousands won't be a problem but @alrman is right you should make sure nothing else is out of spec. Because usually backlash is the same all the way around but you could just have wear on an old gear set. If you find nothing wrong I would pick choice #1 and move on.

alrman said: Is the cross-shaft loose in the crownwheel carrier housing? It may be the cause of the extreme difference. Ideally, you want the minimum & maximum backlash to be within spec. Click to expand... Cross shaft is not "loose" it has 5 to 8 thousandths of jiggle but that's it.

edgephoto said: Nine thousands won't be a problem but @alrman is right you should make sure nothing else is out of spec. Because usually backlash is the same all the way around but you could just have wear on an old gear set. If you find nothing wrong I would pick choice #1 and move on. Click to expand... Nothing seems to be obviously wrong so I'm going to set the gap at 4-5 thousandths on the tight teeth and put it back together. I'll be running 85/140 gear oil in it which is definitely thicker than 85/90. Thanks for the help.

Every time, for the last few years, on any axle or gear case set up, I would throw in some Bardhal gear oil stop leak additive. Not sure if it helps but I haven’t had a leak, that I ever put it in.

To set the differential bearing preload you can make your own special tool referenced in the manual under section 65-30 the Adjustments section, figure 16 so you can actually measure the bearing preload and make sure it's correct. You have pull your brakes apart and use the outside half with some 5/16 bolts long enough to go through the brake half and a piece of steel bar. Take a piece of steel bar, drill two holes in alignment with the bolts when tightened through the holes in the brake half. Put a nut on a bolt and weld the nut to the center of the bar. You can use the bolt to drive with your socket to run the torque wrench. I did have to space the bar off the brake side with some washers under the bar to get it to high enough to clear the right side, side gear with the cross shaft sticking out so make you have or get long enough bolts. Here's a picture

Its all done, back together and working ....for now thanks to @alrman for the help.