Differential Shaft Pin Broken

[bgray]

Hey All,

I opened up my rear differential to investigate some lateral play I was having with my axles (excessive in/out play with each wheel). On inspection, I could visually see a bit of play between the axle ends and the spacer block and a feeler gauge revealed my clearance was a bit excessive at .78 mm compared to .04-.46mm specified in the FSM. Next step was to pull the spacer block to see if there was wear and to potentially order the next size up.

Here's where I come to the issue. On removing the differential shaft pin (see #12 in pic), I learned the bolt had been snapped off by the PO and all that remained was about a half inch of bolt. I've never seen a bolt snap off mid way in a hole, but I was able to use a mirror to view into the hole and it does appear this is the case, though it is hard to tell. So here are my questions:

- Has anyone seen this before?

- What are my options to remove the broken bolt assuming I can't get a straight shot to drill it out (again it's a half inch into the hole and the pumpkin blocks access). Do machine shops or other places like this have special drills/extractors for this type of thing?

- If I'm not able to remove the shaft pin, is there any way to remove the axles, to make the repair or replace the entire 3rd member? If not, am I looking at a new axle short of being able to cut out the spacer with a saw or other?

If it comes down to a new axle, I suppose I'll just put it back together and drive it until a good used one comes along at the right price.

thanks for all your help.
Brian

 

[Pin_Head]

This is not unusual. The easy way to get it out is to put a short piece of 1/8 inch 7018 welding rod in the hole in contact with the remains of the pin. Momentarily energize it with your welder for no more than 1 second to fuse the rod to the pin and then turn it out.

 

[bgray]

Thanks PinHead. That's encouraging. I'll need to borrow a welder or a friend+welder and will give it a try. Thoughts on what caused the bolt to break -- e.g. weakened through wear from the constant hammering that happens w/in the diff?

Brian

 

[Pin_Head]

I don't know why, but it happens. You can use 2 batteries in series if you don't have a welder.

Use as little heat as possible to get the rod to stick to the bolt. You can always restick it if it breaks off.

Be sure to ground off the ring gear or carrier because you don't want current flowing through the bearings.

 

[FJ40Jim]

Are you sure the threaded section is broken off?

Ive seen several that broke the pin end off in the case. The upper threaded section could be removed, but the pin was still in the case, holding the cross-shaft. This is caused by excessive wheelspin, and one of the spiders try to spin the shaft.

Try a skinny pickup magnet in the hole. Wiggle the cross-shaft to&fro while trying the magnet. To turn the cross-shaft, use the whizwheel and put a slot in the end that can be engage w/ a large flat blade screwdriver.

GL!

 

[Shark56]

I've had this on two 40's. Oddly enough they were both 1974 models. I took the broken bolt head part and drilled a hole in it using a drill press. The hole was just large enough to get a 1/8th inch extractor in. I then re-screwed the bolt in and used angle drill to drill the broken part using the previously drilled whole through the nut as a guide. Removed the broken bolt head, tapped extractor in and used a small pair of vice grips to turn it. The broken piece inside, with maybe a 1/4 inch of thread was easy to back out.

 

[Shark56]

Found my old thread.

https://forum.ih8mud.com/40-55-series-tech/230050-rear-differential-shaft-pin.html

 

[bgray]

Hey Guys,

Thanks for the responses and different suggestions. I'll give these a try this weekend and report back.

Brian

 

[bgray]

I was able to get the pin out using the method shared by Shark56. Basically drilling a hole through the head of the shaft pin bolt to use as a pilot to drill a hole into the broken section of the pin, followed by an extractor to remove the pin. I had to pick up a few parts, including a right angle adapter for my drill and a 12" x 1/8" drill bit; and I also had a welding shop drill the bolt as I don't have a drill press. The pin came out real easy once I had the pilot hole, as it only had a few threads left on the broken piece, so I suspect Pin_Head's recommendation w/ a welding rod would have worked great as well (w/ less prep). See broken pin below and the drill set up.

Thanks for all the help. I'll follow this post with another set of questions on the lateral play I'm getting in my axle.

 

[bgray]

Here's a picture of the spacer block and and shaft pin. As mentioned, I have a some lateral (in/out) play with both axles. Using a feeler gauge, I measured .78 mm between the spacer block and axle end, compared to .04-.46mm specified in the FSM. Looking at the spacer block, I'm not seeing any material wear, but I do have a little bit of wear on the shaft pin (see pic). I don't have a micrometer to measure it exactly, but if I lay a feeler gauge on one side, it is about 0.15mm, which if double (each side) would be about 0.30 (equal to my slop). Thoughts on whether the shaft pin alone would cause the excessive play? My thinking is that my bearings are fine as I don't feel any play when I grab the wheel at 12 and 6 o'clock, but let me know if you think this could be the issue.

I'll order a new shaft pin regardless and I can always start by trying it first and then go from there. I'll also pick up a micrometer to measure the size of the spacer block in case I want to go to the next size.

Brian

 

[fortpleilfab]

Exact thing happened to mine, I didn't even notice until I went put a locker in, I had to buy a new bolt direct from Toyota

 

[bgray]

It looks like the differential thrush washer is also available in other widths (see arrow below or refer to item #16 in the SOR diagram above). Does anyone have an opinion whether I should be adjusting the size of the thrush washer rather than the spacer block to take up the lateral axle play? It looks like I can easily remove the spider gears to inspect the washer for wear, but are they a pain to align & reinstall or do they easily roll back into place?

 

[Weber Sarge]

They roll in/out pretty easily , just remove the upper/lower gears first keeping track of their respective thrust washers and top/bottom orientation of each gear .
Looks like that housing needs a good solid kerosene rinse at least ....
Sarge

 

[bgray]

Thanks for the response Sarge. When you mentioned the kerosene rinse, were you referring to the rust on the gears? This rig sat for about 20 years, so the gears that were above the oil line had surface rust. How does do you perform a kerosene rinse in a differential?

 

[Weber Sarge]

If that's surface rust the ring & pinion may be junk , especially if the teeth are pitted . I just fill the whole housing up and spin the drivetrain on jackstands at low speed for a few minutes , drain it for several hours and refill with gear oil . It takes at least one or two oil changes with around 20 miles to clean the housing out and never run 'em over 40mph since some kerosene will dilute the oil .

I'd take a much deeper look at the gears/bearings if it sat for that long .
Sarge

 

[bgray]

So I picked up a new pinion shaft, pin and the next size spacer block; and the tolerance between the spacer block and axle is now w/in spec (.45 mm). The FSM states .04-.46mm, so I'm at the upper end, but w/in spec. However, I still have lateral play and I'm now thinking my my issue is w/ my axle bearings. On closer inspection, here's what I'm seeing.

With the tire/wheel removed, if I lift up and down on the hub side of the axle (where the wheel mounts), I can feel a small amount of up and down play. I didn't notice this when the tire was on (grabbing at 12 and 6), but you can feel it with the tire & wheel removed. There is definitely in/out lateral play, but I wonder if this is the result of bearing slop.

I'm planning to order up a set of bearings tomorrow, but let me know if it sounds like this is my issue or if I should check for anything else.

thanks,
Brian

 

[bgray]

So I pulled the axle to check things out and while there isn't any noticeable wear on the bearings, there was a good deal of rust in the axle cavity. Once I pull the bearing, I'll be able to clean it up, but it's pretty nasty looking on the top. Also, does anyone know if the washer behind the bearing should have play or if it should be pressed tight up to the bearing (see 2nd pic). I can move my in and out about 1/8th of an inch. What exactly is the purpose of the washer -- e.g. to provide a barrier between the bearing and differential?

thanks,
Brian

 

[nuclearlemon]

i would get a long ball bearing style hone to clean the inside of the axle housing of the loose rust. the washer is kind of like an oil slinger iirc (in reverse of what you'd think, to keep some oil in the bearing). i've seen axles with them and some without. the bearing should be back against the washer, or the stop lip on the housing.

as for the pin, it was probably an air tool happy p.o. they don't take a lot of torque. i just snug them with a quick light pop of my palm on the ratchet.

 

[bgray]

Just a follow-up on this thread. I replaced the wheel bearings and seals and I now have a tolerance read of <0.15 mm and all but a minor amount of in/out play is gone. So I'm still not 100% clear how the bearings adding to the lateral (in/out) play, but it seems to have been a factor. I also cleaned up the inner axle housing using a bit of emery cloth; and also pulled out my differential spider gears and side gears to inspect for wear and to clean up the surface rust -- all looked good when I was done. I posted a final pic of the bearings and seal installed for those who like pictures

I did have a final question about the bearing installation. When installing the bearings (w/ the washer behind it), I'm assuming you tap them in until they snug up tight against the recessed lip inside the axle housing. When I pulled my the old set, their was a minor space between the back of the bearings and the lip w/in the axle housing. I know this as I was able to move the washer behind the bearing in and out about a mm or so.

Also, with the new bearings installed and the wheel mounted, I now get a very small amount of play when I grab the tire at 12 and 6 and rock. I haven't driving it yet to get oil into the bearings (waiting on a tire repair), so maybe this is the reason, but I found this a bit concerning as I figured it would be 100% snug with zero play. Unless I hear otherwise, my plan is to drive it a bit and keep an eye on it. The whole process of replacing the bearings and inner race seemed straight forward so I don't see how I could have done it wrong (or differently) provided the bearing sits snug up against the lip w/in the axle. Thoughts here?

Thanks again.
Brian

 

[Pin_Head]

There is no spec for that play, so there is no way to know if it is OK or not. If the bearing is new and there is nothing wrong with the inner race surface, then I would presume it is good.

To be honest, I wouldn't have worried about any of the play issues you have had.