if you ever wonder what size and thread the lugnuts are ona terrapro rear, they are 10mm with 1.25 thread. Could not find any "lug" type so gonna use grade 5 nuts and washers.

 

I assume you have to pull the drum off? I guess I wil find out shortly...

 

The good news is I got it apart and the switch/lever does what it is supposed to do now. I still need to get the brakes bled and put the drum/wheel back on.

I will agree that once you see it, you can follow how it works. I think the reason the levers come out on occasion like mine did is the oring on the lever shaft (where it goes into the housing), shrink some. I replaced that oring and the one on the swing arm housing where the axle shaft attaches to the differential.

I have some pictures and will try to post a step by step write up after its all done and I have a bit more time.

 

anyone that has this issue should be able to do a fix describeld previously in about 2 hours Id guess. a comment about the term "splitting the diff case". You are really not opening up the diff case but rather seperating the differential from the rear axle housing. If you find pictures or diagrams on the net these can help but are hard to understand due to the fact they seem to depict the inside out view and you are normally looking at it from the right side in.

The tricks I can offer are to follow the directions prevously noted but I have some other notes I think might help
1. If your lever/cam has not pulled out of the housing but your lock still won't work

I recommend making sure the springs are working correctly. I changed mine since one was bent and the other was too long. Then I adjusted the cable housing to get the fullest push pull combination of the lever.

If your lever has popped out, likely the o-ring on the back of the lever/cam has shrunk, so be sure to replace it. But if it's pulled out, removing the 10 bolts (2 for the lower shield, and the 4 14mm & 4 17mm) on the inside edge of the diff mounting plate, along with disconnecting the brake lines at the right rear wheel and 2 vac lines should allow the whole differential to pull off the housing. a note about the 17mm bolts - these are very tight, I found you must use a long 1/2" drive breaker bar and/or use a jack to let the machines heavy weight break them free. 3 of the 4 are reachable with the right socket extension combo, and one is only doable with a box/open end. I think its the same for the 14mms but not quite as tight... If you leave it all as one big unit, Its gonna be heavy with the brake drum and everything still on it but I think it's do able.

I don't believe you'd have to take it all the way off but just get it out about an inch or so to allow the cam lever to go back in its spot. Look in the hole and line the flat spot up. The bottom of the lever needs to be as far toward the right rear wheel as it can to align the flat spot on the cam with the spring loaded ring inside the diff housing. Once it pops in, then re-attach the diff, brake lines and vac lines. bleed the brakes from the left rear wheel and should be good to go. I would test it without springs before you finish assembly. on stands or a jack its easy to tell if it is working. rotate tire and move the lever. then move the lever and rotate tire again. you should see the switch from locked to unlocked.

If you decided to remove the drum you can see what you are doing better, then you can remove the brake assembly without pulling all the shoes and hardware. just remove the 4 bolts in the center of the assembly. I think they were 12mm. take the brake cable off the hanger loop under the differential and set the whole assembly aside.

I took the whole diff off and cleaned it throughly before re-install. got to see the whole operation that way.

One other note, the CV shaft goes into the diff, so you have to pop the shaft loose if you remove the diff. Take a medium flat screwdriver and insert in the gap between the cvshaft and the diff. a little pry or twist should pop it out easily. Inserting is just the same in reverse but agian its tricky as its heavy and you are working to get it on the differential spline and the CF shaft into the diff. The spline has a circlip that will pop in place.

I have some pictures but don't see a way to post direct to the site. don't want to have a hosedt option so if anyone needs them, let me know and I can send them with commentary.

This was a big job but worth doing it.

 

I have sort of a reverse of this going on with mine, not sure if it is the same issue, or what. Hope someone can help. Just got this awesome work horse and my differential appears to be stuck in locked position. If I try to start it in high gear, with the diff unlocked, i get nothing, wont even try to start. If I try to unlock it in high while running, in neutral, it kills the engine. It will run unlocked in low or reverse, so not sure if it is designed like that, or something is messed up. Any ideas??

Jess

 

I think I read that the locking diff should only be used in low range. In High range it was not supposed to engage if I recall, much like the PTO. My guess is there is a safety switch that is bad or bypassed someway. I don't know much about it though. Good luck

 

Hey all,

I know this is an old thread but just wanted to give a HUGE thanks to everyone, this thread saved my butt! Brand new atv owner here, haven't owned one in 15 years and never worked on them. Thanks to you I knew what to check, otherwise probably would have thought my differential was shot. Same problem as everyone else, diff wouldn't lock. Switch on the side of the bike seemed fine, check the lever/springs, all appeared functional. After reading this and playing with it for a few minutes to see if it felt"pushed out", I accidentally popped the whole switch out of the diff. I didn't want to take the diff apart, a little too new for that, but I did use a flash light and flat head screwdriver and was able to figure out how that switch worked (spring loaded pressure plate?) O ring looked fine, but the metal slip was bent out a bit so I had to use pliers to bend it tighter and it slid right in. didn't have to removed anything, but it was a tight fit and my knuckles are worse for the wear.

 

I run my machines hard when rough cut mowing which means I cut trees down if the atv can push them over. I cut through some pretty thick brush. Because of that I think sticks and what-not are getting near the Differential lock lever assembly on the swing arm and pulling it out while I am cutting, I find myself with a one wheel drive machine all of a sudden. This has happened a few times now and I have to spend too much time using the fix I have posted above. I am wondering If I could drill through the swing arm at just the right spot so that I could insert a small rod to push the diff lock clutch toward the diff so that I can push the diff lever back into the hole. Essentially I would like to make an access hole. I would do this with the machine disassembled and could cut pipe threads into the housing and plug the hole with a threaded plug. The area is large enough to clean the metal pieces away without a problem. Has anyone tried something like this. I may just fix it one more time and put some sort of wire tie around it to keep it from come out again. Has anyone ever seen a snow blower for the terrapro?

 

Seems like alot of work but looks like it would be easier to try replacing the spring with something solid to hold it in the diff. lock. I never have had any issue with mine coming out of the lock position.
Im thinking about selling mine though due to it never getting used since I swapped a Honda 300 fourtrax in a golf cart.

 

My differential seems to be stuck in the locked position as well, although for some reason I can still use high range. It seems to be solidly locked as I can't get just one wheel to spin even uphill in the loose sand (in high). I kinda like having it this way, but will it tear up the diff lock if I run it in high?

Sidenote-how fast does your go? Mine will do about 25mph in high, that's it.