Been having a heck of a time trying to get my clark 285 shifter to stop slipping between gears. I have replaced some broken and warn parts, (reverse/1st arm and spring, the square trunnions that line up the shifter, and the large spring that holds the shifter in place) but I can't seem to keep it from slipping between gears. Every time this happens, I have to take the shifter off to get it free. I am thinking that the problem is the shifter itself as the bottom part that slides into the gear selectors looks warn. It could also be an adjustment of the spring/plunger in the reverse/first arm. In the ford parts book, it shows a bunch of shims/washers to adjust where the plunger sits. Mine had none when I took it apart. I guess my question is, where do you go for repair information for these transmissions? I have searched and searched online and have gotten no where. I did find a rebuild/service manual but it does not mention anything about the shifter mechanism at all.

Thanks!!!!!!

 

The "tang" end of the gear shift lever could be worn. You can build it up with weld. On our 450 farmall tractor (same design concept) the darn thing can get in two gears at once & the only fix is to pull the lever & reach down in there with a bar & put the rails back in neutral position!

 

 

If the pins that hold the shifter in place in the top cover are loose you'll need to fix that, if the shifter is allowed to rotate any at all if will slip between the gates.
A friends truck was bad about getting stuck in 2nd gear when the shifter slipped out of position, we ended up replacing the shift top and no more problems.

 

This is exactly what is happening. I did replace the two trunnion pins that hold the shifter in place but it looks like it is the slots in the shifter itself that are warn. The shifter definitely has some rotational play and getting stuck in 2nd is exactly what is going on. Its to bad the shifter is one piece. It would be really helpful if you could replace just the lower (wear) portion. At the moment, this "bend to suit" piece from Eaton (see picture below) is the only thing I can find to replace my old shifter. Going out today to tear it back down and do some measuring to see if it will even fit what I have. The ball to tang measurement will be the key, and of course the width of the slots. Anyone know of another option?

 

If the pins are tight in the top and the slots are the problem you can weld them up and recut the slots, just weld where their worn, not the hole slot, recut it with a grinder and cutoff wheel.
Unlikely a Eaton stick will fit a Clark trans but one never knows till they try, I'd want to know I could take it back if it doesn't work.

 

Took it all back apart and am finding that pretty much everything that is meant to move is warn out. Even though the pins are new, the holes in the top housing that they fit into have quite a bit of slop, as do the slots in the "ball" that they ride in. The tang on the bottom that engages the shift arms is warn on all sides. Realistically, unless I can drill out my top and put in bushings, and do quite a bit of filler welding on the bottom tang, I will need to replace the entire top housing and shifter.

 

I was afraid of that.

 

 

 

Have actually done quite a bit of work trying to solve this but so far it still pops right out of position. Here is what I have done so far.
Replaced trunnions in shift top.
Installed brass bushings in shift top for new trunnions. (the original holes were ovaled out badly)
Had the slots in the ball of the shifter (where the trunnions ride) tig welded up and then re machined (they were very warn)
Built up the bottom tang of the shifter with weld
Replaced broken reverse/1st lever, spring and plunger.
Replaced the large spring in the shift top.

None of this has made any difference what so ever which is leading me to believe the problem is deeper. One thing is for sure, all the parts that I replaced or rebuilt were very warn and sloppy. The "feel" is much better now, nowhere near as much play, but it still slides right past 2nd and hits the dashboard.

 

Thanks ND! I am just thinking out loud here as this one has me stumped so far.
#7241 tube possibly bent? It doesn't look bent, but I am working on it with the transmission still in the truck. Looking through the hole in the floor with a flashlight is not very accurate.
#7231 gate just warn to much? It looks pretty used but it is an old truck. It isn't obviously broken or totally warn.
#7E275 spacer. This one has me confused. On my transmission it is just free floating on the tube. Is that how it is supposed to be installed?

In any case I am back on the road(for my day job) and won't be able to work on the truck again for several weeks. I am just trying to put a strategy together while I am out and order parts so they will be there when I get back. I think my next move will be to remove the entire top of the trans (tin cover, shift forks etc) and do a more complete inspection.
Just trying to get this thing back to work before the snow gets here!

Thank you for the insight and help!

 

If it was me, I'd inspect the 7B403 inserts on the shift forks to see if they're still there and haven't cracked apart.

 

Will check them for sure. I just ordered a pair of them just in case (they were under $5.00). I will do all four if these look bad or are missing. Looking at the way its warn, it seems like this truck saw 2nd and 3rd quite a bit. Life as a snow plow from day one I suppose.
Thanks!

 

Just got back into town after being away for work and have been hard at it with the old dump truck. After spending quite a bit of time on the shifter and related parts, I took the top cover off and pulled the shift fork assembly and found the problem. The shift fork support is cracked around the 2nd/3rd shift tube. It is only cracked on one side so when pressure is put on it, the tube moves downward just enough to allow the shifter tang to push by. Fortunately, it did not completely break as the pieces would have been very hard to get out of the bottom of the case without tearing it completely apart. I will post a picture. Also, the slot in the 2nd/3rd shift fork is pretty warn which is possibly why it slipped past in the first place. Now comes the fun part, finding part numbers and locating the parts. I will definitely need the 7E274 piece as per the above picture, and possibly a new 2nd/3rd shift fork assembly (7231). Snowing like crazy outside. Good times. lol.