682 Transmission Problem
 

New poster here trying to decide if it's worth salvaging an old 682. I'm the second owner of it, the original owner being a family member that gave it to me a few years ago. Anyway, on to the issue with it, with one caveat - I'm fairly ignorant on all the part names and terminology....

I'm trying to determine what actually failed, and my guess is the pump. As I was driving forward one day recently, for lack of a better description, something exploded. I quickly killed the engine fearing it was something in the engine. When I took the cover off, what I found was the driveshaft off the transmission, the fan shattered into a million pieces, and both flex couplers on each end of the drive shaft ripped in two. My guess is the drive shaft seized up for some reason, and the torque on it cause it to fail at the couplers. Transmission fluid level was fine, and as far as I know the fluid in it is the recommended type. I've only checked it a few times since I got the thing, and haven't added any myself.

My quandry is where to even begin on diagnosing this, and then determining if it's worth repairing. I'm not super mechanically inclined, but do like to tinker and can figure things out with some direction. I'm including a couple of pics of the carnage. If they post in the order I uploaded them...

First one is under the cover. The fluid everywhere is oil - the drive shaft fell onto the oil filter and ruptured it.

Second is the drive shaft. If you zoom in on the end you can see where the metal was sheared.

Third is part of the flex coupler and fan I found in the yard about 20 yards away from where the tractor stopped.


My initial thought is to replace the drive shaft, drain and refill the transmission fluid, replace transmission filter, and of course replace the oil filter. Is that a logical plan? Should I just take it to the local Cub Cadet repair house and let them deal with it?

:Welcome2:

Flex couplers can wear out and fail, which would allow the engine to throw the driveshaft everywhere and cause some pretty extreme damage. Which includes breaking the hydro filter, breaking the plastic fan, possibly ripping at wiring, etc etc.

I'm no stranger to a failed hydro, but they very rarely fail. Especially on the pump side of things. Can you still spin the hydro input, and will the machine still roll if pushed? If yes to both those, then there shouldn't be anything wrong with the hydro itself. When they fail, one of those 2 will lock up, and usually it's the output not the input.

Your plan of action sounds pretty good, be sure you get new flex couplers too. There's only one transmission filter, as the fluid doubles as gear lube and hydro pump fluid. New filter and fluid and your hydro should be good to go. The recommended fluid is Case IH Hy-Tran, but any other generic off-brand trans/hydraulic fluid will also work.

Thanks!


Yes, it does still roll, both forwards and backwards. Thank heavens, or I'm not sure how I'd have gotten it out of the yard. I can still turn the remaining part of the coupler on the transmission end as well. So that is great to hear that it's likely a relatively easy fix.

Indeed it should be a decently easy repair. You'll most likely have to replace the whole driveshaft and the couplers. The Driveshaft quite possibly got bent during the failure, and it seems all or most of your couplers broke.

When you reinstall the driveshaft, be sure you bolt the driveshaft and the couplers on the engine and hydro pump 90 degrees off from one another. The Flex discs do have 4 holes for a reason! If you bolt them both through the same 2 holes and ignore the other 2, the driveshaft can't "flex" side to side like it should and everything will fail again.

For reference, here's another thread with a similar issue to yours: https://www.onlycubcadets.net/forum/...t=flex+coupler

I can all but assure you that if you take it to a dealer for repairs they more than likely will not want to mess with it and IF they do, I hope you have deep pockets.

The parts cost alone may be enough to put you off even if you do the work yourself AND assuming the transmission/pump ass'y are operable.

I would suggest testing the transmission using a drill big enough to turn a 5/8" shaft.

A failure of this magnitude is likely attributable to lack of periodic maintenance.

Good luck!

And we have a good guy at the top of the page that makes parts that one might find no longer available from "mother Cub"
"Parts By Jeff" is the banner

It was most assuredly caused by neglected regular maintenance. It sat for close to 10 years before my family member and I started tinkering with it and got it back running. I've had no problems with it though in the 5 years I've had it, other than a dead battery once.

Looks like parts are going to run me close to $200 for new drive shaft, flex couplers, and fan. And then I'm not even 100% sure it'll run again after that, nor do I really know if any other parts were damaged that I haven't discovered yet.

BEFORE.....investing in any parts. (A) does the engine run, and run good ??? (B) as stated prior, get any electric drill and spin the Sundstrand Transmission. Does it bind up ??


If A & B check out, then the tractor is worth the investment in new drive line parts.

I agree with the above aforementioned, pull the fender pan off and give the transmission a good cleaning also.

Before this happened, the engine ran fine. I haven't started it since though because the drive shaft fell onto the oil filter and ruptured it.

I'll try the transmission this weekend. I will say it does roll when I push it, and I was able to turn the remaining part that attaches to the transmission, though just spinning it by hand may not tell much.