isolater broken on a 350B

[jdemaris]

. Put engine back into unit, but was amazed at how hard it was to pull the engine together to the reverser case. It went together, but was very tough to pull together.

If that difficulty was caused by pressure on the input shaft, the reverser will burn up shortly after you start the engine. It cannot sustain any kind of thrust load and I've seen many fail after nstallation that were forced together.

It all depends if it came together hard because of the engine/reverser cases - or because of the input shaft/isolator/flywheel coming together. I'm going to assume you checked to make sure the new imput shaft fit the isolator splines as well as the flywheel pilot bearing? The machined stub on the end of the reverser input shaft must be a slip fit into the pilot bearing.

I've never drawn an engine into a reverser with bolts. Also hooked a battery to the engine and bumped the starter while pushing on the engine. If it doesn't go that way - something is wrong.

In regard to the new input shaft - hopefully you adjusted the shim pack with a dial indicator? Not meant as an insult to your skills - but a common mistake many make is attempting to set bearing clearance by "feel" which never works with this reverser.

[gene s]

I'm not insulted one little bit jdemaris, The more one can learn the better and its always apprieciateed, in fact to be honest with you I didn't check the end play of the new reverser shaft because I didn't get into the guts of the reverser, or the diameter of the pilot bearing, probably a big mistake. Over the years I have only encountered a mismatched piolet bearing a few times and that was always when I'd put a sm. block chevy into something it never came out of. My bigger vehicle knowledge is limited to Internationals and I've never had a problem dealing with the DT engines, but I also had a parts guy at the dealer who knew his stuff. I've decided to pull the engine out again, which won't take any time at all, yea rite, since I haven't reconnected any lines etc. I'll check what I've done and also make sure the new isolater slips onto the new shaft easier along with piolet bearing. Rite now its time for a cold beer and figure out how bad the Bears are gonna screw up this Sunday

[jdemaris]

I didn't check the end play of the new reverser shaft because I didn't get into the guts of the reverser, or the diameter of the pilot bearing, probably a big mistake.

The end-play on that shaft if critical. Most of the newly rebuilt reversers I saw fail were due to too much bearing preload. The problem in this. When you are trying to determine how loose - or tight - bearings are on a one piece shaft - it's pretty easy to adjust by "feel." One example is a wheel bearing on a car, truck, or tractor. Tighten until you feel no play - and then back off until you just feel a little. That will put you a zero to couple of thousanths end-play which is fine.

The problem with the reverser is - is does NOT have a one-piece shaft. It not only uses two shafts and three internal bearing assemblies, it also relies on the pilot bearing in the flywheel to support the front input shaft. That pilot bearing is - in essence - a fourth shaft-support bearing for the reverser. So, no matter how tight you make those bearings, there will always be some play that you can "feel" when you try to wobble the input shaft with the reverser not bolted to the engine. That is why it is essential to get a dial indicator on that input shaft - pry it fore and aft - and verify there is some play - and absolutely NO bearing preload.

You said you installed a new input shaft. That means you also installed a new bearing race at the end, and a new bearing assembly on the front? And also, maybe, a new front cover gasket for the reverser? Any one of those items, as well as dimensions on the new shaft could change the clearance specs a bit.

If the reverser is still, in-place and bolted to the trans - there is no traditional way to adjust the bearings. You can still check end-play though and make sure it's OK. If you had to adjust - the reverser has to come out. Adjustments are by shim-pack at the rear bearing quill where the output shaft comes out. To check end-play, the John Deere way -you pull the pipe plug from that rear bearing quill and install a dial indicator there. In your case, you can mount a dial indicator against the front shaft - and then find a way to pry it forwards - and backwards. If you get anything from .001" to .006" movement, you'll be fine.

If you wind up pulling that front cover off for any reason, you might want to take a close look at the oil lube orifice in the output shaft. It sometimes gets plugged. Worse yet, it sometimes gets left out when replacing the output shaft. It faces front and goes against the input shaft. A new output shaft does not come with that little jet installed - and can be a mess if left out. It keeps lube pressure up and helps the clutch packs release.

[gene s]

Just an update on my isolater problem. First off, I finally got my computer back. My 350B is all done now and the machine acts almost like new. Found out that the problem with my first try at putting the engine to the reverser, which was very hard to pull together, was caused by one spline on my new input shaft was a tad bit taller than all the rest causing it to bind on installation. So much for quality control where the shaft was machined, I should have checked the fit before I put it in but I assumed being brand new and being fit into a brand new isolator it would be good. Again I learned the true meaning of ass ume. I checked the tolerences as suggested by jdemaris and all is good. Thanks for the help.

[digitup2]

That is one upgrade that you won't regret I had a early 350C wide track dozer and changed over the flywheel and clutch to new style and it is ten times the clutch .With wide track units they take old style clutches out faster then usual with turning tracks in heavy mud conditions .I also found that if the old style clutch sat with moisture around it the face rusted and the clutch was in a real self destruct mode at this point .I traded up to a late model 350D wide track that had 600 hours three years ago and this crawler was babied by an older contractor retiring so I know this crawler was treated with care .this unit gets used very little it will last me till I retire. It is my smallest dozer and only I run it my self but it goes places other dozers can't think of so it has to be in good shape.Digitup.

[dustin502]

How does the updated isolator mount to the flywheel? Does anyone have a good picture of the isolator? And finally, Do you think it is something a machine shop could make? Thanks in advance

[gene s]

the new isolater mounts to the flywheel lets say the same way a pressure plate from a clutch mounts to a flywheel. The upgrade does require a new flywheel, ther is no way around it. The new isolater sets into the flywheel, then bolted down with I beleive it was 8 bolts, unlike that old setup with springs that was held to the surface of the flywheel. I don't see anyway to make your own, yea you could, anything is possible with enough cash. Then you have to buy the actual isolater, which is a rubber, lets call it a donut, with a steel insert to accept the reverser input shaft pressed into a steel ring/cup that bolts to the flywheel. You have to really see the upgrade to understand what I'm talking about. Have your local Deere dealer fax or e-mail you a picture of parts required and you'll see why you really can't make your own.

[dustin502]

Well, I went ahead and purchased the updated isolater and a used flywheel. My next question is: According to the deere web site the mount bolts for the isolater doesnt require washers. Is that correct? Also, does anyone have the torque specs for these bolts? Thanks in advance.

[digitup2]

It was long enough ago and many repairs since.If they show washers then get the right ones .Most deere fly wheel washers are thicker and made of a different metal than the run of the mill washers .I would say if Deere don't show it don't it dosen't need to exist there .Digitup.

[gene s]

That is correct no washers used. I used lock tite on bolts. Can't remember the torque specs, cause my manual is at the shop. I do remember that since the machine I have had that old cheezy isolator setup my manual didn't show that spec for the new style, so I called the Deere dealer and they told me to use use the clutch presure plate to flywheel torque spec. So far so good, a real improvement for this old machine. I really like that that loud ratteling noise at start up and shutdown has gone away also, but you will still have some noise from the reverser, but thats ok.

[dustin502]

Thanks for the replies, I'll check my manual for the pressure plate torque. Thanks again.