2007 JD 790 4WD problems

[Robert Bolton]

Hi guys. I have a new to me JD 790 with a few problems that I think are probably minor but would like to know for sure. 1.) The tie rod has an "S" curve in it. I will make the attempt to straighten it since I have a press. 2.) The other problem that I have discovered is that the front drive shaft is also bent. What is involved with removal and possible straightening or am I better off biting the bullet and replacing the shaft?
Thanks, Robert.

 

[AKfish]

Robert,

If you look here: John Deere - Parts Catalog

The driveline looks to be a reasonable project to rebuild. Depending upon how detailed the repairs are likely to be and the final cost - I'd be inclined to go with new replacement parts. But, if you've got a good press and can maybe line the shaft up with a laser or similar means to ensure everything is straight-on - then go for it!! :thumbsup:

Otherwise, You might be looking at a leaky pinion seal and bearing in a couple hundred hours or so.. with that woobly front driveline working on making a "wow" on the shaft!

AKfish

 

[RoyJackson]

Concur with AKfish...

 

[kebo]

The tie rod on my 4x4 790 looks like a snake, meaning it ain't straight!! Before you start bending it, make sure it's not supposed to be like that. If your front wheels appear to be lined up and the toe-in looks correct (which you can check with a tape measure), I think I would leave the tie rod alone.

 

[Robert Bolton]

The tie rod on my 4x4 790 looks like a snake, meaning it ain't straight!! Before you start bending it, make sure it's not supposed to be like that. If your front wheels appear to be lined up and the toe-in looks correct (which you can check with a tape measure), I think I would leave the tie rod alone.

Thanks kebo, according to other posters on the list the rod should be straight. The parts book pictures seem to confirm this. I think my tires are slightly toed out ant I think that there is supposed to be 1/4" toe in measured at the rim. In any case I don't believe that JD would make a tie rod that hits the diff. case. I can also see a dimple on the rod where it must have hit something. If I'm wrong please correct me.
Robert

 

[RoyJackson]

Thanks kebo, according to other posters on the list the rod should be straight. The parts book pictures seem to confirm this. I think my tires are slightly toed out ant I think that there is supposed to be 1/4" toe in measured at the rim. In any case I don't believe that JD would make a tie rod that hits the diff. case. I can also see a dimple on the rod where it must have hit something. If I'm wrong please correct me.
Robert

You should have at least one picture showing the tie rod in your operator's manual. IIRC, the picture is in the Service-Lubrication section.
The Operator's Manual also describes toe-in, how much it should be and how to adjust it.

It's been a while since I had a 790 and I think the tie rod should be straight...but, it's been a while.

 

[Robert Bolton]

You should have at least one picture showing the tie rod in your operator's manual. IIRC, the picture is in the Service-Lubrication section.
The Operator's Manual also describes toe-in, how much it should be and how to adjust it.

It's been a while since I had a 790 and I think the tie rod should be straight...but, it's been a while.

Thanks, Roy. I just looked it up in the operator's manual and you are correct, the shaft is straight and the toe in should be 1/8"-3/8".
Thanks again, Robert. (It would be helpful if I just memorized the manual.)

 

[kebo]

Thanks kebo, according to other posters on the list the rod should be straight. The parts book pictures seem to confirm this. I think my tires are slightly toed out ant I think that there is supposed to be 1/4" toe in measured at the rim. In any case I don't believe that JD would make a tie rod that hits the diff. case. I can also see a dimple on the rod where it must have hit something. If I'm wrong please correct me.
Robert

My tie rod is bent (from the factory) to avoid hitting the differential case. That's why I pointed out to be sure about it, before you started bending on it. It's a 2001 model, so it could very be different from yours. This is the best pic I could find of it from my files.

 

[foggy1111]

I owned a 790 prior to my current (3320) tractor. I had allot of stumps in my land and I bent my front tie rod on several occasions. I bought a spare as I felt I would replace it at some point.....but I straightened it several times and ended up to sell it (the unused tie rod went along in the deal).

IMO the 790 tie rod is quite susceptible to damage...as the tractor has a low clearance when used in timber.

I saw your other post asking about a grapple. This is one of the reasons I upgraded my tractor - I wanted a root grapple and the extra loader and hydraulic lift capacity and rear remotes for other equipment....as well as a hydro tranny and a heavier all-around tractor.

I think you could put a root grapple on the 790 as long as you kept the grapple fairly light. I believe you have a pin-on style bucket on your loader? Some of the 48" grapples weight in the 375 lb range....so that may only add 200 lbs or so over your current bucket (?).

OR....perhaps a bucket grapple is what you had in mind? This would add little extra weight and may be a better alternative. It would work pretty well when coupled with a tooth bar IMO.

You can do a search on grapples....for hours of reading. Many of the grapple discussions are over at the attachments section.

I gotta say.....a grapple is the most useful thing for cleaning up branches and logs. I'm not sure how I got along without it. SWEET!

 

[foggy1111]

My tie rod is bent (from the factory) to avoid hitting the differential case. That's why I pointed out to be sure about it, before you started bending on it. It's a 2001 model, so it could very be different from yours. This is the best pic I could find of it from my files.

Kebo.....I dont think yours is bent from the factory. :laughing: I'm pretty sure you must of hit something with it. Mine was a 2001 model too.....and it was meant to be straight. :thumbsup:

I can remember thinking the same thing when I bent mine for the first time. I wondered if it was supposed to be like that? nope...Its easy to bend 'em.

 

[kebo]

Ok, so it may be that mine was supposed to be straight, I just know I didn't bend it!! I bought it with the tie rod already like it is, but the toe in is good so I don't mess with it!! What's funny is that in that pic it looks like it's bent to the rear of the tractor, but part of it is also bent towards the front too (can't see it in that pic). It would take a heck of an effort to bend it like a snake (by getting hung up on stumps, etc) and yet both wheels still be pointing in the same direction.

 

[beenthere]

Here is what shows in the tech manual for the 790. Looks to be straight.

 

[grnspot110]

My 04 790 had a bent tie rod too. After straitening it & bending it again, I checked on a new one, I think it was around $70 last Summer. Old one was pipe, new one is solid stock! ~~ grnspot

 

[Tractor Pilot]

Robert,

I have a 1997 JD770, which is very similiar to your JD790. I went out and looked at my tie rod after reading this thread. It is bowed slightly upward (see picture). But I would agree with the others who think that it should be straight. I am not the original owner of my tractor, so it was probably bent slightly upward at some point in its history. I'll have to bend mine back and adjust the toe-in. Thanks for bringing this up.

Bruce

 

[beenthere]

I can see where the tie rod is vulnerable to attack from stumps or boulders. Good pic of both the drive shaft and the tie rod.

 

[foggy1111]

You know.....when I first saw the bend in my tie rod....I thought that perhaps is was meant to be curved. It was much like Kebo's....just a curve in the middle. I measured the toe-in too....and it was quite close even with the bend. But I bent mine several times.

I considered adding a weld-on angle iron to mine as I bent mine a few times in my stump forsaken land. I reconsidered that idea as it straightened easily each time I bent it. I decided it was better to let the tie rod bend than perhaps break other parts.

The best method I found to straighten only took a few minutes: I used a wide lifting strap looped over the tie rod and then secured to the base of a tree. A little reverse action with the tractor straightened almost to perfection. :thumbsup: