New tractor - a few problems

[TxRzrBk]

I had been working on getting my 77 B7100 ready to take a beating while keeping an eye out for a FEL and a box blade. Well I found both the FEL and the box blade but they were both attached to a slightly newer B7100 (+30,000 on the serial).

It was a deal I just could not pass up even though I already have a tractor. The deal was attractive enough that if this turns out to be only a parts tractor it would still be worthwhile. The newer B7100 shows just over 3600 hours on the meter. Maintenance/repair history is unknown, it was owned since new by a municipality and used to maintain infield dirt on 4 baseball fields, PTO shaft has never had anything hooked to it.

The good news
It runs flawlessly, I have a neighbor that has a B7100 with about 1000 hours and this one runs significantly better. Starts extremely easy, idles smooth, zero blowby and normal exhaust smoke. I suspect it has probably had new rings at some point but I have no way of knowing for sure.
FEL works perfectly, it is a Kubota loader that has it's own pump connected to the front of the engine.

Not so good news
It is making a metallic pinging noise in reverse. When you are sitting on the tractor it sounds like it is coming from the front diff but if you idle it down and listen very carefully the sound seems to be coming from inside the transmission tunnel right around where the transmission meets the rear differential.
4wd is also suspect, while it does not make any abnormal sounds or vibrations in 4wd it also does not seem to be turning the front wheels. I have not had time to jack it up and do proper testing but I strongly suspect the 4wd isn't working

Any direction on these two issues would be appreciated.

 

[North Idaho Wolfman]

Just jump into it and start throwing questions at us... Some of us really like it like that!

 

[TxRzrBk]

So any ideas on the popping noise in reverse? Based on the location of the sound I am guessing it is the UV joint on the transmission end of the driveshaft.

 

[North Idaho Wolfman]

That could be a possibility, I assume this is a geared model?

 

[TxRzrBk]

Yes, it is a geared model. Really hard to isolate where the sound is coming from because it only happens while moving. It sounds like it is outside the transmission but maybe that is wishful thinking.

 

[North Idaho Wolfman]

Sounds like you need to pull the propeller shaft for the front drive or just lift the front up with the loader, hold one tire from spinning and turn the other and listen for noises.

 

[TxRzrBk]

I am going to try that tonight along with seeing if there is anything I can †ell visually from under the tractor. I am torn between these two B7100s, one has a very good running motor and a FEL but has noise coming from the driveline along with a potential 4wd issue. The other has no FEL, a solid driveline, new PTO bearings but has blowby. Taking the better of the 2 would be a pretty significant job.

 

[North Idaho Wolfman]

As hard as it is to get a good loader for one of those I would pick the loader one! The drive train is easy enough to repair.

 

[TxRzrBk]

Got under it and looked - not good. Transmission side of the 4wd yoke is completely missing. The 4wd shaft coming out of the transmission is broken off right about where the pin goes through the yoke. My hope was that I could repair it without getting into the guts of the transmission but that isn't going to happen

 

[mhd12]

You did say it was good enough deal to be parts, would say you have all you need to fix it.

 

[North Idaho Wolfman]

Ouch, That does sound like it could be a kettle of raw fish!
Is your feeling that it's something you could work with?
Broken shafts can be scary, but not the end of the world.

 

[TxRzrBk]

I am willing to give it a try if it makes sense, about the only transmission I have ever torn into was on a motocross bike. I lifted the tractor up and turned the wheels to try to identify the noise I was hearing (which only happens in reverse). The noise is the front drive-shaft banging around, apparently the front hubs are only forcing the drive-shaft to rotate when the tractor is going backwards - not sure if this is normal, if not could be how the yoke and shaft got destroyed to begin with.

I am also considering swapping the transmissions between the two tractors.

 

[TxRzrBk]

I verified that the front hubs & axles are working consistently between the two tractors, the front hubs do not appear to ever unlock, rolling the wheels either direction forces the front driveshaft to spin.
I am thinking I am going to attempt to repair the transmission and yoke and have the transmission swap as a backup plan.

 

[TxRzrBk]

So it looks like I need to R&R the reverse shaft. Anyone with experience getting into these transmissions please chime in and let me know how it went and how difficult you think it is and any other gothchas . I started looking for a new reverse shaft and noticed there are two different potential part numbers (66611-14814 @ $116, 666110-14812 @ $52).

 

[North Idaho Wolfman]

I will have to dive into the transmission layout on the B7100, as with my transmission in my L the reverse shaft is for that, reverse, not for running the front propeller shaft.

 

[TxRzrBk]

I will have to dive into the transmission layout on the B7100, as with my transmission in my L the reverse shaft is for that, reverse, not for running the front propeller shaft.

I was confused by that too, and I could still be wrong. The conclusion that I came to was that the reverse shaft is used for the front wheel drive in addition to reverse. I am attaching the diagram, #4 is the the reverse shaft and #87 is the front wheel drive gear.

 

[North Idaho Wolfman]

I wouldn't buy any parts till you get it opened up and can see for sure what's in there.
One piece of advice, there are a lot of parts and there orientation and placement is crucial to get it to work right, I would have a good flat table set up and as you pull parts lay them out exactly as you pulled them.
And take lots of pic's too.

 

[TxRzrBk]

Thank you sir, I was really just trying to get an idea of the cost. Before any gaskets and assuming best case, only the yokes, cross and reverse shaft need replacing, I am looking at about $325. It would be nice to find some used parts but I have not located any with the minimal amount of searching I have done so far.

 

[etmccaus]

Best of luck. I have a similar issue I need to tend to on mine but hope the damage is not quite as extensive...

 

[TxRzrBk]

Finally getting around to tackling this project. I started setting up to split the tractor and realized that the manual shows removing the fenders, control valve and rear axles before removing the transmission however it isn't clear if this is required to remove the transmission. Can I just split it at the front of the transmission then skip to removing the transmission or is removal of the axles and control valve a prerequisite?