BH90 Dipper Cyl

[AntrimMan]

Guess what's missing in the photo.
I've lost use of the dipper on my BH90. The machine, purchased in Dec. '03, has 190 hours on the clock, about 2/3 of which is fairly hard hoe use.
A call to the dealer didn't help , the fellow I wanted to speak with is on vacation. The sales person ballparked me 3.5 hours + parts to reseal and approx $600 for a new cylinder assembly, I wonder if he can still hear me laughing.
The hoe warranty period has expired and my question concerning a cylinder recall was dismissed. When I asked about just buying a seal kit I was warned that special tools were needed to properly insert the seal. Listen here fellas, my people built the unsinkable Titanic, so there is no reason for me to be afraid of fabing a seal guide. Even the lovely missus thinks I can do it. It just won't be iceberg proof.
I isolated and capped the cylinder ports and I can pull/push the dipper in either direction by hand, it even moves by itself like a pendulum when I move the boom. The oil is freely moving past the piston seal. Problem potentially identified.
When I took the cylinder pins out I found why it failed.
There is a tremendous side load applied to the cylinder because of misalignment between the boom and dipper pin bores. I designed and built custom high speed assembly equipment for ten years and side loads mean early death for cylinders. I may be able to correct this by relieving the cylinder or altering the mounting gap as long as the pin bores are reasonably parallel, I will check the pin bores to rod and bore perpendicularity when dissassembled. The boom and bucket cylinders suffer the same side load so I took them off also and will reseal and make corrections as needed.
This hoe was never heavily side loaded by impact, I bought it new, I'm the only user, so I highly suspect it was delivered in this condition.
I haven't opened the cylinders up yet but I won't be surprised if the bores are scored beyond utility.
I'm less than happy with Kubota at present, last week I was full of praise, so there you go. When asked for an opinion, I will soon be able to say my BH90 is between repairs.

So here are my questions, tendered to the great wealth of information available here on TBN...
Is Tractorsmart the smartest place to purchase repair parts?
Has anyone found special assembly tooling necessary for BH90 cylinders?

TIA,
Martin

 

[aloha]

</font><font color="blue" class="small">( Is Tractorsmart the smartest place to purchase repair parts? )</font>

I think the best place to buy parts is from your local dealer . . . so long as you are treated fairly and with respect (with extra points for while the tractor is under warranty). When the local dealer fails to live up to standards, for Kubota parts I have found Ronnie at Tractorsmart can be relied on to treat customers fairly and with respect, and to responsive, helpful, and a dozen other postive adjectives. He gets my business.

 

[theonlybull]

try a hydrulics supply house. that's where we buy all our seals, and usually get them for less then half compaired to the dealer.

your very right, side load on a cyl means certain death, but not just kobota is guilty of that. i've seen cat loader break pins because they were missaligned.

 

[Junkman]

I would call Kubota in California and ask for Tom Sieper. He is one of the top people in charge of manufacturing at Kubota, and if there is a defect, he will make it right even if it is out of warranty. The dealers have no idea how to resolve problems, and if it was manufactured incorrectly, give them a chance to fix it for you at their expense. If you don't try, then you will never know the answer. You can find the telephone number on the back of any Kubota sales literature. Junk.....

 

[AntrimMan]

Junk,
I hadn't thought about taking it to a higher authority.
Thanks for the tip. I will give it a try when they get out of bed.
I'm sure we'll play phone tag for a while. I'll post any progress.
Thanks again.
Martin

 

[boustany]

I had a 580C with all kinds of problems with seals, etc., though none (yet), with my Kubota gear.

While I would consider rebuilding the little cylinders on CUT implements, its likely gonna be a messey job. I found the best approach is to bring it to a hydraulics shop and say 'fix'.

If I recall, overhauling big cylinders wasn't that expensive.

 

[JimMorrissey]

Calling higher ups definitely works. I've had a go with them in California...Worth a call or four. There is no excuse for what you are dealing with. I would document the situation with digital pictures and measurements so you can immediately email them to the person who contacts you.

Also, hit the regional Kubota person. Put the fire to them on all ends you can think of. If you are correct, they will be forced to deal with manufacturing defects. Be as civil as possible, but don't let up until they fix it.

 

[gippolit]

I'm sorry can I ask a dump question? What does side load mean on the cylinder? Misaligment? Don't the pins keep them alligned?

Regards;

Glen

 

[AntrimMan]

Not a dump question at all...
Yes, it's misalignment that causes side loading. The centerlines of the holes on any or all of the pins are not parallel for some reason.
Side loading causes the piston to continually rub along a line in the bore instead of theoretically floating in the center. The piston motion creates burrs and destroys the seal as it passes over them.
If burrs are present in a cylinder like this one it is a bin job and not economical to resize. Before a new cylinder is installed the problem that caused the initial failure must be corrected or the same thing will recurr.
I have some tools being delivered today that I can use for disassembly and only then can the full extent of the situation be realized. I'll post what I find.
Thanks for asking,
Martin

 

[AntrimMan]

Lady luck is with me (somewhat anyway),
the bore is score free for 360 degrees of the full length.
This pic is 90 degrees CW to the pin bore...