B Series Alternator bracket

[N3BP]

He fellows, I'm in the process of converting from a dynamo to 60A alternator on my B7200. I was able to locate all the necessary mounting bracket and parts. These alternators were an option on the B6200, B7200, B8200, & B9200 tractors, and standard on European models (I believe). Kubota made kits for a while, but they've long since been discontinued.

The only issue I've run into is with the alternator mounting bracket itself. It mounts to the cylinder head in two locations. The first is engine eye-lift location. No issues here. The second is right on top of a cylinder head bolt. Please see attached image.

It's as if there is supposed to be one of those combination bolt/stud fasteners there, but it's just a regular head bolt. I've searched and cannot find one in the kubota parts manual either. Apparently these head bolts are a non-standard M9x1.25 size.

Anyone think it's possible to weld a threaded stud on the top of the head bolt? I'm open other ideas as well.

Thanks,
Brandon

 

[Dave_eng]

Re: B Series Alternator barcket

Please look at the attached parts illustration for a B7200.

Specifically bolt #130.

If I am correct it is not a head bolt but just a plug. If that is all it is then the options are wide open.

If you remove the plug, replace the sealing washer underneath shown as part #140

Dave

 

[North Idaho Wolfman]

Re: B Series Alternator barcket

Please look at the attached parts illustration for a B7200.

Specifically bolt #130.

If I am correct it is not a head bolt but just a plug. If that is all it is then the options are wide open.

If you remove the plug, replace the sealing washer underneath shown as part #140

Dave

That bracket is over a head bolt location, the other plug is further out on the head.

Go online to eBay or a place like Fastenal to get the proper bolt stud combination, Do not try and weld a stud onto the bolt!

 

[N3BP]

Thanks for the reply fellows. Dave, I've had the bolt out and confirmed it's a hardened head bolt and not just a plug. I wish it were that easy!

Wolfman, I've searched high and low on the web. What's making it super difficult to locate is the fact that it's an M9 bolt. You are very, very limited with M9 bolts. If I could only read Japanese I might be able to find one where they are more common, yet still rare. You know any places that make custom bolts?

 

[Dave_eng]

I see this place with M9 1.25 cap screws

http://www.warrenfasteners.com/Hex_Cap_Screws.html

If you can buy a longer one than the original one and then sandwich the bracket between the cylinder head and the bolt head.

Be careful with the bolt grade.

Dave

 

[twomany]

Why the assumption that the head bolt is "hardened"?

Is there a specification available? I have a B7200 and am interested in more electrical capacity also.

 

[Dave_eng]

Why the assumption that the head bolt is "hardened"?

Is there a specification available? I have a B7200 and am interested in more electrical capacity also.

The bolt head is not hardened but rather it deals with the material the entire fastener is made from.

The metric strength system parallels the SAE one with its Grade 2, 5 & 8 classifications.

My caution was to pay attention to the head markings and be certain to not use a new fastener of lower strength.

The attached chart will help.

Also included a page from a different model's WSM showing typical metric bolts used.

Dave

 

[Russell King]

Head bolt is not same as bolt head...
These two terms have been swapped in the discussion above.

The head bolt will have a grade. The head on the head bolt will show the markings that show the head bolt grade.

You may have to use a stud and nut. You can probably get one machined from material that meets the strength of the existing head bolt. You may be able to get the upper portion above the nut turned down to a smaller stud dia and use a nut to hold that bracket down.


Sent from my iPad using Tapatalk

 

[N3BP]

Dave, it is interesting to note that the factory head bolts are not marked on my engine. However, based on the torque spec from the service manual of 47.7-51.4 FTLBS, I have to assume they are 10.9 Grade. I couldn't imagine using anything less on an engine that has high compression and rattles a lot. I did tighten it back down to 50 FTLBS and it held just fine.

Due to the way the bracket mounts to the cylinder head, Kubota did not design it to sit flush on the head. The lower screw hole no longer lines up. You'd have to put some type of metal spacer between the bracket and head. I think at this point I'm just going to Messicks and get another head bolt ($9.00 a pop!) and pay a good welder to weld a threaded stud on the top. I really don't see any other way of doing it.

twoman, I am looking forward to more current! I've purchased a Group 34 Marine battery that actually fit quite well after a very slight modification to the battery trey. 775CCA/955CA puts it at about double the output of stock. But that tiny factory dynamo will never charge it.

Just make sure when you purchase an alternator, you buy one that has two flush front ears and one rear ear, and not the offset ones like I first did. It will not fit. Also, all the ones designed for these tractors are externally regulated. I'm not interested in this type and want a simple internally regulated, self-exciting type. The best one I've found so far is the Denso 100211-400 style. They were used in Toyota forklifts. These seem to be direct replacements for the Kubota internal-regulated style. I'll attach a few pics of the differences, plus the mounting bracket stuff.

The reason I'm going to all this hassle is because I have a 9K winch that draws significant current. The factory power system is not even close to keeping up with it. 6 pulls and the battery is shot.

 

[N3BP]

So it turns out if you spend enough time searching the internet, you find what you're looking for. I was able to locate a M9x1.25 bolt, and it came from the most unlikely of sources. Apparently GM uses a M9x1.25x121 head bolts on their 2012-2015 1.4L Sonic/Cruze. And they were even kind enough to thread the thing in it's entirety. So I simply cut the head off and turned it into a stud. Since it's a 10.9, I was able to torque it to spec. Turned out good.

 

[N3BP]

Figured I post a few more pics of the alternator mounted. This is using the Kubota mounting hardware. Hopefully this will charge the battery up quicker.

 

[twomany]

Are there part numbers for the Kubota brackets and pulley etc.?

 

[Wreckem]

Realize this is an old thread, so you have a part number for the bracket?