Author Topic: Offset Idler Bolt Feedback  (Read 9187 times)

xyzer

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Offset Idler Bolt Feedback
« on: March 22, 2007, 05:23:54 AM »
There are about 25 offset idler bolts out there to correct the incorrect location of the idler gear. I have gotton feedback from one offgrid user using a .055" offset on his 6/1. It was a good report. I have a .045" in my in my PS 6/1 kit engine and it works nice, that is all I really know. I am looking for any feedback out there good or bad! I am thinking of doing another run and that will be a good time to look at suggestions or improvements you all think they might need. Also if you are interested in one let me know so I can get you on a list. Unless I hear reasons otherwise the standard offset will be .040" (maybe .045"?) and some customs offsets will be possible. I need to make at least 20 to make it pay.
Dave
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okiezeke

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Re: Offset Idler Bolt Feedback
« Reply #1 on: March 22, 2007, 06:51:13 AM »
Dave,
The bolt is way too prety to use in the engine, superb workmanship, finished better than anything in a roid.  Simple design, its got to work.  Cant wait to get it reassembled.  Would you look at making a double lobed cam for the oil pump drive.??  I know you could make a good one.
Zeke
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cujet

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Re: Offset Idler Bolt Feedback
« Reply #2 on: March 22, 2007, 05:17:38 PM »
Dave, I probably need one and will purchase one from you if needed. However, I have not measured mine yet to see what the lash is. Do you have a figure in mind that I should look for?

Also, the bearing surface is hard steel? how does it hold up? Can a roller bearing be substituted?

Chris
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xyzer

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Re: Offset Idler Bolt Feedback
« Reply #3 on: March 22, 2007, 06:24:06 PM »
Chris,
A backlash of .011" between the crank and the idler and backlash of .026" between the cam gear and the idler will need about a .040"-.045" offset and keep us on the safe side. The bolt is made of 1144 highstress  steel, and it is not hardened. You could use a roller type bearing if it has its own race. You would have to alter the idler gear to accept it for a press fit with some way to retain it. I don't think there would be any real big advantage doing it that way but like everything it could be done. I don't believe all of us really need a offset bolt but we don't really know till the idler gear fails. They are on the edge of who knows when they will or if they will fail.  But the offset bolt puts them back in spec to where we know they should last as long as an original and will reduce noise from the gear train. I have had no wear issues reported.....yet! That is one reason I started this thread. I really don't expect it to be a issue. The gear is only turning 325 rpm with lots of oil. I would be really surprised if there is a wear issue. My originals didn't appear to be hardened. Are yours?
Dave     
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Tom

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Re: Offset Idler Bolt Feedback
« Reply #4 on: March 22, 2007, 07:01:30 PM »
Hello Dave,

May I suggest an idea to easily measure valve train lash. If one rotates the flywheel until the cam in the location of valve overlap and marks a spot on the flywheel. Then rotates in the opposite direction until cam motion is detected and marks the second location, you will now have a measurement of total lash in the valve train. Would this give you the info needed for the offset? If not it will at least give an indication as weather one needs to investigate further.

My engine shows about 1/4" of rotation at the flywheel rim when tested this way. That seems reasonably tight, but I'm wondering what you and others measure before and after installation of the offset bolt.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

xyzer

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Re: Offset Idler Bolt Feedback
« Reply #5 on: March 23, 2007, 03:46:21 AM »
Tom,
I suppose it could be done that way. I checked mine when it was apart. It was much easier that way. I didn't pay attention as to how many degrees of rotation the flywheel rotated before the lash was takem out. Maybe some of the other guys will have some info.
Dave
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schoust

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Re: Offset Idler Bolt Feedback
« Reply #6 on: March 23, 2007, 04:39:24 PM »
Xyzer, would my Powerline !2-1 benifit from such an offset? I am about ready to start a l0ong run and want to be equiped as best as possible...

xyzer

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Re: Offset Idler Bolt Feedback
« Reply #7 on: March 23, 2007, 05:24:30 PM »
schoust,
That I don't know. If your engine has excessive backlash in the gear train it will help. The Indians seemed to have put them all over the place but the majority seem to do OK they are still loose but they keep going.  Some engines are waaaay out of spec. and will have a habit of eating idler gears. If you have one of them I would say yes. I would suggest you measure the backlash in the gear train and if the total is more than .040" it might be wise. If you can't do that I would suggest you put it in service and monitor the wear pattern on the idler gear. If it starts to get pointed teeth you need one. The Idler bolt can be easily instaled at any time to correct the location problem.
Dave
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MeanListerGreen

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Re: Offset Idler Bolt Feedback
« Reply #8 on: March 23, 2007, 10:55:53 PM »
Anyone have a link on how to measure the backlash?
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xyzer

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Re: Offset Idler Bolt Feedback
« Reply #9 on: March 24, 2007, 04:28:31 AM »
It was discussed in this thread. Look at how biobill did it on an assembled engine. It is a pain but can be done.
http://listerengine.com/smf/index.php?topic=1297.0
Dave
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hotater

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Re: Offset Idler Bolt Feedback
« Reply #10 on: March 24, 2007, 07:16:46 PM »
I   LIKE  Tom's way of measuring.  That's a standard that can be done on any 6-1 while still together and can be done at every oil change without any tool more complicated than a yard stick.

I'll have mine posted soon.
7200 hrs on 6-1/5Kw, FuKing Listeroid,
Currently running PS-Kit 6-1/5Kw...and some MPs and Chanfas and diesel snowplows and trucks and stuff.

BruceM

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Re: Offset Idler Bolt Feedback
« Reply #11 on: March 24, 2007, 10:04:14 PM »
I've already measured my lash via dial guage and music wire extension to the idler and cam gears.  I can check via Tom's method this week before/after installing one of Dave's lovely offset bolts.

Best Wishes,
Bruce

hotater

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Re: Offset Idler Bolt Feedback
« Reply #12 on: March 24, 2007, 10:42:30 PM »
Well, maybe not a yard stick---

I C clamped a small bit of scrap steel to the flywheel rim and then set up an indicator about half way through its travel.  It's easy to see the movement of the cam when it changes direction...it's harder to watch the cam and the indicator at the same time!   ;D

I get .195 TIR on a 24 inch flywheel rim between cam movement in one direction to a change in the other direction.

I had the oil draining from mine when I read the thread.  That's why it was done so FAST.

I have more than enough bronze flakes in the sump to bring worry about the health of the pinion gear, but I cant tell the gear is worn!!  It's 'wearing in'.

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xyzer

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Re: Offset Idler Bolt Feedback
« Reply #13 on: March 25, 2007, 05:33:32 AM »
I'll have to check mine with a .045 offset bolt in it. I like that method also, it can easily be repeated and it is a lot easier to do.  Also cleaner! If I have time I'll put the stock bolt back in and do a comparison.

Tom, Hotater
I checked it but have some questions....How are you checking the overlap stall (not sure what to call it). I had to use a dial indicator on the intake lifter and zero the indicator at the beginning of the stall, then mount one on the flywheel and measure the amount rotation of the flywheel to the point of intake movement again.  Is that how you are doing it? I found it hard to detect the neutral in the overlap unless I had an indicator on it. It is a fresh engine and it feels a tad stiff. It was hard to do a visual for me on the overlap.   
Dave
« Last Edit: March 25, 2007, 08:01:47 AM by xyzer »
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xyzer

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Re: Offset Idler Bolt Feedback
« Reply #14 on: March 25, 2007, 08:05:34 PM »
Tom, Hotater,
I went and did a good setup to check the backlash with the flywheel method. I find it hard to repeat my numbers but came up with .165" on a .045" added offset bolt. I used a indicator on the intake rocker and the flywheel. That was the only way I could get a fairly solid number. That stall spot in the overlap is quicker than the eye! I found it hard to do with certainty on a new motor. But it does give you a clue to what is going on without crawling inside! Put an indicator on the intake rocker and tell me what you find.
Dave
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