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| Posted: Sat Jan 8th, 2011 03:21 pm |
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1st Post |
Darrell Kimball
Member
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Hey All,
I'm rebuilding a Mac 101B I bought on eBay, (mistake #1), the hardware was either mismatched or missing and the powerhead was held together with hi-temp silicone, but onto my issue:
The flywheel was grinding against the rear cover to where it wore away at one of the breaker box cover clips completely, as well as compromising the flywheel and the rear cover. I imagine it was the wrong flywheel. In the event it was something else, I'd like to know what to look for to avoid this from happening again.
Has anyone seen this before?
Thanks,
D
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| Posted: Sat Jan 8th, 2011 10:56 pm |
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2nd Post |
Chris Erb
Member
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Darrell, check the numbers stamped into the crankshaft. The previous owner could have installed the wrong one. You may have to remove both bearings from the crank to read all the numbers. Let me know what they are.
Chris
chrishol@sbcglobal.net
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| Posted: Sun Jan 9th, 2011 01:42 am |
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3rd Post |
Pete Cioruch
Member
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Darrell: If you have the wrong crank I can't help, but I do have a 101B flywheel and points end cover if they are badly damaged. 905-335-0314
Pete
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| Posted: Sun Jan 9th, 2011 06:48 pm |
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4th Post |
Darrell Kimball
Member
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Hey Pete,
Thanks for checking in. What's the best way to remove/replace the crank bearings? While they're off I wanted to replace them with ceramic hybrid bearings.
I appreciate the help,
D
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| Posted: Sun Jan 9th, 2011 07:07 pm |
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5th Post |
Ted Johnson
Member
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The Mac stock bearings have won many a national championship. Why waste your money? You'll never tell any performance difference.
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| Posted: Sun Jan 9th, 2011 08:51 pm |
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6th Post |
David Luciani
Administrator
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Darrel,
first determine why you chewed up the cover.
as far as i can tell there's no way that should happen.
the flywheels are interchangable on the mc motors when you get to the 101 series.
older motors did have relieved backs for clearance but the 101's don't have that problem as far as i know.
if you have an incorrect crank it'll be a mc91 style which will be longer and move the flywheel out away from the block.
you might have an older crank but they're all about the same length wise.
if the crank is badly modified or bent you'll need to replace that before anything else.
as far as the hybrid bearings -- WHY???.
i'm assuming you haven't much experience with mcculloch engines so please forgive me if i'm wrong.
for all i know you many have years of modifying experience and have a great plan.
i'm assuming you're trying to improve the seemingly "loose" bearings with a tighter more persisely built bearing.
so first,if you're concerned about the seemly low toleranced bearings that are loose don't be as they are supposed to be that way.
the correct bearings for the engine are loose when cold and as heat and friction build swell slightly .
not much though because you want a loose free turning bearing in a motor turning roughly twice as fast as original design specs
also that set up that has been tested and withstood stupid stresses in the worst possible conditions.
something that as exhibition racers you wouldn't be doing anyway.
just my two cents
dave
btw removing bearings is easy.
just support the crank and tap the old bearings off with a soft brass hammer.
if you have a press protect the threads support the bearing and push out the crank.
on vka site Scott wrote a whole article about rebuilding mccullochs that applies to all of them
D
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| Posted: Mon Jan 10th, 2011 03:18 am |
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7th Post |
Darrell Kimball
Member
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Hey Dave,
Just to clarify, I received the Mac in its present state - FUBAR! I just didn't know how messed up it was until I tore it down.
Now the real joy begins, I don't have a brass hammer so I used a small claw hammer and a piece of hardwood, and sure enough, the outer ring of the bearing gave way, leaving the inner ring on the crank; and I recovered (11) of the (13) ball bearings.
I've since sprayed the area with WD while I figure out how to remove the inner ring and the second bearing. Either these things have been on the crank for a really long time or they were over-zealously forced on because they aren't budging. A series of taps from a brass hammer is not going to break these free.
Any suggestions are greatly appreciated. Also, I can send along some pics.
Thanks and regards,
D
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| Posted: Mon Jan 10th, 2011 12:37 pm |
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8th Post |
Ted Johnson
Member
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Darrell, it SOMETIMES helps to put the crank in the oven at 300 degrees for a half hour before tapping. The crank MAY not expand as much as the bearing race does. If you tap on the end of the crank, put a nut on, flush with the end of the threads so you don't bugger up your threads. Bearing removers are available at Harbor Freight (cheap). On my KL100, I finally had to notch the inner race with a cutoff wheel in the Dremel, then, while supporting the race, I split it with a hammer and chisel. Didn't harm the crank at all. Attachment: image_735.jpg (Downloaded 55 times)
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| Posted: Mon Jan 10th, 2011 01:08 pm |
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9th Post |
David Luciani
Administrator
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Hey Darrell,
"fred" really Ted is right about heating.
it may just be slightly corroded and stuck good.
if you heat and cool it in the freezer for a couple of cycles you may be able to loosen the dang thing up.
otherwise careful dremel work will do the job as ted/fred said.
i made a rymie there!!!
HEHEHE
seriously if it gives you too much trouble stop by or send it and i'll help you out.
dave
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| Posted: Mon Jan 10th, 2011 01:50 pm |
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10th Post |
Darrell Kimball
Member
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Thanks Dave,
I'll give it a lash! First, pick up a bearing remover for which Tederick/Fredodore was kind enough to post a pic, thank you.
As far as parts, I'm 90+% there, the following is what I need for the 101B:
- Back Cover
- Flywheel
- Breaker Box Cover Clips
- 68886/88845 Big Bore Carb
Also interestingly, the powerhead came w/o a clutch or nut on the PTO end, but it appears to be a RH thread. According to MacBobAust, ALL Mac 101's have LH PTO threads. I'll confirm this shortly.
If I encounter serious hardship I'd definitely like to take you up on your offer. I don't want to overstep, but if possible, I'd box the whole motor up and see about getting it finished over there. All the cast parts have been blasted and prepped. With the right tools and workspace, (of which I have little) putting this Bad Larry together should go smoothly, especially with seasoned tutelage.
Best,
D
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| Posted: Mon Jan 10th, 2011 02:08 pm |
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11th Post |
David Luciani
Administrator
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hi Darrel,
you REALLY NEED to id that crank.
sounds like you have an "assembled" from bits motor.
as i said the mccullochs have a big rate of interchange but that's not always a good thing.
the numbers you want will be stamped on the side of the counterwt. on the crank outside portion.
they're usually hid behind the bearing a little but you've removed the part that would normally obscure them.
once you have that number check it against mcbobs list.
don't panic if it's not there as some cranks have different number to designate bead blasting or whatever.
you also might have an aftermarket crank so ask away if the numbers are weird.
dave
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| Posted: Mon Jan 10th, 2011 02:48 pm |
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| Posted: Mon Jan 10th, 2011 04:16 pm |
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| Posted: Mon Jan 10th, 2011 04:41 pm |
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