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Author Topic: Reinstalling Starter  (Read 3194 times)
Lin
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« on: July 27, 2010, 09:34:40 AM »

I believe my starter is dragging. I have gone through everything I can think of to avoid removing it, but that's what I had to do.  It is a 40 MT, I have it off now, but it was really difficult.  All three bolts required a cheater bar to start.  One required multiple bars totaling over six foot and a lot of time trying.  When it comes to reinstalling it, should it be cheater bar tight?  I have a 150# torque wrench, but I am not even sure I could get it in place for all three bolts.
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bevans6
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« Reply #1 on: July 27, 2010, 09:52:21 AM »

What grade, size and thread type are the bolts?  If you have that info, we can find a torque for you.

Brian
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Lin
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« Reply #2 on: July 27, 2010, 09:58:57 AM »

Brian,

I do not know that info exactly.  I assume that they are special for this application.  They are 5/8 bolts with a collar and then a 5/8 12-point head.  I am sure that they are hardened.  Otherwise, those cheater bars would have done some real damage.
« Last Edit: July 27, 2010, 10:05:30 AM by Lin » Logged

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bevans6
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« Reply #3 on: July 27, 2010, 11:24:50 AM »

They are probably around the same as SAE Grade 8, or possibly SHCS (socket head cap screws, otherwise referred to as "Allen" bolts).  A torque around 180 ft lbs is probably adequate if the bolt threads are fairly dry, if lubricated about half that.  Torque call-outs often have specific lubrication (or lack thereof) requirements, what you really need to do is to stretch the bolt enough to make it lock in place and resist vibration.  The real goal is to stretch it to create a load of 75% of it's failure load.

Holo-krome (a high quality SHCS) calls out 283 ft lbs for coarse thread, 317 ft lbs for fine thread, SAE grade 8 212 ft lbs for coarse, SAE grade 5 186 flt lbs for coarse.  I am suggesting a little lower because the threads are probably not going to be perfectly dry, and you probably aren't going to have perfect washers under the heads and all that.

if you can find a number in a manual, all the better.  In the real world, people have just been doing them up as tight as they can and calling it good for forever. 

Hope this helps a little bit, anyway.

Brian
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gus
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« Reply #4 on: July 27, 2010, 04:54:51 PM »

Lin,

That cheater bar stuff sounds like too much to me. Anyway, bolts/nuts almost always take a lot more torque to remove than to install.

Any 2-stroke DD book should have the starter bolt torque specs.

I presume this is a 8V71??
« Last Edit: July 27, 2010, 05:42:47 PM by gus » Logged

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Lin
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« Reply #5 on: July 27, 2010, 05:33:59 PM »

Gus,

Usually I assume the the bolts have become harder to loosen with time.  However, since I know that the starter was off about 300 miles ago, I was wondering if they had been made that tight on purpose.   I guess I will get them as tight as a can with the wrench and then just add a little more for good luck.
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« Reply #6 on: July 27, 2010, 05:43:04 PM »

My 671 maint manual starter section says it is a 5/8"-11 bolt which takes 137-147 lb-ft. If it happens to be a 5/8-18 it takes 169-178.

These specs are for anything above grade 5 which, I'm sure, includes all DD bolts.
« Last Edit: July 27, 2010, 05:50:59 PM by gus » Logged

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Chopper Scott
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« Reply #7 on: July 27, 2010, 05:56:25 PM »

Torque specs are a lot different with an extension. I always go by the rule of "goodntight" on application such as this. You will be fine. Just use common sense.
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« Reply #8 on: July 27, 2010, 06:23:54 PM »

Chopper,

Extensions don't have any effect on torque specs, torque is torque no matter how you do it.
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« Reply #9 on: July 27, 2010, 06:59:19 PM »

Sorry Gus but you are wrong. Not trying to start anything. Just don't want wrong advise being given out.
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« Reply #10 on: July 27, 2010, 09:30:09 PM »

settle down, we need a definition of "extension" before you two start hurling...

Lin, with the suspected abuse you describe, give those bolts a little clean off on the wire wheel, then run them into place by hand before putting the starter up, to be sure they go in easy and smooth.

You want to be sure the threads are not damaged. If the bolts don't go in nicely, you want replacements, and/or a tap to run the holes.

happy coaching!
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Lin
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« Reply #11 on: July 27, 2010, 10:51:32 PM »

BW,

I will run them in and out first as you suggest.  I think they should be alright since, once broken and loosened a couple of turns, they did turn easily by hand.
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« Reply #12 on: July 28, 2010, 05:02:50 AM »

Lin,

When I installed my starter 3 years ago I just used a wrench and got it as tight as I could. One bolt at the rear was a real pain to get to. It hasn't fallen off yet. Wink Just get it as tight as you can, you should be fine. The hardest part was lifting it into place! Grin
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« Reply #13 on: July 28, 2010, 10:21:20 AM »

When you are not sure of or cannot torque to spec, the best course of action is to recheck regularly. Amazing how many other problems you can head off when you snoop around on a regular basis.

Good luck
Don 4107
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kyle4501
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« Reply #14 on: July 28, 2010, 12:37:39 PM »

. . . . .Just get it as tight as you can, you should be fine. . . . .

Be careful following that advice. Tapped holes in cast iron will strip out.
What you want to do is get as close to the specifications (found in the proper manual) as practical. We all know what too loose or over tightened will do - sucess lies with the number in da' book.

My guess as to why they were so hard to get off is that the threads are dry & are slightly distorted from previous abuses which ads to the friction retaining it.

You won't necessarily need a torque wrench, but you should get them properly tightened but not over tight.

Have fun!  Grin
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