Factory Tolerance Buildup=Trouble - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 10-11-2000, 11:49 AM Thread Starter
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Factory Tolerance Buildup=Trouble

[img]/wwwthreads_images/icons/tongue.gif[/img] There is a recent post about a noisy starter that the Jeeper cannot seem to get to shut up and stop eating the flywheel. You need to be aware that there IS an opportunity for ALLOWABLE MANUFACTURING TOLERANCES to all build up in the same direction and move things enough such that they will not work very well. A "Lemon" is simply an auto that "happens" when the largest bore that is allowable and the smallest pistons that are allowable meet in a dark corner of the engine assembly room. Or when the engine with the most Total Indicated Runout on the flat surface where the bellhousing attaches meets up with the bellhousing that happens to have the most non-parallel surfaces and they are off IN THE SAME DIRECTION. PRESTO! A "lemon" and a life-long problem child is born.[img]/wwwthreads_images/icons/smile.gif[/img] I could not even count the number of times I have been assembling a big vertical hollow shaft electric motor and the shaft was way off to one side. We would rotate the motor 180 degreees and presto.....the shaft is in the center. Sometimes it would take shims in all the right places, however, just like a bellhousing that is machined crooked.[img]/wwwthreads_images/icons/crazy.gif[/img]

CJDave
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post #2 of (permalink) Old 10-11-2000, 12:12 PM
 
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Re: Factory Tolerance Buildup=Trouble

Did you ever notice what the "knee jerk" reaction of the people who had the bad luck to buy one of those lemons? They blame the assembly line workers most times....where it is probably those "tolerances" you spoke of. However, I can't think of a practical solution....building each car one part at a time would be very costly and very unprofitable.[img]/wwwthreads_images/icons/crazy.gif[/img]

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post #3 of (permalink) Old 10-11-2000, 12:28 PM
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Re: Factory Tolerance Buildup=Trouble

Exactly, so in reaction to this problem "blueprinting" was born.

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post #4 of (permalink) Old 10-11-2000, 01:21 PM
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Re: Factory Tolerance Buildup=Trouble

Hey Dave, a funny story that goes along with what you were saying, just kinda opposite. When I was fixing that oil leak I was working on a few weeks ago, I went under to drop the starter so I can drop the pan. Now, the engine has been needing to crank over excessively before it fires (still haven't gotten motivation to set the choke). But when I noticed the starter, it had a full 1/4" gap between it and the bellhousing, and it was hanging off at an angle [img]/wwwthreads_images/icons/shocked.gif[/img]!!!!! Immediately fearing worn / broken / or warped ring gear teeth, I pulled the starter to find... nothing. Everything looked fine on both sets of teeth, and a full check of the ring gear didn't show any unusual wear... Its now securely bolted back and gets checked regularly. Funny thing was, it never missed a start, the bendix never didn't engadge, it didn't chew up, etc... Must've been lucky.

'77 CJ-5: 304/T-150/D-20 F-D44 R-9" Power 4 wheel disk, 36X12.5 swampers
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post #5 of (permalink) Old 10-11-2000, 04:35 PM
 
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Re: Factory Tolerance Buildup=Trouble

Just in case anyone is interested, a stock engine, built by hand, and allowing NOTHING in the give or take category, every rod bearing perfect, or as close to perfect as we can possibly get it, crank bearings the same, all combustion chambers the same, ect... Ect....
Will cost you around $10,000.
If you want ANY goodies, all those are extra.

The time it takes to machine and match parts is incredible.
The average small block that rolls out the door here will have about 300 man hours in it, and that's using all the time saving machinery we can fit through the door!

Just one of the average machines we have is about $30,000 to $50,000.
You need a crank grinder, a boring machine with cradle/ table (not a boring 'bar' like the use on tractors), a head mill with full size table, about $60,000 in machine tooling, a honing machine, a flow bench, and a dyno, a balancing machine, and two cleaning stations one has to be an 'acid' tank, and that's just the MINIMUM to do the job correctly.
---------------------------------

And finding someone that can read a micrometer, AND do simple math so we can start training him is almost impossible.
There is a reason they can't find good help at the local Burger Doodle... the last two crops of kids are morons, and they are loosing ground every day...
And they want to be turned loose on $500,000 worth of machinery the first day, and they can't even do simple addition? But their resume says they have an engineering degree?
Am I missing something?

We pay our help well, but sometimes I wonder how I'm going to replace the older guys when they retire...
I'll probably just sell the business and let the next guy worry about it....
---------------------------------


When I run into loud ford style starters, I just slap a couple of washers under the mounting ears. If that quiets the starter down, then I go get a shim made for the ford style starter....
They come in thicknesses from about 0.030" to about 1/2" thick.
If you try to run the starter with washers under the mounting ears for very long, you will learn a valuable and expensive lesson....
----------------------------------

If his starter was hanging off the block by just 1/4" of bolts... How the hell did it get enough ground to function?
That had to be hard on the armature and commutator....


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post #6 of (permalink) Old 10-11-2000, 04:46 PM
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Re: Factory Tolerance Buildup=Trouble

To be honest, I have no clue how MY starter was functioning.. It was just kinda hanging there, and the bolts were finger loose... It works the exact same now as before, and when it goes, I'll get another from PepBoys. If they won't return it, I'll exchange one where I work... [img]/wwwthreads_images/icons/crazy.gif[/img]

'77 CJ-5: 304/T-150/D-20 F-D44 R-9" Power 4 wheel disk, 36X12.5 swampers
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post #7 of (permalink) Old 10-11-2000, 05:51 PM
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Re: Factory Tolerance Buildup=Trouble

i had a similar problem. i didn't notice my starter was loose until the first bolt had already fallen out and the second one was loose enough to cause the teeth to make noise. a couple of lock washers did the trick.

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post #8 of (permalink) Old 10-11-2000, 11:37 PM
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Re: Factory Tolerance Buildup=Trouble

The HELL YOU WILL, GEORGE!!! NOW I KNOW! And you cant have $hit, we're closed. Of course you can have another starter. Just peel the sticker off yours, swear up and down that you bought it at work, and i'll give you another one. Heck, you dont even have to swear, just say those 4 important words: "I didnt Need This!!" Or better yet, "I dont need this ANYMORE!!"

hehehehe
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