alternator lash problems

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stroker93
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alternator lash problems

#1

Post by stroker93 » Thu Mar 19, 2009 1:00 am

I have installed a mini alternator on my pan,,it takes the same gear as the genny but the lash is real sloppy. I'm not talking a few thou, buy 1/8. When building motor I had purchased all new gears for cam,drive,idler ect...Upon assembly the fit was terrible, the new shafts were fatter in center and the gears were too tight to roll over. The shafts were turned down to correct size and we mixed and matched used gears my builder had on hand til we got a free rolling gear set..I have tried a different size genny gear and just picked up a few used gears,,,so has anyone had this problem? Is it the bolt pattern on the alternator? an help would be great.
Dave



Cotten
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Re: alternator lash problems

#2

Post by Cotten » Thu Mar 19, 2009 2:45 pm

Dave!

It would take a psychic to sort out such a problem over a keyboard, but please explain: "... the new shafts were fatter in center and the gears were too tight to roll over. The shafts were turned down to correct size..."

Do you mean the shafts fit within the gears, but bound upon assembly into the case?
Or the shafts would not fit within the gear's bushings?

....Cotten

stroker93
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Re: alternator lash problems

#3

Post by stroker93 » Sat Mar 21, 2009 1:37 am

Sorry ,,it makes sense in my head ,,,just because I worked on it,,,,,
1st problem ....the shafts for the gears were fatter in the centers,,if you measured them,,,gears would not slide onto shafts.
That was an easy fix ,,,we turned them down
2nd,,when assembling idler ,drive gears found them tthe lash too tight to roll over...
swapped out "new" drive gear for old used gear,,,assembly rolled over nicely
3 and final ,,,The lash in the genny (mini alternator) is tooo sloppy 1/8 play,,,I have tried 13&14 tooth gears still to sloppy,,can't shiim
The entire bottom end is new except 1 gear(driven)..it is a mix of Andrews cam,S&S breather, S&S oil pump,HD pinion,Vtwindrive gear kit& shafts.
I have ordered a new gear to see if I can get the slop out of genny gear,,,,
like most cases it was cracked by the cam hole,,,it was welded by my guy,,he has jigs made for welding these cases,,not his 1st

Dave

mbskeam
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Re: alternator lash problems

#4

Post by mbskeam » Sat Mar 21, 2009 2:33 am

could the holes in the new mini alt be in the wrong place...
does the mini have a boss so that it cant move closer to the gear for proper lash?
turn the hub/lip if it does and see if you can slide it back to what you need, rotate mini and redrill holes in proper spot.....

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Re: alternator lash problems

#5

Post by Cotten » Sat Mar 21, 2009 1:39 pm

Dave!

I'm a little confused as to why you had the shafts turned instead of just honing the gear's replaceable bushings to fit.
(When extreme control of the gear's concentricity is necessary, they can be easily lathe-bored.)

Did they still press sweetly into the motorcase?
Are they now excessively loose in the cam cover bores?
Are you checking for gearbind with the cam cover installed?

At any rate,
If the accuracy of re-turning the shafts was real good,.. Let us say + or - .001",.. And the portion that presses into the case was not touched, then indexing of the shafts (rotating them in their holes) could bring the two shafts .002" closer together, or .002" farther apart.
If the accuracy was 'typical', this indexing variation could easily be .006"
If the entire length of the shafts were turned and they no longer fit the locating counterbores in the case and cover, the variation could be enormous.

Still, when the entire geartrain spins freely, but a huge gap to the generator(/alt) gear still exists, your spaceage gizmo gets the blame! Have you set a real generator into the assembly to compare the mesh?

Beware that many common repop generator gears are extremely loose upon the splines of the armatures; An OEM gear is usually much better even if it is worn.

Good luck!

....Cotten

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