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GundyGuy
 Post subject: Diff Assembly
PostPosted: Sat Jan 14, 2017 12:52 pm 
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Has anyone ever bothered to check the run out on the two bearing spigots after assembling a diff centre
That is after bolting the large driven gear to the spider gear housing
Bit of a trick to do but my one isn't behaving very well as in run-out
Or is this just BMC Quality

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sitnlo62
 Post subject: Re: Diff Assembly
PostPosted: Sat Jan 14, 2017 7:33 pm 
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How much runout do you have?

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Sun Jan 15, 2017 6:29 am 
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sitnlo62 wrote:
How much runout do you have?

it varies as to where i put the crown wheel
0.010" in one position
i moved it 2 holes and its down to 0.003"
I am using a new cross pin centre so i can dial in the hub next to the crown wheel

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sitnlo62
 Post subject: Re: Diff Assembly
PostPosted: Sun Jan 15, 2017 9:17 pm 
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i moved it 2 holes and its down to 0.003

You have got to be happy with that??

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Mon Jan 16, 2017 5:19 am 
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sitnlo62 wrote:
i moved it 2 holes and its down to 0.003

You have got to be happy with that??


No not really
1/2 thou might be ok

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drmini in aust
 Post subject: Re: Diff Assembly
PostPosted: Mon Jan 16, 2017 6:11 am 
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It's a helical gear, so lateral runout is not as critical as a spiral bevel or hypoid gear set.
And it's a 2 piece hemisphere, normal diffs are 1 piece. So tolerances stack up. Maybe worse with an aftermarket gear.
I think you are being a bit critical considering its design.... ;)

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Mon Jan 16, 2017 10:25 am 
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Not really
I am looking at it from an engineering view point
Close enough isn't good enough
If there was a little bit of clearance I could dial the 2 halves in and get it perfect

Sent from my HTC_PN071 using Tapatalk

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Mon Jan 16, 2017 4:53 pm 
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Problem fixed
Took about 5 mins to do and achieved zero run out
Engineering as it should be

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Phil 850
 Post subject: Re: Diff Assembly
PostPosted: Mon Jan 16, 2017 8:21 pm 
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GundyGuy wrote:
Problem fixed
Took about 5 mins to do and achieved zero run out
Engineering as it should be

What did you do to get it to Zero ?

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Tue Jan 17, 2017 5:10 pm 
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I took a few thou off the stem of the bolts and thats all it took to get it to behave

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Phil 850
 Post subject: Re: Diff Assembly
PostPosted: Tue Jan 17, 2017 7:50 pm 
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So the unthreaded part of the bolt just under the head was pulling it out of position !

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GundyGuy
 Post subject: Re: Diff Assembly
PostPosted: Wed Jan 18, 2017 5:16 am 
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Thats correct
the bolts were all different sizes
so i made them all the same
only about 3 thou between them
but enough to cause a problem

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