BE 12 bolt questions
 

Is there a different part number (from a stock 4.10 gearset) stamped into the ring and pinion on a BE COPO 12 bolt gear set? If so, what is it?

Thanks,
-Matt

Re: BE 12 bolt questions
 

The 4:10 ring & pinion gear part #3917971 is what Chevrolet used on the BE COPO.

Re: BE 12 bolt questions
 

"Is there a different part number (from a stock 4.10 gearset) stamped into the ring and pinion on a BE COPO 12 bolt gear set? If so, what is it?".....................the standard ring and pinion in a 410 axle is #526 and #528, while the copo 410 gears are #226 and #228..

Re: BE 12 bolt questions
 

It should look like this:

http://i10.photobucket.com/albums/a1.../RingGear2.jpg

Re: BE 12 bolt questions
 

https://www.yenko.net/ubbthreads/ubbt...p;Number=20330

Per Ed Cunneen:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The part number for the 4.10 set was 3917971.
The ring and pinion part numbers are as follows:
3916226 Ring Gear 3916228 Pinion Gear
Case part number was 3916234 </div></div>

Re: BE 12 bolt questions
 

Ok.... so it looks like I have a set of these gears that came with a 174 posi unit I bought back in October. They have been sitting on the shelf ever since. How do I tell if the posi unit is a COPO unit without taking it apart?

Re: BE 12 bolt questions
 

Here are some photos of what I picked up.

http://i373.photobucket.com/albums/o...o/DSC07049.jpg
http://i373.photobucket.com/albums/o...o/DSC07050.jpg
http://i373.photobucket.com/albums/o...o/DSC07051.jpg
http://i373.photobucket.com/albums/o...o/DSC07052.jpg
http://i373.photobucket.com/albums/o...o/DSC07053.jpg

Re: BE 12 bolt questions
 

I think the correct side gears have no 'flange' on the sides facing the clutch plates. Hard to tell from your picture.

Re: BE 12 bolt questions
 

Matt,
That is a standard duty 4-series unit, based on the posted pictures.
Here is a #234 unit to compare.

Re: BE 12 bolt questions
 

How about the difference in the dates..5-69 and 1-70?..did the factory gears come in sets??..I have a standard 4 10 gear set in my COPO and both gears have the sama date..just curious and do not want to diminish the value of these gears..oh and by the way [img]<<GRAEMLIN_URL>>/Can-I-Have-It.gif[/img] [img]<<GRAEMLIN_URL>>/beers.gif[/img]

Albert

Re: BE 12 bolt questions
 

Alright so the posi unit is just a standard unit. Guess I am going to separate the gears from it.

I was also puzzled by the date spread Albert.

Re: BE 12 bolt questions
 

The date difference is fine as long as the gears are a mated (lapped) pair/set.

When the gears were made, they were produced in equal order quantities. I'll use 100 for the example, as it was explained to me.
The gear plant created an orders for 100 pinions and 100 rings.
During production one more of the ring gears got damaged/scrapped. So there would be extra pinions.
The extra pinions sit in surplus until:
1) An extra ring becomes available from a later production run, do to damaged pinions, to allow a set to be paired/lapped.
2) Enough of them piled up justify a balancing order quantity to be produced.

I was told that the r&amp;p sets only left production as paired/lapped sets.

I have several NOS and used sets that are mixed dates. I think the largest spacing I have is from 11 67 to 5 68 for a 3917971 r&amp;p set.
Hope this helps.
Eric

Re: BE 12 bolt questions
 

Yes this is a matched set out of the same rear end.

Thanks for the information guys!

Re: BE 12 bolt questions
 

Wile we’re on the subject of COPO ring and pinion gears. This is a set of what I believe to be 4:56 COPO gears. I got these with an 0428 BE. My question is why the difference in the stampings and the location of the stamping on this set of COPO gears vs the set shown in the previous pictures. Was this a service replacement set. Eric, anybody, any idea.

http://texasbuiltmusclecars.com/Copo/pin.JPG

http://texasbuiltmusclecars.com/Copo/ring.JPG

Re: BE 12 bolt questions
 

Rick,
Yes those are COPO 4.56 gears p/n 3917973.
They are service dated gears from 1975.
From what I have been able to determine anout the different makings and locactions is that gears like these were made at a different plant than the original production gears.
Here is a set of COPO 4.10s from 1974. that match your 4.56s.
I will post pictures of the different markings that I have found this weekend.