Help Differential dilemma - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bob.workman@shaw.ca · 07-14-2021, 08:10 AM

I have acquired 2 10 bolt 8.5 differentials with most of the parts in a basket.

My problem is there is no way I can tell which parts (most importantly, the bearing caps) came from which diff.

Two of the caps are labeled L and R but which case does it match?

How do I assemble these parts and get everything properly set up?

burnin oil · 07-14-2021, 09:20 AM

If noone has a better way this what I would try. Install the labeled caps the housing and torque them in place. If they didn't fit into place or there is a ridge where they meet then I would call them the wrong set and try the other caps the same way. I am guessing that a boring bar of some sort or a long setup bar through the entire housing to check run out is the proper method. That is a tool I am guessing that most of us don't have.

BASE · 07-14-2021, 03:30 PM

I've always kinda wondered how far off one would be if the caps were switched, but I never think to flip 'em around and see when I have one apart.

I would try and see if you can feel a ridge in there like mentioned above. You may get lucky and have them be far enough off that you can notice. If you have some telescoping gauges you could measure at appropriately clocked angles it might help. If there isn't some sort of measurable offset than maybe it doesn't matter.

I've wondered what I would do if in that spot and that's the best I've been able to come up with.

**kwmech** · 07-19-2021, 11:43 AM

Are the caps stamped with the letters? Pics of the caps and diff face

bob.workman@shaw.ca · 07-21-2021, 11:52 AM

So after vigorous cleaning I did find letters on 2nd set of caps.
I tried your suggestion and one set of caps is definitely not aligning so
it seems the other which does seem to align ok must be the right ones.

Thanks for the suggestion.

bob.workman@shaw.ca · 07-21-2021, 12:08 PM

here are some pics. as mentioned in previous post one set of caps are clearly misaligned, you can feel the difference when you put the caps on finger tight.
The other set does seem to fit. Short of having the diff line bored I will try using these.

Thank all for input
Bob

**kwmech** · 07-23-2021, 02:04 AM

clean off the rusted surface of the housing and see if there is a corresponding mark or stamp

07-14-2021, 08:10 AM	#1
bob.workman@shaw.ca Registered User Join Date: Jul 2018 Location: Winnipeg, Manitobe, Canada Posts: 3	Help Differential dilemma I have acquired 2 10 bolt 8.5 differentials with most of the parts in a basket. My problem is there is no way I can tell which parts (most importantly, the bearing caps) came from which diff. Two of the caps are labeled L and R but which case does it match? How do I assemble these parts and get everything properly set up?

07-14-2021, 09:20 AM	#2
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,921	Re: Help Differential dilemma If noone has a better way this what I would try. Install the labeled caps the housing and torque them in place. If they didn't fit into place or there is a ridge where they meet then I would call them the wrong set and try the other caps the same way. I am guessing that a boring bar of some sort or a long setup bar through the entire housing to check run out is the proper method. That is a tool I am guessing that most of us don't have.

07-14-2021, 03:30 PM	#3
BASE Registered User Join Date: Oct 2016 Location: St Louis, MO Posts: 194	Re: Help Differential dilemma I've always kinda wondered how far off one would be if the caps were switched, but I never think to flip 'em around and see when I have one apart. I would try and see if you can feel a ridge in there like mentioned above. You may get lucky and have them be far enough off that you can notice. If you have some telescoping gauges you could measure at appropriately clocked angles it might help. If there isn't some sort of measurable offset than maybe it doesn't matter. I've wondered what I would do if in that spot and that's the best I've been able to come up with.

07-19-2021, 11:43 AM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,637	Re: Help Differential dilemma Are the caps stamped with the letters? Pics of the caps and diff face

07-21-2021, 11:52 AM	#5
bob.workman@shaw.ca Registered User Join Date: Jul 2018 Location: Winnipeg, Manitobe, Canada Posts: 3	Re: Help Differential dilemma So after vigorous cleaning I did find letters on 2nd set of caps. I tried your suggestion and one set of caps is definitely not aligning so it seems the other which does seem to align ok must be the right ones. Thanks for the suggestion.

07-21-2021, 12:08 PM	#6
bob.workman@shaw.ca Registered User Join Date: Jul 2018 Location: Winnipeg, Manitobe, Canada Posts: 3	Re: Help Differential dilemma here are some pics. as mentioned in previous post one set of caps are clearly misaligned, you can feel the difference when you put the caps on finger tight. The other set does seem to fit. Short of having the diff line bored I will try using these. Thank all for input Bob Attached Images

07-23-2021, 02:04 AM	#7
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,637	Re: Help Differential dilemma clean off the rusted surface of the housing and see if there is a corresponding mark or stamp



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