Locking Differential?
January 7th, 2018, 12:58 PM
#41
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Well,I just went through the Detroit Locker app chart, and while they list the GM 8.6, it's under the "3/4 ton" heading, and we know I've got bigger "hands" than that. So, it looks like I don't get the traction I want. At least until I hit the lottery.
January 7th, 2018, 1:58 PM
#44
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easiest way pull off one of your covers on the rear wheels
the one like I have that I changed to GMC
they have the 7/8 plastic lug nuts
take that off take a pic... and see if its like mine.
the one like I have that I changed to GMC
they have the 7/8 plastic lug nuts
take that off take a pic... and see if its like mine.
January 7th, 2018, 2:01 PM
#45
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You're gonna make me go outside AGAIN? 
From what I'm reading, I'd think it's FF, because apparently semi's max out at around 4500lbs GAVW, and my rear GAVW is 6084 lbs. But you'd know better than I.
From what I'm reading, I'd think it's FF, because apparently semi's max out at around 4500lbs GAVW, and my rear GAVW is 6084 lbs. But you'd know better than I.
January 7th, 2018, 2:29 PM
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Missed my Chance
I missed my chance.... there is a RED extended Express in the junk yard...it has a 3.73 ratio FF
well it did... I went back last week... and well the rear end is now GONE.. I would have never
had thought.. all I would have had to do was remove and replace
opportunity lost... lol
well it did... I went back last week... and well the rear end is now GONE.. I would have never
had thought.. all I would have had to do was remove and replace
opportunity lost... lol
January 7th, 2018, 4:10 PM
#48
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With all the vans in this yard, there isn't one with the FF 3.73? It doesn't have to be RED. But you'd have to get the brakes and related parts. And here is where mods like this need to be documented, so when you need brake pads, you know what year/model the brakes came off of.
But again, why would Chevy NOT use a FF rear on a 3500?
But again, why would Chevy NOT use a FF rear on a 3500?
January 7th, 2018, 5:03 PM
#49
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Teammuir1, in regards to the rear axles: The semi-floating (SF) is Dana 60S, the full-floating (FF) is Dana 70S. Besides obviously telilng the difference by the protruding axle bolts, each axle has a sticker, that tells if it's 60S/70S and if it's a STD/LOC (open vs locking differential). The RPO codes don't tell if you will have a SF or FF axle, but they do tell if it's a G80 (locking diff).
To be fair, both axles are very stout. I had over 300k miles on my stock SF axle with 0 issues, over 100k of said mileage towing at GCW of 18k. lbs or higher. Replacing the axle is easy. If you have Stabilitrak, make sure the replacement axle also has it (or you will not be able to connect the rear wheel speed sensors and ABS light will always be on). If changing the gear ratio, the PCM will need to be reprogrammed in order for proper speedometer readings. I have changed mine from 3.73 SF to 4.10 FF, due to heavy towing my van does.
From probably 10-15 different 2002-2016 Express vans, between all the engine, wheelbase and cargo/passenger options I have had my hands on during the last years, I have yet to discover the logic behind how GM factory picks the axle. It just seems random to me. Here I go:
2002 Express 3500, extended 8.1 cargo van - FF
2002 Savana 3500, extended 8.1 cargo van - FF
2002 Express 3500, extended 8.1 passenger van - FF (all pre-2002 were drum brakes).
2003 Express 3500, short 6.0 cargo van - FF
2004 Express 3500, extended, 6.0 passenger van - FF
2005 Express 3500, extended, 6.0 passenger van - FF
2006 Express 3500, extended, 6.0 cargo van - SF
2006 Savana 3500, extended 6.0 passenger van (my original red van) - SF
2007 Express 3500, extended 6.6 Duramax cargo van - FF
2008 Express 2500, extended 6.6 Duramax cargo van - SF
2008 Express 3500, short 6.0 cargo van - SF
2009 Express 3500, extended 6.6 Duramax cargo van - FF
2012 Express 3500, extended 6.0 passenger van - SF
2015 Express 3500, extended 6.6 Duramax cargo van - FF
2016 Express 3500, extended 6.6 Duramax cargo van - FF
2016 Express 3500, extended 6.0 cargo van - SF
To be fair, both axles are very stout. I had over 300k miles on my stock SF axle with 0 issues, over 100k of said mileage towing at GCW of 18k. lbs or higher. Replacing the axle is easy. If you have Stabilitrak, make sure the replacement axle also has it (or you will not be able to connect the rear wheel speed sensors and ABS light will always be on). If changing the gear ratio, the PCM will need to be reprogrammed in order for proper speedometer readings. I have changed mine from 3.73 SF to 4.10 FF, due to heavy towing my van does.
From probably 10-15 different 2002-2016 Express vans, between all the engine, wheelbase and cargo/passenger options I have had my hands on during the last years, I have yet to discover the logic behind how GM factory picks the axle. It just seems random to me. Here I go:
2002 Express 3500, extended 8.1 cargo van - FF
2002 Savana 3500, extended 8.1 cargo van - FF
2002 Express 3500, extended 8.1 passenger van - FF (all pre-2002 were drum brakes).
2003 Express 3500, short 6.0 cargo van - FF
2004 Express 3500, extended, 6.0 passenger van - FF
2005 Express 3500, extended, 6.0 passenger van - FF
2006 Express 3500, extended, 6.0 cargo van - SF
2006 Savana 3500, extended 6.0 passenger van (my original red van) - SF
2007 Express 3500, extended 6.6 Duramax cargo van - FF
2008 Express 2500, extended 6.6 Duramax cargo van - SF
2008 Express 3500, short 6.0 cargo van - SF
2009 Express 3500, extended 6.6 Duramax cargo van - FF
2012 Express 3500, extended 6.0 passenger van - SF
2015 Express 3500, extended 6.6 Duramax cargo van - FF
2016 Express 3500, extended 6.6 Duramax cargo van - FF
2016 Express 3500, extended 6.0 cargo van - SF
he says there is NO rime nor reason as to what GM did
with installing rear axles in vans.
I would not suspect that you had a FF cause I too have
a 3500 series... and I have a SF.. with disapointment to find out
so I will prolly be upgrading my rear Axle... when I find one.
you mention about changing out parts.. that would not be
needed my rear axle has rear discs... I would not buy a rear axle
with drum brakes I was just wanting the FF
I would like to stay 3.73 gear as well. all I am saying about that RED
van in the yard was it was just like mine RED.. I know that it does not
have to be a RED one lol but that one had rear disc brakes like mine does.
January 7th, 2018, 6:05 PM
#50
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You do know I'm just yankin' your chain on the red thing, right?
In looking at the pics, it seems to me that if you upgrade to an FF, wouldn't that necessitate changing out the hub, and by doing that, need a different caliper? The disc in the two pics you posted look different in diameter. Arties drilled and slotted disc look like they have more surface (wider) than yours.
I could be wrong. Wouldn't be the first or last time.
In looking at the pics, it seems to me that if you upgrade to an FF, wouldn't that necessitate changing out the hub, and by doing that, need a different caliper? The disc in the two pics you posted look different in diameter. Arties drilled and slotted disc look like they have more surface (wider) than yours.
I could be wrong. Wouldn't be the first or last time.