Rear Diff questions? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

phlegm · 06-17-2005, 07:04 PM

I have a couple of questions.

There is still a red tag (which worries me because I dont know many mechanics that put those back on after working) on what I think is the fill valve on the top psg.side of the diff. it tells me to use posi fluid. Is this the right place?

The bolt is round with a square interior, I am guessing I can get a ratchet on it?

I noticed I have a hose coming out of the top of the diff that goes along the frame over to the side of the truck and dead ends. Its open on the end. what is this for?

I do not have a owners manual and could not find the proper weight of gear oil in my haynes manual. What should I use?

fastwillie 696969 · 06-17-2005, 07:15 PM

yes you can use a 3/8 ratch to get the pipe plug off to top off the diff.
and the hose on top is a vent for the rear diff. its ok with nuthing at the end of the hose

jamesi20 · 06-17-2005, 07:18 PM

The hose is a vent I don't know about bolt as I don't have an original posi

phlegm · 06-17-2005, 07:21 PM

Cool, thanks guys,

anyone with insight about the gear lube weight?

fastwillie 696969 · 06-17-2005, 07:26 PM

i would a synthic gear oil like 80/140 for a posi rear end

Longhorn Man · 06-17-2005, 07:49 PM

Agreed

Americanrider · 06-18-2005, 03:46 AM

I would highly recommend that you find a nearby 4x4 shop and get a Diff Breather cap on the end of that line. It will keep the dust, dirt & moisture out of that expensive posi. Think of it as a few dollars worth of protection.

71-longbed · 06-18-2005, 05:37 AM

what brand of posi ??

phlegm · 06-20-2005, 12:42 AM

Thanks rider, I will look for one soon, I didnt like it just hanging there either.

Not sure on the brand Posi, it is stock so whatever they were putting on them in 71.

I got it wrapped up late friday night, and went ahead with the 80/90. I had a call from the wife @ 10.30 my mother in law went in the ER. I had no choice but to put it back with what they gave me @ carquest. Luckily I found the specs in my Haynes book tonight and it matched. At any rate, I got back to my truck to day and the leak is gone!!

Next up I get really over my head and change the fluid in the manual, and try to find the oil leak from the rear of the block (hopefully the gasket on the manual, the block was supposed to be rebuilt 30 k ago!)

06-17-2005, 07:04 PM	#1
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Rear Diff questions? I have a couple of questions. There is still a red tag (which worries me because I dont know many mechanics that put those back on after working) on what I think is the fill valve on the top psg.side of the diff. it tells me to use posi fluid. Is this the right place? The bolt is round with a square interior, I am guessing I can get a ratchet on it? I noticed I have a hose coming out of the top of the diff that goes along the frame over to the side of the truck and dead ends. Its open on the end. what is this for? I do not have a owners manual and could not find the proper weight of gear oil in my haynes manual. What should I use? __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

06-17-2005, 07:15 PM	#2
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	yes you can use a 3/8 ratch to get the pipe plug off to top off the diff. and the hose on top is a vent for the rear diff. its ok with nuthing at the end of the hose __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

06-17-2005, 07:21 PM	#4
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Cool, thanks guys, anyone with insight about the gear lube weight? __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was

06-17-2005, 07:26 PM	#5
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	i would a synthic gear oil like 80/140 for a posi rear end __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

06-18-2005, 05:37 AM	#8
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	what brand of posi ?? __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

06-17-2005, 07:18 PM	#3
jamesi20 Senior Member Join Date: May 2002 Location: NORTHEAST OHIO Posts: 494	The hose is a vent I don't know about bolt as I don't have an original posi

06-17-2005, 07:49 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Agreed

06-18-2005, 03:46 AM	#7
Americanrider Registered User Join Date: Dec 2004 Location: NW, WA. Posts: 1,421	I would highly recommend that you find a nearby 4x4 shop and get a Diff Breather cap on the end of that line. It will keep the dust, dirt & moisture out of that expensive posi. Think of it as a few dollars worth of protection.

06-20-2005, 12:42 AM	#9
phlegm Still Green but learning Join Date: Nov 2004 Location: Central NC Posts: 1,895	Thanks rider, I will look for one soon, I didnt like it just hanging there either. Not sure on the brand Posi, it is stock so whatever they were putting on them in 71. I got it wrapped up late friday night, and went ahead with the 80/90. I had a call from the wife @ 10.30 my mother in law went in the ER. I had no choice but to put it back with what they gave me @ carquest. Luckily I found the specs in my Haynes book tonight and it matched. At any rate, I got back to my truck to day and the leak is gone!! Next up I get really over my head and change the fluid in the manual, and try to find the oil leak from the rear of the block (hopefully the gasket on the manual, the block was supposed to be rebuilt 30 k ago!) __________________ -- Cory 71 Cheyenne 10 - SWB, 350, "3 on the tree" AC cab 07 Suburban LTZ 4x4 2010 Acura TL 98 Mastercraft "FrankenStar" 225 27253 UPS/USPS IIOY....nope never was



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