Tranny lines ( what size ) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sam's 72 · 07-09-2004, 12:31 AM

I am wanting to order some fittings for my tranny lines. I am out at work tonight, and don't have the lines in front of me. I would like to know what size the fittings are that screw into the tranny, and what size is the fittings that screw into to radiator. Can not remember if they are 3/8 NPT or 1/2 NPT. What I am going to do is run areoequiped hoses from tranny to radator, I already have the hose, just need to know what the fitting size is. This is a 700r4, before I pulled my engine out, I had a th350. The stock lines fit perfect to the 700r4. Can some one help me out tonight with this. would like to get the order in tonight.
Sam

*1972C10* · 07-09-2004, 01:34 AM

3/8

krue · 07-09-2004, 02:04 AM

I just replaced the lines on my Th350 and used 5/16 brake line. The way I bent mine a 5ft piece wit great for the top line and was about a foot too long for the bottom line.
Good luck with it.

Bowtie67 · 07-09-2004, 07:26 AM

I believe mine where 3/8, I also used russel fittings and then made up my own lines using braided lines with the russel fittings so that they can be eaily taken on and off. I also made out of aluminum a junction block that mounted to the frame so if I have to pull the trans out I can just disconnect the 2 lines right there and be done with it in about 2 minutes.

JimKshortstep4x4 · 07-09-2004, 09:59 AM

Original transmission cooler lines are 5/16".

Jim

*1972C10* · 07-10-2004, 03:03 AM

He was talking about the cooler line fitting ports. On the side of the trans case itself

sam's 72 · 07-10-2004, 03:12 AM

I am talking about the fitting ports on the tranny, and the fitting ports on the radaitor. I don't really need the line size. Planning on running 3/8" lines. I still need this info. So is the fitting ports 3/8" npt on tranny and radaitor. Or is it 1/4" on tranny and radaitor? I did not have time to go by the shop where my truck is at today to check it out. I have it at a friend of mine shop.
Sam

*1972C10* · 07-10-2004, 03:15 AM

are you talking about the flare adaptor size? its a 5/16 flare nut they make adaptors to go from male flare to threads ..

What kinda lines are you putting back on it?

sam's 72 · 07-10-2004, 03:38 AM

I have some socketless Aeroquip hose left over from plumbing up my fuel line. So, I am going to use this for my tranny lines. I need to know what size are the fittings that screw into the radaitor. I need to know what size the fittings are that screw into the tranny. Planning on buying either russell fittings or Aeroquip fittings for this. So I need to know what size they are. They will either be 3/8" or 1/4". Am I missing something here?
Sam

krue · 07-10-2004, 05:15 AM

The radiator threads I believe are 5/8 fine thread. They are not pipe threads, they aren't deep enough. If you want to know exactly what they are look at the fitting on the end of a piece of 5/16 brake line at your local parts store.

JimKshortstep4x4 · 07-10-2004, 07:31 AM

The radiator female fitting is a 5/16 female flare, (threads are 7/16-20 fine thread).

The transmission case is tapped for a 1/2-20 fine thread fitting with a gasket surface machined for sealing the fitting. A gasketed adapter for the 5/16 male flare screws into the transmission.

In the pic, the transmission fitting is on the left and a 5/16 male flare fitting is on the right. If you are adapting a larger line, than an adapter to a 5/16 flare fitting might be the easy way to go.

Jim

07-09-2004, 12:31 AM	#1
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	Tranny lines ( what size ) I am wanting to order some fittings for my tranny lines. I am out at work tonight, and don't have the lines in front of me. I would like to know what size the fittings are that screw into the tranny, and what size is the fittings that screw into to radiator. Can not remember if they are 3/8 NPT or 1/2 NPT. What I am going to do is run areoequiped hoses from tranny to radator, I already have the hose, just need to know what the fitting size is. This is a 700r4, before I pulled my engine out, I had a th350. The stock lines fit perfect to the 700r4. Can some one help me out tonight with this. would like to get the order in tonight. Sam __________________ 72 LWB chevy truck. Pasadena, Texas

07-09-2004, 02:04 AM	#3
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	I just replaced the lines on my Th350 and used 5/16 brake line. The way I bent mine a 5ft piece wit great for the top line and was about a foot too long for the bottom line. Good luck with it. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

07-09-2004, 07:26 AM	#4
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	I believe mine where 3/8, I also used russel fittings and then made up my own lines using braided lines with the russel fittings so that they can be eaily taken on and off. I also made out of aluminum a junction block that mounted to the frame so if I have to pull the trans out I can just disconnect the 2 lines right there and be done with it in about 2 minutes. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

07-10-2004, 03:12 AM	#7
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	I am talking about the fitting ports on the tranny, and the fitting ports on the radaitor. I don't really need the line size. Planning on running 3/8" lines. I still need this info. So is the fitting ports 3/8" npt on tranny and radaitor. Or is it 1/4" on tranny and radaitor? I did not have time to go by the shop where my truck is at today to check it out. I have it at a friend of mine shop. Sam __________________ 72 LWB chevy truck. Pasadena, Texas

07-10-2004, 03:38 AM	#9
sam's 72 Senior Member Join Date: Nov 2001 Location: Pasadena, Texas, USA Posts: 1,005	I have some socketless Aeroquip hose left over from plumbing up my fuel line. So, I am going to use this for my tranny lines. I need to know what size are the fittings that screw into the radaitor. I need to know what size the fittings are that screw into the tranny. Planning on buying either russell fittings or Aeroquip fittings for this. So I need to know what size they are. They will either be 3/8" or 1/4". Am I missing something here? Sam __________________ 72 LWB chevy truck. Pasadena, Texas

07-09-2004, 01:34 AM	#2
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	3/8

07-09-2004, 09:59 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Original transmission cooler lines are 5/16". Jim

07-10-2004, 03:03 AM	#6
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	He was talking about the cooler line fitting ports. On the side of the trans case itself

07-10-2004, 03:15 AM	#8
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	are you talking about the flare adaptor size? its a 5/16 flare nut they make adaptors to go from male flare to threads .. What kinda lines are you putting back on it?

07-10-2004, 05:15 AM	#10
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	The radiator threads I believe are 5/8 fine thread. They are not pipe threads, they aren't deep enough. If you want to know exactly what they are look at the fitting on the end of a piece of 5/16 brake line at your local parts store. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

07-10-2004, 07:31 AM	#11
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The radiator female fitting is a 5/16 female flare, (threads are 7/16-20 fine thread). The transmission case is tapped for a 1/2-20 fine thread fitting with a gasket surface machined for sealing the fitting. A gasketed adapter for the 5/16 male flare screws into the transmission. In the pic, the transmission fitting is on the left and a 5/16 male flare fitting is on the right. If you are adapting a larger line, than an adapter to a 5/16 flare fitting might be the easy way to go. Jim Attached Images



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