TH350 Cooling Line Fittings

Chad E532 · 12-21-2009, 05:12 PM

Does anyone out there know of a source of a fitting that will thread into a stock TH350 transmission case and get me to a -6AN male fitting? The case has an odd thread that I believe is a 1/2" BSPP thread. From the factory there were brass adapters in the ports to connect to the steel tubing with an inverted flare fitting which I am currently using to get me to -6AN hose but it takes too many connections (possible leak points) so I want to clean up the plumbing and install some quick disconnect fittings on the trans lines, but all the kits that are available that I have seen either have 1/4" or 1/8" npt threads which will not work in this application.
Thanks
Chad

Tom Goldman · 12-21-2009, 05:34 PM

ATI has the proper fittings you need . #6an x straight thread ,with a gasket seal .....You can find them from Parker hydraulics in steel,if you have a counterman willing to take the time to look it up for you. .....Tom

Jim Kaekel · 12-22-2009, 05:11 PM

Tom is correct, the ATI fittings are the best way to go. Most people use 1/4" NPT pipe to -6AN adapters, but be very careful tightening them.

njk53 · 12-23-2009, 09:20 AM

Is the thread for the trans. line on a stock 350 case a 1/4 NPT?

Jim Kaekel · 12-23-2009, 12:36 PM

Yes, the TH-350 is 1/4" NPT, as is the TH-400. I think all NPT to AN adapters made by Aeroquip, Earls, etc. are tapered NPT, rather than the OEM which is not tapered and uses a sealing washer. You can definitely crack the case if one of these type of adapters is over tightened due to the fact it is tapered.

Chad E532 · 12-23-2009, 01:42 PM

I talked with ATI tech and they have 1/4"-18 fittings that have the straight thread that is in my case. The pitch is 18 just like 1/4" NPT but it is straight. I found that there is a NPS (National Pipe Straight) thread that is used on low pressure hydraulics.
Thanks,
Chad

12-21-2009, 05:12 PM	#1
Chad E532 Member Join Date: Jul 2008 Location: Lindstrom MN Posts: 156 Likes: 5 Liked 54 Times in 7 Posts	TH350 Cooling Line Fittings Does anyone out there know of a source of a fitting that will thread into a stock TH350 transmission case and get me to a -6AN male fitting? The case has an odd thread that I believe is a 1/2" BSPP thread. From the factory there were brass adapters in the ports to connect to the steel tubing with an inverted flare fitting which I am currently using to get me to -6AN hose but it takes too many connections (possible leak points) so I want to clean up the plumbing and install some quick disconnect fittings on the trans lines, but all the kits that are available that I have seen either have 1/4" or 1/8" npt threads which will not work in this application. Thanks Chad

12-21-2009, 05:34 PM	#2
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,436 Likes: 776 Liked 700 Times in 204 Posts	Re: TH350 Cooling Line Fittings ATI has the proper fittings you need . #6an x straight thread ,with a gasket seal .....You can find them from Parker hydraulics in steel,if you have a counterman willing to take the time to look it up for you. .....Tom __________________ Tom Goldman 1500 SG , 1506 STK

12-22-2009, 05:11 PM	#3
Jim Kaekel VIP Member Join Date: Jul 2002 Location: Michigan Posts: 1,222 Likes: 134 Liked 498 Times in 104 Posts	Re: TH350 Cooling Line Fittings Tom is correct, the ATI fittings are the best way to go. Most people use 1/4" NPT pipe to -6AN adapters, but be very careful tightening them. __________________ Jim Kaekel 3836 STK

12-23-2009, 09:20 AM	#4
njk53 Senior Member Join Date: Jul 2007 Location: East China, MI Posts: 504 Likes: 0 Liked 0 Times in 0 Posts	Re: TH350 Cooling Line Fittings Is the thread for the trans. line on a stock 350 case a 1/4 NPT? __________________ Nelson Kowal Stock 345

12-23-2009, 12:36 PM	#5
Jim Kaekel VIP Member Join Date: Jul 2002 Location: Michigan Posts: 1,222 Likes: 134 Liked 498 Times in 104 Posts	Re: TH350 Cooling Line Fittings Yes, the TH-350 is 1/4" NPT, as is the TH-400. I think all NPT to AN adapters made by Aeroquip, Earls, etc. are tapered NPT, rather than the OEM which is not tapered and uses a sealing washer. You can definitely crack the case if one of these type of adapters is over tightened due to the fact it is tapered. __________________ Jim Kaekel 3836 STK

12-23-2009, 01:42 PM	#6
Chad E532 Member Join Date: Jul 2008 Location: Lindstrom MN Posts: 156 Likes: 5 Liked 54 Times in 7 Posts	Re: TH350 Cooling Line Fittings I talked with ATI tech and they have 1/4"-18 fittings that have the straight thread that is in my case. The pitch is 18 just like 1/4" NPT but it is straight. I found that there is a NPS (National Pipe Straight) thread that is used on low pressure hydraulics. Thanks, Chad Last edited by Chad E532; 12-23-2009 at 01:46 PM.