What years TH400 look same as 72? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**General23cmp** · 08-21-2016, 12:26 PM

Swapping transmissions for a TH400. Wondering which years look correct and will connect (linkages, bolt to crossmember, vacuum, correct tail length, etc) like a factory BB TH400 1972 setup. Thanks.

**General23cmp** · 08-24-2016, 11:36 AM

anyone?

*randy500* · 08-24-2016, 11:45 AM

The transmission is the same as any year TH400 with a short tailshaft. A bolt on yoke can be removed and replaced with a slip in yoke. I think they had slip yokes, I am removing one later today and can send some pics if you like. The linkage is the TH400 only frame mount and middle piece. The selector "U" shaped piece bolted n the trans is the same as a TH350. I think mount spacers might be the same as TH350 too. The crossmember for automatics is same also. Rod from column I think is the same too.

**General23cmp** · 08-24-2016, 02:19 PM

Quote:

Originally Posted by randy500

.....The linkage is the TH400 only frame mount and middle piece. .....

Sounds like another part I will need. I currently have a TH350. Thanks.

*randy500* · 08-24-2016, 02:24 PM

The TH350 center piece of linkage will work, it just ends up at a bad angle, I have one like that now, 700R4 using TH400 linkage...If you decide to get the right parts let me know, I will be posting a for sale ad soon. I'm starting today to tear down a 3/4 Sierra Grande

**General23cmp** · 08-24-2016, 02:35 PM

Yes, let me know when you are posting the TH400 stuff. I'd like to do it right and get all I need to completely do it at once....providing the cost is reasonable. I could live with a slightly bad angle.

Are there special frame holes, etc. that have to be drilled or is that all the same between TH350/TH400?

**General23cmp** · 08-24-2016, 02:40 PM

I would really like pictures of the linkages and how/where they mount if you have them.

*randy500* · 08-24-2016, 03:07 PM

Send me your phone number and I will get some pics to you.

**70STOVEBOLT** · 08-24-2016, 04:19 PM

The frame should be drilled for either style frame pivot bracket. The pivot bracket is the only difference, the other parts of the linkage are the same for TH350 and TH400.

*randy500* · 08-24-2016, 04:35 PM

Quote:

Originally Posted by 70STOVEBOLT

The frame should be drilled for either style frame pivot bracket. The pivot bracket is the only difference, the other parts of the linkage are the same for TH350 and TH400.

Confirmed via stovebolt and much better said!

**General23cmp** · 08-24-2016, 04:36 PM

Quote:

Originally Posted by randy500

Send me your phone number and I will get some pics to you.

You have my number. I'm the seat screws guy. Thanks.

**General23cmp** · 08-25-2016, 08:47 AM

So is there a difference in the gas pedal, wiring, etc.? I hadn't been anticipating anything except shifter linkages and the like.

**70STOVEBOLT** · 08-25-2016, 08:56 AM

67-70 use a rod type throttle linkage, 71-72 use a cable. So that makes the gas pedal different. There are threads on here about changing from rod to cable. Also, 67-70 use a kickdown switch that is mounted on the carb and activated by the carb linkage. The 71-72 have the switch mounted on the gas pedal bracket and activated by the pedal arm. You will have to run a new wire for the kickdown switch from the fusebox to the switch, and one from the switch to the terminal on the LH side of the trans case.

**General23cmp** · 08-25-2016, 09:03 AM

Understand. Thanks. So for my application where I'm going from a 72 TH350 to a TH400, what about my pedal, etc. would have to change. I know the shifter linkages are different. I just wasn't tracking anything with the throttle side.

Does my TH350 pedal have a spot for a kickdown switch?

**70STOVEBOLT** · 08-25-2016, 09:08 AM

I do not think the TH350 throttle pedal bracket has a provision for the kickdown switch. If I am wrong, someone will correct me. I have a 70 so I had to convert mine from rod to cable, and I bought a complete pedal from the parts board that had a switch already on it.

**General23cmp** · 08-25-2016, 09:26 AM

That stinks. Man, the 700r4 is sounding better and better, but I wanted to stay true to the year.

08-21-2016, 12:26 PM	#1
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	What years TH400 look same as 72? Swapping transmissions for a TH400. Wondering which years look correct and will connect (linkages, bolt to crossmember, vacuum, correct tail length, etc) like a factory BB TH400 1972 setup. Thanks.

08-24-2016, 11:36 AM	#2
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? anyone?

08-24-2016, 11:45 AM	#3
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: What years TH400 look same as 72? The transmission is the same as any year TH400 with a short tailshaft. A bolt on yoke can be removed and replaced with a slip in yoke. I think they had slip yokes, I am removing one later today and can send some pics if you like. The linkage is the TH400 only frame mount and middle piece. The selector "U" shaped piece bolted n the trans is the same as a TH350. I think mount spacers might be the same as TH350 too. The crossmember for automatics is same also. Rod from column I think is the same too.

08-24-2016, 02:24 PM	#5
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: What years TH400 look same as 72? The TH350 center piece of linkage will work, it just ends up at a bad angle, I have one like that now, 700R4 using TH400 linkage...If you decide to get the right parts let me know, I will be posting a for sale ad soon. I'm starting today to tear down a 3/4 Sierra Grande

08-24-2016, 02:35 PM	#6
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? Yes, let me know when you are posting the TH400 stuff. I'd like to do it right and get all I need to completely do it at once....providing the cost is reasonable. I could live with a slightly bad angle. Are there special frame holes, etc. that have to be drilled or is that all the same between TH350/TH400?

08-24-2016, 02:40 PM	#7
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? I would really like pictures of the linkages and how/where they mount if you have them.

08-24-2016, 03:07 PM	#8
randy500 Account Suspended Join Date: Jul 2016 Location: Tacoma, WA Posts: 6,873	Re: What years TH400 look same as 72? Send me your phone number and I will get some pics to you.

08-24-2016, 04:19 PM	#9
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,360	Re: What years TH400 look same as 72? The frame should be drilled for either style frame pivot bracket. The pivot bracket is the only difference, the other parts of the linkage are the same for TH350 and TH400. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

08-25-2016, 08:47 AM	#12
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? So is there a difference in the gas pedal, wiring, etc.? I hadn't been anticipating anything except shifter linkages and the like.

08-25-2016, 08:56 AM	#13
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,360	Re: What years TH400 look same as 72? 67-70 use a rod type throttle linkage, 71-72 use a cable. So that makes the gas pedal different. There are threads on here about changing from rod to cable. Also, 67-70 use a kickdown switch that is mounted on the carb and activated by the carb linkage. The 71-72 have the switch mounted on the gas pedal bracket and activated by the pedal arm. You will have to run a new wire for the kickdown switch from the fusebox to the switch, and one from the switch to the terminal on the LH side of the trans case. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear Last edited by 70STOVEBOLT; 08-25-2016 at 08:58 AM. Reason: more info

08-25-2016, 09:03 AM	#14
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? Understand. Thanks. So for my application where I'm going from a 72 TH350 to a TH400, what about my pedal, etc. would have to change. I know the shifter linkages are different. I just wasn't tracking anything with the throttle side. Does my TH350 pedal have a spot for a kickdown switch?

08-25-2016, 09:08 AM	#15
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,360	Re: What years TH400 look same as 72? I do not think the TH350 throttle pedal bracket has a provision for the kickdown switch. If I am wrong, someone will correct me. I have a 70 so I had to convert mine from rod to cable, and I bought a complete pedal from the parts board that had a switch already on it. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

08-25-2016, 09:26 AM	#16
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 358	Re: What years TH400 look same as 72? That stinks. Man, the 700r4 is sounding better and better, but I wanted to stay true to the year.



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