4spd Manual to Th400 swap.. Info / Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

groundbound64 · 03-06-2013, 09:55 PM

Hey Guys/Gals,

I'm thinking about swapping my 4spd manual for a TH400. Just wanted to see if anyone has advice or has done this before. I've got a line on a new rebuilt Th400 with convertor. I assume i'll need a new trans-crossmember, cooler lines with aux. cooler or new rad, starter ??? ( no sure if manual will work on auto) and probably have to cut driveshaft or have a longer one made up and shifter linkage through floor.. Did I leave anything out ???

**MikeN** · 03-07-2013, 09:26 AM

I'm planning the same swap in a few months. I think you have it covered. You will definitely need a new starter if you're currently using the bellhousing mounted started like I'm using on my 3-speed manual.

groundbound64 · 03-07-2013, 09:45 AM

I think your right.. I replaced my starter last year.. Now I rememeber that when I replaced my starter they parts store gave me one for an automatic and it didn't fit.. So.. maybe I will need one..

414banger · 03-07-2013, 03:11 PM

just did the same swap i went the cheap route and used the crossmember where the parking brake mechanism is located i tool it off fipped it over and bolted it to bottom of frame it worked perfect and motor was level and ye driveshaft will have to be shortened around 6 inches if i remember right goodluck to ya

kieth · 03-08-2013, 10:47 AM

What are you trying to accomplish with the TH400, just going automatic, or do you have a high HP ride for drag racing. If you are trying to accomplish better overall performance on the highway go to a 700r4 you will drop your rpms 30% cruising down the highway......Kieth

BigDan3131 · 03-09-2013, 03:26 AM

Either the 700R4 or a 200R4 for better mileage. The 400 is heavy and eats up horsepower.

koda360 · 03-12-2013, 01:58 PM

... But if you really wanna do it, I'll trade you my TH400 and tublar crossmember for you're 4speed... just sayn...

61_FL_Apache · 03-12-2013, 04:57 PM

I would vote for the 700R4.

groundbound64 · 03-12-2013, 06:52 PM

Quote:

Originally Posted by kieth

What are you trying to accomplish with the TH400, just going automatic, or do you have a high HP ride for drag racing. If you are trying to accomplish better overall performance on the highway go to a 700r4 you will drop your rpms 30% cruising down the highway......Kieth

I'm just not liking the manual on the truck. Plus when I run at 100kph (60mph) it's reving pretty high.. wanted to switch to auto for the convenience. My truck is not high HP.. going to be low and slow but would like to hear myself think inside.. Maybe i'll ask the guy about 700r. I know he has th300and th400's ..

groundbound64 · 03-12-2013, 06:55 PM

Quote:

Originally Posted by koda360

... But if you really wanna do it, I'll trade you my TH400 and tublar crossmember for you're 4speed... just sayn...

Ha, If you were alittle closer i'd probably consider it.. but 12hr drive for a swap is a little long..

groundbound64 · 03-12-2013, 06:57 PM

Quote:

Originally Posted by kieth

What are you trying to accomplish with the TH400, just going automatic, or do you have a high HP ride for drag racing. If you are trying to accomplish better overall performance on the highway go to a 700r4 you will drop your rpms 30% cruising down the highway......Kieth

Is there much difference in the install/parts of the 700r over the TH400 ?

kieth · 03-13-2013, 10:26 AM

NOT MUCH,

1. shorten driveline

2. get a manual drive gear to replace the electronic pulse speedo hook up

3. get a kit that allows use of the TV cable and electric switch for the Od shift.

4. crossmember

others here will know more than me, I installed a later model engine/700r4 combo so I had all the parts I needed except for the speedo drive.

03-06-2013, 09:55 PM	#1
groundbound64 Registered User Join Date: Oct 2012 Location: Greely, On, Canada Posts: 89	4spd Manual to Th400 swap.. Info / Help Hey Guys/Gals, I'm thinking about swapping my 4spd manual for a TH400. Just wanted to see if anyone has advice or has done this before. I've got a line on a new rebuilt Th400 with convertor. I assume i'll need a new trans-crossmember, cooler lines with aux. cooler or new rad, starter ??? ( no sure if manual will work on auto) and probably have to cut driveshaft or have a longer one made up and shifter linkage through floor.. Did I leave anything out ???

03-07-2013, 09:26 AM	#2
MikeN Senior Member Join Date: Oct 2007 Location: Marietta, GA Posts: 782	Re: 4spd Manual to Th400 swap.. Info / Help I'm planning the same swap in a few months. I think you have it covered. You will definitely need a new starter if you're currently using the bellhousing mounted started like I'm using on my 3-speed manual.

03-07-2013, 09:45 AM	#3
groundbound64 Registered User Join Date: Oct 2012 Location: Greely, On, Canada Posts: 89	Re: 4spd Manual to Th400 swap.. Info / Help I think your right.. I replaced my starter last year.. Now I rememeber that when I replaced my starter they parts store gave me one for an automatic and it didn't fit.. So.. maybe I will need one..

03-07-2013, 03:11 PM	#4
414banger Registered User Join Date: Jun 2012 Location: jackson, ohio Posts: 304	Re: 4spd Manual to Th400 swap.. Info / Help just did the same swap i went the cheap route and used the crossmember where the parking brake mechanism is located i tool it off fipped it over and bolted it to bottom of frame it worked perfect and motor was level and ye driveshaft will have to be shortened around 6 inches if i remember right goodluck to ya

03-08-2013, 10:47 AM	#5
kieth Registered User Join Date: Sep 2010 Location: Tulsa, Oklahoma Posts: 1,925	Re: 4spd Manual to Th400 swap.. Info / Help What are you trying to accomplish with the TH400, just going automatic, or do you have a high HP ride for drag racing. If you are trying to accomplish better overall performance on the highway go to a 700r4 you will drop your rpms 30% cruising down the highway......Kieth

03-09-2013, 03:26 AM	#6
BigDan3131 Registered User Join Date: Jun 2006 Location: Maple Valley, WA Posts: 1,913	Re: 4spd Manual to Th400 swap.. Info / Help Either the 700R4 or a 200R4 for better mileage. The 400 is heavy and eats up horsepower. __________________ Custom Painter/Restoration Specialist 1965 GMC 3/4 Ton LB SOLD? 1964 Chevy El Camino in full restoration 1991 Chevy S10 288K+ miles 2nd Owner SOLD 2020 RAM 1500 Warlock

03-12-2013, 01:58 PM	#7
koda360 Registered User Join Date: Nov 2011 Location: White Cottage, Oh. Posts: 99	Re: 4spd Manual to Th400 swap.. Info / Help ... But if you really wanna do it, I'll trade you my TH400 and tublar crossmember for you're 4speed... just sayn... __________________ 1960 C-10 2000 Dakota R/T 1966 Fury I 2dr post 1984 Big Bronco 2002 Durango SLT (Bride's Ride)

03-12-2013, 04:57 PM	#8
61_FL_Apache Who Me? Join Date: Sep 2010 Location: Royal Palm Beach, FL Posts: 4,067	Re: 4spd Manual to Th400 swap.. Info / Help I would vote for the 700R4. __________________ Steve 1997 Tahoe LT 4D 2WD (DD) 2001 Blazer 4D 2WD 1961 Apache 10 (sold) 1965 C10 Stepper (sold)

03-13-2013, 10:26 AM	#12
kieth Registered User Join Date: Sep 2010 Location: Tulsa, Oklahoma Posts: 1,925	Re: 4spd Manual to Th400 swap.. Info / Help NOT MUCH, 1. shorten driveline 2. get a manual drive gear to replace the electronic pulse speedo hook up 3. get a kit that allows use of the TV cable and electric switch for the Od shift. 4. crossmember others here will know more than me, I installed a later model engine/700r4 combo so I had all the parts I needed except for the speedo drive.



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