Manual to Automatic Swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

FrankC · 04-07-2002, 05:20 AM

Thinking about swapping a blown 3 spd out for an automatic. Usually like to keep things original, but would like the convenience of the automatic,

Steering column, linkage, turbo 350 and driveshaft. Perhaps the tranny mount.

Do I need anything else?

**CPNE** · 04-07-2002, 06:03 AM

Crossmember, kickdown cable bracket, and auto dash harness for neutral/safety switch if you want that. Your 3 speed harness will work for backup lights but you'll be able to start it in drive.

------------------
Jeff Jesseman
Cheyenne Parts Northeast
Franconia, NH

67 Chevy SWB Fleetside
70 GMC Burb 1/2 ton 2wd
72 Chevy Burb 3/4 ton 4x4

Parts bought and sold

da-burb · 04-07-2002, 08:40 AM

Your drive shaft will be the correct one. I didn't have to change it going from 3sp manual to th350. The neutral safty switch can be easily wired in if you don't want to change harnesses. Otherwise your list and CPNE's additions pretty much cover everything.

------------------
1971 C-10 Suburban
1972 C-10 Suburban
1969 XL Galaxie Fastback
1968 Galaxie 500 Fastback
1974 SCOUT II

Montrose, Minnesota

FrankC · 04-07-2002, 08:41 AM

Thanks!

Hmmnn an extensive swap list. Perhaps that is why some people just go to a 4 spd on the floor.

Frank

Rod · 04-07-2002, 11:53 AM

The web site has had a tech articles page for many years. It was created so that member could post decent technical articles on some commonly asked question. I wrote a few articles a few years ago and they are still on the pages. You the members can created your own and have them posted by Josh the webmaster. We're willing to have your input... so have at it. We will list your name or user name as the author if you like.
Here's the link of the tech articles page http://67-72chevytrucks.com/tech/index.html and the link of the tech article on tranny swap to automatic.
http://67-72chevytrucks.com/tech/trannyswap.html
And here's that specific post on tranny swap.

Converting a Manual Transmission Pickup to an Automatic
By Rod
Find an automatic truck 67-72 for parts. Here's what you need. The automatic column, The linkage from the column to the trans, The bracket that mounts on the frame to support the shifter linkage. The 350 or 400 turbo trans with the six inch tail shaft. The kick down cable and the brackets that mount near the carb. Torque converter , flywheel, starter. Vacuum lines might as well grab the adapter for the line off the manifold. Some year trucks have a part of the outside wiring harness attaching to the tranny also. The front parts of the drive shaft ( take the whole thing) The cross member from the automatic, keep the four 9/16 bolts and the washers and nuts. Take the wiring harness inside and out this way you'll have the proper neutral safety wiring. If you want full gauges make sure the donor truck was full guage. The plug on the fire wall for an automatic that covers where the shiftboot for the standard clutch linkage goes through the fire wall. Keep the two screws also. Cut out the standard trans cross member, Grind off the rivet heads and knock them out its less obvious that its a conversion that way. Grind off the rivets for the cluth pedal shifter arm mounted on the frame to support the pivot shaft which mounts to the engine and take off that bracket. Start swapping in the parts you get from the donor. All parts will bolt in you dont have to drill or cut any holes else where. The tranny cooling lines and radiator from an automatic you will need also. Grab the speedometer cable too. Another thing is if your staying with a six cylinder or going to an eight or big block. The frame engine mounts are different between these. Grab them too.
Have fun :-)
Rod

04-07-2002, 05:20 AM	#1
FrankC Registered User Join Date: Sep 2001 Location: Raleigh, NC USA Posts: 155	Manual to Automatic Swap Thinking about swapping a blown 3 spd out for an automatic. Usually like to keep things original, but would like the convenience of the automatic, Steering column, linkage, turbo 350 and driveshaft. Perhaps the tranny mount. Do I need anything else? __________________ Thanks, Frank

04-07-2002, 06:03 AM	#2
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	Crossmember, kickdown cable bracket, and auto dash harness for neutral/safety switch if you want that. Your 3 speed harness will work for backup lights but you'll be able to start it in drive. ------------------ Jeff Jesseman Cheyenne Parts Northeast Franconia, NH 67 Chevy SWB Fleetside 70 GMC Burb 1/2 ton 2wd 72 Chevy Burb 3/4 ton 4x4 Parts bought and sold __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

04-07-2002, 08:40 AM	#3
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	Your drive shaft will be the correct one. I didn't have to change it going from 3sp manual to th350. The neutral safty switch can be easily wired in if you don't want to change harnesses. Otherwise your list and CPNE's additions pretty much cover everything. ------------------ 1971 C-10 Suburban 1972 C-10 Suburban 1969 XL Galaxie Fastback 1968 Galaxie 500 Fastback 1974 SCOUT II Montrose, Minnesota __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

04-07-2002, 08:41 AM	#4
FrankC Registered User Join Date: Sep 2001 Location: Raleigh, NC USA Posts: 155	Thanks! Hmmnn an extensive swap list. Perhaps that is why some people just go to a 4 spd on the floor. Frank __________________ Thanks, Frank

04-07-2002, 11:53 AM	#5
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	The web site has had a tech articles page for many years. It was created so that member could post decent technical articles on some commonly asked question. I wrote a few articles a few years ago and they are still on the pages. You the members can created your own and have them posted by Josh the webmaster. We're willing to have your input... so have at it. We will list your name or user name as the author if you like. Here's the link of the tech articles page http://67-72chevytrucks.com/tech/index.html and the link of the tech article on tranny swap to automatic. http://67-72chevytrucks.com/tech/trannyswap.html And here's that specific post on tranny swap. Converting a Manual Transmission Pickup to an Automatic By Rod Find an automatic truck 67-72 for parts. Here's what you need. The automatic column, The linkage from the column to the trans, The bracket that mounts on the frame to support the shifter linkage. The 350 or 400 turbo trans with the six inch tail shaft. The kick down cable and the brackets that mount near the carb. Torque converter , flywheel, starter. Vacuum lines might as well grab the adapter for the line off the manifold. Some year trucks have a part of the outside wiring harness attaching to the tranny also. The front parts of the drive shaft ( take the whole thing) The cross member from the automatic, keep the four 9/16 bolts and the washers and nuts. Take the wiring harness inside and out this way you'll have the proper neutral safety wiring. If you want full gauges make sure the donor truck was full guage. The plug on the fire wall for an automatic that covers where the shiftboot for the standard clutch linkage goes through the fire wall. Keep the two screws also. Cut out the standard trans cross member, Grind off the rivet heads and knock them out its less obvious that its a conversion that way. Grind off the rivets for the cluth pedal shifter arm mounted on the frame to support the pivot shaft which mounts to the engine and take off that bracket. Start swapping in the parts you get from the donor. All parts will bolt in you dont have to drill or cut any holes else where. The tranny cooling lines and radiator from an automatic you will need also. Grab the speedometer cable too. Another thing is if your staying with a six cylinder or going to an eight or big block. The frame engine mounts are different between these. Grab them too. Have fun :-) Rod __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.



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