700R4 swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Guff · 09-30-2004, 12:17 PM

What parts do I need to swap a 700R4 transmission in place of a 69 TH350 on a 69 small block? As I understand it, the 700R4 will bolt in place of the th350 and use the same yoke, I just may need to move the crossmember a little. I guess the 700R4 is only 1/16 or 1/8 inch longer than a th350 with a long tailshaft, so I won't need a different drive shaft? Do I need different shifter linkage? What years had the mechanical speedometer cable? I've been told 700r4's from 4x4's are stronger than other 700r4's but they are the same dimensions, is that true? Should I only look for fullsize truck transmissions or are camaro/firebird/s10 tranmissions ok too? How much should I expect to pay for a working 700r4? I know that's a lot of questions, but it seems like a lot of people do this swap, I just wonder how difficult it is.

71swb4x4 · 09-30-2004, 01:40 PM

I am pretty sure the 700r4 is 1 3/4 inches longer and you will have to shorten the driveshaft. I have a 700r4 from an 86 IROC and it has a mechanical speedo. Not sure what years have it after that though.

Tx Firefighter · 09-30-2004, 02:03 PM

The 9 inch Turbo 350 is the same length as the 700r4 is . I've swapped a bunch of them around. Yoke and driveshaft will reuse directly

On my old trucks, I reuse the stock linkage. Only difference is that it won't pull all the way down into 1st gear with the shift lever.

I use van 700r4s usually, because they kept the mechanical cable speedometer much later than pickups did.

Be sure and get the TV cable geometry and adjustment dialed in properly so you don't melt your overdrive tranny down.

Guff · 09-30-2004, 02:10 PM

Thanks Tx, what other parts will I need if any? Isn't there a wiring plug for controlling torque converter lockup? Also, what kind of bracket(s) do I need for the tv cable. My kickdown cable is currently unhooked because the PO put on an edelbrock intake but didn't get the kickdown bracket.

silvertonguedevil · 09-30-2004, 02:19 PM

Great topic! I will be approaching this obstacle here soon too.

chickenwing · 09-30-2004, 02:40 PM

http://207.44.196.117/vboard/showthread.php3?t=33266 Here's something from the FAQ's. I used the tv cable kit from www.700r4.com , but it is not necessary. I've got the install done but need to play some more with the tv cable....it hunts real bad between 3rd and 4th on part throttle.

neonlarry · 09-30-2004, 03:53 PM

Forget the Cameros and Firebirds unless you want to change the tail shaft.

5150 · 10-10-2004, 10:56 AM

How about late 80's-early 90's Caprice's?

**guyryan100** · 10-10-2004, 01:12 PM

I was thinking that you need to stay below '86 or so to avoid computers. BTW, I have to change my yoke in switching from a 3speed to the 700r4. New tranny has 30 teeth, old had 8. The drive shaft will have to be shortened 1.5 inches or so, and that's with my engine in the forward position.

Tx Firefighter · 10-10-2004, 01:22 PM

Quote:

Originally Posted by guyryan100

I was thinking that you need to stay below '86 or so to avoid computers. BTW, I have to change my yoke in switching from a 3speed to the 700r4. New tranny has 30 teeth, old had 8. The drive shaft will have to be shortened 1.5 inches or so, and that's with my engine in the forward position.

If you have a Turbo 350 now and are swapping to a 700R4, the yokes are the same. Who ever told you different is wrong. I've done the swap way too many times personally.

Look in Vans and Suburbans for your new trans. They used cable type speedometers much later than pickup trucks did. No computer controlled 700R4 transmissions until 1992 or 93, depending on application. Then, it was called a 4L60E and has a huge wiring harness that plugs into the transmission.

Gordo · 10-10-2004, 07:07 PM

You will need the metric bolts for such items as the torque converter, trans mount to tail housing and nut for linkage stud.

**GSFMECH** · 10-10-2004, 07:24 PM

Great topic. Even if you have a trans with the elect speedo you can swap out the parts from an older 700R4 with a mechanical speedo and make it work. I saw a thread on here or somewhere about it. To enable shifting into all of the gears all you have to do is check where the rod coming from the column attaches into the cross shaft and drill another hole about a 1/2" closer to the selector shaft and attach your rod into it. This changes the geometry (the angle of the dangle) and will give you more swing with your shifter and you can get all the gears. If you have an older 700R4 with the rear mount cast into the tailshaft housing you can use the turbo 400 position to mount your rear crossmember. Most of the later 700's have the mount in the trans case directly behind the pan and you will have to drill new holes in the frame using this mount.Hope this helps.
Mike

shade67 · 10-10-2004, 08:33 PM

hold the phone on not hooking up the tv cable, it controls the amount of pressure to the plates and clutches- not hooking it up or not getting it right will cause a really early departure of trans. also there is the matter of the lockup torque converter if not wired up it will not lockup in od which also kills it because it will not cool enough! thats a quote from my trans expert friend! you can get the parts to make it lockup cheaply or buy the kit for around $70

**guyryan100** · 10-10-2004, 09:41 PM

Quote:

Originally Posted by Tx Firefighter

If you have a Turbo 350 now and are swapping to a 700R4, the yokes are the same. Who ever told you different is wrong. I've done the swap way too many times personally.

I'm sure that's true. Going form the 3spd manual, though, required a yoke transplant in my truck.

Longhorn Man · 10-10-2004, 10:43 PM

There is quite a bit written in the FAQ on this topic...more in detail than listed on this thread...and some links with real good reading. Enough to keep you ocupied for the rest of the evening.

grayw0lf · 10-11-2004, 08:51 AM

GSFMECH,

Good one on drilling the hole for the selector 1/2" up from the original spot to allow shifting down into 1st gear. I've been reading for weeks, but I've not heard a solution for that yet.

**John Fabris** · 10-11-2004, 11:37 AM

Just wondering if anyone has had any trouble with the 700r4 tranny hitting the flange at the bottom of the cab firewall? I did a test fit, and my cab was sitting on the tranny. Looked to be about 1/2 inch too high.

72MARIO · 10-11-2004, 05:09 PM

I have heard about someone else having that problem with the firewall hittting the tranny. Is you Motor in the 6 CYL position ? I think that's where you run into the problem or mabye just the odd cab was built a little bit diffirent.

How is your truck coming along ?

Later , Mario

Longhorn Man · 10-11-2004, 05:34 PM

is it a big block engine in a small block truck? How are the cab mounts?

1-PU70 · 10-11-2004, 06:04 PM

I but a BB and a 700R4 in a low hump cab and have lots of room.

Longhorn Man · 10-11-2004, 06:10 PM

Which towers did you use, the 67 - 71, or the 72 towers...did you use the tranny mount spacer that keeps the drive shaft geomitry in line, or did you mount it directly to the cross member. Was it a 1/2 ton 2 wheel drive, or something else?

Lots of variables in the big block fitting in a low hump cab.

chickenwing · 10-11-2004, 06:14 PM

Quote:

Originally Posted by Longhorn Man

...did you use the tranny mount spacer that keeps the drive shaft geomitry in line, or did you mount it directly to the cross member...
Lots of variables in the big block fitting in a low hump cab.

I have a 72 c20, 350cu, had a turbo 350. I left the spacer out. Don't feel anything wrong, was that the wrong thing to do?

1-PU70 · 10-11-2004, 06:16 PM

Its a 1/2 ton LWB with coils. Used 72 mounts. And useda turbo 350 trans mount I think. No real problems. Used original cross member just muved it a little and drilled new holes. As fare as im concerned its a streight bolt in.

Longhorn Man · 10-11-2004, 06:41 PM

Quote:

Originally Posted by chickenwing

I have a 72 c20, 350cu, had a turbo 350. I left the spacer out. Don't feel anything wrong, was that the wrong thing to do?

A small block truck doesn't have the spacer I am refering to...I was refering to 1-PU70's respomce of havng plenty of room.

Quote:

Originally Posted by 1-PU70

Its a 1/2 ton LWB with coils. Used 72 mounts. And useda turbo 350 trans mount I think. No real problems. Used original cross member just muved it a little and drilled new holes. As fare as im concerned its a streight bolt in.

The 72 mounts hold the engine a little lower IIRC, plus, if you don't have the big block spacer inder your tranny mount, then there is another inch or so clearance.

Tx Firefighter · 10-11-2004, 07:14 PM

I've used 67-71 mounts on mine with plenty of room. Every truck I've ever owned has been a small hump truck. There is plenty of room even with a 700R4.

If it's hitting, you need to look at replacing your cab mounts. When I first put my 454 into my low hump truck I have now, it hit the bottom of the cab. New cab mounts raised it right up. Now, I can slide my hand between the trans and cab in all spots.

Yes, I run the trans mount spacer too.

09-30-2004, 12:17 PM	#1
Guff Registered User Join Date: Feb 2002 Location: illinois Posts: 78	700R4 swap What parts do I need to swap a 700R4 transmission in place of a 69 TH350 on a 69 small block? As I understand it, the 700R4 will bolt in place of the th350 and use the same yoke, I just may need to move the crossmember a little. I guess the 700R4 is only 1/16 or 1/8 inch longer than a th350 with a long tailshaft, so I won't need a different drive shaft? Do I need different shifter linkage? What years had the mechanical speedometer cable? I've been told 700r4's from 4x4's are stronger than other 700r4's but they are the same dimensions, is that true? Should I only look for fullsize truck transmissions or are camaro/firebird/s10 tranmissions ok too? How much should I expect to pay for a working 700r4? I know that's a lot of questions, but it seems like a lot of people do this swap, I just wonder how difficult it is. __________________ -Guff 1969 C10 LWB, 350, 700R4, 3.73 gears

09-30-2004, 01:40 PM	#2
71swb4x4 Senior Member Join Date: Nov 2003 Location: Brookings, SD Posts: 10,497	I am pretty sure the 700r4 is 1 3/4 inches longer and you will have to shorten the driveshaft. I have a 700r4 from an 86 IROC and it has a mechanical speedo. Not sure what years have it after that though. __________________ Some people are like slinkies, they aren't good for anything, but you can't help but smile when you see one tumble down the stairs.

09-30-2004, 02:03 PM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	The 9 inch Turbo 350 is the same length as the 700r4 is . I've swapped a bunch of them around. Yoke and driveshaft will reuse directly On my old trucks, I reuse the stock linkage. Only difference is that it won't pull all the way down into 1st gear with the shift lever. I use van 700r4s usually, because they kept the mechanical cable speedometer much later than pickups did. Be sure and get the TV cable geometry and adjustment dialed in properly so you don't melt your overdrive tranny down. __________________ I'm on the Instagram- @Gearhead_Kevin

09-30-2004, 02:10 PM	#4
Guff Registered User Join Date: Feb 2002 Location: illinois Posts: 78	Thanks Tx, what other parts will I need if any? Isn't there a wiring plug for controlling torque converter lockup? Also, what kind of bracket(s) do I need for the tv cable. My kickdown cable is currently unhooked because the PO put on an edelbrock intake but didn't get the kickdown bracket. __________________ -Guff 1969 C10 LWB, 350, 700R4, 3.73 gears

09-30-2004, 02:19 PM	#5
silvertonguedevil Senior Member Join Date: May 2004 Location: Seaside, Oregon Posts: 1,789	Great topic! I will be approaching this obstacle here soon too. __________________ -Greg My Chevy trucks, past and present: 1962 C10 SB Fleetside 1964 C10 LB Fleetside BBW 1966 C10 SB Fleetside 1966 C10 SB Fleetside BBW 1968 C10 SB Fleetside 1971 C10 LB Fleetside 1971 C10 SB Fleetside 1972 C10 SB Fleetside Cheyenne 1972 C10 SB Fleetside Cheyenne Super 1972 C10 LB Fleetside Cheyenne Super 1974 C20 Cheyenne 1979 K5 Blazer Cheyenne 1982 K10 SB Fleetside Custom Deluxe 1982 K10 SB Fleetside Scottsdale 1986 C10 SB Fleetside Silverado 2008 Silverado 1500 4x4

09-30-2004, 02:40 PM	#6
chickenwing Lovin' Life in Miss.! Join Date: Mar 2004 Location: Puckett, Mississippi Posts: 1,937	http://207.44.196.117/vboard/showthread.php3?t=33266 Here's something from the FAQ's. I used the tv cable kit from www.700r4.com , but it is not necessary. I've got the install done but need to play some more with the tv cable....it hunts real bad between 3rd and 4th on part throttle. __________________ The truck... you hear that? No really, you did hear that?!!!

09-30-2004, 03:53 PM	#7
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Forget the Cameros and Firebirds unless you want to change the tail shaft. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

10-10-2004, 10:56 AM	#8
5150 C10 Club Tennessee Join Date: Mar 2003 Location: White House, TN 37188 Posts: 8,281	How about late 80's-early 90's Caprice's? __________________ Bryan www.gmtruckshow.com Project "Andes"-Halen's First Truck Project: Patina Burb for he is God’s servant for your good. But if you do wrong, be afraid, for he does not bear the sword in vain. For he is the servant of God, an avenger who carries out God’s wrath on the wrongdoer. Romans 13:4

10-10-2004, 01:12 PM	#9
guyryan100 Registered User Join Date: Sep 2001 Location: Cumming, GA Posts: 470	I was thinking that you need to stay below '86 or so to avoid computers. BTW, I have to change my yoke in switching from a 3speed to the 700r4. New tranny has 30 teeth, old had 8. The drive shaft will have to be shortened 1.5 inches or so, and that's with my engine in the forward position.

10-10-2004, 07:07 PM	#11
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	You will need the metric bolts for such items as the torque converter, trans mount to tail housing and nut for linkage stud. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

10-10-2004, 07:24 PM	#12
GSFMECH On the road Join Date: Jan 2004 Location: NATCHITOCHES LOUISIANA Posts: 815	Great topic. Even if you have a trans with the elect speedo you can swap out the parts from an older 700R4 with a mechanical speedo and make it work. I saw a thread on here or somewhere about it. To enable shifting into all of the gears all you have to do is check where the rod coming from the column attaches into the cross shaft and drill another hole about a 1/2" closer to the selector shaft and attach your rod into it. This changes the geometry (the angle of the dangle) and will give you more swing with your shifter and you can get all the gears. If you have an older 700R4 with the rear mount cast into the tailshaft housing you can use the turbo 400 position to mount your rear crossmember. Most of the later 700's have the mount in the trans case directly behind the pan and you will have to drill new holes in the frame using this mount.Hope this helps. Mike __________________ Mike Castro- 72 SWB. Ochre and White. 496/400 turbo, GV OD ,Dakota Digital dash , tilt, Vintage Air, PS, hydro boost, factory buckets, console, QA-1 Coil over suspension, 20/20"Billet Specialties Magnetos 72 SWB. Med blue. 454/400 turbo, tach, tilt, Stock AC, PS,PDB, factory buckets, console, ECE 4/6 drop w/ 2" blocks and C-notch, 20/20"Coys- Crashed and destroyed by drunk driver Sept 2019. New 72 build in the works. My new build thread "Castro" https://67-72chevytrucks.com/vboard/...d.php?t=820934 My old build thread, the blue truck http://67-72chevytrucks.com/vboard/s...d.php?t=271489 www.louisianaclassictruckclub.com

10-10-2004, 08:33 PM	#13
shade67 Registered User Join Date: Jan 2004 Location: Portage, WI Posts: 89	hold the phone on not hooking up the tv cable, it controls the amount of pressure to the plates and clutches- not hooking it up or not getting it right will cause a really early departure of trans. also there is the matter of the lockup torque converter if not wired up it will not lockup in od which also kills it because it will not cool enough! thats a quote from my trans expert friend! you can get the parts to make it lockup cheaply or buy the kit for around $70 __________________ Scott 66 chevy short step 327 4speed 67 chevy Short Fleet tpi 350 700r4 72 chevy K10 swb 01 GMC Sierra 01 Pontiac Bonneville

10-10-2004, 10:43 PM	#15
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	There is quite a bit written in the FAQ on this topic...more in detail than listed on this thread...and some links with real good reading. Enough to keep you ocupied for the rest of the evening.

10-11-2004, 08:51 AM	#16
grayw0lf Registered User Join Date: Apr 2004 Location: Clanton, AL Posts: 1,253	GSFMECH, Good one on drilling the hole for the selector 1/2" up from the original spot to allow shifting down into 1st gear. I've been reading for weeks, but I've not heard a solution for that yet. __________________ 85' CUCV M1009!!! The newest addition! 6.2diesel, Th400, NP208, & only 36k miles! 70' C-10 LWB Fleetside - Looking good these days! 05' Dodge Neon 88' Winner Escape Sport 1750 - 4.3v6 94' Seadoo SP 84' Honda TRX200, bare nekkid. Just a frame & tires. Always looking for another project or any good deal!

10-11-2004, 11:37 AM	#17
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	Just wondering if anyone has had any trouble with the 700r4 tranny hitting the flange at the bottom of the cab firewall? I did a test fit, and my cab was sitting on the tranny. Looked to be about 1/2 inch too high. __________________ John Fabris 67 C10 SWB



Register or Log In To remove these advertisements.

10-11-2004, 05:09 PM	#18
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,052	I have heard about someone else having that problem with the firewall hittting the tranny. Is you Motor in the 6 CYL position ? I think that's where you run into the problem or mabye just the odd cab was built a little bit diffirent. How is your truck coming along ? Later , Mario __________________ 1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD

10-11-2004, 05:34 PM	#19
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	is it a big block engine in a small block truck? How are the cab mounts?

10-11-2004, 06:04 PM	#20
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	I but a BB and a 700R4 in a low hump cab and have lots of room. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

10-11-2004, 06:10 PM	#21
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Which towers did you use, the 67 - 71, or the 72 towers...did you use the tranny mount spacer that keeps the drive shaft geomitry in line, or did you mount it directly to the cross member. Was it a 1/2 ton 2 wheel drive, or something else? Lots of variables in the big block fitting in a low hump cab.

10-11-2004, 06:16 PM	#23
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	Its a 1/2 ton LWB with coils. Used 72 mounts. And useda turbo 350 trans mount I think. No real problems. Used original cross member just muved it a little and drilled new holes. As fare as im concerned its a streight bolt in. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

10-11-2004, 07:14 PM	#25
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	I've used 67-71 mounts on mine with plenty of room. Every truck I've ever owned has been a small hump truck. There is plenty of room even with a 700R4. If it's hitting, you need to look at replacing your cab mounts. When I first put my 454 into my low hump truck I have now, it hit the bottom of the cab. New cab mounts raised it right up. Now, I can slide my hand between the trans and cab in all spots. Yes, I run the trans mount spacer too. __________________ I'm on the Instagram- @Gearhead_Kevin

Register or Log In To remove these advertisements.