how would i do this - The 1947 - Present Chevrolet & GMC Truck Message Board Network

trailwart · 03-21-2003, 06:16 PM

i just dusted another 700r4. 2nd one in about 600 miles. its my 84 scottsdale 4x4, i have a 350thd layin around and thinkin of putting it in there. the first time i blew the 700 i measured the 350 and its a differant length, so my Q is do i need a dirrerent cross member, change my shift linkages, driveshaft. i not sure whats all involved to make it work. just sick of blowing up these slushboxes. any insight would be great .

thanks

PHOENIX · 03-21-2003, 06:23 PM

What are you doing to destroy the trans? Do you have everything installed correctly? Theres a few guys here that have them and love them. What kind of power are you putting down?
If you are putting down some serious power that the 700 cant take, youd be better off with the 400, then the 350.

bigblock73 · 03-21-2003, 06:28 PM

If you convert to a th350 from a 700 you will need to slide the crossmember forward and drill new holes to mount it...because like you discovered, the 350 is shorter than the 700.

-Jeff

LOHRTBT · 03-21-2003, 06:29 PM

What are you doing to them?? 2 700's in 600 miles??? you trying to push 3000 hp through them??? dayum!
There is something not right if you are wearing them out like that our your rebuilder is forgetting some peices.
More info...

trailwart · 03-21-2003, 06:36 PM

everything is installed right. engine is built real stout. have not had it on the dino yet but the engine builder gave rough estimates for my set up that he did. he said this engine set up produces about 350 hp and anywhere from 375-425 flb of torque. the origanal trans lasted 65 miles before it blew the rear ring gear in half. and this one has lasted a little over 500 miles before it grenaded. have not torn it out of the truck yet so i not sure exactly sure whats went wrong yet. i know my trans builder told me not to waste my time with a new 700 the first time but i insisted, cause i wanted overdrive, he tried talkin me into a 400 cause he said that was the only thing that will hold up to my engine.

LOHRTBT · 03-21-2003, 07:10 PM

You should have no problems...I know guys pushing 700 hp through them without those problems. My motor is stronger than that and will soon be about 100hp stronger and it has no issues.
I would have to question the integrity of the tranny rebuild.

**swervin ervin** · 03-21-2003, 07:53 PM

I would say you have the wrong year of 700R4 if they are going this quick. Find a 88 through 92 model. The early years were crap. If the year is good, I would guess you didn't have the TV cable adjusted correctly. What about an external cooler?

To install the TH350 in place of the 700, they holes should already be in the frame for either one.

LOHRTBT · 03-21-2003, 08:42 PM

Yeah they should be in the frame but for some reason they werent on all of em.

I had to have holes put in my frame from the TH350 to 700R4 Swap.

Blue Beard · 03-21-2003, 11:02 PM

Won't you have to lengthen the drive line for the shorter case? Or does yours have the one that can be changed to the longer unit?

LOHRTBT · 03-21-2003, 11:55 PM

If I remember correct its shorter for 700R4 and longer for TH 350

79BIG10 · 03-22-2003, 06:54 AM

We did this kind of swap on another members truck. He has a 83 Blazer subframe and drivetrain. We pulled the Th350 out and installed the 700r4. On the TH350 to mount up correctly to where you don't need any new driveshafts you need a spacer made for this. His had it on there to make up the difference fromteh 700r4. When we pulled the TH350 the holes were there for the 700r4. We realized then the truck had a 700r4 originally, then the TH350 and now back to the 700r4. You might contact 4x4 places and see if they have this spacer you need.

03-21-2003, 06:16 PM	#1
trailwart Registered User Join Date: Mar 2003 Location: michigan Posts: 356	how would i do this i just dusted another 700r4. 2nd one in about 600 miles. its my 84 scottsdale 4x4, i have a 350thd layin around and thinkin of putting it in there. the first time i blew the 700 i measured the 350 and its a differant length, so my Q is do i need a dirrerent cross member, change my shift linkages, driveshaft. i not sure whats all involved to make it work. just sick of blowing up these slushboxes. any insight would be great . thanks __________________ 72 chevy 3\4 ton 4 speed 4x4 84 1\2 ton 4x4 (gone but not forgotten, thanks for the memories) 1999 suburban 4x4 1982 chevrolet S-10 V-8 (Thanks uncle EARL)

03-21-2003, 06:23 PM	#2
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	What are you doing to destroy the trans? Do you have everything installed correctly? Theres a few guys here that have them and love them. What kind of power are you putting down? If you are putting down some serious power that the 700 cant take, youd be better off with the 400, then the 350. __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

03-21-2003, 06:29 PM	#4
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	What are you doing to them?? 2 700's in 600 miles??? you trying to push 3000 hp through them??? dayum! There is something not right if you are wearing them out like that our your rebuilder is forgetting some peices. More info... __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

03-21-2003, 06:36 PM	#5
trailwart Registered User Join Date: Mar 2003 Location: michigan Posts: 356	everything is installed right. engine is built real stout. have not had it on the dino yet but the engine builder gave rough estimates for my set up that he did. he said this engine set up produces about 350 hp and anywhere from 375-425 flb of torque. the origanal trans lasted 65 miles before it blew the rear ring gear in half. and this one has lasted a little over 500 miles before it grenaded. have not torn it out of the truck yet so i not sure exactly sure whats went wrong yet. i know my trans builder told me not to waste my time with a new 700 the first time but i insisted, cause i wanted overdrive, he tried talkin me into a 400 cause he said that was the only thing that will hold up to my engine. __________________ 72 chevy 3\4 ton 4 speed 4x4 84 1\2 ton 4x4 (gone but not forgotten, thanks for the memories) 1999 suburban 4x4 1982 chevrolet S-10 V-8 (Thanks uncle EARL)

03-21-2003, 07:10 PM	#6
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	You should have no problems...I know guys pushing 700 hp through them without those problems. My motor is stronger than that and will soon be about 100hp stronger and it has no issues. I would have to question the integrity of the tranny rebuild. __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

03-21-2003, 06:28 PM	#3
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	If you convert to a th350 from a 700 you will need to slide the crossmember forward and drill new holes to mount it...because like you discovered, the 350 is shorter than the 700. -Jeff

03-21-2003, 07:53 PM	#7
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I would say you have the wrong year of 700R4 if they are going this quick. Find a 88 through 92 model. The early years were crap. If the year is good, I would guess you didn't have the TV cable adjusted correctly. What about an external cooler? To install the TH350 in place of the 700, they holes should already be in the frame for either one. __________________ Mike 1985 Chevy C-10

03-21-2003, 08:42 PM	#8
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	Yeah they should be in the frame but for some reason they werent on all of em. I had to have holes put in my frame from the TH350 to 700R4 Swap. __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

03-21-2003, 11:02 PM	#9
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,834	Won't you have to lengthen the drive line for the shorter case? Or does yours have the one that can be changed to the longer unit? __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

03-21-2003, 11:55 PM	#10
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	If I remember correct its shorter for 700R4 and longer for TH 350 __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

03-22-2003, 06:54 AM	#11
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	We did this kind of swap on another members truck. He has a 83 Blazer subframe and drivetrain. We pulled the Th350 out and installed the 700r4. On the TH350 to mount up correctly to where you don't need any new driveshafts you need a spacer made for this. His had it on there to make up the difference fromteh 700r4. When we pulled the TH350 the holes were there for the 700r4. We realized then the truck had a 700r4 originally, then the TH350 and now back to the 700r4. You might contact 4x4 places and see if they have this spacer you need. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson



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