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#1 |
Registered User
Join Date: May 2000
Location: Storm Lake, Ia
Posts: 1,449
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700-r4 decision
I have a 72 3/4 ton with a 402 engine 400 tranny and 4:10 rear end. I like driving the truck but at 65 mph the thing is turning around 3500 rpm. I have a 700r4 I picked up at a swap meet. Do you think it would be worth it to swap it in. Any ideas what I would be turning for rpms at 60-65 mph.Besides shortening the drive shaft,shifting the tranny cross member,tranny mount and tranny linkage hookup (tv Cable)
what other problems or unexpected pieces am I going to need. Will the current driveshaft bolt up splines wise. Just hate to start the project and be dissappointed with the results or the cost of unanticipated part needs. Thanks Solver
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#2 |
Designated A-hole!
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,450
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Re: 700-r4 decision
The 400 has a yoke while the 700r uses the same splines as the TH350's iirc.
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"If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. ![]() We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" |
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#3 |
Registered User
Join Date: Sep 2006
Location: Shelley Idaho
Posts: 876
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Re: 700-r4 decision
I did this same thing in a 72 Gmc 3/4 with a 402 a few years ago. The drive shaft front one will need to be shortened about 2 inches, the trans mount from a th350 will bolt right on the 700, the hardest part about the swap is getting the tv cable hooked up right. The converter will bolt up to the th350 holes in the flexplate.
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#4 |
Senior Member
Join Date: Dec 2004
Location: Southern Pines NC
Posts: 3,853
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Re: 700-r4 decision
The only concern would be is the can the trans handle the BB especially if you tow with it
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#5 |
Senior Member
Join Date: Apr 2005
Location: Joppa, Maryland
Posts: 4,408
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Re: 700-r4 decision
I'm going to be doing this same swap. I have did some research on beefing up the 700r4. I have read that you should change the stock servo to a Corvette type and also change the booster to .500 size. From what I have found, these are cheap parts and easy to change. I also plan on changing the converter to around 2000 stall. Here's a parts sight that has the best prices I've found. I haven't bought from them as yet.
http://www.bulkpart.com/Merchant2/me...&Store_Code=2s You are also going to have to do some lockup converter wiring on this trans.
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1997 GMC Sierra Ext 1965 Mustang |
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#6 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: 700-r4 decision
need to make sure the bellcrank on the carb is of the right diameter and shape, the rate of pull and sensitivity of it needs to be dead on for tranny life. you'll also need a lockup controller too.
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#7 |
Registered User
Join Date: Sep 2006
Location: League City, Texas
Posts: 732
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Re: 700-r4 decision
With a 4.10 rear and 29 inch tires about 2160 in 4th with lockup
Your tires are probably a little taller that that though on a C20. Here is a great gear calculator: http://www.xse.com/leres/ss/calculator.html Last edited by Texasdeere; 10-17-2006 at 03:33 PM. |
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#8 |
Msgt USAF Ret
![]() ![]() Join Date: Jan 2005
Location: Kalamazoo, Michigan
Posts: 8,714
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Re: 700-r4 decision
Here's a site I like. It has a lot of info and a gear ratio chart at the bottom.http://www.transmissioncenter.net/700r4.htm
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
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#9 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: 700-r4 decision
I like mine, but I'm on the second one.... as longhornman said... set-up is absolutely CRUCIAL in a 700R4.
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! Last edited by 67ChevyRedneck; 10-17-2006 at 04:40 PM. |
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#10 |
Woof?
Join Date: Jun 2005
Location: Raleigh, NC
Posts: 276
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Re: 700-r4 decision
Biggest concern is, can a used TH-700 in potentially unknown operating condition stand up long to big block torque? If your engine is more or less stock, it should hold up for a while. As long as you're not abusive towards it. Classically, though, TH-700's just can't be built up as strong as a 350 or 400.
A TH-700's overdrive ratio is .8 to 1. 3500@65 seems awfully high to me, and I don't know that .8:1 ratio is going to bring it down to 2100 @ 65.
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1968 LWB CST BB 2004 Avalanche Z71 LT3. 2003 S-10 ZR2 (hers). 1997 Astro 1992 Caprice wagon, 500k stock miles. Nursing wounds after a bad wreck. 1997 Saturn - need gas mileage from something! |
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#11 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: 700-r4 decision
Actually the 700 has overdrive of 28% so the multiplier would be .72--- Your 3500 rpm times .72 would theoretically come down to 2520, without the lock-up. A stronger set-up would be adding on a Gear Vendor unit that has a 22% overdrive.
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#12 |
Registered User
Join Date: Sep 2006
Location: League City, Texas
Posts: 732
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Re: 700-r4 decision
TH700R4 4-Speed Automatic Transmission Gear Ratios: 3.06, 1.63, 1.00, 0.70 (1st through 4th)
The overdrive is pretty steep on these. With the lockup not engaged the rpms will be higher. These trannys can be set up with no lock up or even a hydraulic lockup. (no wires) As everyone has said before proper cable set up is a must. The 700R4 is a good strong tranny but not as strong as the TH400. I would think that a stock big block shouldn't hurt it with normal use. If you pull with your truck just use third gear 1.00:1 for pulling. If you are going big horse power and torque, especially torque a TH400 with a Gear Venders overdrive is the way to go. I think the Gear Vender overdrives are over $2500 ![]() Sorry, I'll stop now ![]() Last edited by Texasdeere; 10-17-2006 at 09:43 PM. |
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#13 |
Registered User
Join Date: Sep 2006
Location: League City, Texas
Posts: 732
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Re: 700-r4 decision
You beat me to it kwmech. I just type too slow.
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#14 |
Woof?
Join Date: Jun 2005
Location: Raleigh, NC
Posts: 276
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Re: 700-r4 decision
I could just say I hit the wrong number key, but I won't. Oops! Maybe the 200 had a .8 overdrive. Or maybe I'm just dumb.
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1968 LWB CST BB 2004 Avalanche Z71 LT3. 2003 S-10 ZR2 (hers). 1997 Astro 1992 Caprice wagon, 500k stock miles. Nursing wounds after a bad wreck. 1997 Saturn - need gas mileage from something! |
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#15 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: 700-r4 decision
700R4 is .70 to 1 and a 4l60E is .67 to 1.
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
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