Stick with the TH-400, or go to my 700R4?
04-04-2005, 09:22 PM
#1
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I went searching and came up with this as being the most popular post on the subject....
I'm considering the 700R4 or 2004R conversion... Mainly because I'm having problems with the TH350 in the car, I have an 81... Upon inspection I found some cracks and a hole in the bellhousing.....
I did a 700R4 conversion back in the 80's, so it's been a while....
Which would be my better choice, the 700 or 200???
I don't drag race, well maybe the occasional stoplight to stoplight with some annoying little fart canned car....
I tend to drive VERY fast.... The overdrive would be very nice to have.... Yes, I know some of you don't like speeding on the highway's, just stay out of the left lane....
Like I said, haven't seen a 700 or a 200 in a long time, are they cable drive or electric drive speedo's???
I was looking through BTO's site, I can get the Tranny, crossmember, shifter, TV and lockup relay through them... Have the driveshaft shortened (would an 82 driveshaft work???) Anything else????
I'm considering the 700R4 or 2004R conversion... Mainly because I'm having problems with the TH350 in the car, I have an 81... Upon inspection I found some cracks and a hole in the bellhousing.....
I did a 700R4 conversion back in the 80's, so it's been a while....
Which would be my better choice, the 700 or 200???
I don't drag race, well maybe the occasional stoplight to stoplight with some annoying little fart canned car....
I tend to drive VERY fast.... The overdrive would be very nice to have.... Yes, I know some of you don't like speeding on the highway's, just stay out of the left lane....
Like I said, haven't seen a 700 or a 200 in a long time, are they cable drive or electric drive speedo's???
I was looking through BTO's site, I can get the Tranny, crossmember, shifter, TV and lockup relay through them... Have the driveshaft shortened (would an 82 driveshaft work???) Anything else????
04-05-2005, 12:25 AM
#2
Race Director
Originally Posted by blunsford
Sorry guys but doing the swap for fuel mileage just doesn't figure. .
i did the 700r4 swap from a TH350 and i love it, and would never go back.....i did the mileage calculation just for kicks and figured it would take tens of thousands of miles to pay for itself....however when cruising at 70 at 1700 rpm it makes you smile....and the first gear is a real blast with my 3.08s.... i'd never go back....make sure you get the right stall speed torque converter. the parts with out the trans and torque converter cost me $574 from BTO
04-05-2005, 07:42 AM
#3
Melting Slicks
Originally Posted by SHAKERATTLEROLL
If you want a trans that will live try the L80 trans it is built on a turbo 400 main with the added gear for over drive. But you would have to get a stand alone computer system to control it. The added benifit of an overdrive is not just milage but overall satisfaction of the driving experiance of the car. Not to mention it will reduce wear and tear on on the engine. reduced engine noise inside of the car at highway speeds. I am sure I missed others but that is pretty much it in a nut shell. 
Jim
04-05-2005, 11:17 AM
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I'm still weighing my options here.... Did anyone try not cutting their driveshaft and using one from an 82? I may be wrong on the tranny but wasn't the 82 a 700R4???
How about speedo cable and gearing the speedo???
How about speedo cable and gearing the speedo???
04-05-2005, 12:48 PM
#6
Melting Slicks
If I could turn back the hands of time,I'd have gone with a 400 instead. Every transmission shop I talked to prior to doing the 700r4 swap told me it would not hold the power I was making with the 406.I was sold on a high performance 700r4 for the overdrive and lower 1st gear. Now I'm afraid to smash the gas for fear of transmission destruction.Blew the 700r4 in a week after the initial swap.
04-05-2005, 01:00 PM
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Originally Posted by blunsford
Sorry guys but doing the swap for fuel mileage just doesn't figure. Absolute best case scenario you could save maybe $400 per year on gas, even at todays prices. When you figure the cost of the tranny, conversion, speedo, et al. I just don't see how you'd justify it based on increased fuel mileage.
The above fuel savings is based on a 5mpg increase @ 15,000 mi per year driving. I think that's not unrealistic, but optomistic.
The above fuel savings is based on a 5mpg increase @ 15,000 mi per year driving. I think that's not unrealistic, but optomistic.
Lets see, I spent $10,000 on a car that got 15 MPG.
Blew $8000 on an engine that brought that down to 10mpg if I'm lucky.
Calculate the payback on THAT swap
04-05-2005, 02:20 PM
#8
Drifting
Originally Posted by turtlevette
if you don't care about gas mileage, put the 700 in and swap in 4.11 gears.
You will still have a better overall highway ratio but when you jump on it from a stop all hell breaks loose. Its a lot more fun with performance gears!
You ain't gonna kill the 700 with a mild small block.
[Modified by turtlevette, 9:20 AM 7/3/2004]
You will still have a better overall highway ratio but when you jump on it from a stop all hell breaks loose. Its a lot more fun with performance gears!
You ain't gonna kill the 700 with a mild small block.
[Modified by turtlevette, 9:20 AM 7/3/2004]
100%
04-05-2005, 04:37 PM
#9
Race Director
Originally Posted by 3Quarters
How about speedo cable and gearing the speedo???
mine just connected right up....no problem and the MPH seems to be real close
04-05-2005, 05:20 PM
#10
Melting Slicks
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Originally Posted by The Money Pit
If I could turn back the hands of time,I'd have gone with a 400 instead. Every transmission shop I talked to prior to doing the 700r4 swap told me it would not hold the power I was making with the 406.I was sold on a high performance 700r4 for the overdrive and lower 1st gear. Now I'm afraid to smash the gas for fear of transmission destruction.Blew the 700r4 in a week after the initial swap.
Hey Money Pit! How about pounding out a couple of dozen hard quarter mile runs and let me know which transmission I need and what parts I still need to upgrade?
04-05-2005, 05:58 PM
#11
Melting Slicks
My understanding is a TH350 and 700r4 are aproximately the same torque rating.(350 ft lbs)If you're torquing 500lbs (aprox)I would go with a TH400 which was used behind 455 Olds/Poncho's that pushed 500 lbs of torque back in the early 70's.
With the 700r4 I plan on taking it easy for a while,though on one fine day I did roast the tires through 1st,2nd and into 3rd.I don't think I'll "break onything",but the clutch packs in the transmission probobly won't hold up for long if I continue to run it hard.
With the 700r4 I plan on taking it easy for a while,though on one fine day I did roast the tires through 1st,2nd and into 3rd.I don't think I'll "break onything",but the clutch packs in the transmission probobly won't hold up for long if I continue to run it hard.