200r4 to 700r4

[turbo chris1970]

I know this may sound ludicrous but just out of curiosity I was wondering if anyone in the community has replaced their 200 with a 700tranny either for fuel economy or whatever???? And if so what results were found so guys
Please give me some feedback or advice !!!! Note my 200 is great shape but I'm just really curious because I don't race my car I drive it during the usual season and put it in the garage in the winter but take long drives 90 miles to the jersey shore and I'm just trying to save as much fuel as possible

 

[turbo nasty]

2004r has a better od than the 700

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[Pronto]

Both in stock form are lock ups. You want to save fuel, stay out of boost...

 

[monteperformanc]

I can't think of any reason why switching to a 700 would be an advantage. They are both overdrive transmissions. The 200-4r had better gear ratios and is a better trans in my opinion plus the 700 would require modifications to make it fit. Bellhousing, crossmember, driveshaft. I'm sure there are other things too. If your 200 is working good I would leave it alone!

 

[TexasT]

My car had a 700r4 from about 1990 until a few years ago. I went through more than a couple 2004r units when it was new and couldn't find anyone to build a 2004r back then and my trans guy talked me into going to the 700r4 as he was good at them. It worked good for 20 or so years.

If you go that way you will need a trans to engine adapter, shorten the driveshaft, We made a plate to adapt the tail of the trans to the crossmember. Depending on the 700 you use you might need a 30 spline torque converter and will nee a different dip stick tube to match the 700.

For all that work you get a deep first gear, and a big jump to second. Not even worth the trouble as the 2004r parts and knowledge has made great strides thanks to many of our great supporting vendors.

That said I am back to a 2004r. With the help of this forum i assembled it myself and yea, im pretty jazzed.
http://www.ihadav8.com/forum/index.php?topic=3729.0

 

[gunzandgearz]

Agree with TexasT absolutely no gain in fuel mileage and too many mods to convert, keep the car with its oe stuff. I build a lot of 700s for guys but that's just because I do a lot of chevy stuff and they are more available.There are a lot of quirks with the 700 such as the first ones that were built by Chevrolet were junk and had multiple valve body issues as well as 7 vane pumps. The later ones were built by turbo hydra matic (1986.5 to 1992) which would be the ones that you would want go after and the only ones that I will build, if you decide to go this way,as they have the ten vane pump and the valve body issues worked out.You can tell these units by the casting line that runs from the servo cover over to the bellhousing(kinda looks like a camels hump), on the passenger side,but like I said earlier, keep the original 2004r as these are better units and have better gear ratios and no gain in mileage.

 

[turbo nasty]

700 has a steep first gear drop off vs the 2004rs closer ratio and then the 4 th gear is .70 in the 700 vs. .67 in the 2004r. Then you need to do all the above mentioned monkey motion above and beyond.....not favorable

 

[77 cruiser]

And no WOT 4th gear!

 

[RmvBfrFlght]

And no WOT 4th gear!

Not entirely true, from the factory the Corvettes and the police cars with the B-body fix kit will up-shift and hold 4th gear. Once above about 80 MPH at WOT it won't downshift to 3rd unless the stick is pulled back. A simple TV sleeve mod fixes it in the other 700R4's.

For the OP, I too would stay with the 200-4R. The best thing for mileage is to use closed loop fueling, the correct amount of spark advance, and a lean cruise highway mode.

RemoveBeforeFlight

 

[turbo chris1970]

Thanks to all that replied to my thread ,and I'll have to agree why waste a perfectly fine 200 which has a kit shifts fast and maintains boost in every gear . Also with all the other things I would have to to make the 700 fit just to save maybe on a 90 mile trip a gallon of fuel I'll pass on the 700 and save up for a stage 2 200 for when this one quits on me which I don't see happening anytime
Soon so I'm keeping my car the way it is and at 65-70mph in lock-up my RPMs are at 2200 no boost so a v6 should get more gas mileage,again thank you guys for the advice and be safe this season

 

[INEEDAGN]

I'd like to know where you think you'd save fuel by going to a trans with a less favorable overdrive ratio.

 

[bison]

You could probably save 3 gallons of fuel by driving 55mph and never stepping on it


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[turbo chris1970]

Thanks bison I've had people basically yelling at me since I posted this yesterday and your a staff member and gave me a simplistic answer and to the point so I thank u for that plus I usually set cruise on my trips down the shore plus it was a hypothetical question boy oh boy some people any way in cruise at 65 my RPMs are about 2300 in lock-up so it's not bad

 

[bison]

Thanks bison I've had people basically yelling at me since I posted this yesterday and your a staff member and gave me a simplistic answer and to the point so I thank u for that plus I usually set cruise on my trips down the shore plus it was a hypothetical question boy oh boy some people any way in cruise at 65 my RPMs are about 2300 in lock-up so it's not bad

Sounds high for 65mph. Should be more like 1900 with a 26" tire

 

[robzombie]

You could go to a taller tire which will drop the RPM. Or if you really like cruising at 70mph you could combine the taller tire with a 3.23 ratio and really lower the cruise rpm.

A 28" tall tire is what I run and it puts me at around 2g if I remember correctly at 70/75 mph.

Your speedo will be off about 5mph with a 28" tall tire unless you have it corrected.

 

[INEEDAGN]

Thanks bison I've had people basically yelling at me since I posted this yesterday and your a staff member and gave me a simplistic answer and to the point so I thank u for that plus I usually set cruise on my trips down the shore plus it was a hypothetical question boy oh boy some people any way in cruise at 65 my RPMs are about 2300 in lock-up so it's not bad

I saw the comment in my profile, I did not mean to come across as a dick. Typing things out in text takes away all tone of voice and emotion. I made it blunt because it had already been posted that the OD ratio was better in the 200 and you still replied implying a gain. I realize most don't have all hydramatic ratios memorized (including myself). I am sorry if I sounded like an asshole or "yelled at you" (lol).

Truth is, the ONLY real gain to be had from a 700 is that the trans guy down the street (or in whatever town you happen to break down in) has a better understanding of it than a 200-4r.


bob

 

[SpeedRacerX]

Boy, I hated the 700r4 back in the day. I think both my 86 Camaro IROC tpi and 88 Vette had it. Broke both a couple times.

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[turbo chris1970]

I saw the comment in my profile, I did not mean to come across as a dick. Typing things out in text takes away all tone of voice and emotion. I made it blunt because it had already been posted that the OD ratio was better in the 200 and you still replied implying a gain. I realize most don't have all hydramatic ratios memorized (including myself). I am sorry if I sounded like an asshole or "yelled at you" (lol).

Truth is, the ONLY real gain to be had from a 700 is that the trans guy down the street (or in whatever town you happen to break down in) has a better understanding of it than a 200-4r.


bob

Oh I understand like the trans shop down the street!!!! If we talked about the issue like back before these damm phones this would have never happened lol I guess I'm old fashion
Well bob looks like we understand each other it's all good have a safe Easter and a great week bud! Chris

 

[turbo chris1970]

You could go to a taller tire which will drop the RPM. Or if you really like cruising at 70mph you could combine the taller tire with a 3.23 ratio and really lower the cruise rpm.

A 28" tall tire is what I run and it puts me at around 2g if I remember correctly at 70/75 mph.

Your speedo will be off about 5mph with a 28" tall tire unless you have it corrected.

I run the tallest drag radials I can during the season for that reason thank you for your comment and good idea