700R4 Conversions-How do you like yours?
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,211
Likes: 5
From: Nashville TN
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I love the 700r4 in my car. By far I would say it changed the car the most. Got it out of the hole a little quicker and made it liveable on the freeway. I have a 3.55 gear in the car and 80 mph on the freeway was a pain.
Biggest lesson learned is to make sure that you find a good trans guy to build the trans. There are a number of performance mods that can be made to the 700r4 to help it live. You also want someone that can properly set up a TV cable, if the geometry it not correct you will smoke the trans.
Keep in mind that my speedo read about 10 mph low and this is with a 3.55 rear gear !
Biggest lesson learned is to make sure that you find a good trans guy to build the trans. There are a number of performance mods that can be made to the 700r4 to help it live. You also want someone that can properly set up a TV cable, if the geometry it not correct you will smoke the trans.
Keep in mind that my speedo read about 10 mph low and this is with a 3.55 rear gear !
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I definitely agree with all the above statements. You'll notice a big improvement in the hole shot, but the shift from first to second is a bit obnoxious. The TV cable set-up is integral to the performance of the transmission as well. When mine was attached improperly, the transmission was driving very sloppily.
Fuel economy for me went up a bit. On the city, it went from 10 to ~11 mpg. Nothing major. On the freeway, I get 15-17. I really need to figure out why my economy is so bad... but before, with the TH-350, I never got better than 12 mpg.
-Steve
Fuel economy for me went up a bit. On the city, it went from 10 to ~11 mpg. Nothing major. On the freeway, I get 15-17. I really need to figure out why my economy is so bad... but before, with the TH-350, I never got better than 12 mpg.
-Steve
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I had a stock L98 injection on the rebuilt original L48 engine with muncie 4 speed...about 250 hp or so....and got 24 mpg on the freeway, limited to about 75 mph cruising....busy engine...
when I put in the present roller cammed engine it went up to about 410 hp...and still 355 ci...and headers now...and 700r4, car gets only 19-20 at 80 mph on freeway.....but engine is happier at 2500 rpm's...just on the cam....
I credit 700r4 for saving what fuel it does....
GENE
when I put in the present roller cammed engine it went up to about 410 hp...and still 355 ci...and headers now...and 700r4, car gets only 19-20 at 80 mph on freeway.....but engine is happier at 2500 rpm's...just on the cam....
I credit 700r4 for saving what fuel it does....
GENE
Instructor
Joined: Oct 2001
Posts: 155
Likes: 0
From: Corrales, NM
Re: 700R4 Conversions-How do you like yours? (JRChurch)
Rick,
I also agree with everyone that has replied so far. For me changing over to a 700-R4 was a very cost effect way to improve driveability and performance. With a OD your engine will turn lower RPM's on the highway and the lower 1st gear is a blessing to the underpowered late 70 - early 80's C-3.
One suggestion is to put a transmission cooler in at the time of the conversion. Heat is very harmful to your automatic transmission.
Good Luck!
Ken
I also agree with everyone that has replied so far. For me changing over to a 700-R4 was a very cost effect way to improve driveability and performance. With a OD your engine will turn lower RPM's on the highway and the lower 1st gear is a blessing to the underpowered late 70 - early 80's C-3.
One suggestion is to put a transmission cooler in at the time of the conversion. Heat is very harmful to your automatic transmission.
Good Luck!
Ken
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I'd take care of the other items before the 700R4. I did most of my other mechanical work (engine, suspension, brakes, etc.) and when my TH350 really started to show signs of wear (and my bank account was sufficiently swollen), I bought the 700R4 kit from Bow-Tie, had the driveshaft shortened, installed a new differential, rear brake calipers, rebuilt half-shafts.... I did all the removal/installation myself in my garage. All I can say is: What a large project! Take your time and get a buddy or two to help with the trans and differential install (beer and pizza work wonders).
With proper planning, this project should go without a hitch you will be happy with the results.
With proper planning, this project should go without a hitch you will be happy with the results.
Pro
Joined: Dec 2000
Posts: 531
Likes: 0
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I never drove mine without the 700r4, but I love it. Even with a 4.56 gear I get 18mpg on the highway. I never would have dreamed of this in '73. Just put the 700r4 on your list of "must haves".
Safety Car
Joined: Apr 2001
Posts: 4,795
Likes: 1
From: Regina Saskatchewan, Canada.
Re: 700R4 Conversions-How do you like yours? (Racer16k)
I felt it was a little faster off the line but that's only because I installed a 3000 stall at the same time as the 700-R4. It sucks it a straight line though. You need a fairly torquey engine to make up for the inherent rpm loss. I'd rather have a 200-4R or a lockup 350 for drag racing.
Racer
Joined: Apr 2000
Posts: 499
Likes: 0
From: Kristiansand
Re: 700R4 Conversions-How do you like yours? (JRChurch)
I have mixed feelings.
Positive:
Got a milage increase of ca 30% on highway driving (OD only). During city driving my milage went down a little bit. Which is expected since my 700r4 only locks in 4th gear, the old TH350C had 3dr gear lockup.
I don't see how milage increase can justify the conversion with the current US gas prices. (We pay 4$/gal over here...)
I big improvement was noise. At 55mph in OD I cant hear my freeflow exhaust, while the noise in unbearable in 3dr gear.
Negative:
I cant believe all the problems people have with the 700r4 compared to TH350/400. Fried band/clutches and also broken hard parts.
Mandatory upgrades are TransGo shift kit, Corvette band servo and .500 TV boost valve. 29 element Borg Warner sprag also recommended.
And aux cooler if you live in a hot climate.
The lockup makes a dramatic drop and cause bogging during city driving. You have to manually use 3dr gear, making the trans not really automatic.
I think it would be better with hydraulic lockup in a non-computer car since you can the set the lockup speed different (higher) than 4th engage.
I have a section on 700r4 upgrade at my page.
Positive:
Got a milage increase of ca 30% on highway driving (OD only). During city driving my milage went down a little bit. Which is expected since my 700r4 only locks in 4th gear, the old TH350C had 3dr gear lockup.
I don't see how milage increase can justify the conversion with the current US gas prices. (We pay 4$/gal over here...)
I big improvement was noise. At 55mph in OD I cant hear my freeflow exhaust, while the noise in unbearable in 3dr gear.
Negative:
I cant believe all the problems people have with the 700r4 compared to TH350/400. Fried band/clutches and also broken hard parts.
Mandatory upgrades are TransGo shift kit, Corvette band servo and .500 TV boost valve. 29 element Borg Warner sprag also recommended.
And aux cooler if you live in a hot climate.
The lockup makes a dramatic drop and cause bogging during city driving. You have to manually use 3dr gear, making the trans not really automatic.
I think it would be better with hydraulic lockup in a non-computer car since you can the set the lockup speed different (higher) than 4th engage.
I have a section on 700r4 upgrade at my page.
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Safety Car
Joined: May 1999
Posts: 4,445
Likes: 0
From: Mandeville, Louisiana
Re: 700R4 Conversions-How do you like yours? (JRChurch)
Hey Rick, I am out of Bagram, and back in Kuwait for a while.
When I had my '70 I had the 700R4 behind the 300 horse 350ci small block. I was till running 3:08s too. Man that baby took off!!!! It really got the torque to the tires! Then on the highway, I was getting 22mpg from my unrebuilt 156,000 mile motor. On several occasions I had her up to 145-155mph and the motor was harldy working in overdrive.
That is an improvement to your C3 that you will never regret!!!!
Oh yeah, if I ever buy another C3, that is the first thing I will do to it!!! Put in another 700R4
[Modified by Eric 96, 11:08 AM 5/26/2002]
When I had my '70 I had the 700R4 behind the 300 horse 350ci small block. I was till running 3:08s too. Man that baby took off!!!! It really got the torque to the tires! Then on the highway, I was getting 22mpg from my unrebuilt 156,000 mile motor. On several occasions I had her up to 145-155mph and the motor was harldy working in overdrive.
That is an improvement to your C3 that you will never regret!!!!
Oh yeah, if I ever buy another C3, that is the first thing I will do to it!!! Put in another 700R4
[Modified by Eric 96, 11:08 AM 5/26/2002]
