1979 Transmission recommendations
Thread Starter
1st Gear
Joined: May 2008
Posts: 1
Likes: 0
1979 Transmission recommendations
Hello all,
Just picked up my first vette and really enjoying it. Car is in excellent condition; however, the previous owner didn't do a very good job on the interior, so I'm planning to recondition it.
First thing first, even though the drive tran is solid, the 350 Turbo 3 speed (assuming it is a 350) has a something left to be desired with $4.00+ gas price and the high rpm's on the highway. Looking for recommendations on the best course of action? I've seen some postings on transmission swaps and overdrive units.
Thanks,
Just picked up my first vette and really enjoying it. Car is in excellent condition; however, the previous owner didn't do a very good job on the interior, so I'm planning to recondition it.
First thing first, even though the drive tran is solid, the 350 Turbo 3 speed (assuming it is a 350) has a something left to be desired with $4.00+ gas price and the high rpm's on the highway. Looking for recommendations on the best course of action? I've seen some postings on transmission swaps and overdrive units.
Thanks,
Racer
Joined: Feb 2001
Posts: 405
Likes: 15
From: Minneapolis
Before you do anything consider your annual miles driven. This forum has links to web sites that describe how to replace the 350 for a 2004R or 700, either of which will give you an overdrive, which will drop the RPMs down to a more economical level. How much is anybody's guess, but I wouldn't hold my breath for 20 MPG.
The bottom line is that the '79 engine technology with a Quadrajet, no ECM to control fuel/air ratios at various engine conditions, just isn't going to get you very far in the MPG dept.
The money you're going to pour into an old 'Vette to get some respectable MPG would be better off spent pouring it in the gas tank.
That's what older 'Vettes do, they convert lots of gas into noise.
The stark truth is if you want economy you're driving the wrong car.
The bottom line is that the '79 engine technology with a Quadrajet, no ECM to control fuel/air ratios at various engine conditions, just isn't going to get you very far in the MPG dept.
The money you're going to pour into an old 'Vette to get some respectable MPG would be better off spent pouring it in the gas tank.
That's what older 'Vettes do, they convert lots of gas into noise.
The stark truth is if you want economy you're driving the wrong car.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
I did a 2004R after a Lot of research, built it myself and have about $900 in it with everything. Rebuild kit, hot rod parts, replacement parts, converter, crossmember, cables...
My target is anything over 20mpg and I will get it.
The 2004R is an easier swap than the 700 and has some other advantages
You would have to drive it a Lot of miles to make up the cost of having the tranny installed by someone, $1800 is in the zipcode to have it done. But there is a lot to gain besides just the mileage
My target is anything over 20mpg and I will get it.
The 2004R is an easier swap than the 700 and has some other advantages
You would have to drive it a Lot of miles to make up the cost of having the tranny installed by someone, $1800 is in the zipcode to have it done. But there is a lot to gain besides just the mileage
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
I replaced my 79's TH350 with BTO's 2004R level 3 a couple of years ago. I usually get ~20-21MPG hi-way. My 79 has the 355 rear and the overdrive definitely dropped my RPM's down. That said, my engine is not stock. It is a mildly built 355 (see sig) with true duals. Others obvious factors contributing to better MPG is how aggressive you drive, engine timing, good tune up, and proper tire inflation.
Burning Brakes
Joined: Aug 2006
Posts: 1,155
Likes: 0
From: San Diego California
I replaced my 79's TH350 with BTO's 2004R level 3 a couple of years ago. I usually get ~20-21MPG hi-way. My 79 has the 355 rear and the overdrive definitely dropped my RPM's down. That said, my engine is not stock. It is a mildly built 355 (see sig) with true duals. Others obvious factors contributing to better MPG is how aggressive you drive, engine timing, good tune up, and proper tire inflation.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
OD trannies are thousands of dollars. To recoup the cost in a gain of a few MPG would require years of driving.
Mild Modding of the motor is the way to gain MPG
Mild Modding of the motor is the way to gain MPG
Last edited by gkull; Jul 4, 2008 at 03:18 PM.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Hey Marsh. My 80 is VERY similar to your vette- with a mildly built 355, and I've just finished researching BowTie Overdrives for a 200 4R. I originally planned to get a level 2 trans, but a local shop recomended the level 3 that you have, since I want it to REALLY KICK when manually moving the shifter- I now have a Transgo Shift Kit in the TH350. So whats your evaluation of the shift firmness and hook up on the level 3- its only $200 more than the level 2. Also how is the accelleration due to the gearing in the 200 4R with 355's in the rear, from stop, compared to the TH350? Thanks for any comments- I want to get this done before the end of the summer. Jim
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Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
For me, it's not just about mpg.....
When I cruise at about 75-80mph in 4th gear, the engine is screaming at about 3,700 rpms, more or less. Prolonged driving like that simply cant be good for the old girl.
When I cruise at about 75-80mph in 4th gear, the engine is screaming at about 3,700 rpms, more or less. Prolonged driving like that simply cant be good for the old girl.