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7004r swap


Guest Larry Delazzer
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Guest Larry Delazzer

Hi, this subject has probably been beat to death but I can't find anything on the forum. I read where swapping a 7004r required some minor surgery on the floor pan and the exhaust and non was required for the 200r4 swap - true - false? Thanks.

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It could be true or false...it depends on the individual car. My '70 has a 700R4 and there were no issues with fit. I did have to have a different neutral safety switch/ backup light switch assembly made, but that was due to my having 2 1/2" exhaust pipes than the original 2" pipes.

Some have had to make some transmission tunnel mods...I didn't.

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My 700R4 swap required cutting the corner off the passenger's footwell. The most difficult parts were the shifter and the TV bracket and adjustment. BowTieOverdrives was my preferred solution.

If buying a rebuilt tranny, I'd go with a 200-4R just for the gear ratios.

jack vines

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RQB3263 ...81 AVANTI ii ...(chevy 305 eng)....I just finished installing a 700 in 3263 and removing a 350th...I had to open the hole in the frame x member (cut out the web between the two holes) where the exhaust pipe goes thru to allow the pipe to be moved to the right about 1 1/2 to 2 inch to clear the trans pan at the aft right corner...a new drive shaft of course...a new trans mount crossmember fabed from 1/4 inch plate....and minor shifter linkage changes..and thats it ...other than a very hard days work.....works great ....700 is the way to go ....RQB3263

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3263......And did I mention...Im taching 1750 at 70 MPH and in the first 2 weeks of June I averaged 21 MPG on a 3300 mile road trip....beat that if you can ....3263

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  • 2 weeks later...

I did a 200R4 switch from a Turbo 400 in my 76 Avanti 3 years ago. I had 23000 miles carefree operation until I lost the overdrive in Williams AZ on the recent Great American Tour. I finished the tour with the other 3 speeds and found out later it was a stuck throttle valve that dropped overdrive. Cleaning the valve and a simple trans service got it going fine again. I have gotten up to 27.5 mpg with the 200R4 setup with the 400 motor. The trans dropped 1000 rpm's at 70 mph from 3000 to 2000. When the overdrive was gone, I really missed it. It's definitely a good swap to do on your pre-overdrive transmission Avanti.

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  • 2 weeks later...

I recently converted 63R3453 from the original 3 speed auto to a 200R4 overdrive. Prior to the conversion 60mph required 2700rpm's. With the 200R4 70mph is at 1700rpm's with TT 3.31 gears. There was no interference problems other than connecting the speedo cable. It required a 90 degree adapter. The only other concerns might be making sure the drive shaft angles are correct at the trans and differential. The work shop manual references the angles. If they are not correct a vibration may occur. Depending on the new angle requirements an adjustment may be necessary at the torque arms. My differential tilted requiring lengthening the torque arms so their rubber bushings could fit properly. It is a great improvement in my opinion.

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So I hate to hijack the thread but I'm in the process of installing a 4l60e transmission (same housing, etc as the 7004r, just electronic instead of the TV cable) into another members Avanti. he bought this shift linkage kit from Dan Booth, and I'm having a bear of a time getting the linkage that goes from the transmission to the steering column to fit properly (that prevents you from being able to take the keys out while not in park). With it in there you have to really push hard on the shifter to get it to go into park. With it out and just the other linkage its fine. Does anyone have any experience with this?

On a related note I'll let y'all know how this transmission is. It's kinda neat because since it's all electronic, we have a stand alone computer to run it and you can adjust your shift points, how firm it shifts, TCC lock up points, etc all at the touch of a button.

Edited by CaffeineRacer
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  • 2 weeks later...

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