Hey There Vette Fans ,

TH350 vs 700R4. Whats the difference (advatages/disadvantages) and would a 700R4 be a direct bolt in on a 79?

Thanks,

Luke

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LukesVette said: Hey There Vette Fans , TH350 vs 700R4. Whats the difference (advatages/disadvantages) and would a 700R4 be a direct bolt in on a 79?

Well the 700R4 is overdrive, I think it is a tough transmission. I don't think it would be a direct bolt in though....you will have to lock the converter on it somehow I assume (electronically). A new crossmember which I did find on at

http://www.bowtieoverdrives.com/catalog/catalog.php?Action=GETSUBCAT&CATID=YA1A2

which also means a new driveshaft. Then new rear gears possibly. Pretty involved I think.

Well I just finished a 700r4 swap in my 1979 vette. I suggest you go to bowtie overdrives web site and look. Lots of helpful info. My opinion is that it made one hell of a difference in the comfort and performance of the vette. The overdrive makes the car alot more comfortable to cruise on the highway in. less rpms means less noise and fuel consumption. on the low end of the gears, the 700r4's first is lower than the 350's so that means it launches better at the light. I had a 3.08 rear ratio in my vette and after this swap I now want a higher ratio to take advantage of the trans. I am going to 3.55. The swap is easy but you will need some additional things along with the trans. A trans crossmember is needed to fit the longer transmission. bowtie overdrives sell these for under $120. a tv cable set up is also needed. also BTO sells these. You will need to shorten your drive shaft because this trans is longer than the th-350. also you will need a converion kit for your shifter. Shiftworks or BTO sells these for around $100. I spent about $1300 for the whole swap including the built up transmission designed to handle 450 hp. you should look BTO up and call them up to ask questions.

I've got a 700R4 just waiting to be installed in my 73 to replace the TH-400. I too went to Bowtie Overdrives.

I believe the 700R4 is a direct bolt on replacement for a TH-350 or TH-400. By direct bolt on I refer only to the bolting of the tranny to the engine.

You will needs a few new parts and you'll need to shorten the driveshaft (as Tumarr mentioned).

The best thing to do is to visit the BTO site. They have everything you'll need and the folks there are very friendly and helpful.

Give me another couple months or so and I can tell you my experience with the change to the 700R4. It is on my list of things to do on the 73.

I am going to keep my THM400. But you cannot go wrong with the 700R4 conversion. The low end is better, and the top end is better. It's a win, win. You will be happy with it. So why don't I do it? Cash.

The 700R4 will work but you will need to change the crossover, shorten the drive shaft, change the shifter detent, wire in the lock up converter, and hook the TV cable to the carb. I went with BTO's 200 4R so I didn't have to change the crossover or shorten the drive shaft. The timing on the neutral safety switch will not match the new detent so I modified mine. You will need to make a bracket for the lockout cable if you still want it to work.
http://hometown.aol.com/bmclau5079/page4.html

Went with the 700R4 in my '76. Everything the others posted is right on. The shift detent and indicator can be found several places. 3.55 gear is what I used and is perfect. It has great low end and 70mph is about 2200 - 2400 rpm. 2200 stall conv. was my choice and worked out fine.

You will be happy!

Thanks guys, I'm sold!! A little bit o cash is all it takes!!

Anybody get a shop to do this? If so, about how much did it cost. I'm dropping in a new engine with fuel injection and a new transmission soon and I'm thinking about swapping out the TH350 for the 700R4 because it would probably be more beneficial for me. And pretty much labor only... I'll probably go ahead and buy everything from BTO first.

|UPDATED|7/28/2004 5:44:16 AM (AZT)|/UPDATED|

I'm planning on doing the 200r4 swap. I've been doing research on his and it seems to have the least amount of hassle factory involved.

My initial concern was the strength of the 200r4 because I will be making around 400 to 425 HP with about the same amount of torque and I plan on adding a 100 to 125HP shot of nitrous on top of that.

So in my research I got hooked up with some of the Buick T-type and Grand national sites online. These guys run the 200R4 in almoust all of their cars and are making serious HP and Torque, not to mention runing mid to low 9's in the quarter. So after some research I found Out there two places that come highly recommended.

http://www.ptsnctb.com/index.asp


http://www.levelten.com


I have no doubt that the Bow Tie Over Drive piece is a good piece, buy they recommend no more then 450 HP and with nitrous on my application I'm going to have to one of these vendors and get the rest of the install kit from Bow Tie.

Something to think about.