i'm getting ready to dump some pretty decent money into a new transmission and i've noticed a lot of people using the 700r4's... i was just wondering of any advantages and disadvantages of these compared to a th350. of course overdrive would be awesome, and the lower first gear sounds nice... how much of a conversion is it from a th350 to a 700r4?
i know the motor has a lot to do with it.. it is a pretty strong 350-.30 over. not sure of the horses. 305 heads shaved a bit and flathead pistons. some pretty good torque out of it.

thanks for any help
later

Two big advantages with either a 700R4 or 200R--1) Low first gear for faster acceleration 2) Higher fourth gear for more relaxed highway cruising (less engine wear and better gas mileage). Both trans require a new or modified crossmember, new torque converter, TV linkage; the 700R4 also needs a shorter driveshaft. The disadvantage is cost. The conversion will cost you 3-4 times as much as a TH350 rebuild unless you go the wrecking yard swap route.

Everything you need and wanted to know about the 700R4 conversion BowTie Conversions (http://www.700r4.com/sitemap.shtml). They're very helpful and will answer all your questions.

yeah, i've been checking out that sight for a while and it has some pretty good information. so, if having the 700r4 is this good, then why should i stick with the th350? (besides cost of course)

the only reason to stick with the TH350 is the minimal(?) cost of repair/replacement using the factory hardware.
Which I feel is more than made up in the fuel savings and less wear and tear on the engine.
Your initial investment might be somewhat high, especially if you buy a 700R4 from somewhere other than a bone yard, but even if you buy one built for racing, It will be far better in every catagory over the TH350.
If you plan on keeping this particular Elk, then the 700R4 is the finishing touch. (The 200R4 is just a lighter duty version) GO 700!

It's not true that the 200R4 is necessarily weaker than the 700R4. If both trans are similarily beefed up they can safely handle about 450 lb-ft of torque. In my opinion the 200R4 has two advantages--easier conversion and better gearing.

the 350 is a good transmission, it will last, i like them, and i hope to swap my thm250 for one.

I just had my 400 redone from inside out. But, before i did that i asked the trans man (which i grew up with) if it would be to my advantage to replace it with a 700r4. His words: "No, man, i wouldn't put one in there. Those and fords are what keep me in business". So the next day he refurbished my 400.

When I swap out my th350 I'm goiong with the switch pitch th400. My dads got one in his '65 Riviera and boy is that a fun transmission, its like having two torque converters in one. :cool:

you know it! it IS FUN 8) .
BTW what kinda engine does he have in that Riviera, 396 or 427?

When I was a kid my uncle bought a brand new Riviera with the two four barrel Super Wildcat engine. I used to borrow it and go street racing; it held its own even against the musclecar 409s, 426s, 413s of those days. I believe it had that switch pitch turbohydromatic.

I realize this thread is wandering off line, but as a 65 Riviera owner, I have to say that the transmission out of a 65 Riviera will NOT bolt up to a Chevy engine. There has been an awful lot of discussion on Riviera websites begging someone to make an adapter plate so that the Chevy bolt pattern transmissions can be used behind the 401/425 Nailhead engines. (Mostly to get better mileage out of an overdrive, 11 mpg just ain't too good with gas prices what they are headed toward today.)

Ever heard of Gear Vendors (http://www.gearvendors.com/). This is an easy (but not cheap) way to double the gears in any transmission. A friend of mine uses one in his GMC pickup and increased his gas mileage from 9-10 mpg to over 15 mpg. Use Gear Vendors on a 700R4 and you got 8 speeds! Use it with a T56 and can row thru 12 gears!