rayluka

I want to do a transmission upgrade. I want a simple solution, is there a major difference in installations as far as mounts cables etc...Opinions?

76CSRvette

200r4 from what I heard wont need the drive shaft shortened.

sstopczy

That's right, no need to shorten the drive shaft. 700 is more plentiful than 200 if you are looking to buy local and rebuild.

riverracer au

i have just done this in a '72, going from a t400 to a 700r4.
here is a read about all the little things i found along the way, the "fiddly bits" as i called them.

https://www.corvetteforum.com/forums...ddly-bits.html

i used the tail extension fron an ’80-’82 Caprice or SS Impala, and slotted my x member holes slightly to line up.
this made the 700r4 almost the same length as the t400, (+/- 5/16")

had to shorten the driveshaft (got name correct this time) approx 2 1/2" - 3".

lock-up control, i used the B&M unit, with a few slight addons, brake and vacuum switches.

used BTO for the TV cable brackets and associated items.

happy with the result, doing less rev's = better fuel mileage for our long runs

7T1vette

It depends on what trans came in your car. If it has a THM-400, the 200-4R is the best choice. If you have a THM-350, my understanding is that a 700-R4 is the better swap.

Do your research. It has to do with matching the length of your existing transmission so that you don't have to swap out driveshafts. But, there are still LOTS of details that need to be altered/replaced:

brackets mounted to the tranny sump need to be replaced or altered to fit with the different bolt hole locations on the new trans;
deal with the rear trans mount;
modify the e-brake pulley location (if necessary);
dipstick tube changes:
lockup clutch details and how to actuate/release it [to keep from damaging it];
dealing with the shifter detent plate to set it up for 4 forward ranges and still work with NSS and backup lights;
Throttle Valve (TV) cable installation, correct adaptation to your carb, bracket mounting, and MOST IMPORTANTLY, adjusting it correctly {failure to do so results in early trans failure}.

If you are doing this yourself, this is not for the "faint of heart". It's a lot of research, a lot of part chasing/adapting, and a lot of installation modifications. In general, I would suggest that if you don't drive a lot of miles on the highway, just leave it as-is. You'll never 'break even' based on gas mileage savings when you only put 3000-4000 miles per year on your car. But, if you drive on the highway a substantial part of that mileage, reducing the RPM's will save unnecessary wear & tear on your engine. [Engine will run at 2/3 that rpm level with an overdrive transmission.]

SH-60B

I went from a th350 to a 200 4r. Very straightforward. Same driveshaft and cross member, just remove th350 bracket. Shift detents were fine, I just couldn't manually shift into low. Bracket does need a mod at trans, no big deal. Get a TV bracket and cable from BTO.

mikem350

Don't forget the speedo gears for calibration. Newer trannies (electronic) don't have outputs for a mechanical cable. But they need a TCU to control everything, so beware...

riverracer au

i had a few problems with fitting it in, turned out my x-member was bent upwards
my 700r4 had a mechanical speedo installed to start with.
the e-brake on my x-member was fine and didn't need to be shifted.
i must have struck it lucky with the detents, as all mine line up ok, even 1st is selectable,
but i have the shiftworks kit to change over soon when i have the console apart next.

i went with the 700r4 as it was used in local cars, we don't have the 200-4r available down here.

Alwyn678

My 700R4 installed pretty easily. It is the one to use if you are putting down some serious HP

'75

The 2004R can be built to take anything the 700 can. There are plenty of Buick Grand nationals running 9 and 10 second quarters with them. 700 has a very low first gear and a somewhat wide split to 2nd. 2004r has a better gearing in my opinion. No tunnel mods needed, the left side exhaust pipe is tight up against the pan and will need slight modification, other than that it's pretty straight forward.

riverracer au

i was told on here that if you have a 3.08 or 3.36 diff ratio, that a 700r4 is the best.
as it makes better use of the 1st gear in the box.
any other rear ratio, a 200-4r is the better option.

my '72 had a 3.08 rear end.

johnt365

Here is a thread that shows what is involved in a 200-4r swap from a TH400.

https://www.corvetteforum.com/forums...-pictures.html

I agree with the concerns about the rear gears. My car has a 3.55 rear and the donor 200-4r came from an 87 Monte Carlo SS with 3.73 rear. I am not so worried about first gear as I am with shifting into OD with a 3.08 ratio. Just something to think about.

The 200-4R is pretty much a bolt in replacement for a TH400. All I needed was a different yoke and the cross member, drive shaft and Ujoints all stayed the same.

7T1vette

A 3.08 rear gear is not a problem with a Corvette, as it has plenty of torque. But, with intercity/interurban driving (40-55 mph) and a 3.08 axle, you may want to keep it in 3rd range (instead of in overdrive..4th) or you may get some low rpm 'lugging'.

Otherwise, not a problem.

riverracer au

i tend to keep mine in "D" unless i'm going around 80km/h (50mile/h) then i put it in "Od"

Dirk76

I have read a lot about this.

I am going with the 200r4 for a nice close 1st to 2nd shift not like the 700, also with a 3.9 rear end, ls3.

riverracer au

with the ozzie $ at the moment, it will cost a fortune to ship a trans over here.
i know, i looked into it.
at least the 700r4 was used in vn-vq holdens.