spille85

Ok, I have a 79 L82 with a turbo 350 in it with 4.11 gears..and when I am cruising at 55 mph my rpms are pretty high. I am almost afraid to run it at 70 mph. Not sure why this car was set up this way, but with a little research I found out that this was an option for this year. Anyways, I am considering going to a different transmission and several people have suggested a 700r4 transmission or a fellow forum member suggested changing gears from a 4.11 to a 336 or 355 gears. What kind of modifications if any would I have to make to my car to make the swap to a 7004r transmission or will changing gears lower my rpms at higher speeds. I have lots of people say stick with the 4.11 gears but i sure would love to cruise the interstates with my car. Anyways, I would just love to find a nice set up for the car I have. Any suggestions would greatly be appreciated. thanks everyone.marty

sam74c3

I have a 55 chevy truck w/ same set up.(3.90 gears) The 700r4 will give you overdrive, and will help rpms. The downside is that you may have to change or cut your driveshaft, and move your transmission crossmember. Not sure how your shifter would work. If I were you though....I'd get the ring and pinion changed. It would be alot cheaper and easier to just go with more streetable gears.

mrvette

The 200 4r is a much cleaner, better swap, it's lighter weight also...the 700 has some design flaws that cant' be beat by mods....the 200 4r can handle Grand Nationals, putting out like 600 hp or so....plenty tough enough for most sharks....requires no mods either it's basically a bolt in for you....
Wish I knew of the 200 4r when I installed a 700 in my '72 here, back in '97, I have 336 gears and find the first gear in the 700 to be about useless, among other failure/weak points....
look at the parts list for rebuilding a 700 and you find about 4-5 versions for the 3/4 clutch pack alone, that right there tells you about the problems designed into that setup right there from the git go...

MIKER

A lot of people have had good success using a well built 2004R. It has two primary benefits. One is that it will bolt in without having to modify the drive shaft or cross member. Another is that it has a slightly better gear split between 1st and 2nd gear.

The 700R4 is also a popular swap. A well built 700R4 is certainly not any less reliable than a well built 200R4 as Gene would lead you to believe. His bias is based on grief that he has suffered with his 700R4 and the dismal reliability of the early production units.
However it does require that you have the drive shaft shortened and that you modify the O.E. cross-member or purchase an aftermarket cross-member. Ease of installation does make the 200R4 a bit more attractive.

Search the archives and all of your questions will soon be answered.

RPM vs Speed with 700R4


RPM vs Speed with 2004R

mrvette

OK, lets go a bit further, the 700 is larger, heavier, and may well require widening the hump/tunnel on the pass side to clear the widest parts....it also has a larger pan making exhaust pipes do strange twists to get throug the cross support....do able, but takes a man who knows his tschit to get er done....
I am switching to a 200 4r for all the above reasons, and get a useful first gear.....I think the 411 gearset needs disappear too, unless you drag racing, and even then with automatics, they are less effective than used to be....go to near 336 ratio....honestly I"m thinking of 308 for my car, because of all the freeway driving, any automatic can turn tires with a 273 rear....so for street fun, it's not critical to have anything wilder than 336 at most...my munice 336 is still in there...

Twin_Turbo

the 700R4 is a cleaner swap..why? Because an 82 came with it so you can get all the parts you need to bolt it right up. All you need is the little bracket for the 700R4 offset, it bolts to the 78-82 crossmember. In fact, I still have it here somewhere. Also you'll need the 82 tailpiece and a mech. speedo drive. You can get the alu speedo drive housings brand new somewhere, a buddy of mine has one lying on the shelf..I could check where he got it.

Then you will need the 82 tv cable or one from tvmadeez.com.

the 700R4 does not require any tunnel modifications, the tunnel is exactly the same as the earlier cars, I know because my bastard corvette had an 80 body on an otherwise complete 82 rolling chassis..no interference problems anywhere. The exhaust routing is also almost identical to the earlier cat con years that have the late style crossmember and a 2-1-2 system

As for the driveshaft, just buy an 82 shaft or the alu one from an early C4..it should be a direct fit.

Jack71

Why are you considering a tranny swap?

Another option would be to put taller gears in your car, 3.36 or 3.55 would be good choices. That will give you much better highway gears.

4.11s with an overdrive is a lot of gear. Your first gear will last about 1 second before shifting. Unless you are ~very~ performance oriented, I would just switch those gears to something more suitable for the street.

Its easier on the wallet too.

jdmick

An overdrive is one of the best things you can do for these cars. I went with a 700r4 mainly because I was able to get a good one fairly cheap. The crossmember mod is pretty simple or you can buy one ready made. If you are considering someone like Bowtie I would probably go with the 2004r since the ratios are better for a 4.11 and the install is simpler.

marshrat99

I swapped out the TH350 on my 79 L82 with a level 3 Bowtie 2004R this past winter. Mine has 355 gears. Was a relatively painless swap. No issues thus far but would suggest an aux tranny cooler.

Bee Jay

I have a 79 L82 that came with the 350 and 3.55 gears. I switched to the 700r4 over 20 years ago. Not a popular swap back then, but the 3.55 was driving me crazy. I knew a guy with a Vette shop, and 82 owners were paying good money to get that piece of crap 700r4 out of their car. I picked one up for little of nothing. Me and my drag race friend rebuilt the tranny with some B&M internals and did a lot of engineering. I wanted a functioning lockup converter, and the Turbo Regal 2004r converter had the right splines and the right amount of stall. I think the 84 and later Corvette 700r4s are different. I had to modify and cut my driveshaft, and I had to modify my crossmember, and I lost my parking brake.
I've said it before and I'll say it again, the best mod I made to my car, ever. 700r4 or 2004r, your choice, but get the overdrive and lockup converter. You will fall in love with your car again.
I drive around in 3rd, but when I get up on the highway, I put it into D. Sometimes going up steep long hills, I tap the brake with my left foot to unlock the converter. Almost as good as downshifting.

C3Racing

Just make sure that the 700r4 is fully upgraded (internal parts) the original (82) tranny had nothing but problems.

windsoreight

In my opinion the 700R4 is the better swap. Sure the early ones had problems and it is a little more complicated swap. I spent many years as a trans bulider and I also met the GM engineer who designed the 2004R. Sure it held up in the Grand nationals but barely. And when you consider the are based on the Chevette 200 metric. I am going with the 700/4L60 in my 79 with 3.55 gears. I would like the lower 1st gear. I already have my core to build.

markdtn

I agree with everything you said except you can only use an 82 driveshaft on the later aluminum diff cars. There is enough difference so that the length is wrong for an iron diff. I tried one myself. But having a shaft cut is no big deal.

doug_dayson

Hi Gene...

700's fit Sharks fine, and nothing needs to be done aside from moving the Crossmember's Hand Brake Pulley, shortening the Driveshaft, and drilling a couple of holes in the Crossmember. The aftermarket can provide a custom Crossmember as well.

700's fit the tunnel fine, the Shifter works fine, the Cooler lines work (they don't as easily with a 2004R I've been told), and it's essentially a bolt in.

There's no strength differences between the 200 and 700 if both are well built, and they weigh in pretty close as well, though the 200 has a closer ratio gear set.

IMO, if you have a 3.08 or higher rear gear, use the 700 (3.06 first), and if you have a 3.55 or lower use the 200 (2.75 first?). If you have a 3.36, take your pick?

I've had a 700R4 behind a warm 406ci in my 71 Coupe for 15 years or so, and it's been great. Best MPG I did was 18.9 at cruise with the AC on (Q-Jet on the 406ci)!

Doug

Jspyder23

I have a 74 with a turbo 400 that I have had rebuilt soon to be 5 times in the last 4 years by 2 different builders(not funny but true) this 2004r may be my ticket just wondering if I can use the stock crossmember from what I gather from all the posts the driveshaft isnt an issue

Avette4me

i just did the 700 r4 swap. twin turbo is correct with his assessment...

i should have done it a few years ago..

Before (click to enlarge)...



After...

sho nuf go

Hey
I went with the 200R4 had it grand nationalized and am running 3:55 diff. gear, bury the 240kph @5k rpm. Hooked up a hurst ratchet shifter so I can shift or let the tranny do it's thing. I love my car!
Sho nuf go!

Xakk

700R4

rosslato

yes, u can use the stock crossmemeber and driveshaft. i've got the 200r4 on my 73 and installed it & love the switch i have the 3:70 gears and turn 2200rpm's at 70

Pete K

There is a huge selection of aftermarket parts for the 700 because there is a demand for them. I install them behind 600 ft lb torque(at the wheel) cars with no (knock on wood) failures. I have a fondness for them because they have worked well for me. Most failures are the result of poor builds. They are remarkably good units if blueprinted properly.