Thinking about replacing my th350 for a th700-r4 or a 4l60 4-speed auto in my '77 vette, mainly for fuel econemy as UK fuel price have recently risen to over £1 a litre!

Did a search but couldnt find much on the forums.
Which would be the best tranny of the two 4-speed autos to go for?

Would it be a direct fit? what mods would have to be done to fit one of these? Crossmember/yoke alterations etc?

Anyone here done this mod?
Thanks in advance for any info.

Earl

 

You forgot a 4 speed auto, the TH200R4. Ironically, the one you forgot would be a better fit in your '77.

The only hurdles are the slight misalignment of the transmission mount bolt holes and the lock up relay harness to control the lock up torque converter.

It'll bolt right up to your engine, and the stock drive shaft will work fine. Like I said, you may have to slightly modify the transmission mount bolt alignment, but that's a small obstacle.

I have not done mine yet, but I have mine and it's ready to go in.

 

Thanks for the reply, yeah was thinking about the th200 r4 but missed it off.

So would be just looking at modifying tranny mount bolt holes and lock up harness. Doesnt sound too bad.

What wouldv have to be done to make the lock up work?

Any mods needed to the shifter- i'd like to keep my stck one,
would the stock kick down work or need to be modified?

Thanks.

 

Check these folks out for info and parts.

http://www.bowtieoverdrives.com/PhoneExtensions.htm

There are alot of folks here that have done the 2004R swap. I did it in my 77 love it.

Michael.

 

For the 2004r no modification is needed to the croosmember. It will bolt right in.Remove the triangular bracket that the thm350 used. The 2004 will bolt to the crossmember. The only things you have to get right is the tv cable adjustment. And the Tcc lockup. Bowtie has this information. And the detent in the shifter needs to be changed. Try to stay away from any the were powered by a diesel. Here is a list of vehicles you could find the 2004r.http://members.aol.com/powerrslid/thm2004r.html

 

There are many many posts on this topic. Do a search for 700R4 swap or 200R4 swap. The 700R4 and 4L60 you mention are the same transmission. the 4L60E is an electronic version and requires a computer, it would best be used with an LSx swap or even LT1 swap. I personally prefer the 700R4 as it was used by GM behind BBs, in Corvettes, and in trucks/vans/SUVs. The 200R4 was never used in a stock application behind anything larger than the 307 Olds. The 200R4 is a good transmission and will take a lot of abuse IF AND ONLY IF you rebuild it and use good internals. This fact is often not mentioned in these posts. A bone stock 200R4 will NOT hold up to high performance usage. The 700R4 got a bad rep because of early failures. If you get an '88 up core (and not from a 4.3L application) and adjust the TV cable there is nothing wrong with a 700R4. By the time you rebuild them both and do it right, the cost difference is not so extreme. If you have a TH350 or a 4-speed the 200R4 will use the same driveshaft and yoke. If you have a TH400 you will need to shorten the driveshaft and use a different yoke anyway. With a 700R4 you have to shorten the driveshaft either way (if you have an 80-81 with aluminum diff, you can use an 82 driveshaft, but not in an iron diff car). With the 700R4 you can buy a tubular crossmember from BowTie and save some weight and possibly get rid of a rattle with the exhaust through the crossmember. Good luck with it either way you go.

(I do know you have a 77 and a TH350 but I wanted to provide a complete picture for future searches)

 

How long did Grandsport run a TH200R4 in his strip car, maybe 500+ HP, before swapping it out? It didn't fail if I recall correctly, and I think it was a stock rebuilt transmission.

 

DB - I assure you it was a built tranny. About 2 weeks ago, my dad picked up a 4L80E from a guy up close to Chicago. Anyways, he use to rebuild transmissions for a profession and had tons of autos just laying around. He said that he would never even think about puting the 200-4R behind anything. He was saying that for street use the 700R4/4L60 was hard to beat. Now I am not saying that the 200-4R is a bad tranny because I have seen them built to handle some HP, but I thought I might give you the thoughts of a former transmission builder.

BTW - He had a REAL nice maroon '66 Chevelle SS w/ a 502 and TH400. If I remember correctly, the car ran in the 11.8's in the quarter.

 

I'm all for suggesting it be properly rebuilt...I just know I have seen a lot of guys with that transmission in their C3s and I can't recall seeing a single failure story.

I am planning on building my own, using quality parts and high performance components, and it should only cost me a few hundred if I do it all myself.

Also, about the shift indicator, I think you can use the stock shifter and gate setup, except you won't be able to drop it down into 1st manually...second would be as low as you could go. I seem to remember though that someone filed an extra slot in the gate, allowing it to shift into first.

 

There is also a kit out by Corvette Central.. I can try to find a part number if ya like. It even comes with shift indicator that reads P R N OD 3 2 1...

Edit: CC no longer has it on their site, but I found them at Ecklers... http://www.ecklers.com/product.asp?p...dept%5Fid=1887

 

Yeah I found one of those kits too...and I will probably get one, even though I don't see the need to shift into 1st manually.

Here's the one I found.

http://shiftworks.com/corvette.htm

 

Thanks for all the advice

The bowtieOD link is gonna prove invalueble i think!

Just been looking at them 4speed shifter kits myself at ecklers.com

Looking like the 200r4 is the one i'll be going for, even though its been questioned how much horsepower etc these trannys can handle, i'll only be using the '77 mainly as a cruiser, and once i've rebuilt my motor later on its only gonna be running around 300hp.
Also, looking at most rebuilt 200r4's for sale-they mostly seem to have been rebuilt with some uprated parts etc, even in basic street form.

So as i can gather up to now, for the swap i'll be looking at-

-Mod stock crossmember mount
-Install aftermarket lock up harness
-Intall aftermarket 4sp shifter kit
-TV cable correct adjustment to suit

(retaining stock shifter/propshaft/yoke)
Just out of interest are the torque converters interchangable from th350-200r4?

The swap is sounding quite easy, and not to expensive too, and will soon pay for itself with the incresed mpg!

 

The 2004r torque converter is a diffrent animal all together.

 

You may want to concider the shift kit. I think the linkage from the cable to the tranny is different? It was on a th400.

Michael.

 

i did the 700r4 swap in my 77 and i sourced the parts from BTO except for the trans which i got locally. and yes i am very happy with it.

 

The shifter kit from Bowtie $90 & you use the original handle.
http://www.bowtieoverdrives.com/cata...AT&CATID=LA2A2
Avner