CF members who converted to 200R4, still happy? Comments?
 

I really need to do the conversion from a TH400 to a 200R4 (or 5 speed Tremec). Wondered if those who made the change to an AOD are still happy with their choice and had any comments or suggestions. As always thanks :cheers:

Road trip of 1012 miles, 75 mph, 25 mpg. I am thrilled!!!!

If you do a search, you will find MANY happy people that swapped to a 200 or 700. Overdrive is a great thing. Not that I know, I'm with you and still have a 400.

I made the swap in april 2012. I wanted a 2004r to handle 400hp+. After researching all the big venders I desided to have a local independent trans shop do the build. This new trans has a full preasure valve body. The shifts are a bit harsh but the good thing is the TV cable only controls shift points therfore eliminating the posibility of burning up the trans due to improper tv adjustment. I have the lock up feature set up to only apply in 4th gear. This transmission has a much lower 1st gear than the th350c so still have the factory 2:87 to 1 rear gear. I did all the mods for install myself and did purchase a new crossmember from BTO. Resent trip to WA coast 145 miles one way netted 20mpg. This 81 with the new engine and trans is now truely a hotrod. Very pleased with the mod.

I swapped out a perfectly functioning THM-400 for a 700R4 two years ago, primarily to help the engine survive longer. I like to drive it to car shows anywhere in Tennessee, but driving longer distances on the highway was out of the question without an overdrive transmission. Nearly 3000 rpm for 2-3 hours at 70mph was uncomfortable for the engine and ME...too hot, too noisy, too much wear on an original engine with 200+K miles on it.

Now, the engine lopes along at just over 2000 rpm and gets over 20 mpg at 70mph. It is comfortable for me, the engine will last that much longer, and more Tennessee folks get to see a '71 Corvette on the weekends.

Except for the few headaches of working out the installation 'bugs' and some additional cost, it's a "no-brainer" modification for those needing/wanting to do more highway driving. I will say that an O.D. transmission is NOT for everyone. If you don't do much highway driving and/or you have a differential with less than a 3.36 ratio, you might want to think about it a little more. With a 3.08 rear gear, you will need to place the shifter in 3rd range for in-city and suburban driving, or it will want to 'hunt around' shifting from 3rd to O.D. Of course, on the highway, a 3.08 car with O.D. will be running at 1750 rpm at 70 mph. Just realize what the results of an O.D. tranny in your car would be, before you take the plunge.

:iagree::thumbs:

Still very happy with the mod/upgrade.
Install page

I don't know what I could add that hasn't already been said. It is a no regret decision.
Things to plan for:

~Cross member mounting - I got a custom cm from BTO. Some original cm's will work
~You will have to install a TV cable. Adjustment is critical. - Not the same as a kick down cable
~Be prepared to have a circuit plan to control torque converter lock up - Lots of options here
~You will need to modify your shifter for an OD detent - Kits are available
~TH350 yoke and drive shaft length match 2004R but I don't know about TH400 or 7004R

Even with all this it is well worth it!

Wow, thanks to everyone for the great response and for all your comments and suggestions. A tremendous amount of good and useful ideas. I have been researching this for a while here on the forum. I am leaning toward changing my 3:08 rear gear to a 3:55 for a little more fun. Also thinking about and researching the MSD TBI Fuel injection.

Anyone wish thsy had gone to a Tremec or any other 5 speed manual setup?
thanks again!! Mark :cheers:

Couple more things to throw into the mix. TH350's have a 2.50 1st and 1.00 3rd, with 700R4's having 3.05 1st and 0.70 od 4th, so maybe not such a hurry in switching out the 3.08 axle. Friend of mine did a Keisler TKO 5 speed conversion in his 79' with 3.70 axle Muncie 4 speed, and with the TKO's lower 1st gear, could easily get by with less rear axle. I did a 700R4 conversion on another BB car with 3.70 axle, and 1st gear is a real burn out king.

Looking at the Tremecs TKO 400/500 these are a wide ratio box with a 3.27 first gear. The TKO 600 is a close ratio box and has a 2.87 first gear. The 700R4 has a 3.05 first gear, while the 2004R has a 2.78 fist gear. I have the original TH400 with a 2.48 gear.
There's a thread here on the forum and on Bowtie Overdrives website that discussse the torque multplication and effect of using 10 as your target for first gear selection. For example, take the TH400's 2.48 gear x the rear gear of 3.08 and this equals 7.63. Now if go to 2004R with a 2.78 gear with the 3.08 rear gear and this moves closer to "10" at 8.56.
Now switch out the rear gear to a 3.55 and this number moves up to 9.86, with a 3.70 rear gear =10.2.
With a 700R4 wit the 3.05 gear and 3.08 rear gear this gets close to 10 with a 9.39, with a 3.55 rear gear =10.82
Only issue I see the the 3.05 of the 700R4 is the spread between fist and second. Not as bad with the 5 speed Tremecs with the extra gear.

I installed a 700R4 in my '71 SB car, because I had access to that transmission at a very good price. But, if all things were equal, the best choice for me would have been the 200-4R trans. The gear ratios are a bit better (although neither trans needs to start in 1st gear for normal driving), but the installation would have been much easier as the driveshaft and crossmember would not need modification/replacement.

Great information all. I have the 350C which I despise. A 2:87 rear axle ratio and want it to be able to get respectable mileage and cruise the highways. The 200 R4 sounds like the ticket. :thumbs:

:lurk:

Fantastic thread guys, very informative. Question.....as far as the 200 goes; is there any specific year/application that we should be looking to pull these trannys from? Or will any 200 do?

Thanks for the advice.

Brian

Researched this subject to no end until I decided to go with a Richmond 6spd.My 76 had a TH350 with a 3.08 rear gear,pretty boring to drive around.Didn't want the added expense to change rear gears so I needed at least a trans with a 3.XX first gear.The Richmond 6spd was the best choice.The gear spreads are just about perfect with not much rpm drop between shifts.The .76 6th gear OD works well with the 3.08 rear gear,I can use 6th as low as 45 mph without lugging the motor.Rowing thru all 6 gears is a blast and the engine just humms along at hiway speeds returning an average 20mpg....The trans is close to same length as the TH350 and I was able to use the same driveshaft with a TH400 yoke.Here's my write up: http://forums.corvetteforum.com/c3-t...am-change.html

My Trans builder said next to the 442/GN/SS trans, which are getting hard to find, The full size Caddy's with 307 olds power are the best. Late 80's~early 90's.....If you are junk yard hunting, Grab the cable bracket as well. Fits nicely on a chevy Q-jet.

Or mid-80's Buick Gran Sport with 200-4R auto. But, any of them can be re-built with stronger components so they will hold up well to V8 power. Find one and have a local trans shop (NOT one of the chain stores) rebuild it for the HP you have. Or call and see if they have one they will exchange for your old tranny.

Going to look at one out of a Caddy tonight! 307 Olds motor and TH 200R4 transmission. :rock:

I'll be doing this swap into my recently acquired '73 LS4 with A/C. My trans came out of an 87 Buick GN, but like an idiot I didn't get the converter (which I think is the highest stall stock at 1900 rpm)...so I guess I'll have to buy aftermarket or look for a used GN converter.

Sounds like a great score. Just so happens mine is installed in a 73 LS4 as well. Only it's a chevelle & not a vette. Mine was installed in '09. So far so good. It works great at the track, And 75mph @ 2200 rpm locked up is hard to beat as well. You may have some problems if you are still running the original 7043200 q-jet. No kickdown attachment. You'll either have to swap carbs or install a late model throttle shaft into you'r q-jet. Beware that a th-350 kickdown attachment is slightly different than a overdrive attachment. I am running a late model truck non-ccc q-jet with the proper OD kickdown attachment. I cut-sectioned & welded up some small block cable brackets to work on the big-block. I didn't like any aftermarket brackets. They seem to be flimsy & flex @ full throttle. For me, That was the biggest hassel with the swap.

I have a couple of CCC Q jets, can I pull the kickdown attachment off one of those ? I have a couple of stock GM Q jet throttle and kickdown cable brackets that bolt to the carb...no aftermarket garbage.

Probably not,You'll have to swap the entire shaft. The original carb should have nothing that hangs down below the throttle point. Is the original carb still on the car? I believe they were 7043200 across the entire 454 lineup in 73. the original th-400 is electrically controlled for downshifts. The CCC q-jet shaft should work with the exception of the acc pump rod hole. Larger on a CCC carb. Maybe weld shut & re-drill? late model truck carbs have the standard pump rod hole. There is another thread on here somewhere where someone swapped shafts.

Been running a BTO-built Stage 2 200-R4 in my 68 since 2007 and have had zero problems with it

If you are going from a 400 to a 200 you will need a yoke for the tranny. I got mine from Bowtie Overdrive.

Hum great thread,:thumbs:
So I have a 454 "warm" 400th at the moment and was gonna toss in a 700 but would the 200 be better for me?
I also at some point want the rear gear in the 2's low end is something I have lots of.....:D

Would someone post up the essential difference between the 700R4 and the 200R4? Why one would choose one or the other. A clear description from someone who knows would be a nice addition to this thread.

2004R is the direct swap out for the 350 turbo on my 78. No driveshaft or crossmember mods needed. I used it on my older SBC. I am currently using it on my LS engine. They can be built up to withstand a lot of HP. In OD my RPM is 1800 at 70 mph.

I swapped my old TH350 for a newly rebuilt 700R4 about 4 years ago. I used all of the BTO conversion parts (crossmember, Shiftworks kit, carb brackets, wiring kit, etc.) and installed the recommended TransGo kit. Relatively easy conversion, though setting up the TV system was tedious and time consuming.

I've put roughly 20k miles on it, couldn't be happier. :cheers:

The 700r4 sucks. First gear is WAY too deep (3.07) and it's just fragile. Of course, you can spend lots of money building a stout one, but for any car with more than 3.36 or 3.55 rear gears, first will be a smoke show.
The 2004r came behind Buick's GN and can be built into a capable performer. First gear is 2.74, so it "plays better" with deeper rear gears like 3.73 and 3.90. It's lighter too. It fits where a TH400 would have been and is less bulky. Art Carr swears by them.

Heres a great thread on the swap. It shows good pics of tv system..


http://forums.corvetteforum.com/c3-t...ictures-2.html

Some advantages of a 200, it takes less HP to run, so less parasitic loss. TH400 consumes about 40-45 HP and I understand the 200 uses about 1/2. Weights are the same, Like mentioned, if swapping out a 200 for a 400 the cross member and driveshaft can be used.
Gear spacing is better in the 200 over the 400 and the 700.

TH 200R4 - 2.74 1st, 1.57 2nd, 1.0 3rd, .67 od
TH 700R4 - 3.06 1st, 1.62 2nd, 1.00 3rd, .70od
TH 400 - 2.48 1st, 1.48 2nd, 1.00 3rd
:cheers:

Overdrive on a 200 4r is .7 I think...and 700 r4 is .75 ? Neither is .67

Typo corrected 200 is correct at .67 on the od and the 700 is .700 on the od :cheers:

Has anyone ever considered a Doug Nash 4+1 5 speed (Richmond Gear)with a 4+3 od bolted on the back of it ? That's what Callaway did initially with The Sledgehammer Corvette before the ZF 6 speed came out. I think a 2.73 or 3.08 rear gear with the 4+1 would be awesome, and the od of .6 or .68 would cut cruise rpm to nothing. Fragile though...I wonder if it would stand up on the highway just for cruising to lower engine rpm and increase mileage in top gear ? Anyone with any experience ?

I put a bowtie stage 3 200-4r in with a rebuilt 3.55 rear end. I love it. Especially those second gear tire chirps ;-). Shifts tight but youll get use to it.