mike1976

Just wondering what transmission to go with for my Cutlass? It has the original 2 speed auto in it and I would like to get better drivability out of it and better mileage while cruising on the highway. I was thinking of going with the 700R4 and installing the floor shifter as I have the console for it. What other options are out there that can be done for relatively cheap?

White_Knuckles

No expert here but I'm in the same movie. The ol' JetAway needs to GoAway. Thing is, it's a cool trans when you think about it. I've got the pitch-shift, converter functional where it works great and is fun to stuff the pedal and have her "kick-down". These were an upgrade compared to a power glide. Unfortunately, they're rare and parts are getting scarce.

The first consideration is not getting the wrong case 'cause the guy said it'll fit. There are housing adapters but it's easy to source BOP cases. That would be, Buick, Olds, Pontiac. Only these trans cases fit properly. Rebuilders often stock them.

The following comments are biased to my fussy car not necessarily good for others. Exploring electric lock-up the associated mods and tweaks needed to adapt a 700R4, I thought hmmm, what about a step back in tech. Found out a TH350 pops in without pain. The column shift linkage moves over and with enough slop, allows you to select 1st gear. The driveline bolts right back up. What could be better? A street torque converter, cable kick-down, flex dipstick tube, a mild shift kit and $500 later, she's done.

Yeah, it's only a 3-speed but I only run the car to scare women and children. Kind of a summer, week-end deal. Mileage is not a concern. Having a real first gear and knowing the thing is bullet proof is what'll work for me.

I haven't done yet it 'cause that stupid slush-pump keeps working fine. I keep thinking it will slip or something but nooooo.

tmaleck

My car has the 700R4 conversion. It is a 67, so it already had both sets holes in the frame for long and short transmissions. It also had a performance rebuild, shift kit, fluid OD conversion and high stall converter. Not for the faint of heart, the total ran about 2500. I would recommend the 200R4 instead. I still have the 3:08 rear gear and this trans would be better with 3:42 or 3:55. Another plus is the 200R4 fits in the same spot as the Jetaway, the driveshaft even works as is. Other than cost I can see no reason not to go overdrive. My typical highway mileage is 21-22 if I stay around 65mph.

Tim

White_Knuckles

^^ Interesting. About those gear ratios? One noticeable affect going from 3:08 to 3:55 is the cruise RPM is going to jump up. Hmmmm, if it were just a three speed, what RPM would 70 mph be? 3500? I never considered limiting myself to a three speed should I change gearing. I better think about this.

Aceshigh

IMHO I would buy a built up 2004R instead of the 700R4.
Even the modern 700R4's (4L60e) from GM are weak and burn up the 3-4 clutch packs quickly.

Plus from everything I've gathered, they're an easier bolt in with the mixed GM / BOP bolt pattern

Answers you seek will be answered by this tool.

http://www.angelfire.com/fl/procrastination/rear.html

coldwar

One note, my own half good 330 4bbl two speed Cutlass with duals easily did 20mpg highway, mostly stock, with 93 octane gasoline. Just regular tuning with timing pushed up to where it would just start hot.

joe_padavano

^^^^This.

The 200-4R is nearly a bolt-in for the Junk-a-way two speed. The driveshaft is the same and it bolts to the BOP bellhousing pattern. The major change you will need to make is to move the trans crossmember back. The 200-4R puts the crossmember in the same location as the TH400, but unfortunately the TH400 was not offered in the 1966 A-body cars, so your frame won't be drilled for it. So long as you don't have a convertible or HD boxed frame, this is simply a matter of sliding the crossmember rearward and drilling new holes. Boxed frames present a small challenge in that the trans crossmember bolts to tabs welded to the frame on those cars. You'll need to weld an extension to the tabs to have enough meat to drill new holes.

Moving the crossmember also affects the e-brake cable since it hangs off the crossmember. Since the 200-4R puts the crossmember in the same location as the TH400, use the front and intermediate e-brake cables from a 1967 Cutlass/442 with the TH400. These are readily available from NAPA and RockAuto.

Shiftworks sells a kit to convert the stock console shifter to a four speed OD shifter.

Finally, the 200-4R is very sensitive to heat, so be sure you have a quality trans cooler.

mike1976

Thank you for all of your information. I am thinking that the 200 4R is the way to go for what I would like. Likely not going to happen until it gets parked for the winter along with some other work I want to do to the car. I am just going to get the rad re-cored for now since it is the only necessity for the time being. I will be posting a few pics of the car soon. I am pretty sure that it still has the original paint on it and the interior is close to new in condition.

White_Knuckles

Good info. surfaced here so thanks for letting me hi-jack the thread with a '67. I thought they had the same crossmember mounts.

The ratio calc is a nice tool. 3500 RPM with 3:42 gears = 67.3 MPH.

joe_padavano

The TH400 was offered in the 1967 A-body cars, so the crossmember mounts are already there to accommodate the 200-4R. The original question was about a 1966 car, which was NOT available with the TH400 and thus the mounts are NOT there, as I noted in my post.

jag1886

I did a non lockup converter 200R4 conversion to my 65 last year and it has work out real well. I posted all the pictures and what had to be done to make it work.
This was a pretty easy swap and the car gets just over 20MPG now with a 3:90 gear. Your 66 will be almost identical to mine.

White_Knuckles

oops, your first post was what I meant by, "thought they had the same ... mounts". This was good to discover. Sorry I was unclear where you thought it needed restating.

64Rocket

In my opinion when going to an overdrive trans and 3.23 or numerical less, when in overdrive the engine rpm is to low to be effective. You lug the engine down and it doesn't like that. If you run a numerical higher ratio you put the engine in an rpm range that is more effective.

Gene

joe_padavano

I'll disagree. Both my 84 Custom Cruiser and 86 Caprice wagon have pavement-ripping 140 HP 307 motors, 200-4R transmissions, ~4000 lbs curb weight, and 2.7-something axles. Neither one has any problem pulling in O.D.

Kibby70

Thanks, Joe, you've helped me decide on changing my TH350 to the 200 4R, I'll start looking the parts I'll need after I finish with the interior. Then on to the motor and trans.
1970 Cutlass Supreme Convertible...Kibby 70

coldwar

Yeah, but like everyone who wants and then does this conversion which is currently magazine popular, you don't then provide figures on the net mileage gain realized against total cost involved and former performance. I can do that for you based on what I know: NO net mileage gain, or the mileage gain then attributed to careful driving trying to demonstrate the merit of the conversion. My own '66 two speed car with a tired 330 could do 21mpg, a 72 350 2bbl with TH-350 could and did get 22.5 even in hilly country. What are the OD jobs doing, and doing setting aside the change in diff ratio change as 64rocket suggests to optimize the RPM for best VE at cruise rpm? Answer: No one at anytime comes back to report huge mileage gains against the large cash outlay in making the change for the sake of change. I'll advance the argument a step further and suggest that even in cases such as this when a bad transmission is in need of some kind of replacement anyone will have to have a mountain of successful data to disprove the logic in a ±$450 TH-350 swap to replace ST-300 as a direct bolt-in. Just one guys opinion.

droldsmorland

Additionally some like myself do the OD just to get the engine down off 3000+ Rs at cruse. Who cares about mileage just want to increase engine life and get the drone out of my head at 70 mph

joe_padavano

^^^This.

I don't care about mileage either. I want the 0.68 fourth gear (and the 2.74 first gear, by the way) so I can run 4.33s and still drive on the freeway.

mike1976

I too am just looking for a bit better performance out of the 330 that is in the car and make the motor last as long as possible. With the overdrive at highway speed I might actually be able to hear the one speaker that is in the dash on whatever AM station I can tune in. The car is all original aside from the wheels and soon to be the transmission too. I do like that with the dual exhaust you can get peoples attention and it would be nice if the car actually accelerated the way it sounds like it can.

Mike