Mr.Smooth

Hi all. Im looking for recommendations for an overdrive trans. I have a stock 400/400 combo with a 308 rear. Im not worried about gas mileage, im more concerned about rpm on the highway. I think around 60mph im close to 2500rpm? I can remember but its higher that id like for 50 year old parts lol. I like to go for highway cruises and would like to bring the rpms down. I dont want gear venders or do tunnel mods so that kinda leaves the 200 and 700r4

Thoughts? Opinions?

A little back story about the car, my father bought a year old, it has 74k miles. when he passed the car became mine. Its mostly original. It will always be a family car and never leqve the family. Im really concerned about originality since it will never be sold

Bubba68CS

The 700R4 has a pretty awful gear spread, especially 1-2. It’s also pretty weak like the 200-4R. So either one requires building with quality parts. 200-4r bolts right in, just need to check driveshaft length and tweak cooler lines. Do keep in mind your rear end gear is already tall, and that 200-4r overdrive will pull you under 2000 RPM. I ended up with the same fuel economy switching from 3.08s to 3.73s, because anytime I went up a grade, the 3.08s would shift out of overdrive.

That said, I was never happy with my built 200-4rs. Super harsh shifts, which I understand are a side effect of building them to handle power. If I wanted an auto, I’d be putting a gear vendors in there, as I’ve never had issues with the TH400s. What I ended up doing was a Tremec 6-speed, which does require cutting the tunnel.

Best of luck.

66_Jetstar

My guide to a 2004r swap is simple. Skip buying the trans, burn 3-4k cash. Punch yourself in the ***** 17 times and leave your car on jackstands for a year.
The 200 is a garbage, smog era trans that requires way too much work to make barely work ok. Your way, way better off with a 4l80e.

But..

2500 rpm on the highway is nothing to worry about. Absolutely nothing. I regularly turn mine at almost 4k... for hours! Rpm is nothing to be worried about.

oldcutlass

That car will drive all day long @80mph with 3:08 gears in it.

Fun71

That is exactly what I was thinking.

Sugar Bear

Leave the TH400 in it. Service the TH400. Service the differential.

Replace the timing chain if it has been done.

Drive on...

66_Jetstar

You could swap the rear gears to a 2.73 or even higher. That would be much easier than a trans swap.

SY2455

A little late responding to this however you have the perfect gear for hwy cruising in my opinion. I had that combination when I was in the service in the 70's. Young and dumb in those ages. Routinely ran 100+ mph going from the Bay Area to Southern California 448 miles in 4hr and 20 minutes. I regretted selling that oldsmobile as it was my first one. 1965 Cutlass 2 door post with a 71- 442 455 turbo 400. The only power options it had was steering and brakes. That car was really light.

joe_padavano

RPM at highway speeds is not an issue. The engineers who designed these cars knew what they were doing. People who have only driven newer cars don't seem to understand that. Personally, 3.08s are highway gears as far as I'm concerned. With tires close to the original 26.7" outside diameter, you should only be turning 2400 RPM at 60 MPH. That's nothing. Don't fix a problem that doesn't exist.

BangScreech4-4-2

Put me firmly in the "if it ain't broke" camp, especially with that family history. I'm sure your dad would appreciate it!

droldsmorland

Why not do the GV OD? Simple, simple, simple!...use the same trans, no durability issues etc. Only real big mod is the drive shaft length. Call Dennys and have him whittle you a nice light aluminum shaft. Chances are your shaft is junk anyway. That 2 piece automatic trans shaft is notorious for out-of-phasing as it ages.

Now you can upgrade the rear gear set to a mid to high 3:1 ratio. That = launch and highway manners. Win-win-win.

BangScreech4-4-2

Yeah, for $$$ ... the cheapest basic GV unit appears to start at $2700 and that's before you account for custom driveshaft, floorpan mods and who knows what incidentals, let alone the other drivetrain mods you're suggesting. OP could be into the project for $10-12K before he's done, depending on how much (if any) of the work he can do himself.

Now add to that the fact that if you read the original post he specifically says that originality is a major priority and also clearly states that he doesn't want a GV unit and now I'm wondering if maybe you posted in the wrong thread?

bccan

Worrying about 2500 rpm at 60 mph is inventing problems. That’s not even high by many modern car standards. It’s moderate load driving below the midway point to red line. IMO cruising below 3k would be of no concern, above that it would be more of a tolerance thing.

If the issue were to be rolling 100 mph regularly, I can see reducing the rpm. That said, I love the OD driving experience. 2300 rpm at 70 mph w/ 3.90 & 26.5ish tire or 1800 rpm at 70 mph with 3.08 & 26” tire. Combined with lower first gear, the 200-4R has worked well and is completely reversible if originality were to return as a priority. I think the red car’s stock BRF with a shift kit has close to 200k miles on it. OD trans kinda lets you eat your cake and have it too. The two I have are in the 15 year age range since install and have been reliable, they do/did require some initial tweaking for speedo accuracy and governor performance, IF that’s important. Once done, they’re done, ready for a seamless life of driving, same results with others that I’ve had my hands on.

One tip on 200 or 700 - DO NOT UNDER BUILD THEM. Build them for more power and abuse than you ever intend to give them.

Then again, one can burn a whole s**t load of gas for what it now costs to update the drive line in the quest for reduced cruising rpm. I briefly looked into sending a long ago injured 200 (under built) out to get rebuilt and have as a spare. I saw today’s prices and decided it can sit as a core!

My 2 cents? Use good oil, keep up with maintenance and run what you’ve got.

…

matt69olds

I’d have to run much more gear than 3.08s before thinking about overdrive. That car would cruise all day at 80mph with ease.

Using the gear calculator, 3.08 gears with a 27 inch tire will put the engine at 2500 rpm at 65mph. Granted, that’s not including the normal slip of the torque converter at speed.

Is your speedo accurate? What are you using for a tach?

if you want to make the car more comfortable on the highway, put a taller tire on it, with some quieter mufflers.

Bubba68CS

Exaggerating doesn't help your case. There is no chance a gear vendors ends up at 10-12k. No chance at all. My Tremec 6-speed conversion from an auto was less than 7k, full in. The transmission cost more, it also required a custom shaft, but adds in substantial tunnel mods (cutting out a big chunk of the tunnel and welding in a new one), new crossmember, hydraulic clutch, bellhousing, machining the crank, VSS reverse lockout unit, pedals, custom flywheel (old pattern - not the readily available 455 pattern), plus all the tiny bits and pieces.

A gear vendors is literally the unit, a new driveshaft, maybe minor tunnel mods (hammer only - no cutting), and...that's it.

BangScreech4-4-2

I'll concur, except to point out a few things: Everything I've ever done to any of my cars cost more and took longer than expected regardless of whether I did the work myself or paid somebody else. And I'm guessing OP would be looking at paying somebody else, which raises costs exponentially.

What exactly did you get for your $7K? Did that include outside labor (or your time)? Did it include all mods and incidentals? Did you change the rear end gear as was recommended to OP?

I'm just trying stay in the spirit of the original post and the poster's inquiry instead of trying to sell him a solution he clearly doesn't want.

redoldsman

This is an interesting thread. I am wondering how many miles you drive the car in a year and how long the payback for the mods would be. Just something to think about.

Bubba68CS

It included absolutely everything needed for the install, including the machining of the crank. In fact, machining of the crank was literally the only thing not included in the kit from SST. Even things that didn't come with the kit initially, were sent after the fact free of charge - that included the spacer for the throwout bearing, a new speedometer cable, and the custom flywheel when it was realized the bolt pattern for the original they sent was for the newer Olds motors. I did my own labor, as most (but granted, not all) people with old cars do. Even so, I guarantee paying someone to bolt in a GV isn't going to cost $6000 from any reputable shop. Adding more projects doesn't count to the budget for the overdrive. That's like saying my brakes cost 40k, because I also did a complete restoration at the same time. Ridiculous.

OP would not need to change rear gears for a gear vendors. The overdrive is mild, unlike a 200-4R or 700-R4. Those likely would require a gear swap because the overdrive is so much taller. Also, OP doesn't know what they want. They literally were asking for suggestions. Yes they say they don't want a GV, but that may be based on misconceptions - like thinking it requires major tunnel surgery when it doesn't. They clearly think the 200-4R or 700-R4 are good choices, when, in my experience, they are god-awful choices that got overhyped by magazines and people who like breaking the tires loose at light throttle when the thing shifts gears. We have no idea what they were/are thinking as they haven't made a single post since starting this thread, and haven't been on the forum since the beginning of September.

maddoctor

I have 3.91 gears. That is what it came with an M21, with little 14 inch tires. If I was going 65-70 on the highway my 400 g block was screaming 3600-4000.
I put in the Richmond 5 speed od, 15 inch tires. Now in 5th I rev 2500-3000 tops doing 65-70.
As too many others have said, keep what you have, if you want to ensure reliablity of engine, trans, diff, have them serviced/rebuilt. As Joe pointed out these parts were put in by people that knew what they were doing. I know Ford guys that wished they had those parts!

BangScreech4-4-2

My bad. I didn't notice date of OP -- a bad habit of mine. Maybe he's already solved his problem without all of our input.

matt69olds

Putting a Gear Vender in a A body will require some floorboard modifications. You don’t have to cut anything, just reshape the floorboards for additional clearance.

droldsmorland

Nope correct thread.
Mr Smooth was asking for ...Thoughts? Opinions? That was clearly stated.

BangScreech4-4-2

Well, as noted above, he hasn't been back to look at any suggestions in quite awhile so it looks like it'll be kind of a moot point.

LOUCKES'6487

Properly built 200-4R , 2200-2300 stall with lockup, manifold vacuum switch for proper converter lockup cruise on highway with throttle position. Even put a button switch on the console to unlock it at will. TV cable with linkage from late model Quad.
Use 3 when you want, just grab it. 3.08 and OD will get great easy cruise 75-85mph and MPG, leave turning 2500+ at a snails pace 60mph behind.
If it wasn't the thing to do GM engineers wouldn't have put some variation of OD and tall highway gears in all last gen B Body exception maybe the SS having lower option for kicks. Remember 3.08 is a trailer tow gear vs 2.73:1 , use D3 if you feel it's too heavy.
The 200-4R does more work with less power, can you imagine a late Caprice or Roadmaster spinning 60s era RPM at highway speeds today stuck at 1:1 with a 3.08. Yes , some highways were posted higher years ago and fuel stops were frequent.
Take a late Caprice for a run, leave it in D3 and cruise 75-80mph and see how long it takes you to bump it up into OD instead of watching the gas gauge.