Hello,
Is there a modern OD auto trans that will fit a '70 A-body without cutting the transmission tunnel?
Thanks.

 

Define "modern". Also, automatic or manual? The 200-4R is the easiest OD automatic swap, but it went out of production 30 years ago, so I don't know if that meets your definition of "modern". Yes, it requires internal mods to live behind a real motor.

 

I was thinking something lalong the lines of a 6L90, something that will not need to be beefed up.
Thanks.

 

Your first post specified "without cutting the transmission tunnel."
Have you even looked at the size of one of those? Even a 4L80E requires some tunnel massaging. You're talking a trans from a one ton truck. It also weighs nearly 100 lbs more than a TH400.

And note that the problem isn't length (which is somewhat longer), it's width and height. Those extra gearsets and clutch packs need to go somewhere. And do you really need a 4.02:1 first gear with two overdrive gears? That's for pulling a five ton trailer.

 

Some photos to consider




4L60E on the left, 6L80E on the right.




6L80E in a Camaro tunnel.

 

Thanks Joe. I thought more modern transmissions were more compact.

 

As engines have gotten more compact and lighter in cars, transmissions have gotten larger and heavier with more gears.

 

You ain't kidding, and they're not fun to drive, either.

 

As Koda knows, the six, eight, ten speed automatics were not created to increase performance or to make driving fun. They are designed to approximate a CVT, so the engine stays in it's most efficient power band and maximizes mileage on the CAFE drive cycle. I had a 2019 Camaro SS rental car in L.A. a while back, and while it performed very well, using the paddle shifters with the ten speed AT was an awful driving experience. The gear ratios are so close that you are constantly watching the tach and shifting - that's all you do. First gear winds out by the time you get across the crosswalk, and second hits redline about the time you get across the intersection. There isn't an option to start out in a higher gear, so you're stuck rowing the paddle shifters. After about ten minutes of that, I gave up and left it in DRIVE. What a disappointment. As I noted above, the 6L80E and 6L90E are truck transmissions, thus the granny first gear. Frankly, you'd be better off with a 4L80E, which is a TH400 with an extra 0.75 OD built in. Plenty strong, many of the internal parts are common with the TH400, and it fits in an A-body tunnel with only minor massaging. Of course, it only comes in a Chevy pattern case, so you need the adapter plate.

 

idk my daily is a 10 speed w 375 hp and 470trq. I enjoy driving it especially accelerating on highway on ramps, it gets up to speed faster than most and makes passing a non event in most instances.

re paddle shifters cmon joe if you want a manual trans get the manual, my wifes car has paddles....ive never moved it to the M position.

 

I think they're LESS fun. One of my other old ones is a 73 Ford Club Wagon, 302, 3 speed column standard trans, 4.11 rear, manual everything. Took it for a drive yesterday, turned around to head home. Got out of first gear in the intersection, out of second by 20 mph, put the hammer down and went 20-60 in drive, and that old thing, with the steering, suspension, brakes, and rear is all in by 65. It's not a 455 or anything, but it will move that old van better than one would assume. Point being, it's nice to go 40mph delta V in one gear.

 

A couple years ago my wife leased a Chrysler 200 with the 9 speed trans. I hated driving it when she first got it! Maybe because I’m a transmission guy I’m more in tune with transmission function. I hated the fact that it shifted 3 times before crossing a. Intersection. It wouldn’t go into 9 gear until 65ish mph. It did get excellent mileage, and was reasonably peppy for the tiny engine.

After driving it a few months, I learned to just “dislike” the transmission. I suppose I should get use to it, the new transmissions are here to stay.

 

That wasn't an option on the rental.

 

I attended a BMW performance driving school a few years ago and the instructors said the new automatic transmissions have such good programming that their instructors / professional drivers don't even bother with trying to use the paddle shifters. I found that they were correct about that, but I don't know if other cars have similar multi-levels of shift programming to choose from (Sport, Sport+, Advanced, etc).

 

I would concur with that. I also had a 3-series rental car, and the trans programming was impressive. It was always in the gear I would have chosen myself. The rest of the car was just awful, however. Talk about THE worst human factors design of the controls. I got in the car for the first time in the dark after flying to LAX. I couldn't locate most of the controls, and naturally there is no owner's manual. What a cluster.

 

Yeah, the Owners Manual is a digital version and you have to know how to operate the infotainment system in order to access it. Catch-22.

 

The 6/8/10 speeds might have come to be because of c.a.f.e., but They have also made today's cars much faster.
I drove a turbo 4 banger Mustang, it is was quick. The auto trans shifted fast, and was a blast to drive. Turn in was much better than the v8 in the nose also. I call that a win. Haven't driven the turbo Camaro, as no one seems to have them.

 

Transmissions with wider gear ratios like these have definitely been a big part of the improved performance of cars with smaller engines like these. Whether or not you really need them on a car with a big block is questionable. For those of us who enjoy rowing the gears, they definitely suck all the fun out of driving.

 

Cars aren’t designed today to be fun. To 95% of the buying public cars are just transportation. I’m guessing that’s the biggest reason most new cars today share the same basic dull characteristics.

 

As evidenced by the public desire for self-driving cars... So much easier to text while driving that way.

 

Plus a self driving car will be much safer than half the idiots on the road!

 

Right, because that worked out so well for Boeing...

Look, one of the aspects of my day job is looking at failure modes and testing of safety critical software in aerospace applications. Suffice to say that the aerospace world conducts MUCH more rigorous testing and configuration control of software. We absolutely do not do "over the air" upgrades. We verify every single new load on flight hardware. Despite that, mistakes are still made. I have zero confidence in the self-driving auto crowd, especially the ones who are not mainstream automakers.

 

Yes with a big c.i.d. engine Automatics with 10 gears seems silly, The paddles even more so, as the computer is faster than you.
BUT, many of today's factory hot rods are daily drivers, and sorry as much as I like to row my own, it day to day traffic driving to work, they are a p.i.t.a. This depends on where you live and such, but 60-90 minute crawls with a clutch in bumper to bumper traffic, Did that for 3 years. All set with that.
I thought about dropping a manual in one of my fun vehicles, but the cost is nuts.

 

When the average commute is more than 45 minutes each way. For many it is over an hour+ each way. Comfort trumps, fun.
The designs well, there is regulations for everything now, they don't have freedom to design character into them as much as they did decades ago.
I hate that most newish cars the side doors are so high you can't put your arm on the top, Safety you know.
Even in the muscle car years, most of the buying public bought vehicles to get to point a to b. nothing more. The "hot" cars was a tiny % of the model line sales. Just because every 2 barrel v8 64-72 car now has a built v8, they didn't leave the factory that way.

 

Like Joe said earlier, modern engines are designed to spend as much time around, say, 2k rpm, as possible. Government, which ruins everything, makes no exception on car performance, and there is a spot that gets good efficiency and good emissions and they want you there in the rpm band as much as possible. Also, horsepower is a function of rpm. RPM is variable, so you can have a little engine that you can wind up tighter than Dick's hatband and get good HP out of, while keeping it little and economical. But torque is related to displacement, and that, other than the "2 4 6 8 Now The Block Disintegrates!!" GM cylinders on demand, is less adjustable. So, engines are smaller to get better emissions and economy from less combustion and less weight, and they sacrifice torque, which is the true measure of an engine, to do it, by making a workaround with umpteen million gears and it downshifts 3 times to get power.

I drove a turbo 6 F150 with ten gears a couple years ago. It was...ok. I think low end truck torque is a thing of the past. Gas was cheap back then, and transmissions were not so evolved, so a simple trans and a big torque band was the solution. This is why we can put a more modern trans behind a big engine and have a monster.

 

I think we are spoiled .
It was not all that long ago, that light duty trucks had 180 hp. and 3 speed transmissions. A co-worker has a f150 with the bigger of the two turbo v6 I want to say 3.7ltr. not the 2.7ltr.
It goes and pulls a load just fine. has more low-mid range torque than the 5.0 v8.
We are lucky, our government doesn't do what a bunch of other countries do, tax by engine size/power and jack the fuel cost to help force you into a smaller engine/vehicle.
I am not sold on turbo's yet, I remember the first round of trying to put them in mainstream use. Time will tell if the under hood heat problems of before have been addressed to not cook everything under the hood. In vehicles with cramped engine bays.

 

The gov't doesn't give a rip about what RPM your engine is at. All they care about is the car's performance on the CAFE cycle. Physics says that it is relatively easy to optimize economy of an internal combustion engine over a very narrow RPM band (as opposed to using variable geometry intake and exhaust tuning), so the automakers have chosen that design solution. There are other design solutions that work, but they cost more money, and profits trump everything else.

 

Yes, that's what I meant more concisely. Thanks.

 

Vehicle cost is a factor, you have to have customers that can afford what you sell, it is bad enough that the vehicle market is on borrowed time. Only thing keeping it from sinking is very low % rates and leases. It can't last. And when it sinks, it is going to drop like lead.

 

Turbos are a proven design. There is no problem with the OEM designing components to deal with the underhood heat.

My biggest question with these self driving cars is where does liability really end? Once self driving cars become common, sooner or later there will be a software glitch or some other problem that causes injury or a death. And in this “sue happy” environment we live in, the vultures (sorry, lawyers) will be circling just waiting for the opportunity. Do you sue the car owner? Car manufacturer? The company that developed the software? Where does the liability and responsibility really reside???

 

You sue all of the above and your brother.

 

I agree. I've had a turbo 5 cylinder transverse engine vehicle in the stable for 16 years now with no issues related to heat, even in the Phoenix 115+ summers (well, other than losing 100 or more horsepower in that summer heat - hopefully the new front mount intercooler will help with that).

 

Turbo's are proven. the cooking of wiring and sensors is also.

 

To quote the late great entertainer Al Jolson, "Ladies and Gentlemen, you ain't seen nothing yet!"

 

Once again, the OEM spend far more time and money testing and evaluating the methods used to build the cars than most people imagine. It’s far cheaper to revise a design before production than to deal with the consequences in the field. Sure, occasionally a bad design does make it into production, but it’s rare. If sensors and wiring can’t take the heat of the underhood environment, it’s not going to be mass produced.

 

As long as it makes it past the warranty period. yes yes it will. And it isn't rare by any means.

 

While it’s been 25 years since I turned wrenches for a living (a Buick and Cadillac dealership) today I’m sure I’m hopelessly out of date. The motto then was “if it was round, black, and said A/C Delco, replace it!” That was referring to the mass airflow sensors used then.

Having said that, what modern sensor/harness is a well known almost immediate suspect in today’s cars? The last few trips to the dealer for any repair to my wife’s cars (2016 Chrysler 200, 2019 jeep Cherokee) have been solved with software updates.

 

Oddly my wifes car too. The trans started downshifting abruptly w a clunk while coming to a stop. A SW update ‘fixed’ it.

what i did not understand was why it happened after 4 years and 50k miles? Was the original SW programmed that way?

 

This is how legal precedent will be set: suing everybody and letting the courts sort it out. As cases are decided, patterns will emerge and criteria and variables will be set to determine who's on the hook. Of course, the civil court system doesn't really subscribe to the notion of who's right and who's wrong; it's more about who has the greater resources to fight, so in the end the little guy almost always loses.

 

It got you and the unit into the dealership. right about the time to sell a transmission fluid flush.
belts/hoses/ maybe a cabin filter, air filter, etc etc.