Thinking about converting from 4speed to 904 or slant six 727.

Has anybody ever gone from a 4 speed to an automatic? Did you regret it? What did you do with the hole in the floor and clutch pedal?

Clutch pedal goes under the carpet, the car was a 69 Dart GT with a console and I believe the shifter was mounted there. The car was bracket raced for years with the four speed and then the auto but the plan was to reinstall the four speed after the drag strip action was done.

Car ran about the same number with the auto just more consistently. The 340 was ran for 49 years on one ring and valve job before new pistons and heads.

If you have a big slanty, it will do well with an A998 close-ratio LU and decent rear gears. The ratios are the same as the Regular A904, but it should have a decent stall, around 2400.
Because of those features; compared to the A833od box; the auto acts like it has 4.5 gears
Lets say you currently have 3.73s.
Your roadgears are 11.52-6.23-3.73-2.72 in the which, the cruiser gear is 65=2200
Take off ratio is 11.52, and 35mph is about 2700; all pretty good numbers.

Now, let's say you really like that 6.23 Second gear.
The convertor, is a TORQUE convertor, that inside it, has the potential to nearly double your engine torque at Zero mph. Let's assign a value of 1.8
So the rest of the roadgears then are;
16.45 at zero mph, dropping to ~12.8 at shift rpm.
Coming into Second, you might see a ratio of 7.00, and into direct @ 4.47, and into LU at 3.73
Ok so lets line these up; These are all at WOT.
16.45>12.80-7.00-4.47-3.73. I count 4.5 gears; compared to
---------11.52-6.23-3.73-2.72
You see what I see?
Well firstly it's gonna cruise at 65=3020 in LU, and secondly
Second gear is ~7.00, compared to 6.23 with the od box, so we could give up 12% without noticing a thing., and
Lets say the average thru first gear is 14.62, compared to 11.52 with the odbox, so we could give up 27% of that gear and take off would feel the same.
Now getting down to 2.72 from 3.73 is not so easy, as that is a difference of 22%. You could give it up in First, but Second will definitely hurt.

Ok then, Say we give up the just 12% of the 7.00 second gear and see how that looks. This will take a rear gear of about 3.33, and lets round down to the available 3.23s.
The OD numbers are still;
----------11.52-6.23-3.73-2.72 . compared to the A998LU, at ;
14.24>11.08-6.09-3.88-3.23, and 65=2615 in LU. IMO, this is an acceptable trade, for the slanty; and the bonus is that you have two passing gears, maybe three.
So say you want to pass a guy going 55mph. and you're gonna floor it;
If the trans only comes out of LU, the Rs will rise to 55= 2430@10% convertor slip/ 2650 at 20%.
If it goes to Second NOT-LU, the rpms will rise to 3850@20% slip but, if you are able to keep the LU engaged
then, 55=~3210

All-in all, there are plusses and minuses.

If you do not currently have at least 3.73s with the A833od, my question is why not? , lol.
Happy HotRodding

You can always mount an aftermarket shifter on the hump

Leave the pedal and say it has a clutch flite

So the a998 bell will bolt to a slant?
Or the 998 was behind a later year slant?

Yes. A998/A999s come in both slanty and SBM flavors.
IDK what year they came out, probably late 70s/early 80s.


I had an A998 slanty, which had the alternate gear ratios like as come in the A999,
but mine did not have the LU. I swapped the gears into an A904 V8bell, for my 318. The 318 loved it, even tho the ratios were a lil further apart, cuz the 318 has enough torque to pull them with a low-number rear gear. Well to be fair, I installed a 2800 convertor at the same time, Yeehaw!
For you, in the quest for fuel economy, I recommend the A998LU, which usually have ratios of, 2.45-1.45-1.00, splits of .592-.690; but may have the alternate ratios
of, 2.74-1.54-1.00, splits of .562-.649
You can see that, comparatively speaking the 2.45 gearset is slightly tighter, especially on the 2>3 shift. Honestly, the difference, in a low-rpm, lo-po engine is hardly worth searching for. At 3600rpm the 2>3 shift difference is just 148rpm.
So just grab a LU whatever it might be.
If you have a choice, well, I'd pick the standard ratio.
As far as auto-transmissions go, the Torqueflite series are simple and cheap to rebuild. After just a bit of experience, almost anybody can slam the main-box together ..... blindfolded. but save your eyes for the VB, as certain of them have interesting spring and ball variations.

I rebuilt my first 727 in 1985. I did a reverse valve body mod, that 383 would smoke some rubber and it was a pretty quick car. That lasted a year and it locked up on me cruising at 40 mph. I thought the 4:10 diff locked up until I looked under the car and saw bellhousing pieces on the ground. And a big splotch of fluid. I did another after that but sold the car a few years after. And pretty much gave up owning a muscle car. 28 years later I picked up a 66 dart with a slant and 833od.

It's a fun car, but I'm older and really have been thinking about getting into automatics again. I dont want to get rid of the car, just considering going automatic.
Thanks for your knowledge.

I luv the story.
If you're getting to the age where leg power is getting to be a thing; I just want to offer this. That od trans works best with whatever gear gets you to cruising at ~2400 rpm. That means your rear gear will be somewhere around 3.73 depending on your tire size. This will put second gear into an rpm that around town, you almost never have to shift until the Rs fall below ~20 mph.
And your clutch pressure plate preload is adjustable;
And your pedal-ratio can also be modified.
The point is that you are only as married to getting rid of the manual trans, as you allow yourself to be, which may or may not have anything to do with your current or future physical limitations.
Jus saying, lol.
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Having said that;
Personally, I like the combination of a 2800 stall and hiway-type gears.
About 24 years ago, I had a winter motor for my DD Barracuda. Every fall, I would swap from an HO 367 to a POS low-compression 318. This swap was always accompanied by a rear gear swap, and usually from a manual to an automatic, but not every time.
One winter, I ran that A998 with the 2.74 low, the 2800, and 2.76 gears.
For me, that was a fun winter.
That 318 wore a Thermoquad and I installed the TTIs back on the 318 that had come off the 367.
With that combo, I could floor it off the line, get it up into Second asap, (manual shift VB) and wait, no tirespin. The engine would spool up to stall, and just hang there, slowly climbing to 3200@ 65mph, still in Second, the TQ roaring the whole 17 or whatever, seconds. Then into Drive for 65=2230@ a calculated zero-slip, which was actually ~2300/2400 on the tach, so about 3% slip. I loved that roaring poser, pos, lazy-azz lo-compression 318 winter motor..
That car, with the lowered front end, in winter, spent a lot of time being stuck, which I knew would happen cuz of the way I used to drive lol. But with the automatic, the 2800, a posi in the back, and studded tires all round; I was never stuck for long.

That same 2800 used to be in my slanty car, the one that I had when I got married. In fact that 2800 has been in just about every Mopar/automatic car that I have ever owned.
>> IDK if you've ever had one, but if you haven't, lemmee take a second to tell you how mine works;
Off the line, when I floor it, the engine begins to rev up, on the way to the stall. As it goes, it sorta feels like the car is stuck, and somebody has one of those flat snatch ropes laying on the ground between me and his high-powered diesel. When He accelerates away from me, the rope stretches to it's limit, then, the momentum of his truck, snatches my car out of whatever it was stuck in and, Shazzam! the car is catapulted towards the truck ahead of me and we both better be alert. NEVER buy a short snatch-rope, lol.
That's what starting off feels like.
>Now, say I am in Second gear, with a manual-shift VB, just tooling along, at say 1200rpm and I get the urge to accelerate; but I leave it in drive. BAM! the engine revs up, and the tug is imminent. This never gets old........ for me
>Now say I am stuck behind somebody that I want to pass, but I'm not in a hurry about it. So then, I leave it in gear at 55=1900 rpm. The convertor spools up, hits hydraulic lock-up at or near 2800, and watch out, here comes the Tug !
I loved that TC so much, that I took it out of every Mopar I ever installed it into, before parting the rest of it out.
I'm gonna guess I bought it in 77/78, and I still have it ! .......
just not in a vehicle that I still want to drive ........... but I could. I mean if a sweet power-bulge hood, F-body showed up in my driveway.........