What are the options for getting an additional gear or two in an automatic transmission for e-body? Is surgery of the floor pan or cross member required to fit them in? My last project was a four speed, so never messed with automatic e/b body cars. Looking for possible options on a 70 Challenger.

Thanks.

I am using an A518 in my 70 Challenger.

I trimmed the case and made a rear mount of my own. A few pic are here in this thread.

https://board.moparts.org/ubbthread...4/re-four-speed-overdrive-automatic.html

I am using the whole Magnum 5.9 EFI, Trans wiring, and ECU from a 95 Ram Truck. If you want to keep your Carb there are controllers that kick the overdrive in based on vacuum and a couple other factors.

Good info here.
https://board.moparts.org/ubbthreads/ubbthreads.php/topics/140864/re-727-to-a518-swap.html

If you are gong Big block and want to use an A518 then here is some info.
https://board.moparts.org/ubbthread...8-overdrive-conversion-lots-of-pics.html

Otherwise Passon sells a 4 speed overdrive manual and there is always the gearvenders unit.

I’ve been running a 518 for 3 yrs and love it.
I built my own controller, not hrd.
PM me if interested in a simple pdf info package I put together.
Everything you need to know here:

http://www.cuda-challenger.com/cc/index.php?topic=84774.0

I have a 518 behind the Hemi in my 70 Cuda. No floor mods necessary. I didn't use a lock-up. There is a button on the console for activation and an adjustable vacuum switch for automatic OD drop out. I had A&A build a valve body for it.

Very happy with it and would do it again in a minute. My only regret is not doing it sooner.

To the Fellow who came up with the idea to notch the transmission case to make it fit: my hat is off to you. Used to be a significant butcher job before the case notch.

44rh for me: more power to the wheels.

There is also the Silver Sport 4-speed automatic... I believe its based on the GM 4L60 tranny... I've heard good things from pleased customers... I'm considering it myself.

Probably the best option if cost is not a factor, looking at $6k or more.
I’m all in at $2.5k you could go cheaper if you don’t want/need the automatic control.
Still by far the best money spent, car is so much more enjoyable to drive.
Only 2500 RPM at 80mph, 3.73 gears

Did I miss somewhere clarifying big or small block ?

If you are running a big block, I highly recommend TranzTech in Dubuque Iowa. They installed a 518 in my 65 C body and it is by far the best thing I have ever done for that car as far as drivability. I'm running 496 ci around 500 hp and so far it is doing well ! Just can't say enough about their work.

My install was a little complicated since I first had to convert the column from cable shift to linkage etc. (One year only) they worked with all that and everything works perfectly !

Running a 46rh ,, 518 in my 68 Charger, yes I know its not an E body :), 512 lowdeck, it is one of the best things I did to my junker, I had to trim the upper part of the torsion bar x member & build a custom trans x member. I converted my stock shifter to a cable. mine is also a lock up converter 4.1 gear

I believe that was 1wildRT that came up with the notching.

To me, the down side of the 518 is the crappy 2.45 first gear ratio is a carryover from the 727. The 700R4/4L60E has a 3.06 first gear but second is a tall 1.62. That is a wide spread, sort of reminds me of the 833 OD 4 speed.

I thought the Mopar OD’s had low gear sets in them compared to old 727’s. ??

Unless there's been a price increase? I've done the SST GM 4L60 for just under $5K for the Mopar BBlk set up complete kit


Mike

And yet another option is to run a 2004R from Extreme Automatics with a lock up converter. I did have to cut the center loop out of my torsion bar cross member and reinforce it. Their Stage 3 trans will hold up to 1000 hp/850 ft lbs of torque. Uses a Reid bell housing to bolt up to small block, big block and Gen 3 Hemi's.

The gear ratio's are perfect with a 2.76 first and a .66 overdrive. With the lock-up on a 3800 rpm stall converter, its like having a 5th gear. Best functioning transmission I've ever driven. One wire for lock-up.

I painted mine black, and have never been asked if its a GM trans, Shhh.

2.45,1.45,1.0, .69 even with a 3.54 gear my car pulled great, 1.55 60ft, VERY mild 512. 4100lb pig

Agree.

Taking off in first or the first to second gap is not an issue unless you have a real dog like a slant six.

A 545rfe with a 5.7 is a party in first and second. Once that thing hits third, the party is over: 1.5, 1.6ish ratio 2nd gear to 1:1 third is a big jump.

Over $6 grand for it AND GM base tranny????? I can afford it but looking at it, is it feasible? If I pull the trigger for OD, I can't see having a GM anything on my car it has to be Ma Mopar. IMHO

My street car would Grenade a 4l60

$6k can buy me A LOT of gas..It would take me YEARS to recoup the investment . even at 5 or 6 miles per

Bearing in mind I plan to drive the snot out of the car locally. BUT,,,,,,,and/if I should decide to make a longer distance trip. I'll rent a truck and trailer for a few days

I never thought about costs versus return on fuel. Car will have a decent build 440. I haven't finalized the build options as I tend to always want to go overboard. But stock stroke and 0.30 over pistons. I have a completely done set of 452 iron heads with minor smoothing, no porting. And a set of used Edelbrock heads. Not sure which way to go there. Drivetrain is not numbers matching and I started to think about making it more modern with fuel injection, more gears in the transmission, and other changes. The idea is to do that versus buying a modern muscle car. I'd love a manual, but was leaning towards keeping it an auto.

Thanks for all the suggestions. Certainly some options to think about.

IF the budget matters, the 518 goes in for 1/2 the price of the GM based ODs. And you do not have to mod the tunnel. With the torque that our big blocks make, the difference in 1st ratios is a non issue.

What is there to think about?

The car below had a Gear Vendors attached to the 727. The OD wasn't all that great at .78. I JUST bought a Tremec 5 speed kit from Silver Sport....

Like I said, I'd rather keep it all Ma Mopar and the other thing to consider is that I'm hoping I don't have to mod the tunnel was the other thing. The tranny will be behind a 400 stroked to 470. Have you done this DaveRS?

Yes, I have. I posted a few details in an earlier post in this thread.

You’re absolutely right, even the 518 doesn’t make financial sense for most.
I struggled with making the swap, because I’m cheap and always feel compelled to do a cost benefit analysis.
The 1 thing you can’t put a price on is enjoyment. I found myself not driving the car as much because it was so annoying running along at 4k RPM in the slow lane getting passed by minivans while my teeth rattled.
My only regret is not doing it sooner.
If you’re only doing city driving and stoplight to stoplight runs, save your money.

BDW nailed it.

I will also add your money invested into an engine build will last much longer. Overdrive is directly responsible for today's engines lasting 200,000 miles.

The days of a833's, 727's and 4.10 dump truck gears are over.

I finally pulled the trigger on a 518 for my 71 Barracuda when one popped up at a local you-pull-it. $250 and a fun afternoon later we had it out and loaded. I was on the fence for quite awhile, looking at all the different 4LXXe bell housing swap options. I wanted electronic control, but the fairly direct shifter hookup to my slapstick is a great trade-off. I plan to use 4.56s, which will give plenty of starting line ratio while still manageable with the OD for the highway. 3.06 for the 4L60 was actually a concern for me, that's quite a steep hit and I'm not planning to run Stock Eliminator.

However, am I wrong in thinking the low gear 727 gear sets would work in the 518s?

Curious what the angle of the engine/trans is without modifying the tunnel. The 518 is even larger than most transmissions at the rear, and with it pointed down enough to clear the torsion bar crossmenber and floor, it must angle down at quite a large angle.

Don't forget about the lil 42RH. Smaller body for a better fit and has the 2.74 first gear. You will definitely need to beef up the internals, but if you are doing a rebuild anyway, won't be that much more.

My 518 went in my Challenger and matched the 727 angle without mods to tunnel.
I shimmed it to 2 degrees downward.

How can you shim it down? That is not possible. A shim would raise the tail end.

Wow, surprisingly good angle for no cutting of the tunnel metal.

FYI, I did the A518 swap on my 73 Cuda 3 years ago. I was able to get a transmission tailshaft angle of 3.2 degrees down (below horizontal) without cutting the torsion bar crossmember. Any angle less than that will require notching the crossmember. So check for interference carefully before you install your transmission.

This is the point i was trying to make
My car is not a long distance driver. More or a local cruise in and around town. Playtoy type of car.

I might take it to Phoenix once or twice a year.....maybe.
But.....if i do. Ill live with it at 65mph. .
Or ......I'll take back roads and see the country.
Anything farther than that. Ill rent a truck and trailer and haul it .

Unless you have 2.73s in your car, spend a weekend with an OD unit in your car and you will see what you have been missing. It makes it a different car. A better car and by every measure. Other than effort and money, there is absolutely no down side.

Yep....it was Randy. Hate that he ain't here anymore!

It may seem like crap on an rpm formula but that 2.45 is what we consider close ratio. This is ideal for powerful engines. You put the deep ratio in the rear and now you have less rpm drop between gears.
The 3 something ratios you speak of are from an era of gutless engines. The 4L60E and 833 OD are for moving heavy vehicles with weak engines off the light and with no consideration for big rpm drop between gears.

I hear what you are saying but until you have tried both, don't be shy of a tall 1st.



On an unrelated note. This is 518 vs NV3500. They soak up alot of power. I did a 518 swap in a truck. While climbing a bridge near me. I had to turn off the overdrive and unlock the converter to climb this bridge in 4rth. When I swapped to the 5 spd manual. At the same rpm I could easily climb the bridge in 5th gear. The same truck had a 3 mph increase in trap speed and 2 mpg improvement.
I am not saying a Silversport 4L60E would be any better than a 518 but after seeing the numbers for me, I'm not a fan of 518. The rpm change seems to be the only thing talked about but poor mileage in Ram1500's make me thing they are not the way to go.

has anyone used a 518 with a manual valve body ? if so, was it a forward or reverse pattern ?
did you buy the valve body or change it over with a kit ?
as always, TIA.

I have a forward manual valve body in my 518. The Hemi wants shifted at 6,800. To get the most out of it, manual shifting was the only real answer. Besides, I didn't want a strong hit going into 2nd and didn't want reverse to bang in with the 850 RPM idle.

I called A & A and they got it right the first time. It works good with the Slap Stick.

how is overdrive engaged? with the manual valve body or through an electrical switch?

The valve body won't allow overdrive except through high gear so no OD in 1st or 2nd. There are only 2 or 3 pins on the VB connector and diagrams are posted in several places. One pin is power in which is hot with the key on. Then OD is activated by grounding the other pin on the OD only 2 pin trannies. On 3 pin trannies that have OD and lock-up, then the lock-up is activated by grounding it's pin. There are a lot of ways to do the grounds. Most are really simple.

I have a 2 pin connector which is a non lock up converter version. The 518s with lock up converters are more plentiful because they made them longer. I went with the non lock up version only because the converter companies said that I had more and better choices with the non lock up converters. Besides, a few percentage points of efficiency wasn't important to me.

I actuate OD with an on/off button on my console. I also wired in an adjustable vacuum switch on the engine, so that when I crowd it and the vacuum drops, it drops out of OD and then back in when I let off. Much like passing gear. All of it is simple, cheap, and effective. And fun.

I don't do a lot of hiway running. But it is an exciting new dimension to my Cuda to pull onto the Interstate and cruise with anything out there even with 3.91 gears. I actually use the OD most of the time on 2 lane roads. In the 50 to 60 MPH range. The car is much quieter, you can hear the radio, talk without yelling, the wife is more comfortable, and the engine just sounds more relaxed. And if I feel rowdy, I drop out of OD and crack open the cut-outs. The best of both worlds.

I wished that I had installed the 518 years before I did.

Here’s what I did



Completely automatic, wanted my daughter to be able to drive it.

The control module automatically turns on/off the overdrive and lock-up for the transmission.

The 518 (46RH) is hydraulically controlled and uses 2 servos to enable the OD and LU.
The 3-pin connector on the transmission supplies the control voltages.
The center pin always has 12V power connected. The 2 outer pins are switched grounds. The front pin is the OD ground, the rear pin is the LU ground.

The module works according to the following sequence.
1) The 12V toggle switch supplies voltage to the relays and transmission center pin.
2) When the hydraulic pressure trips (50mph/adjustable) the pressure switch, ground is supplied to the vacuum switch. When speed is below 50mph, hydraulic switch opens, disabling OD.
3) When there is enough vacuum, the vacuum switch closes, providing the OD relay ground. Under heavy acceleration, vacuum drops, opens switch, OD is disabled.
4) When OD relay has ground and 12V, it waits 10sec, then supplies 12V to the LU relay and ground to the transmission OD pin, enabling OD.
5) Now the LU relay has 12V, it's already grounded. It waits the 10 sec programmable delay then provides ground to the transmission LU pin. So lock up doesn't occur until OD has been enabled and on for 10sec.
6) The programmable delays for both relays fix the situation when speed is fluctuating around 50mph. This would normally cause the OD to kick on/off, the 10 sec (programmable) delay stops this from happening.