Exploring Overdrive options...

[Malicious]

Starting to explore some options for overdrive's and was looking for some input. This would be for a 68 dodge coronet with a 440 and 8 3/4". I have an lsd 4.56 and an open 2.76.

Australia is a bit out of the loop so most of the options are going to cost the same from what I figure loosely and most of the parts will come from the states.

Gear Vendors:
Obvious, keep the 727, minor tunnel 'dints', new/modded tail shaft, '6' speed, small over drive (means I need to build a 3.55-3.76 diff to get the rpm-speed I'm after - 2200-2300 60mph max) probably not the same accel as the 4.56 518. All brought in from USA.

518od
Rare here (not sure I can actually get one), good over drive, 4 speed only, would need to be 'built' for performance (extra cost), could put my 4.56 lsd back in and get acceleration and highway, new tailshaft? Need bell adaptor, clearance?

4L80-e
Gm (prefer mopar ;)), locally available, can get the rest of the pieces for the TCI kit from Jegs, new tail shaft, expected tunnel work, new shifter, computer controlled, needs to be 'built'. probably the more expensive option by maybe a G or two.

6L80-e
Wild card option, not sure if you could do with all the same convertion bits as the 4L but use the 6L instead? Available locally, 6 gears, tougher that the 4L maybe run as is?

Not looking at manuals at the moment but if I was then an LS1 t56 would be what's available locally. Seems like a lot of work from the build thread on here and I'm leaning toward an auto for cruising.

I'd appreciate an input you might have.

Cheers!

 

[furyus]

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[Kern Dog]

The 518/618 transmissions have a .70 OD ratio. Not bad but there are floorpan modifications that will be needed. I considered it but decided against it.

The Gear Vendors unit is the least intrusive. Yes, a couple of small dents are needed to clear the case but everything else is easy. Forget the "Gear Splitting" thing they keep bragging about. When you are accelerating fast, there is no time to engage and disengage this OD, IT does not operate that fast. If you have a heavy truck with a narrow RPM range that the engine makes power, the gear splitting might make sense. In reality, you should just look at it like what it really is: An add-on 4th gear. Not a bad one but I would have liked to see a bit more than .78, maybe closer to .70 like the 518.

The GM based 4L60E that is offered in the Silver Sport Transmissions kit is basically an electronic version of the 700R4. 3.06 first gear with a .70OD. No floor cutting but holy crap....Be ready to open the wallet!

 

[RamRunner]

I am currently running the 46RE with lock up. I thought many times about the gear vendors (even loaded it in the shopping cart a few times, but did not pull the trigger), but I do not regret using the Ram transmission. I have 3:73 gears and rev about 2000 RPM at 70. You would need the 1995 and under as it is hydraulically shifted, PACT sells the kit to operate the o.d.

 

[Malicious]

The 518/618 transmissions have a .70 OD ratio. Not bad but there are floorpan modifications that will be needed. I considered it but decided against it.

The Gear Vendors unit is the least intrusive. Yes, a couple of small dents are needed to clear the case but everything else is easy. Forget the "Gear Splitting" thing they keep bragging about. When you are accelerating fast, there is no time to engage and disengage this OD, IT does not operate that fast. If you have a heavy truck with a narrow RPM range that the engine makes power, the gear splitting might make sense. In reality, you should just look at it like what it really is: An add-on 4th gear. Not a bad one but I would have liked to see a bit more than .78, maybe closer to .70 like the 518.

The GM based 4L60E that is offered in the Silver Sport Transmissions kit is basically an electronic version of the 700R4. 3.06 first gear with a .70OD. No floor cutting but holy crap....Be ready to open the wallet!

Pretty much what I was thinking. I like the 518-618 but availability and the performance build worry me. I can live with the floor pan mods if needed, but ideally I don't have to cut the car.

100% on the gear vendors, I wouldn't even consider another option IF it was a higher OD. As it is, its probably still the front runner but I'd like more lower end gearing.

So TCI offer a 4l80e kit and you can get the pieces separately through JEGS, so I can get the trans here and get the supporting bits in as needed. Quicktime has a bell as well, they do have the 60 and 80 listed as separate Bell's. The TCI controller lists that it can control the 6L80E as well, which is where the mind started ticking over. A true 6 speed auto would be perfect. Just not sure about fitting the 6L to a 4L Bell housing...

Anyway, yes the 4/6L80E will be more expensive, but I'm thinking by maybe 1-2000 at most. I need to run the numbers properly, so that might end up higher, but being able to get the heaviest part locally, and the 6L80E should be able to handle my torque as is, might even things out a little.

 

[Malicious]

I am currently running the 46RE with lock up. I thought many times about the gear vendors (even loaded it in the shopping cart a few times, but did not pull the trigger), but I do not regret using the Ram transmission. I have 3:73 gears and rev about 2000 RPM at 70. You would need the 1995 and under as it is hydraulically shifted, PACT sells the kit to operate the o.d.

Excuse the ignorance but whats PACT? No help on google! How are you running the electronic shifting trans? or do you mean the 46RH? What is the 518/46RH rated to torque wise? I notice the 618/47RH is rated to about 610nm of torque, which would do me, at least for the time being.

Out of the 4-speed options, this is the most ideal from a rpm v speed and acceleration point of view... just finding one might be hard. Then everything else that comes with it I guess.

 

[RamRunner]

I hear the 6L80e's are not as reliable as the 4L80E's. I have a few LS pals that dislike them, saying electrical problems. Have you shop used Gear Vendors?

 

[RamRunner]

Sorry, spelled it wrong PATC Performance Transmissions, Torque Converters & Parts, you can also shop COMPUSHIFT Mini for Chrysler A518/46RH and Chrysler A618/47RH . The A518 is pretty strong, basically a 727 with overdrive. Keep in mind it was meant to be used in a truck pulling loads on a heavier frame, I don't know the exact power limits.

 

[Malicious]

I hear the 6L80e's are not as reliable as the 4L80E's. I have a few LS pals that dislike them, saying electrical problems. Have you shop used Gear Vendors?

No I haven't shopped used units. To be honest, its often cheaper (significantly) to ship from a company like summit or Jegs than it is to get something shipped over by the 'average joe'. I have no idea why, but even Ebay the shipping prices are excruciating, where the big two are sometimes reasonable.

I might call around a few Jeep wreckers and see what transmissions they might have in. If they can get them then I can at least get a better idea of the viability of that route.

Still tossing up the manual direction too. Really like the double overdrive on the t56... but I want the wife to be able to drive it as well; she drives manual daily as well, but LHD and manual might be too far. Plus cruising through traffic is nice in the auto. Gives me brain power to concentrate on the handing and gauge vitals!

 

[Malicious]

This JEG's page lists the separate parts so you can purchase them individually:
http://www.jegs.com/i/TCI/890/271701P27/10002/-1

Just wondering if that could used a 6L80-E instead. they claim its a 6 speed in a 4L80E? So either thats 6L guts in a 4L or??

 

[cdr]

The 518/618 transmissions have a .70 OD ratio. Not bad but there are floorpan modifications that will be needed. I considered it but decided against it.

The Gear Vendors unit is the least intrusive. Yes, a couple of small dents are needed to clear the case but everything else is easy. Forget the "Gear Splitting" thing they keep bragging about. When you are accelerating fast, there is no time to engage and disengage this OD, IT does not operate that fast. If you have a heavy truck with a narrow RPM range that the engine makes power, the gear splitting might make sense. In reality, you should just look at it like what it really is: An add-on 4th gear. Not a bad one but I would have liked to see a bit more than .78, maybe closer to .70 like the 518.

The GM based 4L60E that is offered in the Silver Sport Transmissions kit is basically an electronic version of the 700R4. 3.06 first gear with a .70OD. No floor cutting but holy crap....Be ready to open the wallet!

A518,618.46rh.47 are .69 overdrive.

 

[Kern Dog]

Oh, thank you. I knew that I was close but thanks again.
I try to be as accurate as I can be.

 

[Dennis H]

Might as well...if you look at a Tremec TKO 5, don't get an early version. High rpm 2-3 shift issues, and mine leaks a lot. Keisler. Highway cruise is fine at 2150@70. 3:54 Dana.

 

[RamRunner]

This JEG's page lists the separate parts so you can purchase them individually:
http://www.jegs.com/i/TCI/890/271701P27/10002/-1

Just wondering if that could used a 6L80-E instead. they claim its a 6 speed in a 4L80E? So either thats 6L guts in a 4L or??

Looks like they got the Transmission wrong, if you click on the part number for the transmission, it states it's a 6 speed. Man that is a big price tag, for less than half you could be in a Gear Vendors.

 

[RamRunner]

Before you really talk floor mods, how solid are floors in your 69. I choose the 46 for a couple of reasons, one of which my floors needed some work anyway, two is I am running a 5.9 magnum with all the wire harness, and last because it has great gearing. basically a 727 with overdrive.

 

[Malicious]

Yeah the TCI kit comes with a massive price tag. Which is why I was looking at just the add on bits (controller, bell, etc) then sourcing a trans locally. I could easily get a 4L80 or 6L80 for maybe a 1/3 of that price, even with a performance rebuild it might be around half the price of the TCI trans.

As far as my floors go, they are really good. Only just finish 'restoring' the car, just had almost a year of driving it and found that the gearing is a major draw back for me. I've either got a bullet with no highway speed or a slug with great highway manors.

So I would rather not cut the floor. Did your 518/618 require much modification to the floors?

I need to talk the manual option over with the missus a bit more. She was pretty hesitate last night to be honest.

 

[747mopar]

I took this today on the freeway, Viper 6 speed.

 

[RamRunner]

The floor only require a few small dents near the tailshaft area, but the cross member is a different story.

 

[Malicious]

I took this today on the freeway, Viper 6 speed.View attachment 406826

Yeah that is real tempting... I was using your thread as a point of information for the T56. Its a great read. Just need to work out if its right. I have a manual pedal box, I just don't have the clutch pedal for it!

 

[Kern Dog]

The 518/618 requires removal of the stock torsion bar crossmember in the middle. The stock middle section is a hollow U type channel that needs to replaced with something thinner, yet as strong or stronger. The floor pan may need to be cut and patched to allow the tailshaft/OD section to not only fit but have a little bit of clearance around it.
I have seen online pictures of 518/618 installations where the trans tunnel is NOT modified. These have the trans pointing down at the driveshaft yoke. This is a bad way to go, since the driveshaft angle is waaaaay off, leading to vibrations and excessive U joint wear and early failure.
Mopar Action magazine installed a TCI 6 speed auto in a 69 Road Runner. It was even worse, PLUS that transmission is cast iron! Holy crap, I can only guess what that dude weighs!