A518 vs 727

Which is the better tranmission

  • 727

    Votes: 48 63.2%

  • A518

    Votes: 28 36.8%
  • Total voters
    76
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PanGasket

PanGasket

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My transmission is a 727 that is pretty leaky and has some issues. That being said, I wanted to get it rebuilt or a better transmission rebuilt and put it back behind my 318 in my '74 D100. Here's what's going on. If I get a 727 or an A518, it'll be the same price to get them rebuilt with a nice shift kit. $800.

So which should I go for? I wanna get pretty decent gas mileage but still be able to romp it and have some fun. I have a junkyard full of good cores to chock up.

What's the disadvantages of each?

Which one is the best overall?
 
JMO always favor the overdrive. If for nothing else, being able to enjoy driving on the highway.
 
magnumdust said:
JMO always favor the overdrive. If for nothing else, being able to enjoy driving on the highway.
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anyone know what the h. power limit on the 518 is, before it becomes un reliable. or who can build one to take 700 h.p. ?
thanks, bob
 
From what I understand valve body choices for the 518 are limited. Just looking for a shift kit then suppose that does not matter. From everything I have seen about the 518 it takes some surgery to fit it. But you can't beat OD. From what I have been told the 518 has some oiling issues.....
 
The A518 is basically an A727 with an overdrive unit in the tail housing. They can both be built to handle the same amount of torque by using basically the same parts. Either one can be built to handle 700 HP, but not for $800. The guys with pumped up Cummins powered trucks have pretty much solved any of the strength issues. An A518 will have some of the crap parts common to all later model Torqueflites like plastic servos. Sonnax makes nice billet replacements.

If you have 3.23 or taller (highway) gears, you wouldn't see much advantage. The nice thing about the overdrive is the ability to run 4.10 gears on the street and be able to cruise comfortably.

To put the A518 in the D150, it should be a pretty straightforward swap, requiring some rear mount mods and maybe shortening the driveshaft. To swap into an A-body requires moderate modifications to the unibody and rear mount and possible driveshaft shortening.
 
C130 Chief said:
The A518 is basically an A727 with an overdrive unit in the tail housing. They can both be built to handle the same amount of torque by using basically the same parts. Either one can be built to handle 700 HP, but not for $800. The guys with pumped up Cummins powered trucks have pretty much solved any of the strength issues. An A518 will have some of the crap parts common to all later model Torqueflites like plastic servos. Sonnax makes nice billet replacements.

If you have 3.23 or taller (highway) gears, you wouldn't see much advantage. The nice thing about the overdrive is the ability to run 4.10 gears on the street and be able to cruise comfortably.

To put the A518 in the D150, it should be a pretty straightforward swap, requiring some rear mount mods and maybe shortening the driveshaft. To swap into an A-body requires moderate modifications to the unibody and rear mount and possible driveshaft shortening.
Click to expand...


I'd like to run a really short gear. Like a 4.57. I wasn't really looking for a 700hp transmission, but something that will last me a good long while and take a beating
 
The 518 no doubt. The only disadvantage is the 727 has no overdrive. They're the same freakin' transmission! As DarTT stated this is going into a TRUCK and not an A-body! Should drop in. Dodge did not change the basic frame architechure until the new Ram came out in '94.
 
May be way off base here as this conversation was 10 years ago or so. The gas od unit and the diesel od unit have some differences. Think it was the planetarys? Gas was 4 pinon and diesel was 5? Years ago the only way to get the better od parts was to buy a diesel case , I think. Pretty sure one of the shafts needs to be drilled so enough lube gets into the od unit. Conversation with my trans buddy about this stuff was a long time ago so I may be way off here......
 
For your application in a truck with steep gears, the 518 will probably be the way to go. The thing to consider is cost. You're gonna be doing mods for the the OD install vs. the 727 being a straight replacement. Not huge, but something to consider. Hell, I'ld do it.
 
the 518 being the same as the 727 isn't as true as you may think because the later parts used weren't as strong as the earlier 727 even though the gear ratio is the same for the first 3 gears. One of the reasons persons here use a 200 or 700 4R transmission from GM.
727 and 518 use a 2:45 first gear - 200 4R a 2:66 first gear and a 700 R4 a 3:07 first gear.
Using a 2:45 first gear in a 518 and lets say a 4:56 rear, may be able to cruise at 65 mph at around 2000 rpm where as using a 3:07 first gear in the 700 R4 with a 3:23 will come out of the chute like it had 4:56's and the 4th gear will cruise under 2000 rpm at 65 or 70 mph.
On another note: I run a 3:42 rear in my truck with a T56 trans ( 2:66 first gear like the 200 4R ) where-as 2000 rpm @ 70 mph in 5th gear.
At 2000 rpm in sixth its doing 90 mph and at 70 mph, its at 1150 rpm.

Gear ratios of both transmission and rear end can work with each other or against each other. Choose your rear gears wisely along with your tire size...
 
HotLines said:
the 518 being the same as the 727 isn't as true as you may think because the later parts used weren't as strong as the earlier 727 even though the gear ratio is the same for the first 3 gears. One of the reasons persons here use a 200 or 700 4R transmission from GM.
727 and 518 use a 2:45 first gear - 200 4R a 2:66 first gear and a 700 R4 a 3:07 first gear.
Using a 2:45 first gear in a 518 and lets say a 4:56 rear, may be able to cruise at 65 mph at around 2000 rpm where as using a 3:07 first gear in the 700 R4 with a 3:23 will come out of the chute like it had 4:56's and the 4th gear will cruise under 2000 rpm at 65 or 70 mph.
On another note: I run a 3:42 rear in my truck with a T56 trans ( 2:66 first gear like the 200 4R ) where-as 2000 rpm @ 70 mph in 5th gear.
At 2000 rpm in sixth its doing 90 mph and at 70 mph, its at 1150 rpm.

Gear ratios of both transmission and rear end can work with each other or against each other. Choose your rear gears wisely along with your tire size...
Click to expand...

I'm pretty sure the use of the 200r4 in these cars is purely because they happen to fit better than the larger dodge trannies.
 
magnumdust said:
I'm pretty sure the use of the 200r4 in these cars is purely because they happen to fit better than the larger dodge trannies.
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My car is set up for a 4l80e, plans are for a 572 HEMI. I want something with a lock up convertor and that is electronically controlled. I know there is a place in Canada that sells an adapter to put a 518 behind a big block but when I discussed this with my friend that will be building the trans for me some day he just laughed......I will not repeat the rest of it because I know how sensitive some folks are about certain things around here.....
 
Why would you not choose overdrive on such an easy swap?

You're lucky you don't have a /6 A-body. I wish I could easily install od :banghead:
 
If you do go with the 518 please post it here as some of us would like to do the same. For me I have a 88 D350 360 with 4.10 gears I would love to have a overdrive and have been doing price compairason with the Gear Vendor vs 518 vs Keisler automatic setup. Looks like total cost will be in the $2500 to $3000 range when all said and done.
 
I am in the process of doing this swap with a '94 318 magnum & a-518 into an '87 Ram two wheel drive. The 518 is a little longer, but i had an old'78 Cordoba driveshaft ( i think) that went right in perfectly! I also had to add a small dimple to the left hand hump to clear one of the plugs in the trans. Check out the PATC website to find out how to get the trans to work properly without much hassle. I'm still waiting to get everything to try it out, but i'm really looking forward to more power and economy over my old 318 and 727(assuming of course, that my $200.00 engine and trans combo all work OK). Sorry, just had to brag a little!
 
Pound said:
I am in the process of doing this swap with a '94 318 magnum & a-518 into an '87 Ram two wheel drive. The 518 is a little longer, but i had an old'78 Cordoba driveshaft ( i think) that went right in perfectly! I also had to add a small dimple to the left hand hump to clear one of the plugs in the trans. Check out the PATC website to find out how to get the trans to work properly without much hassle. I'm still waiting to get everything to try it out, but i'm really looking forward to more power and economy over my old 318 and 727(assuming of course, that my $200.00 engine and trans combo all work OK). Sorry, just had to brag a little!
Click to expand...

PATC????

And I'll be sure to put a swap thread on here. I already like this truck better than my Dart in a lot of ways. Working on it is so easy and roomy. Putting those cheapo Hedman Hedders on there was pretty easy and they clear great! Best $20 I spent at the junkyard :toothy10:
 
I've done this swap but didn't take any pics but will as soon as the ground dries out. I had enough parts from all the 727 I rebuilt and didn't have to by any thing. I also didn't need to rebid the overdrive unit. I did rework the valve body to shift better, I did this myself and didn't buy a kit. any way, the 518 I have is a lock-up unit and has to have the convertor for it. I was able to get everything for a guy changing over to a 4-speed in his truck. also get the flex plate. the 518 bolts right up to my 318 in my 81 dodge ram 250. now the trans mount and driveshaft is another matter. you have to fab that and have the driveshaft shortened. the kick down linkage fits as does the shift linkage. there is three ways to get it into overdrive. one, change over to computer controlled fuel injection(never could get that to work for some reason)the brain is suppost to shift it. two, there is a vacuum kit that puts it in overdrive automatically, I think someone already mention that. three, this is what it did before and after the fuel injection retrofit. install a fused lighted rocket switch on the dash in easy to reach and see place. now on the trans you have a male three prong electrical connection just behind the shifter mechanism, this is the overdrive solenoid. the middle one is grounded to the chassis and the other two is for overdrive and lock-up. these two are wired to that rocker switch you just installed. so now when you're out for a drive and get the trans in third gear reach up and push the rocker switch on. it will go into overdrive in a few seconds and drop the engine rpm 1000rpm's. now and this is what you always have to remember or the motor will tell you to do is turn the switch off when slowing coming to a stop.
 
You're basically asking to compare the same transmission to itself. The 518 is simply a 727 with an overdrive unit. They are actually better than a 727 because they have a bigger direct drum for more clutches and more pinions in their planetaries along with several other modern upgrades.
 
Right. But the reason Mike wants to use an overdrive is the same reason it's built.
 
trucks and vans
all you need is the donor cross member

car hauler
we used a ultra bell to adapt to the 440

0132.jpg


we then decided to change it to cummins power
used the same 518 cross member

005-5.jpg


then finally decided on on a 5-speed, because the cummins 518 we used was not a lock up convertor

Our RV (swat mobile) is a 360,was a bolt in
using the cross member from a 92 van

007-2.jpg


006-5.jpg
 
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