A518

[70 Charger RT]

Does anyone have a A518 trans with overdrive behind their big block?  I'm thinking of putting one behind a 426 and installing in my Charger.  I'm not sure if tunnel work is required and it would be nice to do the sheet metal work now as opposed to after it's too late.   Has anyone done this trick?  Thanks in advance for  your response.

[Budnicks]

Just use your 727 & put a lock up converter in it & 518 type kit, go to Performance Automatic Transmission Center website they have complete conversions available @   www.transmissioncenter.net/727transmission.htm

[70 Charger RT]

Thanks.  It make more sense to change the TC and add a few pressure switches than to change the whole transmission.

[gtx6970]

Thanks.  It make more sense to change the TC and add a few pressure switches than to change the whole transmission.

I'm not familiar with the above website / conversion.

But adding a lockup convertor is a lot more involved than just a new convertor and switches.
Valve body is different , ft pump is different , input shaft , Case, etc etc etc .

Also, the A518 is a small block based transmission. and I do not know if a small block to big block bellhousing  conversion is avail in the aftermkt

[Troy]

There's JW Ultrabell - but you need to cut off the bell housing. Doesn't look terribly complicated but it isn't cheap either. By the time you get a "good" A518, modify it, and buy the parts to hook it up you'll have +/- $2,500 in the conversion.

Also, the PATC conversion is to put an actual A518 in the car - in which case you still need to mess with fitting it correctly. The transmission cross member need to be completely customized and you may or may not have to "massage" the floor pan. You can let it hang in the back but then your drive shaft angle is off and you'll have lots of noise and/or wear stuff out in a hurry. PATC recommends the earlier transmissions as they have simpler electronics which can be easily retrofitted to cars that never came that way.

Troy

[John_Kunkel]

Just use your 727 & put a lock up converter in it

The lockup case is different and there was only one big block lockup 727 made and only in one year; most were changed out for non-lockups.

[Tilar]

Doesn't the 518 have overdrive? That would be a plus for road driving over the 727. I had bought a A518 for my 68 but Troy twisted my arm so I bought a 4 speed from him.   

[flyinlow]

I have a A518/w lock up behind my 446 in a 73 Charger. Minor tunnel mods with a ball peen hammer on my car, don't notice with carpet and a console.  Paul G. put one in his 72 which would be closer to your body as far as the transmission crossmember. I cut the smallblock bellhousing off and mounted the trans with a JW Ultrabell. Full weekends work with a lift and talented helpers.

[Paul G]

I know the lockup and non lockup converters are splined differently. Wont interchange, and lock up converters are not cheap. I used  Hughes 11" converter, 2500 stahl, almost $500. The Ultra Bell is a very good way to go. You can also get an adapter plate kit to mount the A518 behind a big block. You will still have to massage the tunnel some to get the pinion angle right. I have not read of one swap that didnt have to hammer out the tunnel a bit. It is not noticible under the carpet. The tranny mount does have to be modified.

All in all I would do it again. The drivability has improved greatly. It just so nice to have that extra gear come in at 40 MPH, lock up at 50. Cruising at a nice low RPM with 3.91 gears.

[Budnicks]

Just use your 727 & put a lock up converter in it & 518 type kit, go to Performance Automatic Transmission Center website they have complete conversions available @   www.transmissioncenter.net/727transmission.htm

Sorry I guess I should have worded it better, but there is a conversion to make a 727 more like a 518 {the 518 is a Small Block "overdrive trans" & needs to be converted for use on a big block} I will look back thru my stuff & see were it was I saw, the parts for the conversion, for the 727 BB trans to still be used....

[Dino]

I'm still undeceided on what route to go with this as well.  I like what Paul did, it's probably the best thing to do to get an auto with OD without breaking (most) of the bank.  On the other hand I still would love to have a manual as well.  The problem is not just the cost though but where to do the conversion.  All I have is my 2 car garage, no lift and nobody to help.

[Troy]

Just use your 727 & put a lock up converter in it & 518 type kit, go to Performance Automatic Transmission Center website they have complete conversions available @   www.transmissioncenter.net/727transmission.htm

Sorry I guess I should have worded it better, but there is a conversion to make a 727 more like a 518 {the 518 is a Small Block "overdrive trans" & needs to be converted for use on a big block} I will look back thru my stuff & see were it was I saw, the parts for the conversion, for the 727 BB trans to still be used....

The A518's overdrive unit is hanging off the back end. This is where all the fitment issues come from. Other than that, the A518 is pretty similar (based on) the 727 so I think it's possible to remove everything from an A518 and install it in a big block 727 case. In a way that's probably cheaper than using a JW Ultra Bell - unless you were starting with a freshly rebuilt A518 that didn't need to come apart.

Troy

[flyinlow]

A 518 is basically a small block 727 with a .69 Overdriven planetary built into the tailshaft housing, plus a lock up torque converter if you have that year 518.

My 518 with the JW Ultrabell installed looks just like a 727 until you get to tailshaft. It is 3 1/2 " longer and bulkier. I do not think you can bolt a 518 tailshaft and valvebody to a 727. The pasages for the OD clutch fluid and torque converter lockup would not be present in a 727 case. The port for the OD and Lockup solenoids would not be there either.

My 518 came out of a one ton Dodge van with a 360 engine, so it was a more robust unit. Similar to a SB 727. I put a Transgo kit in it and use a B&M plate cooler. 16K miles so far. I beat on the first three gears just like I would a torqueflight. The OD and lockup are for cruising. I try not to subject them to full throttle. I am considering upgrading the clutches,bands, OD spring and sprag.... its on my list.

You can do this without a lift. A lot less convenient. The 518 is heavier than a 727,so a helper would be good. You do need to fabricate a new way to attach the trans mount. Mini grinder,welder. I used a C1500 trans mount.

[Dino]

I'm not too worried about the 518's strenght or lack thereof compared to the hd 727.  I have read several reports from users who put on serious miles and stomp it from time to time without any issues.  I cruise my car more than anything else, on occasion I will get off the line quick just for fun, usually when nobody's around, but I'm far from stressing it as you would on the track.

I think worst case scenario I would kill the trans and have to find another, at least I can convert most of the parts like the ultrabell. A guy was selling two rebuild 518's locally for $200 each, I should've jumped on them but I didn't.

I know someone here used a chevy trans mount which worked pretty good.  I don't have a welder but can fabricate the mount and either rent a welder for a few hours or go by a shop to have it welded.  I just don't see how I could do the work without a lift though, changing the rear pig was more than enough of a hassle!  Nobody around to help me either.  If I could do most of the prepwork I could possibly drive the car to a shop and have the mechanics do the swap but now I'm burning money.

[70 Charger RT]

Each time someone chimes in with comments, I learn more.  Keep them coomments coming.  The deeper I dig on the subject, the more I lean towards leaving the original 727 alone and don't have an OD.  Most of my driving will be in town anyway.

[Dino]

Each time someone chimes in with comments, I learn more.  Keep them coomments coming.  The deeper I dig on the subject, the more I lean towards leaving the original 727 alone and don't have an OD.  Most of my driving will be in town anyway.

Think about what you want and what you need.  I would like an OD to be sure but honestly since I put the 2.96 gears in there I no longer need it, the car cruises great and still has plenty pull off the line.  It won't win any races though!

Now a manual trans is an entirely different matter, that just changes the whole driving experience.  I too need to think twice about it though as it will increase my lead foot.

[flyinlow]

The 727 is hard to beat for ruggedness.

I live in the country,  everywhere I go starts with 15 miles of hi way driving, so the 518 is great for my car.

[Budnicks]

Just use your 727 & put a lock up converter in it & 518 type kit, go to Performance Automatic Transmission Center website they have complete conversions available @   www.transmissioncenter.net/727transmission.htm

Sorry I guess I should have worded it better, but there is a conversion to make a 727 more like a 518 {the 518 is a Small Block "overdrive trans" & needs to be converted for use on a big block} I will look back thru my stuff & see were it was I saw, the parts for the conversion, for the 727 BB trans to still be used....

I think after looking thru my trans books, it would be far easier & probably way cheaper to just go with a lock up type  1976-78 or latter 727 BB trans, there are way too many parts to have to buy or change/modify to convert a 727 to a Lock-up style, the reaction shaft support & reaction shaft, a 23 spline lock-up input shaft, throttle body with lock-up bypass tube & valving module, a lock-up converter {Chrysler Lock-up converters are very specific & very different, from most any of the lock-up style converters on the market}, torque converter control switch, planetaries have a different inner spline, front pump is also different, governor & probably many others...  You could just buy a 1976-1978 or later Lock up style 727 & have it reworked far cheaper in the long run if your dead set on a 727 BB case... Good luck & I'm sorry for any confusion I may have caused, I could have sworn it was far easier, maybe I will research it some more...

[ugly2u]

I was all ready to make this swap in my 69, but the crossmember would need to be removed and modified to fit the back of the the trans. Or you could lower the back of the trans and mess up piñon angle.

I just had the 727 rebuilt, rather than mess with all that. Over drive would have been sweet.