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Re: 727 to A518 swap
[Re: stumpy]
#140864
10/24/08 12:33 PM
10/24/08 12:33 PM
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Joined: Jun 2003
Posts: 21,427
It's a dry heat
gtx6970
Too Many Posts
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Too Many Posts
Joined: Jun 2003
Posts: 21,427
It's a dry heat
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Quote:
vacuum and pressure switchs
on a mopar ? not that I'm aware of
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Re: 727 to A518 swap
[Re: gtx6970]
#140866
10/24/08 12:59 PM
10/24/08 12:59 PM
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Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
Management Trainee
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Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
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Quote:
Quote:
vacuum and pressure switchs
on a mopar ? not that I'm aware of
Bill this is a cut & paste from PATC's site, I've been linkung their site for years, good info...
replace your three speed transmission with a 1995 back A518 overdrive transmission with a three wire connector (gas). A 518 transmission has a 31% overdrive and will produce a 30 to 40% increase in gas mileage on the road over a three speed transmission. Remember overdrive is only 3rd gear high range anyway. There are two wire 518 transmissions out there, these have a non-lock-up torque converter. With this three wire setup you have a four speed transmission plus a torque converter lock-up feature. The extra gear is 3rd high range. We've been asked this question for years, so I decided to put it down in black and white. What we're actually going to do here is control the overdrive and torque converter lock-up normally controlled by the computer using one vacuum and two oil pressure switch. Instead of using an electronic speed sensor and throttle position sensor we will use a mechanical / hydraulic / electronic speed sensor and a vacuum / electronic throttle position sensor. This will be accomplished with the use of three GM parts and some trick wiring. The Chevy and Ford guys make the swap to overdrive all the time, it's time for the Dodge people to have the same option. Lets say you drive an average of 400 highway miles per week, at that rate you could save as much as $1000.00 per year on gas. This can be made to work with a diesel motor also with or without a vacuum pump and vacuum regulator.
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#1. The center wire on the transmission is the hot wire and the two other wires are ground wires for overdrive and the lock-up torque converter. The front wire is the overdrive ground and the rear wire is the torque converter lock-up ground. You can get a three wire female connector from a junk yard or buy one from us.
#2. Run a 12 volt fused wire that turns on and off with the key to the vacuum switch, then to the center wire on the transmission connector. This is a normally open vacuum switch that takes 7 inches or more of vacuum to shift into overdrive and lock-up the torque converter and 3 inches or less of vacuum to down shift and unlock the torque converter. Lets say you're in overdrive going 54 miles per hour at very light throttle, when you press on the throttle and the vacuum drops below 3 inches the transmission will immediately shift back to 3rd gear low range without lock-up or even a lower gear depending on the throttle position.
#3. At the governor pressure tap on the transmission install a tee fitting for two oil pressure switches. Say a 44 PSI oil pressure switch for overdrive and a 52 PSI oil pressure switch for the torque converter lock-up. Or any other combination of switches you may want. At light throttle the transmission will shift into overdrive at 44 MPH and the torque converter will lock-up at 52 MPH. The pressure switches go on the outside of the transmission case in the governor pressure port. It's located on the right side, at the upper rear of the main transmission case. The figures on the pressure switch will only be correct if you have a stock tire size and rear end ratio.
#4. Run a wire from the front pin on the transmission connector to the 44 PSI oil pressure switch and a second wire from the rear pin on the transmission connector to the 52 PSI oil pressure switch. Now at 52 MPH when you step on the gas the transmission will shift back to third gear and the torque converter will unlock at the same time. It can't get any easier than this.
#5. Install a toggle switch in the overdrive ground wire. When the switch is turned off you will have 1st, 2nd and 3rd low range, exactly like a 727 transmission with the same ratios. When the switch is turned on you will have 1st, 2nd and 3rd gear low range plus 3rd high range. When the toggle switch is on the transmission will immediately shift into overdrive at light throttle over 44 miles per hour whenever it’s in drive range on the gear selector. Once in overdrive the transmission will not come out of overdrive until the overdrive solenoid is turned off, or the vehicle speed goes below 44 miles per hour, or the vacuum drops below 3 inches. The only electronic parts on a 518 transmission are the overdrive and torque converter lock-up solenoids.
NOTE: People make this swap all the time, but I've never heard of anyone doing it correctly. They drive down the street flipping a toggle switch on and off at every stop. This setup works automatically.
NOTE: The way governor pressure works is 1 pound of pressure per square inch equals 1 mile per hour unless someone has changed the tire size, or rear end ratio, or governor springs and weights. The vacuum switch acts as a throttle position sensor and the oil pressure switch acts as a speed sensor.
NOTE: Use a lock-up type torque converter if possible, this could get you as much as 5% better gas mileage and the transmission will run much cooler. Running cooler will make the transmission last longer.
NOTE: You can also run the torque converter ground wire through the brake switch if needed.
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Re: 727 to A518 swap
[Re: 1_WILD_RT]
#140868
10/24/08 02:56 PM
10/24/08 02:56 PM
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Joined: Jun 2003
Posts: 21,427
It's a dry heat
gtx6970
Too Many Posts
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Too Many Posts
Joined: Jun 2003
Posts: 21,427
It's a dry heat
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Well, thats a new one on me.  But, I'm not much into non-stock swaps either. carry on
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Re: 727 to A518 swap
[Re: stumpy]
#140869
10/24/08 03:09 PM
10/24/08 03:09 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
I am going to do this swap and was wondering if anyone who has done it knows where to get the vacuum and pressure switchs at a reasonable price other than from PATC.
those pressure switches are used in TH350's, I think for converter lockup. go to any transmission shop, they're about $8 each. that's where I got mine. I got the vac. switch from rockauto, it's a TC lockup switch for an early 80's caprice, I want to say the PN is Standard Motor Products #VX1. Feets is using pressure switches from a K-car A/C system, IIRC....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 727 to A518 swap
[Re: stumpy]
#140870
10/24/08 04:38 PM
10/24/08 04:38 PM
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Joined: Jan 2003
Posts: 25,784
Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,784
Rio Linda, CA
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One vacuum switch that is commonly used is available from any GM dealer, the P/N is 14014519.
For the 40 psi switch a low pressure switch from an A/C drier will work if it's 1/8"-27 NPT which many are.
The INTERNET, the MISinformation superhighway
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Re: 727 to A518 swap
[Re: dgc333]
#140872
11/23/09 10:58 PM
11/23/09 10:58 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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hey whats up man lisen im having trouble with my conversion with the plumming on the pressure switches do the oil lines to the radiator stay the same or do they change?help me out bro if you have pics even better
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Re: 727 to A518 swap
#140873
11/24/09 11:50 AM
11/24/09 11:50 AM
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Joined: Nov 2006
Posts: 2,255
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,255
IL
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I think I've said this in other OD posts, but with my a500 conversion I found the
#71V2. Universal adjustable vacuum switch
to be very hard to dial in, tiny amount of rotation of the set screw made a huge change, I went back to the GM one.
Also, the adjustable line pressure switch vs. the set GM ones are very nice. If you do a performance build on the tranny and jack the line pressure up, the GM switches will have you into OD by 35mph. I have a '62' GM switch on the OD that actually shifts at a true 45mph on my car. I have one of the adjustable ones for the lockup side that I have set to not come in until 55mph. The car is MUCH more responsive when set up this way and you don't bog the engine around town.
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: 727 to A518 swap
[Re: JohnRR]
#140875
11/24/09 12:48 PM
11/24/09 12:48 PM
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Joined: Nov 2006
Posts: 2,255
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,255
IL
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Should have said I have 28" tires and 3.91's. I messed around with the shift points a lot and for my needs 45 and 55 works well. If a guy had 3.55's then you might even want as high as 55/65 as the points.
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: 727 to A518 swap
[Re: hooziewhatsit]
#140877
11/24/09 01:23 PM
11/24/09 01:23 PM
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Joined: Nov 2006
Posts: 2,255
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,255
IL
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part numbers for the pressure switches? the '62' GM one was just the highest one my tranny guy had, they aren't listed in any book, have no idea what it came from. The adjustable switches- I have a spare one at home I can look up the PN on it.
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: 727 to A518 swap
[Re: furious70]
#140878
11/24/09 01:39 PM
11/24/09 01:39 PM
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Joined: Aug 2004
Posts: 425
Eastern Ontario
shaker340
mopar
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mopar
Joined: Aug 2004
Posts: 425
Eastern Ontario
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The A518 is a small block trans? Can A518 be mated to big block?
2008 Challenger SRT8
1940 Chrysler Royal coupe
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Re: 727 to A518 swap
[Re: shaker340]
#140880
11/24/09 01:58 PM
11/24/09 01:58 PM
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Joined: Nov 2006
Posts: 2,255
IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,255
IL
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yes, a couple different ways. My a500 is behind a 383. TranzTech in Dubuque IA did mine, he lops off both bellhousings, and has a jig to weld the BB727 one to an adapter that then bolts to the OD tranny. OEM shifter and kickdown linkage as well as starters all work exactly as they should doing it this way.
The other method of using a spacer/adapter can cause issues.
70 Sport Fury
68 Charger
69 Coronet
72 RR
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Re: 727 to A518 swap
[Re: stumpy]
#140882
11/24/09 06:15 PM
11/24/09 06:15 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I used the low side pressure switch from a mid 80s K car to control the OD solenoid on my truck. The one Napa carried apparenntly has a higher setting than the brands you get at other stores. It should fit in your truck just fine. Here's my write up from another forum with pics and part numbers: http://www.dieseltruckresource.com/dev/another-way-fix-od-t156988.html?t=156988
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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need to convert it with a JW Ultrabell