Posted By: racecar43
what is the best o/d auto trans for small block - 09/10/13 08:57 PM
I have a 64 Barracuda 360,727,..9"rearend w/411 what's the best o/d trans to use....?
what is the best o/d auto trans for small block
Posted By: 340SHORTY
Re: what is the best o/d auto trans for small block - 09/10/13 11:04 PM
518
Posted By: gdonovan
Re: what is the best o/d auto trans for small block - 09/10/13 11:07 PM
Quote:
I have a 64 Barracuda 360,727,..9"rearend w/411 what's the best o/d trans to use....?
A-500 or 42RH will give you more room.
http://www.forabodiesonly.com/mopar/showthread.php?t=178459
Posted By: Magnum
Re: what is the best o/d auto trans for small block - 09/12/13 05:15 PM
The 518 requires floor modifications and something is required to control the overdrive and lockup.
Keisler Engineering sells a kit that is based on a GM 4 spd auto.
Keisler Engineering sells a kit that is based on a GM 4 spd auto.
Posted By: Polarapete
Re: what is the best o/d auto trans for small block - 09/12/13 05:43 PM
Do all the 518 automatics come with the lockup converter or can you change it to non-lockup? I have had expensive experiences with lockup converters and don't want one in my latest project. 
Posted By: gdonovan
Re: what is the best o/d auto trans for small block - 09/13/13 10:05 AM
Quote:
Do all the 518 automatics come with the lockup converter or can you change it to non-lockup?
No, some were non-lockup. I'm not sure of the year, you can tell by the plug on the case (2 pin vs 3 pin)
Posted By: gregsdart
Re: what is the best o/d auto trans for small block - 09/13/13 02:34 PM
Keep in mind that with the OD, your real rear ratio would be like a 2.79. That will push the converter real hard, and if it is a higher than stock converter you will see quite a bit of slippage. In a stall converter test article using different rear gears the rpm didn't go down a lick after going a 3.55 gear. Below 3.91 started to show too much slippage to be worth it with the converter they tested. A better alternative might be a 904 with the lockup converter and something close to a 3.55, and if it would work for you, a 3.55 would put you at 3,000 rpm at 70 mph with a 27.5 inch tire. Or 2600 at 60 mph. The lockup could be set up to only work in high gear, high vacuum to avoid hurting it. this would obviously also save you the aggravation and expense of drive shaft mods and tunnel clearance issues.
Posted By: gdonovan
Re: what is the best o/d auto trans for small block - 09/13/13 10:09 PM
Quote:
Keep in mind that with the OD, your real rear ratio would be like a 2.79.
My Duster came with a 2.45 FDR, you say 2.79 like its a bad thing ;-)
Posted By: hp383
Re: what is the best o/d auto trans for small block - 09/14/13 01:29 AM
My 92 Dakota has a 518 with the electronic OD, and hydraulic lockup.
It also has a Mopar Performance 2200 RPM converter.
It works great, and lock up functions correctly. It will cruise at 70mph and be at 2200 RPM. I get 17mpg out of the 5.2 Magnum.
As for the 518's with no lockup I know for sure that the early (92-93) diesel and V10 trucks had the non-lockup 518. It uses a standard 727 converter. Thats what I used with an Ultra Bell in my 93 Ramcharger with the 440.
PATC sells an easy to use kit that used pressure switches, and a vacuum switch to control the OD and lockup if required.
Easy to use, and you dont have to constantly push buttons, or flip switches.
It also has a Mopar Performance 2200 RPM converter.
It works great, and lock up functions correctly. It will cruise at 70mph and be at 2200 RPM. I get 17mpg out of the 5.2 Magnum.
As for the 518's with no lockup I know for sure that the early (92-93) diesel and V10 trucks had the non-lockup 518. It uses a standard 727 converter. Thats what I used with an Ultra Bell in my 93 Ramcharger with the 440.
PATC sells an easy to use kit that used pressure switches, and a vacuum switch to control the OD and lockup if required.
Easy to use, and you dont have to constantly push buttons, or flip switches.
Posted By: gdonovan
Re: what is the best o/d auto trans for small block - 09/14/13 01:47 AM
Quote:
PATC sells an easy to use kit that used pressure switches, and a vacuum switch to control the OD and lockup if required.
Easy to use, and you dont have to constantly push buttons, or flip switches.
Or use what I came up with.
Posted By: BDW
Re: what is the best o/d auto trans for small block - 09/14/13 06:17 AM
Nice block diagram!
Got any more details with the actual components and some pics?
Got any more details with the actual components and some pics?
Posted By: gdonovan
Re: what is the best o/d auto trans for small block - 09/14/13 11:37 AM
Quote:
Nice block diagram!
Got any more details with the actual components and some pics?
http://www.forabodiesonly.com/mopar/showthread.php?t=178459&page=4
Some notes-
1) Only one hobbs *adjustable* pressure switch is required for this setup, they generally tend to be the most expensive items and you should be using relays anyways since I have seen pressure switches fail from handling the amp load of solenoids.
2) Time delay relays are used for two reasons- Reason one is that pressure switches tend to flutter around the set point and can cause the transmission to rapidly shift back and forth between forth and third, not good. This way once the PSI switch settles down the relay will finally time out (5 to 10 seconds in my case) and you get a solid shift. Note that each time the switch flutters, the timer on the relay restarts! So you will not get a shift till you time out which is a good thing.
You can also extend the mph at which the trans shifts by simply extending the time of the relay- Instead of 5 seconds make it 10 or even 15. I may make it 10 in my case since we get a lot of traffic in this area which floats back and forth in the 45-55 mph range. I could set the pressure switch higher raising the mph point or just set the relay to come on a touch later. I would rather have the relay come on later since my Duster is happy to cruise on the backroads with OD and LU active at 55-60 mph while turning 1700 rpm. The 5.9 has more than enough grunt at this low rpm to pull away without using very much pedal. A 5.2/318 might be want a bit more road speed and a higher mph set point to make up for the less available torque. Your engine, rear end ratio and tire size will determine what works best for you in regards to mph PSI setting and time delay on the relay.
The second reason is it does away with having to have two pressure switches, the lockup time delay relay is keyed into the first relay and makes the car feel like it has a five speed trans (I can hear and feel lockup when it happens) plus it also protects lockup from the same flutter condition that can happen in overdrive. Remember, the timer for the LU relay does not start till the OD relay has timed out and made the shift into OD!
By time delaying the shift it gets you further out of the zone when flutter can happen.
Even if you do get in this zone then you have to just deal with just OD going back and forth and not both at the same time.
For less complexity you could do away with one relay and just have OD and LU come on at the same time, I ran the car for several weeks that way. The relays are dirt cheap though, I picked up three 0-30 second relays shipped with bases for less than what you would pay for a single pressure switch and they even have LED's that show when they are powered up and have timed out.
The dash switch kills everything of course, just a regular 904 at that point Mine is disguised as a map light switch in the factory location.
I really don't like the vacuum based switch for WOT- If you are undercarbed then at WOT you will draw a vacuum at higher rpm's and overdrive will trip back in!
Any questions feel free to fire away!! Diagram is in handy 8 x 11 printing format. Red lines indicated 12V+ circuits, black indicate ground side of circuit. The relays were cheap on ebay, only a few bucks a pop.
http://www.ebay.com/itm/DC-12V-H3Y-2-Del...=item19cf08b2ed
Gary
EDIT- Been chewing on a good solution for a problem- How do you maintain overdrive activation at WOT? (example, high speed driving on the highway) The only good AUTOMATIC solution I can think of is to add a second pressure switch in and have it set to the top speed of the car while in third and say 5500 RPM (120 mph). This way when the car hits 120 mph the second pressure switch will disable the "kickdown circuit" and force an immediate shift into overdrive while still at WOT.
