C130 Chief
Mechanical Genius
Take a look at a TH400 style setup, usually on the gas pedal.
42RH / A-500 in a Duster with pictures.
- Thread starter gdonovan
- Start date
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I'm curious to see how you have the o/d controlled too. I just swapped an a500 into my 87 dakota, but haven't wired up the o/d yet. Not looking to flip a switch on and off all the time.
Something a few of you have been waiting for I'm sure ;-)
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! I'll be swapping to a mechanical switch off the carb for this reason since I'm only running a 625 cfm Carter.
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.
Gary
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! I'll be swapping to a mechanical switch off the carb for this reason since I'm only running a 625 cfm Carter.
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.
Gary
magnumdust
Well-Known Member
I've got two questions:
1. I see a people hacking that center piece and using a plate to make the new support, how thick does that piece need to be?
2. what's the difference between the 42rh and a500?
1. I see a people hacking that center piece and using a plate to make the new support, how thick does that piece need to be?
2. what's the difference between the 42rh and a500?
1) Well, the center of the crossmember has to come out, no if ands or buts. And this piece has load from the torsion bars on it. So your guess is good as mine but if you don't have enough the center of the floor pan will pull in/down from the load of the front springs.
2) The 42RH is a refined version of the A-500 with several improvements and upgrades over the original. I'll try to scan in the information from my instructors manual today and post. It was the last "904" based transmission that still had a hydraulic governor which is why I selected it.
How a material handles load is not all about its thickness. How the material is shaped transfers the load/stress to its other facets. Those 3 and 4 sided elements in the car now are a good example. Their wall thickness is more relative to the attaching hardware used. The majority of it is 11 gauge which is very close to 1/8 wall thickness.
We cant all be engineers but we can study is/was engineered and take our cues from those examples. Hope this helps
We cant all be engineers but we can study is/was engineered and take our cues from those examples. Hope this helps
While this is true, for this application which is somewhat space limited not an option unless you were going to graft in parts of another floorpan from another vehicle.
More work than required.
Some jackass on another board tried to say there was no difference between a A-500 and a 42RH, here is a dozen pages from the Mopar instructors automatic book detailing the year to year changes in transmissions.
In nice printable format ;-)
Woods74
Broke Senior
If I may add, sub-frame connectors should negate worrying about replacing the tunnel 'U' piece you cut out, especially with a beefy stock style cross member either fabricated like gdonovan did, or, connecting the cross member into the frame connector in a 'T' type fashion like so:
Taken from an episode of powerblockTV stuffing a 426 hemi into a 74' Duster. Crossmember fab comes in at 6 mins or so, which also gives detail on wall thickness of steel used:
http://www.powerblocktv.com/player/show_player.php?ep_show=MC&ep_num=MC2012-11
I've gonna say, if it's strong enough for a 426 new Hemi, it's strong enough for a 360 running a 42RH. :glasses7:
:burnout:
Also found another style of cross member fab on this episode:
http://www.powerblocktv.com/player/show_player.php?ep_show=HP&ep_num=HP2012-07
magnumdust
Well-Known Member
If I may add, sub-frame connectors should negate worrying about replacing the tunnel 'U' piece you cut out, especially with a beefy stock style cross member either fabricated like gdonovan did, or, connecting the cross member into the frame connector in a 'T' type fashion like so:
Taken from an episode of powerblockTV stuffing a 426 hemi into a 74' Duster. Crossmember fab comes in at 6 mins or so, which also gives detail on wall thickness of steel used:
http://www.powerblocktv.com/player/show_player.php?ep_show=MC&ep_num=MC2012-11
I've gonna say, if it's strong enough for a 426 new Hemi, it's strong enough for a 360 running a 42RH. :glasses7:
:burnout:
Also found another style of cross member fab on this episode:
http://www.powerblocktv.com/player/show_player.php?ep_show=HP&ep_num=HP2012-07
But is that stiff enough for us using who are still using t-bar suspension? They went alterkation on that dart sport.
you say "into a "T", but wouldnt an H be more appropriate? or am i mis-interpreting this concept
IE: see my crappy paint art of the sub-frame
Hopefully this isnt construed as hijacking, i think its still pertinent to the 42rh swap.
One more Q: is there a size difference from the 42rh/46rh or is it just different internals?
I don't mind some back and forth, it might help someone else out and spark some ideas as long as it doesn't get out of hand.
Yes, 518/46RH (727) is a little larger and it was already tight with the 42RH against the factory floorpan.
Woods74
Broke Senior
Good point, I do know from experience those 2x3 steel beams are no slouch in the strength department, they do a pretty amazing job at keeping, not just that infamous 4 foot run they cover, but the whole 16+ foot car from turning into a pretzel every time you jack it up, or step to it with some power.
With that being said, I'd think its pretty safe to say, the last thing one would be worried about is telegraphing strength the 3-6 inches forward to the original support, in our application, that this technique displaces.
So instead of leaving y'all with the know-it-all "Yeah, it won't be a problem with no proof." attitude, tell you what, I want to know too.
When I do this swap to my car in the next few months, I will do the 'T', most likely, ladder bar technique, which is more of a 'H' than a 'T', cut n' cap off the ends of the original cross member, slap in my spankin' new 1" torsion bars and a support plate welded around their homes, and all the supporting systems that goes with this. Then I'll go take it around some corners a little faster than I should with my hot 360 and let you know how it washes on this thread. I'll add some key point fab pics too.
Until then, I don't expect the front end to fall off when I pull the trigger.
Thanks, I know this thread will really help our community!
P.S. It's more like this:
The pressure switch is a hobbs adjustable which you can find on Ebay for $30-$50, the one I have was used for years on my Reliant. Just do a search for "hobbs pressure switch" and look for one with either three contacts or just "normally open" two contacts in the 35-60 psi range. The correct switch is black and gold with a hex on the end for adjustment. At NAPA the same switch sells for $85!
The relays are also from ebay "DC 12V H3Y-2 Delay Timer Time Relay 0-30 Second 12VDC & Base" or you could simply do a search for "12V time delay relay" The ones I found are the first referenced and only $7.50 shipped each.
The WOT cut out can be either mechanical off the throttle or vacuum, the vacuum one I used is part number "PSF-102 PRESSURE SENSOR" $12 shipped.
I'm going to be swapping to a switch off the throttle, they are typically $14 for a universal WOT switch from Summit or Jegs.
68-GTS
Super " Senior " Member
Interesting read to say the least.
Furious65
C-body Guy
Late to the party as usual, I would like to know what you did for the trans lines to the radiator/trans cooler? Did you use the factory type fittings or go to the old school compression fittings like our 60's and 70's cars used?
Also, I would really like to see what you did to the trans internally. I looked for a thread covering it but did not find one.
Also, I would really like to see what you did to the trans internally. I looked for a thread covering it but did not find one.
1) Just bulk 3/8 steel line with ATF rated rubber hose at the transitions.
2) I have not done a thread yet on internal changes, been rather busy building a garage.
Gary
Furious65
C-body Guy
Thanks for the info. I'll be watching for that info in the future.
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