42RH in 68 Dart advice/request

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FWIW, I did mine without the “special” tools, just a $28 amazon digital caliper.
The round bar is 5.5. “, and the caliper extends enough to down to where yo need, you just need to be careful to measure to the right “landing” and subtract 5.5 inches from the reading to get to what the chart is calling for.
For the 2nd measurement,
The flat slotted bar is .5” thick. A guy on utube used 1/4” plate, I used a piece of .620 square tube. You just have to be certain it is straight. He had to add .25 to compensate to get what the chart was looking for, I had to subtract .120.
 
I used 1” rigid conduit cut to length and a piece of 1/2” key stock with a hole drilled in it so I could slip my caliper depth gauge through. Worked fine in my application. You also don’t need the “assembly shaft” either. Use your intermediate shaft and build the OD Section first then pull it out and build the trans.
 
OP - I still don't get how you are shifting into and out of overdrive. I have an RH42 in my 70 Dart and it works great. I went for simplicity and the overdrive and the converter lock up are both on switches on the console. I know there are kits to provide computerized shifting, but it sounds like your trans has neither of those.
 
No, I for some reason have to complicate everything. I used a Cope reverse manual valve body. He engages O\D manually. You use a standard ratchet shifter, but it goes PR1234, you don't have neutral. I sure hope I don't regret going this route, and it is causing me some angst.
 
I cannot understand how it is possible for that to work. I'm not saying that it doesn't, I just can't wrap my head around this. Overdrive is actuated by an electric solenoid inside the trans. I have no idea how you could manually shift into overdrive as there is no linkage attached to the OD system. Is it possible that this is what trashed things when you tried to use it? I think you said that you have never gotten the car up to speed to use OD, is this correct?

Do you have a lock-up torque converter and how is it triggered?
 
Cope's RE manual shift valve body has 1-4 on the manual valve. There is no solenoid needed for the 3-4 shift as that is done manually on the shifter. The only solenoid that is needed with the CRT valve body is for lockup.
 
Thinking back, I'm reasonably sure I MIGHT have hit O/D, but I KNOW I didn't L/U.
In stock form, The O/D, though engaged via a solenoid, is still a hydraulic function. The solenoid opens a valve that sends fluid to the O/D piston. In this valve body, he just directs fluid physically just like 1-2-3.




The L/U does remain solenoid activated, and I haven't yet gotten that circuit completely wired. Initially, I will switch it on/off nice and simple. Eventually I figure on something where IF I'm in O/D, AND vacuum is up, L/U will engage, but IF I hit the brakes OR vacuum drops, it disengages.
 
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Thanks for all the information! I have about 6000 miles on my RH42 and am still figuring out if I want to do some sort of automatic activation. So far I have gotten pretty good at doing the OD lock out manually and don't often miss doing it as I slow down (usually on an interstate off ramp).
 
I have a cope Transbrake valvebody as well. You actually do have neutral. You get reverse by holding the Transbrake button while in neutral. 4th is operated like previously mentioned with the manual valve. Very simple. The valvebody didn’t “trash” his transmission unless there was something leaking internally or trash in it. It is a proven setup that hundreds of people run.
 
I don't have the Transbrake version. Maybe I should have gotten that one, but I didn't think I wanted to hold a button while backing in/out of parking spaces with manual steering.
I think it was a botched rebuild job. I found a snap ring that everybody says doesn't belong in any Mopar transmission. There is visual evidence of a piston seal that had flipped in part of it's bore ( but I'm not sure if that short a distance would have left the visual "staining") but about 1.5" of it was definitely rolled the wrong way at some point. If nothing else, it was not a "do all the performance tricks" build I had requested. It was a V-6 level freshen up.
 
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rbkt65 said:
Patc offers a simple kit that will make the od shift real good. We have 2 of them in use and for us, it is way better than toggle switches. As it allows the trans to downshift naturally without having to remember to toggle the switches.
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i was looking at that but there sure don't seem like $110 worth of parts in that kit but thats what they charge for it...
 
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the idea of a manual valve body and being able to run the RE trans is enticing in that they're way more prevalent out here. but that price tag and no neutral (not to mention cope's history) are steering me right back to the 42/46 RH

lots of great info in this thread.
 
i was wondering if they modified the vb (or made a complete different one from scratch maybe) with an added hydraulic circuit to take the place of the (normally) needed solenoid so that OD can activate hydraulically, kind of the reverse of how they converted these transmissions from "RH" to "RE" when it came to giving up hyd. governor control to a solenoid....
 
Not sure if there’s a question there, but the valve body is a hybrid I guess, original cast valve portion with billet block plate

IMG_4116.jpeg


IMG_4115.jpeg
 
RogerRamRod said:
Not sure if there’s a question there, but the valve body is a hybrid I guess, original cast valve portion with billet block plate

View attachment 1716231126

View attachment 1716231127
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Yes the fluid passages use a new billet plate. Where your ~1.5”x2.5” plate that states 22XODLU is is where the Transbrake solenoid would go which. Call cope and ask for the Transbrake plate and solenoid. All that is is a fluid passage and with a solenoid in place your blocking fluid to that circuit until you open the valve by pressing the button. Here is my valvebody for reference

IMG_1573.jpeg
 
Don't think I'd want a trans brake in a truck though
 
@Turbosmblk Thanks for that info. I might be able to use a push-on/push-off toggle switch to leave reverse engaged if I need both hands for parking lot maneuvering rather than a momentary contact push button.
 
@RogerRamRod yes that’d be fine. You just need some electrical switch to close so the brake will energize. It doesn’t care if it’s momentary or constant. I know it won’t work in your application, but I use the Holley efi software to turn on the Transbrake when in “neutral” so I can back up without holding the button. If I want neutral I can press the “bump” button while in neutral only to turn off the brake
 
Got a related question about these transmissions
When they changed the naming system from "a500" to "42/44RH" what would be the differences within, between them?
Would the 44 have more clutches and Steels than the 42 version, more planetaries, what?
 
Yes the second digit is always the load rating from the manufacturer. The 42 is for a 6 cylinder jeep, the 44 came behind a 318.
 
hey chris, while we have you on the line... what's the HP/torque rating for a 42/44 vs the 46? since the 42/44 is 904 based, i assume all the parts & practices to beef one up in order to handle more power would be the same?

i guess what i'm asking is would it be worth it to build out the 42/44 over a 46 for a mild application to take advantage of the lower parasitic losses? or is that a bunch of nonsense and the cost to build one is the same as a 46 and the power loss is negligible?
 
The cost to build the 46RH/RE for more horsepower is significantly more. The upgrades are basically the same as the 727.

The disadvantage of the a500 style trans is the lack of upgradeable parts (lockup input shaft namely). So similar to the 904, 500hp would be pushing it for the a500 in my opinion.

Slightly less geartrain power loss, but with the overdrive that will be the majority of power the loss with both transmissions.
 
Duster346 said:
The cost to build the 46RH/RE for more horsepower is significantly more. The upgrades are basically the same as the 727.

The disadvantage of the a500 style trans is the lack of upgradeable parts (lockup input shaft namely). So similar to the 904, 500hp would be pushing it for the a500 in my opinion.

Slightly less geartrain power loss, but with the overdrive that will be the majority of power the loss with both transmissions.
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thank you so much for your time and expertise on the matter.

i was weighing the difference between beefing the smaller trans vs just running the bigger unit with good parts/more clutches, etx. and it sounds like kind of a wash and either would do for the power level i'd wind up with.
 
remember that there is more to be done to accommodate a 46RH in an A-body as opposed to a 42RH as far as floor pan mods.
 
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