46RH (A518) Conversion project

[Sasquatch]

I just started down the rabbit hole.  I have been researching an 46RH (A518) trnsmission swap for a while now.  I have researched more about these transmissions than I would have thought possible.  I was ready to pull the trigger when a 46RH popped up on CL for near nothing.  It is about a 1992, non-lockup, two wire, from a diesel.  I bought it.


While this will not be a step by step how to build thread, I will post important information and my feelings on the project for others to use if they are considering it.



I will be installing it in this:



1976 Executive on a Dodge M500 chassis, 440-3/727 combo.


This will be updated over the next few months as I acquire parts, fully rebuild and upgrade the 46RH, and do the swap.  I will be taking a trip from Boise to Phoenix in March which will be the real test.


What am I trying to accomplish:
1. Lower noise levels inside.  At 65mph I am turning 3100 rpms, the girl is noisy.
2. Be able to cruise at 70 easier.  Out here in the west we have endless miles of open freeway with 80+ mph speed limits.  65 gets old real quick.
3. Maybe better economy.  But I am not holding my breath there.  Lower RPM's does not always equate to better mileage.  As long as I get #1 and #2 without loosing mileage, I am ok with that.


Regarding point #2.  The chassis on my coach has not only been completely rebuilt, but upgraded with Bilsteins, air ride on all four corners, larger sway bars, 225/70/19.5 radials, all new brakes from the master cylinders to wheels, and a fully rebuilt steering system.  I feel quite comfortable and safe in her at 70.


Issues that I needed to consider and address:
1. Reliability of the 46RH.  Through quite extensive research, the real reliability issues showed up when they went to the lock up torque converter.  I do not have this.  Other reliability issues have been completely taken care of by the aftermarket performance industry over time.  These issues will be handled during the rebuild process on mine.  Many of the reliability myths floating around the net, while based on some level of truths, have either been blown out of proportion, or were tracked down to misuse or poor servicing.


2. Will it handle the load?  Yes.  Countless Dodge one ton diesels have traversed this country towing massive 5th wheel trailers once the few issues were dealt with without much issue.  They are pulling much heavier loads than I am.  Many with over 200k miles on the transmissions with needing nothing but regular servicing and adjustments.  A well set up cooling system is a must.


3. Differences between the gas and diesel versions of the early 46RH.  Namely the difference in shift points.  I already found how to address this and have a new hydraulic governor assembly from a gas unit on order.  The other differences are actually a benefit to my application.  Stronger planetary gear sets, more clutches in a couple of the packs, stronger shafts.  These are all good things.


4.  How to mate it to the 440.  The easy route is by cutting off the original bell housing and installing an Ultra Bell adapter.  $450 and direct bolt up.  I am going to make an attempt at removing a bell housing from a BB 727 and welding it onto the 46RH.  I have a full machine shop and am a proficient welder.  My time is free.  It will be a process, but I am in no real hurry, and if it does not work to my liking I will just go the Ultra Bell route.  I have read threads on Mopar forums where others have done this with good results.


5. Dealing with the loss of the tail shaft mounted parking brake:  First, I rarely use the barely effective stock parking brake.  I have HWH hydraulic leveling jacks and always park on level surfaces in RV parks anyway.  So I am going to use a manual line lock for the rear axle for the short term needs where I need more.  I can add an aftermarket disk type parking brake to the drive line down the road if I feel I need it.


6.  Electrics; controlling the overdrive.  It is just a two wire system, hot and ground.  I am going to put a toggle on my shifter and an adjustable vacuum switch on the engine.  When the OD is on, and if I am on cruise control and start up a hill, if my vacuum falls below my preset amount, it will automatically kick me out of OD.  If the conditions are right where it hunts between 3rd and OD, I can just manually shut it off.


So grab a cold drink, follow along with Sasquatch's follies, I am sure there will be some mistakes that will give you something to laugh at.  If you have info you think I should know, pipe up.  If you want to harass me for such a project, go ahead, say what you want.  Other than that, enjoy.

[legomybago]

I like it 

[Rickf1985]

The 46RH IS a lockup converter transmission and that IS what you want for lower transmission temps and better overdrive performance. There are plenty or high quality torque converters out there. Be sure you don't use the diesel converter since it is a very low stall converter and you will be below your power band.



"The 46RH transmissions that were used from 1990-'95 have a three-pin electrical connector on the driver's side of the transmission which controls two solenoids, the overdrive solenoid and the torque converter clutch solenoid. These two units are mounted inside the valve body on one common bracket."

Quoted from, https://www.hemmings.com/magazine/mus/2006/07/Chrysler-A-518-Overdrive-Transmission/1301453.html

[Sasquatch]

Rick, with all due respect, the first generation 46RH in the DIESEL trucks (90-92.5) were not lock up converters.  All 46RH transmissions mated to gas engines were.  You can tell the difference by looking at the plug on the transmission, 2 wire is non lock up, and 3 wire is lockup.  (2 wire simply switches overdrive, 3 wire switches overdrive on one pin, lockup on the other (3rd is ground))  To add to this, the non lockup 46RH transmissions will accept standard big block 727 torque converters.  The transmission I have is a two wire, non lockup unit.  The second check is to look at the input shaft and torque converter, if the shaft is splined to the end of the shaft, it is non lockup.  If it has about 1.5 inches machined like a pilot shaft with no splines on the end, it is lockup.  The final is that I checked the transmission part number stamped on it and it showed it as a non lockup unit from a 1992 3500 turbo diesel.

But I do agree with you that lockup will allow the transmission to run cooler.  And I agree to not use the diesel torque converter.  After much reading on the diesel Mopar forums the consensus is that the heat can be easily controlled in the trucks for hauling heavy loads by putting a massive transmission cooler on the front of the radiator and not using OD while pulling up hills.  I have one in the works for this.  I also have a sump temp probe in my 727 that I will transfer to the new transmission to keep a watchful eye on it.

I will be buying a new torque converter when I am ready.  I already spoke with a reputable builder about my project and he said he will build me a weighted TC for my externally balanced 440 that will have the right stall speed to function properly for my application.  He was quite excited about the project and said I was on the right path so far and asking the right questions.

I also learned that if I have my vacuum switch working properly that switches OD off at the right point, the transmission will not get too hot, especially with a properly sized cooler.  But load it by pulling a hill in OD, and yes, temps will go up.  I will just have to watch the temps and calibrate the sensor and learn.  Worst case is that I will just switch it off in the hills with the switch on the shifter.

And you are probably right that the lockup unit would have been the better choice, with less "learning" to keep it cool.  But, I got this one right, so I am going to deal with it and see how it works.  If I fail, I will hang my head and admit my mistake and then buy you a beer... =)

[Rickf1985]

Sounds good and since I don't drink you get by cheap with buying me coffee.   Be sure to keep us updated.

[Sasquatch]

Well, I don't drink either, so coffee it is.

Update:  I found a good used 727 out of a motorhome for sale locally for $50.  I am going to try and cut the bell housing off of the 727 and the 518 and weld the 727 one on to the 518.  The front housings are almost identical castings between the two, so that will make it easier.  I have a full machine shop, so getting the two housings machined to match each other while time consuming, will not be a problem.  I have seen this done a number of times with success, so I am taking a shot at it.  Worst case scenario is that it does not work to my satisfaction and I have to remove it all and just order an Ultra bell adapter which bolts to the pump housing using longer bolts.  So the worst case is it costs me some hours and an extra $50.  If I can pull it off like I think I can, it will save me $400.  Lots of measurements, and patience will be required for this part.

I hope to start pulling the 46RH apart this week, or maybe this weekend to assess it's condition.  I spent some time talking to the very knowledgeable folks at the local trans parts supplier and getting parts pricing for all the rebuild stuff.  Replacing everything inside will run me about $325.  I wish my Porsches and BMW's were that cheap.  He suggested pulling it apart first and finding out what it needs, but I may opt to just replace everything with new.  Breaking down in the middle of nowhere in a coach does not interest me.  Not like we are talking thousands of dollars here.

[srosa707]

Sounds like a fun project.  Ill be watching this one for sure.

[Sasquatch]

11/17/17 Update:  Donor bellhousing is removed from core 727 case.  46RH mostly disassembled.  I am not seeing anything in the transmission yet that screams problem.  The o-rings are hard, probably some pressure loss, bands look good, etc.  I will pull the clutch packs when I am ready to start assembling.  I mainly want to get the front case bare today so I can start measuring where to cut....

[Rickf1985]

Pictures man!! We want pictures!!!!

[Sasquatch]

I pulled the 518 apart and rough cut off the bellhousing, I also rough cut the 727 bellhousing.  Then chucked them in the mill to dress them to final size.  They fit perfect.  Will weld either tomorrow or on Monday.  I am beat today and I need to clean on them a bit because cast aluminum is a bit tricky, then add oil to the mix....

[Rickf1985]

Getting the oil out of the castings is going to be tough. Are you TIG welding? Some REALLY nice work there! DAMN I wish I had a mill and lathe!

[Sasquatch]

There is also the brake and shear.  But all they do is create work for yourself.  Yes, I have a nice Lincoln square wave TIG that I will be using.  I had a hard time deciding between the TIG and JB weld though........ =)

[Froggy1936]

I would try spray choke cleaner , It penetrates the surface well and lifts out oil , then finish with brake clean spray Stay away from welding area both are highly flamable  , Unless you decide on JB Weld , You could also add some straps on the outside  W%  Frank

[TerryH]

 :)rotflmao :)rotflmao :)rotflmao :)rotflmao

[Rickf1985]

The only way I have found to get oil out of castings for welding is heat and soapy water alternating. Heat on the kind of machined surface you need will be iffy though, curious to see how you go about it.

[Sasquatch]

I am far from a professional welder, but I can usually get it done.  Sometimes it is not pretty, but it will be strong.

My technique for dirty cast is I do my best with simple green and a wire brush.  Then I use a new flapper disk on the angle grinder and grind the entire surface I am welding.  If it was really bad, like this one, I will also use a propane torch to heat the area and boil out the oil.  Like you said Rick, heat, clean, heat, clean. 

My final step is the weld itself.  I use the "Clean" setting on my Tig and just pour the heat into the weld allowing the crap to come to the surface.  In cases like this I am not going for pretty.  No stacked dimes.  I want it strong.  If it starts to go to crap, I stop and reevaluate the situation and start again.  It should be fine.  I will be welding it on Monday.

Froggy, If I am not happy with the weld, trust me, I thought about adding some webbing across the weld in some critical areas.  I highly doubtful it will come to that.  I would just say I added fins for cooling... Makes it go faster.

[skloon]

I worked at a machine shop and they had a huge oven thing that they baked parts in to get oil out- don't know if it would work on this

[Sasquatch]

I worked at a machine shop and they had a huge oven thing that they baked parts in to get oil out- don't know if it would work on this

Well, I am single and can remove the batteries from the smoke alarms at home.....

[skloon]

Well, I am single and can remove the batteries from the smoke alarms at home.....

That sounds like me using the oven to cure powder coating-

[Sasquatch]

I would not do it.  Just joking.  That stink would linger all winter in a house.

I forgot an old trick we used all the time back in the VW days, easy off oven cleaner, let it soak, then blast it with a hose.  Should take care of the big build up, then work on the weld areas by hand.  I will update tomorrow.  Hopefully it welds good.

[legomybago]

This 518 tranny was out of a 90's small block 4x4 truck, he was able to buy a 440 bolt up adapter. It is going in an FMC coach. Is this the same tranny you are using?

[Rickf1985]

My question on that adapter would be what is he doing about the extra length of the adapter? Spacing the converter out from the flywheel is about the only option and that adds stress to the mounting points on the flywheel/flexplate.

[legomybago]

yeah good question Rick, I don't know about the TC/flexplate spacing, he was able to retain the factory starter motor mounting position by relieving some of the 518's case. it's in a motorhome now being tested though....

[Sasquatch]

Basically the same transmission I am using Lego...  Mine is from a 1992 Dodge diesel.  The diesels have a stronger planetary sets, and more clutch plates in a couple of the packs I believe, but basically the same.  Mine is from a 2wd.

I picked up a master overhaul kit, new bands, and a Transgo shift kit this morning.  $331.  Not bad.  Photos from the welding to follow later today.

Lego, keep me posted on how the testing is going.

[Rickf1985]

So much for "Taking my time"! I figure you will have this in and running by Christmas.