A518 auto trans. question

[niceolddart]

I pulled a A518 trans out of a 1990 4wd Ramcharger that I'm scraping. How difficult would swapping over to 2wd be? Just a tail shaft change? Output shaft change? Has anyone done this & is it worth doing? It was a working truck when I bought it, so I know the trans works. TIA

 

[rbkt65]

mopar parts giant does not show a difference between the intermediate shaft from 2wd to 4wd. so you should be able to measure the select washers and just swap the o/d unit.

 

[TT5.9mag]

I pulled a A518 trans out of a 1990 4wd Ramcharger that I'm scraping. How difficult would swapping over to 2wd be? Just a tail shaft change? Output shaft change? Has anyone done this & is it worth doing? It was a working truck when I bought it, so I know the trans works. TIA

Send me the trans crossmember! Wait, 4wd might be different.

 

[1WildRT]

As mentioned the O/D unit needs to be swapped...

 

[niceolddart]

If I can find a cheap, used O.D. unit for this trans, I'm going to try it. It will at least be a learning experience. I've never messed with one before, aside from fluid/filter change & adjustments & whatnot. Thanks all! I know small block 518/727 are getting more difficult to find, that's why I can't scrap it.

 

[1973Barracuda]

Be careful with that OD section. I am not a transmission dude, but from what I understand there is a big spring in there. Was told that when I was going to do the 518 swap.

 

[Bobzilla]

Be careful with that OD section. I am not a transmission dude, but from what I understand there is a big spring in there. Was told that when I was going to do the 518 swap.

Correct, there is a big coil spring in the overdrive assembly that needs to be compressed to get a snap ring out, then the spring tension released properly for disassembly. But you CAN remove the overdrive assembly from the transmission safely without concerns of that spring. The spring only comes into play during that disassembly of the overdrive unit itself.

 

[Bobzilla]

Send me the trans crossmember! Wait, 4wd might be different.

Are you converting that old Dodge truck to overdrive?

 

[TT5.9mag]

Are you converting that old Dodge truck to overdrive?

It will have a 46re in it eventually

 

[67Dart273]

Probably the most difficult part will be actually finding a 2wd donor!!!

 

[Bobzilla]

I pulled a A518 trans out of a 1990 4wd Ramcharger that I'm scraping. How difficult would swapping over to 2wd be? Just a tail shaft change? Output shaft change? Has anyone done this & is it worth doing? It was a working truck when I bought it, so I know the trans works. TIA

The problem is you will likely find a whole rear wheel drive transmission and then instead of swapping the overdrive unit you can just use the rear wheel drive transmission. They are out there. If you get desperate drive up here to Michigan and I will show you where the self serve yards are at.

 

[mbaird]

Probably the most difficult part will be actually finding a 2wd donor!!!

I keep an eye on pickaparts for 46rh ‘s . Look for 90-92ish vans and 2wd trucks .

 

[Bobzilla]

You can find the RH models in anything that was still running an OBD1 PCM with the single large PCM connector. That can be all the way through 95 model year and some early 96s, as long as they were not three speed auto or any of the manual transmissions.

 

[JDMopar]

Will an OD unit from a 2WD 46RE transmission work on a 518/46RH? If so, it may narrow the search a little.

 

[Bobzilla]

I don't remember the specific differences in the overdrive section between the RH and RE models. Good question.

For a view of the rear wheel drive 46RH with the overdrive section removed check out this thread below. Also for @TT5.9mag it shows how he was able to use the old style three speed crossmember and mount to install his 46RH. The crossmember was changed for the trucks that got those transmissions from the factory and it used a mount that spread the load across a larger area. I posted pictures of two of the styles of crossmembers in that thread as well.

A518 46RH rebuild

 

[mbaird]

I just found 8 potential rwd 46rh donors in a quick online search of our pickaparts

 

[Bobzilla]

I just found 8 potential rwd 46rh donors in a quick online search of our pickaparts

We have a bunch here too in Michigan but the problem is they randomly come in waves, then there are dry spells when none are around. Also it is somewhat regional. Some areas simply did not have as many of these trucks driving around their area, so they are not as common in the yards in there. With Chrysler headquartered here there are usually some to be found in our yards.

 

[TT5.9mag]

I don't remember the specific differences in the overdrive section between the RH and RE models. Good question.

For a view of the rear wheel drive 46RH with the overdrive section removed check out this thread below. Also for @TT5.9mag it shows how he was able to use the old style three speed crossmember and mount to install his 46RH. The crossmember was changed for the trucks that got those transmissions from the factory and it used a mount that spread the load across a larger area. I posted pictures of two of the styles of crossmembers in that thread as well.

A518 46RH rebuild

I remember that thread. For some reason I stopped getting alerts from it even though I had commented there. Thanks Bob, good info there.

 

[rbkt65]

I have a friend that was the instructor at the St. Louis Chrysler training center, the district manager and now an auto teacher at SIU Carbondale, Ill. We discussed this very thing about changing the 46re tail housing to 46rh. He said it should work. The reason that I want to do it is for speedo cable installation to run my speedometer.

 

[Bobzilla]

I have a friend that was the instructor at the St. Louis Chrysler training center, the district manager and now an auto teacher at SIU Carbondale, Ill. We discussed this very thing about changing the 46re tail housing to 46rh. He said it should work. The reason that I want to do it is for speedo cable installation to run my speedometer.

I can't find the 1993 service manual I have. I was going to look at the internals. I think the RH has an actual governor assembly in the overdrive unit, but I cannot remember for sure. I know the RE does not. It uses a solenoid to modulate "governor" pressure, simulating the effect a mechanical governor would have inside the valve body. That is a generic oversimplification of how the RE operates from a big dummy.

So, if you put an RE overdrive onto an RH it would not have a way to modulate governor pressure. But would it work if you used a manual valve body? You can use a manual valve body in an RE trans and then the electronic governor system would not be used, you just shift the gears.

Going the other way, putting an RH overdrive onto an RE to get the speedo connection, I am not sure.

 

[mbaird]

Problem is it’s the 2wd rh overdrive unit that makes it desirable. Unless you can find a truck owner that has a 2wd 46rh and wants a 4wd version you are better off finding a complete 2wd 46rh. Or go to a 42rh which is easier to fit in the tunnel.

 

[Bobzilla]

I agree. If you find an overdrive unit, it is probably still attached to a good transmission core, so just get the whole thing and make life easier.

 

[volaredon]

I didn't think it would work from RE to RH or vise versa. From 2wd to 4wd no problem as long as both of them are the same/both RE or both RH.
There's 2 tubes that come out of the tail for the RH that plug into the front housing (oil supply for the governor, the very thing that makes an RH an RH) that the RE doesn't have.
Wait a minute.
The last RE I overhauled needed a new OD support. (The parts the piston goes into on the back of the main housing.) the aftermarket one came with 2 plugs that got used in the RE version. I THINK that they were left open for those tubes for using that support for an RH. So with a new OD piston support you may be able to... But electronics in the valve body are different between RE and RH so valve body would have to change to go between versions.
I do know the OD on a 42/44 version will swap with one off of a 46 of the same series (again RE vs RH) I've done that before.

 

[volaredon]

A couple of years of the "RE" still had the Speedo gear like the older ones did. I think they went to the rear abs sensor doing Speedo drive duty started around 98-99. If you can find a 96-97 "RE" it should still have the regular Speedo drive. The newer ones also deleted the spline on the output to drive one.

 

[DionR]

I do know the OD on a 42/44 version will swap with one off of a 46 of the same series (again RE vs RH) I've done that before.

I was getting ready to ask if the 500/42H overdrive was the same. Maybe those are easier to find?

I remember being told one time that there was a spacer or shim that meant you had to do some measuring and figuring if you swap an OD unit from one trans to another. But I'm no transmission guy either.