Transmission swapout

[THuebner]

Hello to all,

And thank you ahead of time to those who respond.

OK, I have a non-intercooled 91 with the 727 3 speed auto.

With the high cost of fuel, I want overdrive.

Should I buy an aftermarket overdrive unit, or just replace the 3 speed with an overdrive transmission.

I do not tow or haul heavy loads. I do plan on putting an Outfitter Apex

9-1/2' pop up slide in camper on the truck. But that seems like a rather modest load for this truck.

Two further thoughts:

1- The 727 is bulletproof if not fancy. The 4speed trans that replaced it in later trucks seem more fragile.

2- Since the 727 does not have a lockup torque converter, if I decide to install an exhaust brake later, I will need to do something with it anyway.

Any and all suggestions and observations are very welcome.

Tom

 

[dpuckett]

The later, non lockup OD 518s are basically a 727 with an OD unit thrown on behind it. All the guts for gears 1-3 are identical, from what I understand. I know a guy who will have a 518 core within the next couple weeks.



If you are looking for the best of both worlds, get a 47RH from a 94-96, and have it built to match your engine output (or what you want to eventually end up with). That way, you can lock the convertor and use the exhaust brake.



The main problem with the 518 is the TPS that controls OD engagement.



Daniel

 

[cerberusiam]

If you are going to the work of swapping in an OD trans, do the 47RH. If you can get a 518 cheap, it can be upgraded to a 618 with little trouble.



Either way, that lockup gives you much better rpm for efficiency and really puts the power where it does the most good.

 

[THuebner]

Thanks for taking the time to reply. 47RH it will be then.

OK, what will have to be done to my truck and or the trans to get the 47RH to function properly?

Tom

 

[Steve Graham]

IIRC, thoses trucks came with 3. 07 gears, your going to need 3. 54 gears to gear it correctly. The bad part is the axle housing is special to the 3. 07 and nothing is interchangable with the other housing, you have to change out the axle to change to 3. 54 gears.

Do not add a exhaust retarder (brake) to a truck with an automatic, you will burn up the transmission in short order. What happens is your using the engine as a brake, the engine goes to idle and starves the trans for fluid. IF the trans had a pump connected to the output shaft you could get around this, but they don't have one.

 

[cerberusiam]

Thanks for taking the time to reply. 47RH it will be then.

OK, what will have to be done to my truck and or the trans to get the 47RH to function properly?

Tom

From a 1995 model truck with auto trans you will need:



Engine adapter

Flex plate (this is an upgrade from the gen pieces)

Starter





From a dodge dealer you can get a pigtail that has the correct wiring plug on it for the OD and TC lockup. This plug is a bit tricky as it is not listed in the regular system but a seperate little book that has a multitude of wiring connectors in it. At least it was when I did mine. If I ever get home long enough I will check and see if I still have the PN numbers.



To control lockup you can do a simple mystery switch, or, get an electronic control box from ATS that will allow it to work automatically and allow you to use and EB with it also. A few more dollars than a simple switch but more versatile.



The 47RH is 2. 25" longer than what you have, at least a 518 and I believe the 727 was the same length. The extra length is in the TC for the lockup. This means you will have to move the bell crank for shifter back on the frame by drilling new holes, lengthen the shift rods on the t-case shifter, and change the mounting point for the t-case. The t-case mount can be done by adding an extender plate and using the factory position of the cross member with good results.



You may or may not have to change drive shaft lengths. A lot will depend on the stance of the truck. The rear should have enough slack to not need shortened and the front will be real close. I have seen it done both ways and it is a personal choice and usage that will determine what you can live with.



Steve brings up an excellent point, if you have 3. 07's it will be tall in OD and with lockup you will have some hefty rpm drops. The 3. 54 is better suited for all around use but some have and like the 3. 07's. A lot will depend on your towing weights.

 

[cerberusiam]

Do not add a exhaust retarder (brake) to a truck with an automatic, you will burn up the transmission in short order. What happens is your using the engine as a brake, the engine goes to idle and starves the trans for fluid. IF the trans had a pump connected to the output shaft you could get around this, but they don't have one.

Not quite sure where you are going with this, but, the thousands of trucks running around with EB's on them would seem to disprove that theory.



When you use and EB you have to knock it out of OD to get any engine braking out of it. Yes, it will over run in OD but that is known and provided for. Any time the TC is turning the pump is circulating fluid and supplying pressure. The pressure, or lack thereof, is the bigger issue. One normally does not run an EB long enough to hurt the trans for fluid flow but unless the rpms stay up somewhat the clutches could slip. This is the reason most brake srelease at 35 mph or so.



With a lockup TC you don't have this problem as part of the EB install is to lock the TC and hold it until brake release. Coupled with down shift to drive there is no chance of damaging the trans for lack of fluid flow from that perspective. Obviously a good TC clutch and enough pressure to hold it is a prerequisite.

 

[Steve Graham]

Besides the possibility of a fluid puressure problem there is the fluid heat build up from using a EB with an auto, a autos worst enemy.

When I had my EB installed by Cummins years ago, they were quite adamant they would not put a EB in a Dodge with a automatic and it's only been recently that Dodge has allowed a EB to be used with their automatics under warrantee.

 

[Cummins Thunder]

So long as line pressure is adequate and you have proper cooling and or a locking converter you will be fine. Remember the fueling is at an idle but the pump is still turning the same rate as the engine typically at least 1300rpm when the EB is engaged.



And as for dodge just recently allowing the EB on autos... Did anyone else notice that came along around the same time as the electronic line control? Why do you think BD makes that pressure loc thing.

 

[cerberusiam]

Besides the possibility of a fluid puressure problem there is the fluid heat build up from using a EB with an auto, a autos worst enemy.

When I had my EB installed by Cummins years ago, they were quite adamant they would not put a EB in a Dodge with a automatic and it's only been recently that Dodge has allowed a EB to be used with their automatics under warrantee.

What Dodge will allow for warranty and what actually works are 2 entirely different animals. :-laf I think that has been proven often enough.



People have been using EB's on autos for years with no ill effects, provided the install was done correctly.



As I said before, as long as the TC is turning you have adequate pressure and cooling flow. The engine will not go to idle unless it is in overun mode or the speed has dropped enough break the fluid coupling. Increase the tighness of the converter and you decrease the speed cutout. Pretty easy to try oneself. Knock the trans out of OD at 65 mph and watch your rpm, downshift into 2 at 45 and watch the rpm. As long as that rpm doesn't drop under 1200 rpm's or so you will have no issues with flow and pressure.

 

[THuebner]

Thank you to all who are responding to this thread.

The truck does indeed have a 3. 07 rear end.

Cerberusiam, thanks for the excellent detail on how a refit with a 47RH would have to go. I have to admit to feeling uneasy about the need for drilling holes and repositioning the transfer case etc. in an otherwise perfectly good truck.

Is it possible to have a lockup torque converter in a 727 or 518? At this juncture, I may just get a Gear Vendors underdrive/overdrive unit.

One interesting thing on their website that I do not understand, they list three different length tailhousings for the 727 trans: 18",12",8" How and why the different lengths? Would that make a difference as to how readily a 47RH could be retrofit?

Gear Vendors Under/Overdrive Dodge/Dodge RAM 2-Wheel Drive 3-Speed Automatic.

Thanks.

Tom

 

[cerberusiam]

Is it possible to have a lockup torque converter in a 727 or 518?

It should be possible but not positive. There are those that claim it can be done on a 518 so it should be possible on the 727. Something to research if you are so inclined.

three different length tailhousings for the 727 trans: 18",12",8" How and why the different lengths? Would that make a difference as to how readily a 47RH could be retrofit?

IIRC, there are different shaft lengths for the different applications the 727 was used in. I don't think one of those will fit between the trans and t-case without moving the t-case, but, its worth a shot to call them. If you gotta move things around and drill with it, well, your choice.



The addition of the gear vendor as opposed to the 47RH is an old argument. You loose a LOT by not getting a lockup TC. You will have to basically rebuild your 727 to work correctly with the OD unit anyway and even with a tighter converter it still not as effective.



It is definitely a bit of work to retro a 47RH in there but the results are quite good. Your truck, your money, your choice. I am just giving you pros, cons, and my thoughts.

 

["Mad Max"]

Let me float a couple thoughts too



Regarding mileage - what is your fuel mileage as it is now? For the most part, those of us with 518's and 3. 54 gears are getting an average of 20 mpg. I'd guess you may be close to that number with your current set-up?



Not to dissuade, but let's discuss some costs. After all is said and done, the cost of a GV will be over $3000. Assuming :-laf you'll be dialing up the engine output, you'll want/need a better-than-stock 518. The cost of a good 518, one that has been rebuilt and has at least a good aftermarket converter (DTT, Suncoast, ATS, TCI, etc) and valve body, will be about $1500.



Your biggest issue is axle gearing - any transmission change will likely 'need' an axle swap. Swapping out axles from, say, a '93 Cummins rig (which will have a dana 60 front and 70 rear, likely with 3. 54s. . maybe 4. 10s), will cost about $1100 (assuming a rebuild is not necessary). Any rear dana 70 at/near 160,000 miles will require a rebuild soon - thay ALL do at that point, and a quality rebuild goes for about $1300. If you're looking at towing/hauling a heavier load or a trailer you'll definitely want more engine power.



Now, all that said, you may get everything you need by simply cranking up the engine power. My '93 came stock at ~130 hp. I am now pushing ~300 hp... and I get the same highway fuel mileage - 20 mpg. The engine will only use the fuel it needs to maintain speed, so the fuel mileage tends not to change on 'normally' modified rigs.



If your current mileage is close to 20 mpg, I'd recommend a $19 dollar 366 spring (which will give you a LOT better highway legs), and some turbo/exhaust upgrades. With the increased power... you may not need to change out the gears and transmission.



Lastly, have you considered a 5 or 6-speed swap? With, for example, a nv4500 5-speed, 1st and 2nd gear are very low range - lower than 1st gear in either a 727 or 518, so with your 3. 07 gears you'll actually be able to use 1st and 2nd with 5-speed. Plus, there's the top gear over drive.

The nv5600 is even better with the additional gear, giving you 5 gears before the fial overdrive verse the 5-speed which has of course only 4.



I am doing a nv5600 conversion on my '93 - mainly for the lower initial gears and, most importantly, the exhaust brake ability. The cost for a manual trans conversion can be close to $4000 - about $3000 for a good transmission, and about another $1000 for clutch and misc parts.



So, in the end, you're looking at serious cabbage for either transmission swap. You could do some engine mods now and see if you get what you like. If not, maybe then look at transmission swaps. There's really no bad route to go - just depends on what ya really 'need'. Lot of $ to save ~2-4 mpg.



- M2

 

[dpuckett]

THuebner- If you had a p/u dually, I'd say lets meet in the middle and swap axles- I got a set of 3. 54s. Try the spring- you may be surprised. Also, keep the OD with your 3. 07s- you have the same ratios as you do in your 3spd with an OD for extra RPM drop/ MPG at highway speeds. There are a few guys running 3. 07s and OD in one form or another, and get great results (the exception being Philip, and his 18-19mpg). With the low end capability of the VE'd trucks, I dont think you will want to go any lower than 3. 54s, unless you tow heavy (20K+ GCVW) daily. Otherwise, you just waste RPM and fuel. How many newer trucks do you see with only 280hp and 700+ torque?



Daniel

 

[THuebner]

Thanks to you all, gentlemen, for taking the time to educate me.

1-As for a retro fit to one of the excellent manual trannys, I really prefer sticking with an auto trans. Good thought though.

2-I do not haul heavy loads. The most I envision on this truck is a 1600 lb Outfitter Apex 9-1/2 foot pop up slide in camper and a small (1000 lb. ) trailer.

3- I like having the 3. 07 rear end. If an upgrade or modification for efficency comes with more power great, but I am more interested in efficiency and reliability than raw power.

4-The truck averages 16-18 mpg doing mostly around town driving. The truck has 122,000 original miles on it. It was dyno tested at 115,000 miles and at 60. 3 mph put out 152 hp and 1411 what they termed R1 torque. At 50. 2 mph on the dyno it put out 142hp and 1585 R1 torque, and at 39. 7 mph the figures were 125hp and 1770 R1 torque. the duration of the test was a minimum of 60 seconds at each speed.

5-Extra power has not been a major interest, but reading all of your responses made me realize that certain modifications for extra power may yield the economy I am really craving.

6-Ceberusiam, you said: You will have to basically rebuild your 727 to work correctly with the OD unit anyway and even with a tighter converter it still not as effective. " May I ask why? I assume it once again goes back to the current lack of a lock up torque converter. So even if I go the easiest route of buying the Gear Vendor unit, I will still at least need to do a certain amount of work to the transmission I already have in order function properly with the Gear Vendor unit.

7-This is a really nice, basicly stock truck, maybe I should just sell it and buy a good used 96 in order to get O/D.

8-Hey Max, I live in Colorado Springs! And you are right, it is a lot of $ for a modest pickup (pardon the pun) in fuel economy.



Great info. Very interesting discussion.

Tom

 

["Mad Max"]

Holy smoke! (pun intended) yer in the 'Springs? Well shoot, I think we needs to have us a 1st gen party out at the ranch. We're actually in the NE corner in Falcon, out by the intersection of Woodmen Rd and HW-24.



I'm working on our '78 Ramcharger in the shop now and I'm getting ready to do the pump - no reason we can't do 2 - maybe three if my buddy T. J. brings his W350 out. I've been thinking of setting up a 'Pump Party' at the shop - we do about 1 a year, and maybe this is a good time to set one up. Interested? Won't cost much at all for parts, and I'll organize it all in advance so there's no surprises.

Typically at a pump party it involves cracking open as many 1st gen VE's as possible and going into them no further than replacing 'the spring', making some adjustments, and freeing up some free power - literally.

I have a couple recommendations for some good parts to get, namely the 366 spring ($20) and a new pump-to-throttle linkage kit ($35?). Those two items, plus the tuning, and I bet we can crank out 30 hp and make the truck feel a ton better. It's really amazing what a few simple mods can do.

While we're at it we can convert your 1st gen transmission shift lever over to the 2nd gen one - the one that has the O/D on-off button at the tip of the lever . It takes about a 1/2 hour and you'll love the retrofit, and it's a 100% bolt-in gig. T. J wants to do his too.



So anyway, come out to th shop sometime and while I'm wrenchin' on the RC we can talk trucks - one of my favorite past times.



See ya Tom



- Sam

 

[cerberusiam]

While we're at it we can convert your 1st gen transmission shift lever over to the 2nd gen one - the one that has the O/D on-off button at the tip of the lever .

Getting a bit ahead of things there Max? He doesn't even have an OD, yet. Ahh, the exuberance of youth, its wasted on the young. :-laf:-laf

I will still at least need to do a certain amount of work to the transmission I already have in order function properly with the Gear Vendor unit.

I would highly reccomend it. With the miles you have and the fact that transmission was just borderline capable without OD at the stock power level, it may eat itself up in a hurry without attention. I would be worried with any weight on, 3. 07's, and an OD it would want to slip the direct clutch pack due to the low rpm's and line pressures.



Its a personal thing to put the kind of money into one of these trucks to update it. Some would say not a good investment, but, its the reason a lot of us drive these trucks.

 

[Tippin Spotted Cow]

I'm pullin my 518 O/D'd transmission out and replacing it with a Getrag that DPuckett is building for me. Right now it works, but its got some issues.



At idle in gear with your foot on the brake, for some reason it brings the idle of the motor down to around 500-600rpms. If you shift into neutral or park the engine goes right back to normal.



When you take off, it smokes like a freight train and barely moves for a second or two, then kicks in and takes off, but even then the truck is rather sluggish. Luckily when I'm moving my turbo is spooled and my truck has enough power to still move out pretty good... it just feels like you're riding the brake. The transmission is a reman unit, all brand new internals. They won't warranty it because they don't believe the cooler lines I have on there are factory lines. They made me go to a Dodge dealer and have them put factory lines on, but the dealer I went to, $98 later for a “visual inspection” claims that the lines are factory, have no leaks, and should not attribute at all to the transmission failing. I talked to the owner of the shop that installed it, and he believes it's something electrical and the the torque converter is staying locked up. Yes, I did tell him it's not a lockup. All his mechanics leave before 4:00, that's when I get out of work and it's an hour drive, so I didn't get to talk to them.



Knowing about 2. 5% about how an automatic transmission works or even what one looks like inside, my SWAG is that one of the clutches is getting stuck shut. Is that possible? Is it probable? Is it my cause? I haven't the foggiest. Others have told me it sounds like a torque converter issue.



Anyway, I would believe that 95% of the internals are still good. It was a fully reman unit that was put in about 2 months ago. My truck has a lot of upgrades and that's why I'm switching to a manual. This transmission should be ok behind your motor. If you find someone who knows about autos, they might be able to get this one runnin like a dream for you. After all I've been through with stock autos behind a non-stock motor I'm sure it wouldn't take a whole lot for me to part with this one. I have no need for the torque converter, which is also new, so not knowing if that's what the problem is, I'll just throw it in with the transmission if you want it. I'll give you the TPS for the overdrive, the factory dash mounted O/D button, and any other electronics that come with the auto transmission that you might need. As well as the cooler by the radiator, the one on the side of the motor, all the lines, and even the underbed auxiliary if you want it with the transmission too.



Depending on what I find for my Getrag swap, for a little more I might be able to part with my t-case adapter and t-case as a whole assembly with the transmission if your interested. But I'm not positive that I'm not gonna use them yet.



Anyway, I'm not trying to give you some sales pitch. I just will have no where to go with this thing, and I know it's at least worth a core. It'll probably sit in the basement for a while otherwise, or I'll take it to the place that remanufactured it and see if I can get anything. If you're considering it but not sure, just let me know and I'll hang on to it for a while.

 

[THuebner]

Good evening gentlemen,

Cerberusiam, I get the idea that the 727 cannot be upgraded to the point where it will handle the load that a Gear Vendor unit, lockup torque converter (if I can get one for the 727), an engine brake, and the 3. 07 rear end will place on it. You had mentioned in an earlier post that the 518 can be upgraded to a 618. What is the difference and will the 618 bolt in to replace my 727 in like a 518 apparantly will?

Dan (Puckett) in an earlier post you mentioned:The main problem with the 518 is the TPS that controls OD engagement. What is a TPS, and can the problem be aleviated? Is there a similar problem with the 618 transmission?

I'm still thinking that my best option might be to sell the 91 and get a 96.

Thanks to all you guys.

Tom