Cummins 4BT & Diesel Conversions Forums banner

If you were to chose the best Trans behind a 4bt what would you choose?

  • TH400

    Votes: 0 0.0%
  • 4L80e

    Votes: 1 25.0%
  • 4L60e

    Votes: 2 50.0%
  • AT542

    Votes: 0 0.0%
  • 47rh

    Votes: 1 25.0%
1 - 17 of 17 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
I have an 89 burb 2500 4x4, I already have a 96 4bt 130hp..it came from break truck and had Allison trans but I only got the engine. If i get the At542 will I still need to get an adapter plate etc.? If so I might as well get a different trans that has OD.. I've been recommended 4L80E and 47rh. Please help me decide what I need to get this burban going asap.

my intentions are for A. reliability, B. durability, C. comfortable highway driving. Not going to off road or pull anything heavy.. just want strong and capable reliable drivetrain. Any help is greatly appreciated!!!
 

·
Registered
Joined
·
1,658 Posts
Let's start with the basic information. Do you still have the SAE bellhousing adapter and flexplate?

130769

If so, what size?
 
  • Like
Reactions: Dougal

·
Registered
Joined
·
12,063 Posts
Let's look at your transmission choices and planned vehicle use. The TH400 never came behind a Cummins and is not designed for it. 4bts got the TH475 and even that one was only so so. No OD gear so top speed is about 50-55 MPH unless you have very high ratio differentials. The Allison AT542 is kind of in the same boat. No OD gear or lock up torque converter. Was mostly used in low speed medium duty trucks and school buses. Would require an SAE3 adapter setup. The GM 4L60e is an OD transmission but is too light duty for a Cummins. Now we get to the 2 workable units. The 4L80e can work and has been used by several members. It can be mounted using the stock GM/Cummins adapter or an aftermarket unit. Neither is very cheap unless you can find a used set of the Cummins parts. I can provided you the part numbers of the factory setup if you need them. Also, since that transmission is computer controlled you will need an outboard controller and a TPS mounted on the injection pump. Now for the 47RH. That one came behind the Dodge 6bt and has OD and a lockup torque converter. Often used because all the attaching parts for a 6bt will fit the 4bt. Does not have to have an outboard controller but there are units for it to control the OD and lockup functions. Other transmissions that have been used are the 46RH which is like the 47RH without lockup function, 47RE, 48RE, Allison 1000, Allison 3060, and a few models of Ford automatics.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #6 ·
Let's look at your transmission choices and planned vehicle use. The TH400 never came behind a Cummins and is not designed for it. 4bts got the TH475 and even that one was only so so. No OD gear so top speed is about 50-55 MPH unless you have very high ratio differentials. The Allison AT542 is kind of in the same boat. No OD gear or lock up torque converter. Was mostly used in low speed medium duty trucks and school buses. Would require an SAE3 adapter setup. The GM 4L60e is an OD transmission but is too light duty for a Cummins. Now we get to the 2 workable units. The 4L80e can work and has been used by several members. It can be mounted using the stock GM/Cummins adapter or an aftermarket unit. Neither is very cheap unless you can find a used set of the Cummins parts. I can provided you the part numbers of the factory setup if you need them. Also, since that transmission is computer controlled you will need an outboard controller and a TPS mounted on the injection pump. Now for the 47RH. That one came behind the Dodge 6bt and has OD and a lockup torque converter. Often used because all the attaching parts for a 6bt will fit the 4bt. Does not have to have an outboard controller but there are units for it to control the OD and lockup functions. Other transmissions that have been used are the 46RH which is like the 47RH without lockup function, 47RE, 48RE, Allison 1000, Allison 3060, and a few models of Ford automatics.
Thank you very much for the advise!! I really appreciate it as I’m just embarking on this fun journey! I don’t want to get discouraged as I already have the 4bt and the suburban I’ve priced out all the necessary parts but just am lost as to what trans I should use .. most of the advice I’ve received thus far from fb forums are to change direction and use 6bt because burban is too big etc.. since I won’t be muddin pullin or hot roddin and only looking for reliability and comfortability at highway speed would you recommend the same or think the 4bt would suffice ?
 

·
Registered
Joined
·
12,063 Posts
Either a 4bt or 6bt can be made to work. Since you already have the 4bt that seems the logical route to follow. You mention you engine is the 130 HP model. That could be the one with the P7100 injection pump unless you have one of the kind of scarce ones with the P3000. The P7100 engine would be CPL1839 which is the king of the 4bt models. With a little work and adjustments you can have it to 200 HP. That will have torque equal to or higher than a 454 big block gas engine. The basic mods you'd want to do are install a set of 3000 or 4000 RPM governor springs, replace the torque plate in the injection pump with a #10, and advance the pump timing to 16 deg. One other minor mod can be replacing the overflow valve in the injection pump but that isn't mandatory. Those valves sometimes get weak and need replacing. The stock turbo on that engine should be the HX30W which is excellent and stock injectors are good too. Always wise to pull the injectors and have them tested. Poor injectors can cause lots of headaches. No other major mods at that power level but there can be a few if you get into it. Head studs are preferred over the factory head bolts. Not horribly expensive. If your pull the oil pan and inspect the bearings, you need to replace the rod bolts. Cummins does not recommend reusing those. At that point you could upgrade with ARP bolts. Again, not super expensive. New gaskets and seals are a basic. Pull the front cover and do the KDP repair. At the same time remove the bolts behind that cover, clean the holes, and reinstall them with blue Loctite. Some of those little devils like to work loose and can cause grief. Whether you replace the oil or water pump is your call. If you have the engine serial number I can look it up and see if there was anything unusual. In your transmission selection, if you stay with the 4L80e your transfer case should bolt up. There is also a 4L85e which is a little stronger. If you opted for the Dodge transmission you might also consider using their transfer case. I believe yours is passenger's side drop. Dodge would have used the NP205 on the Cummins which is super strong. Something to think about.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #8 ·
Either a 4bt or 6bt can be made to work. Since you already have the 4bt that seems the logical route to follow. You mention you engine is the 130 HP model. That could be the one with the P7100 injection pump unless you have one of the kind of scarce ones with the P3000. The P7100 engine would be CPL1839 which is the king of the 4bt models. With a little work and adjustments you can have it to 200 HP. That will have torque equal to or higher than a 454 big block gas engine. The basic mods you'd want to do are install a set of 3000 or 4000 RPM governor springs, replace the torque plate in the injection pump with a #10, and advance the pump timing to 16 deg. One other minor mod can be replacing the overflow valve in the injection pump but that isn't mandatory. Those valves sometimes get weak and need replacing. The stock turbo on that engine should be the HX30W which is excellent and stock injectors are good too. Always wise to pull the injectors and have them tested. Poor injectors can cause lots of headaches. No other major mods at that power level but there can be a few if you get into it. Head studs are preferred over the factory head bolts. Not horribly expensive. If your pull the oil pan and inspect the bearings, you need to replace the rod bolts. Cummins does not recommend reusing those. At that point you could upgrade with ARP bolts. Again, not super expensive. New gaskets and seals are a basic. Pull the front cover and do the KDP repair. At the same time remove the bolts behind that cover, clean the holes, and reinstall them with blue Loctite. Some of those little devils like to work loose and can cause grief. Whether you replace the oil or water pump is your call. If you have the engine serial number I can look it up and see if there was anything unusual. In your transmission selection, if you stay with the 4L80e your transfer case should bolt up. There is also a 4L85e which is a little stronger. If you opted for the Dodge transmission you might also consider using their transfer case. I believe yours is passenger's side drop. Dodge would have used the NP205 on the Cummins which is super strong. Something to think about.
Thank you very much for the info.. it is the cpl 1839! Would I realistically be able to drive it everyday and take 1-2hr trips comfortably at highway speeds in a 2500 burb? Given all the recommended mods? Or would you recommend I just go with 12 valve ?
 

·
Registered
Joined
·
1,658 Posts
You should have no issues with daily driving your Burb. With your planned usage the 4bt will be fine.
I agree, as long as you use an overdrive transmission. You want to keep your highway RPMs below 2,000.
 

·
Registered
Joined
·
12,063 Posts
Ditto on that. The mods I mentioned will make it more drivable, especially with an automatic transmission. A 6bt probably wouldn't need any mods as its power is already in that power region. Just a bit of info. You engine shows it was built on March 14, 1996 at Consolidated Diesel here in North Carolina. Doesn't show it has ever been rebuilt by Cummins. Don't see a power steering pump so you'll need to source that and you will need a vacuum pump if you keep the older vacuum brake booster. Flywheel housing shows to be SAE2 and just a guess but does it have an Eaton 5 speed. That was about the only one that used SAE2 on those engines. Good transmission but no OD gear. Appears to be an original unmolested engine. That can be good or bad. You never know how many miles it may have on it. You'll have to decide how much of an inspection tear down you want to do. Like I mentioned earlier, a minimum would be new gaskets, seals, bearings, rod bolts, and KDP repair. If you pull the head to inspect the cylinders, that will require a new head gasket and probably head bolts or studs if you go that route. The one mistake you never make is assuming the engine is in good condition internally. It might be perfect or might need a complete rebuild.
 

·
Registered
Joined
·
76 Posts
Because an engine swap is in my future plans what kind of mileage are you expecting with the 4bt?? and good luck.
 

·
Registered
Joined
·
12,063 Posts
Just for info, the mileage you get depends on a lot of variables. Vehicle weight and aerodynamics, engine condition and mods, location on the planet, and and especially how you drive it. In heavier vehicles like trucks which are common swap vehicles, the engine will probably max out at 25 MPG with a manual transmission. You'll lose about 2-3 MPG with an automatic. More realistic numbers are usually in the neighborhood of 20 MPG. You always feel better to estimate lower and come out higher than the reverse. Don't expect to get 30 MPG in a 3/4 ton 4x4 truck. Not likely to happen. We have had a very few rare ones get into the mid 30 MPG area, but like I said those are rare. As the vehicle and load gets heavier the mileage may dip into the mid to upper teens. But that is still double what the original gas engine got.
 

·
Registered
Joined
·
2 Posts
Let's look at your transmission choices and planned vehicle use. The TH400 never came behind a Cummins and is not designed for it. 4bts got the TH475 and even that one was only so so. No OD gear so top speed is about 50-55 MPH unless you have very high ratio differentials. The Allison AT542 is kind of in the same boat. No OD gear or lock up torque converter. Was mostly used in low speed medium duty trucks and school buses. Would require an SAE3 adapter setup. The GM 4L60e is an OD transmission but is too light duty for a Cummins. Now we get to the 2 workable units. The 4L80e can work and has been used by several members. It can be mounted using the stock GM/Cummins adapter or an aftermarket unit. Neither is very cheap unless you can find a used set of the Cummins parts. I can provided you the part numbers of the factory setup if you need them. Also, since that transmission is computer controlled you will need an outboard controller and a TPS mounted on the injection pump. Now for the 47RH. That one came behind the Dodge 6bt and has OD and a lockup torque converter. Often used because all the attaching parts for a 6bt will fit the 4bt. Does not have to have an outboard controller but there are units for it to control the OD and lockup functions. Other transmissions that have been used are the 46RH which is like the 47RH without lockup function, 47RE, 48RE, Allison 1000, Allison 3060, and a few models of Ford automatics.
Sick of people saying, Can't put a 4l60e behind a 4bt, too light duty. better watch this
 

·
Premium Member
1989 Jeep Wagoneer, 360v8, 727, stock for now,
Joined
·
2,675 Posts
Sick of people saying, Can't put a 4l60e behind a 4bt, too light duty. better watch this
edit.........
Episode 14 he breaks the 4l60e.

The 4L60E is still too weak for the 4BT. It was not designed for the torque that a low speed makes.
 
  • Like
Reactions: Russ McLean
1 - 17 of 17 Posts
Top