Passing power with the 4L80E or lack of

[Kaiserjeeps]

I completed my 4L80E install quite a while ago. It made the truck. I brought my RPM's down from 3K to 2 to 2100 at 60-65. I run tires just a shade shy of 33 inch. I put a mandrel bent 2.5 dual rear exit exhaust with free flowing Diesel Donaldson mufflers on. I need at least a full mile to pass anyone only doing 60-68 MPH. The trans shifts out of lock up and there are no issues there. And recently this last summer towing my CJ-5 (4200LBS) on a 900 lb car trailer I slowed to 10 MPH on a pass here. I got pretty bummed as I was hoping to tow better than that. I did read the towing thread. I realize I am outside the expectations of the 6.2 But my original question has me curious if my motor is ailing with no load. I still have the original gearing. I want to say my flat bed truck weighs in at 7200? I need to check at the local scale again.
I did just receive a diesel compression tester, but have not had a chance to check that yet. I am considering a gas motor swap. I checked thoroughly on a cummins swap and I am not interested for the 6K it requires. I can do a LQ4 motor or an LY6 for a lot less. Or a summit crate motor with no computer.

Is my lack of passing power at that speed normal? Or might I have an issue?

 

[Chaski]

What percentage of grade were you pulling when it got down to 10mph? That does seem slow. Are you sure that when you floor it the arm on the injection pump is reaching the end of its travel? The throttle cables can be junk, especially the aftermarket ones.

I have never had my rig over 10,000 pounds. A normal firewood run puts me at 8,500-9,000 pounds and it isn't exactly peppy.

 

[The FLU farm]

Big trannies such as a 4L80E sucks more power than do smaller ones. I'm surprised that you went with a 4L80E rather than a 700R4.
Wouldn't hold up? Mine did, in a Banks turbo'd M1009 (no, it didn't have the stock 3.08 gears), although it was built to handle upwards of 500 ft.lbs. if memory serves me.

 

[rustystud]

Big trannies such as a 4L80E sucks more power than do smaller ones. I'm surprised that you went with a 4L80E rather than a 700R4.
Wouldn't hold up? Mine did, in a Banks turbo'd M1009 (no, it didn't have the stock 3.08 gears), although it was built to handle upwards of 500 ft.lbs. if memory serves me.

The transmission doesn't suck power from the engine. In fact the 4L80E is just the TH400 with a overdrive in it. Far superior then the weaker 700R4 or 4L60E as it is called today. If you have the wrong torque converter that can cause a lot of problems though. If it was made for a car that was made to rev up to 4,000 to 5,000 RPM's it will not work right in a diesel 6.2 which is not made to rev that high. The power band is much lower in the 6.2 and the torque converter must be made for that range. Also the lock-up clutch must come in and let off at the correct RPM's. So what vehicle did you get this 4L80E transmission from ?

 

[cucvrus]

The transmission doesn't suck power from the engine. In fact the 4L80E is just the TH400 with a overdrive in it. Far superior then the weaker 700R4 or 4L60E as it is called today. If you have the wrong torque converter that can cause a lot of problems though. If it was made for a car that was made to rev up to 4,000 to 5,000 RPM's it will not work right in a diesel 6.2 which is not made to rev that high. The power band is much lower in the 6.2 and the torque converter must be made for that range. Also the lock-up clutch must come in and let off at the correct RPM's. So what vehicle did you get this 4L80E transmission from ?

Rusty I am always glad you are here to clear the air with these transmission issues. They are not one of my stronger points. But I sure appreciate your input on these matters. I use all my CUCV's stock and over the course of 20+ years of CUCV ownership. I have learned what they are good for and what they are NOT good for. I use the appropriate vehicle for the task at hand. And I still put safety, comfort and reliability at the forefront of changing the design. Sometimes the CUCV is NOT the vehicle to get the job done. Plain and simple. I have found newer vehicles more useful for towing and handling trips in more comfort and with safer operation. I have personally had the stabilitrack system save me on more then one occasion will driving and towing. But back on track. I like the TH400 for its reliability and simplicity. It is hands down one of the most reliable transmissions that were ever designed and it compliments the CUCV. Thank you for your knowledge and I hope you are recovering well.

 

[richingalveston]

The 6.2 non turbo just does not have the horse power at that low of rpm. The reason it works with the th400 is the rpms are at the top of the HP curve for the motor.
I was disappointed with mine also. I am changing to 6.5 turbo.

If you turbo the 6.2 it will help but some turbo 6.2's don't last.

My torque converter would unlock just to go over an overpass on a flat highway. The 6.2 needs the high rpm to get to that last bit of HP.

I hope to have the engine back in the truck next month.

Rich

 

[cucvrus]

Simpler yet. Get another truck that has all the good towing equipment, power and gets the job done. At 30+ years old these CUCV's would need a complete redesign to accomplish what the newer lighter trucks are doing in stock form with more safety and efficiency. I used to have a CUCV as my only method of towing. That was when they were only 10 years old. Now I would NOT want to do the traveling that I did back then with a CUCV. Locally fine but after 20 miles. I hear bush cricket and katydids. Good Luck. This is my opinion. Others may differ. That's fine.

 

[Chief_919]

You are simply expecting too much from the 6.2 in its stock form when you are running an overdrive plus oversized tires that also change the overall gear ratio.

33 inch tires + overdrive reduces your effective gear ratio to a 3.31 or close to it. With a stock 6.2 and gearing like that you can't expect much.

Thah said I will ask how many miles are on your injection pump. You will often slowly lose power with a worn pump and it is a gradual drop so you don't notice it. A rebuilt IP might give you a good bit more pep if it has a lot of miles or age on it. My M1028 with a 700r4 passes just fine on the highway but it also has stock size tires and a fresh slightly turned up IP. And the 700r4 OD ratio is higher than the 4L80, so that makes your oversized tires close to a wash comparing them making me think your IP is weak.

Buu you are going to drop into low speeds on big mountains towing. That's just what it is.

 

[gimpyrobb]

I've got 235/85r16 on my civy truck with a turbo 6.5 and 4:10s. Thats roughly 31 inch tall tire. While towing up steep grades, I still shift to 1:1 to keep it in the power band. When was the last time you had your injectors serviced? If never, maybe its time to swap in some new or re-built ones. They DO have an effect on power and mileage.

 

[Barrman]

Al, nice to see you came in from the Yurt to post again.

What controller are you using for the 4L80E? I ask because if you aren't dropping gears enough as others have pointed out, you won't have any power to the ground.

How does your M35 do on the same pass empty? How would your M715 have done if you still had it on that pass?

I have a 6.2 in my M715 with a NV4500. 2000 pound trailer with a 6,000 pound M1009 on the trailer has me able to hold 42-48 mph in over drive and not get over 205° engine coolant temp on flat ground. I drop it to 4th and I can attack hills and get over them in the 52-56 range without getting the engine hot. But, if I ever get below 1,500 rpm in any gear on a hill. I will not be able to hold speed and usually end up around 20 in 3rd waiting for the hill to end. Or slower depending on the hill and head winds.

My point is your experience seems to track with mine when I don't keep the revs up or don't attack the flat at the bottom of a hill.

You have the ability to put any engine you want in there. It will probably be a show example of craftsmanship just like all your other projects. Try fuel filter, air filter, IP timing first though. Maybe even a Banks or 6.5GM turbo weekend project.

 

[The FLU farm]

The transmission doesn't suck power from the engine. In fact the 4L80E is just the TH400 with a overdrive in it. Far superior then the weaker 700R4 or 4L60E as it is called today. If you have the wrong torque converter that can cause a lot of problems though. If it was made for a car that was made to rev up to 4,000 to 5,000 RPM's it will not work right in a diesel 6.2 which is not made to rev that high. The power band is much lower in the 6.2 and the torque converter must be made for that range. Also the lock-up clutch must come in and let off at the correct RPM's. So what vehicle did you get this 4L80E transmission from ?

Excellent point on the torque converter, which I thought about after posting last night. A mismatched converter can screw up the performance of an otherwise good setup.
But that transmissions don't suck power I disagree with. I think we can agree on that there's a noticeable difference between flywheel and rear wheel horsepower.
Are you saying that only the the transfer case (if applicable), driveshafts(s), and rear differential are responsible for the power loss, none of it soaked up in the trans?

 

[Kaiserjeeps]

The transmission doesn't suck power from the engine. In fact the 4L80E is just the TH400 with a overdrive in it. Far superior then the weaker 700R4 or 4L60E as it is called today. If you have the wrong torque converter that can cause a lot of problems though. If it was made for a car that was made to rev up to 4,000 to 5,000 RPM's it will not work right in a diesel 6.2 which is not made to rev that high. The power band is much lower in the 6.2 and the torque converter must be made for that range. Also the lock-up clutch must come in and let off at the correct RPM's. So what vehicle did you get this 4L80E transmission from ?

It came out of a 1993 chev truck. I had it rebuilt by a shop in Spokane. The torque converter was remanufactured by a second shop. So the same one for the 93 chev. It had a 6.5. This is a bad story. I planned on a super write up only to get it running and forget about it. I was essentially taken for 2K. Rustystud, you warned me about what to look for in a questionable shop. When I got there trans in hand, all the signs were there. I continued onward with hesitation. The guy lied to me and in the end I got back a trans with a cracked case. It sat under a bench for a couple months till I could tackle it and discovered a crack that I swear was not there beforehand. They told me to take a hike. I almost threw it through their front window. I decided it was better to walk away. I found a replacement case and discovered it was cracked in the very same spot. A mounting ear. That California shop stood behind their ebay purchase and sent me a new case with a brand new better rear bushing in it. They were great. In short I bought manuals, watched videos, bought one critical tool for a case change (H tool for end play measurement) and went after it. I found dirt, shavings and chinese parts. I took pictures of all of it. It was a bad experience to say the least. I got it all done after ordering quality kevlar bands and proceeded to get it going. It has worked great. You warned me. I had high hopes. That was wrong there.

 

[Kaiserjeeps]

I've got 235/85r16 on my civy truck with a turbo 6.5 and 4:10s. Thats roughly 31 inch tall tire. While towing up steep grades, I still shift to 1:1 to keep it in the power band. When was the last time you had your injectors serviced? If never, maybe its time to swap in some new or re-built ones. They DO have an effect on power and mileage.

Hi Chris... Good to hear from you. I had considered new injectors. I may try that after a compression test. I understand what the guys are saying about asking this truck to do hard work. I really like the truck and after a total rebuild on the 205 and adding a crossmember for rear support, converting to a slip yoke eliminator, well the truck is really helpful around our new place. I think I will try new injectors as driving it no load, well I hope this helps.

BTW I used a US shift controller. I have been real happy with it.

 

[Kaiserjeeps]

Al, nice to see you came in from the Yurt to post again.

What controller are you using for the 4L80E? I ask because if you aren't dropping gears enough as others have pointed out, you won't have any power to the ground.

How does your M35 do on the same pass empty? How would your M715 have done if you still had it on that pass?

I have a 6.2 in my M715 with a NV4500. 2000 pound trailer with a 6,000 pound M1009 on the trailer has me able to hold 42-48 mph in over drive and not get over 205° engine coolant temp on flat ground. I drop it to 4th and I can attack hills and get over them in the 52-56 range without getting the engine hot. But, if I ever get below 1,500 rpm in any gear on a hill. I will not be able to hold speed and usually end up around 20 in 3rd waiting for the hill to end. Or slower depending on the hill and head winds.

My point is your experience seems to track with mine when I don't keep the revs up or don't attack the flat at the bottom of a hill.

You have the ability to put any engine you want in there. It will probably be a show example of craftsmanship just like all your other projects. Try fuel filter, air filter, IP timing first though. Maybe even a Banks or 6.5GM turbo weekend project.

Hi Tim, Also really good to hear from you too. Lots has happened. Liz and I got sick of the drug houses around us in Oregon. The yurt was actually cool while I tore down the house to the ground. (black mold). But we moved the the northern Idaho panhandle after having had enough. 30K in permit costs, meth thefts, etc I have relatives nearby which helped us decide where to go. I am in washington by 1000 feet about 45 miles from Canada. Here the neighbors are really nice and I can do body work all day long and only disturb wildlife. I specifically required absolutely no neighbors near by. The ones we have are just super. I have become everybody's go too guy. They are all just normal people who just like space in Gods play ground. I have 500 miles of roads to explore around me. We are happier than ever here. I sold my Duece to a guy in Maryland. It was hard to watch it go. Loaded to the very top with engines, parts, tires including the M105, off it went on the back of a semi truck. I believe he is a member here. I can't drive it here as the roads are too tight. I collect firewood in the CUCV now.
My M715 was sold to a guy in North Seattle. I accidentally discovered it on Craigs list less than two hours from me getting absolutely butchered with Chev K30 axles and a diesel engine. I was going to go look at it but did not. I wanted to save it and all the work I had done, but could not afford it. You have to let things go sometimes. I struggled with that one.

The shift controller in my current and only remaining MV is a US shift. It works well and it does down shift. I should probably add that the CUCV came with a 6.5 injection pump in a box. I have a few parts for my truck here I need to install. A new harmonic balancer. etc Lots of good they do on the shelf eh? I have a car er jeep restoration that is due to go to it's owner in July. I have had stuff on hold for years because of that.

I think I will go after new injectors like Gimp suggests. Do a compression test and see what else could be up. I also want to say that having to preheat is kind of a pain here. We were -22-25 with a solid 4 feet of snow for over a month. That took planning to go anywhere. I have a coolant heater and an oil pan heater. It works but takes planning. I miss participating online. Now that our lives are finally settling after 7 years of trying to get a good house and shop under us, things are going just great. I appreciate all the input offered here. Everybody here at SS has always been great. Feels good to post again.

 

[Kaiserjeeps]

Are the injectors for our J code engines the same as the Civi motors? It looks like it, I thought I had better ask.

I had better take a look in the manuals too.

 

[Chief_919]

Are the injectors for our J code engines the same as the Civi motors? It looks like it, I thought I had better ask.

I had better take a look in the manuals too.

Yes.

 

[Kaiserjeeps]

Yes.

Thank you. I was just logging on to take a look at the manuals. I drove the truck to town today. The truck scales were busy so I drove past. It sure does feel anemic. I hope to improve matters with a little work. Thanks for the quick answer.

 

[rustystud]

Rusty I am always glad you are here to clear the air with these transmission issues. They are not one of my stronger points. But I sure appreciate your input on these matters. I use all my CUCV's stock and over the course of 20+ years of CUCV ownership. I have learned what they are good for and what they are NOT good for. I use the appropriate vehicle for the task at hand. And I still put safety, comfort and reliability at the forefront of changing the design. Sometimes the CUCV is NOT the vehicle to get the job done. Plain and simple. I have found newer vehicles more useful for towing and handling trips in more comfort and with safer operation. I have personally had the stabilitrack system save me on more then one occasion will driving and towing. But back on track. I like the TH400 for its reliability and simplicity. It is hands down one of the most reliable transmissions that were ever designed and it compliments the CUCV. Thank you for your knowledge and I hope you are recovering well.

I appreciate your good wishes ! I am feeling better now. For the last two weeks it was pretty rough though. The TH400 is one of the best automatics ever made and the statistics back this claim up. Just check "ATRA" (automatic transmission repair association) for the most dependable automatic of all time. The 4L80E is basically the TH400 with a few extra parts and is very reliable. Now the 6L90E is right up there with the Alison 2000 series. Extremely well built. I totally agree with you about the capabilities of the CUCV. It is good for what it was designed for. A utilitarian vehicle capable of doing extremely hard work. Comfort ? No, and on a long trip all I gotta say is you better have some pain meds ! I plan on buying a newer Chevy 1 ton to tow our travel trailer when we go back east. I like to be able to walk after driving for a few hours !

 

[rustystud]

But that transmissions don't suck power I disagree with. I think we can agree on that there's a noticeable difference between flywheel and rear wheel horsepower.
Are you saying that only the the transfer case (if applicable), driveshafts(s), and rear differential are responsible for the power loss, none of it soaked up in the trans?[/QUOTE]

All components cause some power loss, but to say one transmission over another sucks more power is wrong. This "urban legion" came about from the racers using the 2 speed GM "Powerglide" in place of a TH400 or even a TH350. They used this and actually continue to use the Powerglide due to the fact the race is over in less then 8 seconds and the transmission never has a chance to shift into 3rd gear ! When you have an engine coming close to 10,000 RPM's there is no need for a 3rd gear ! So people started talking saying they did this because the 3 speeds used to much power which is totally bogus !
There used to be a chart that listed the parasitic drag of transmissions and transfer-cases and differentials we had in Tech school. The numbers where miniscule. So I stand by my statement.

 

[rustystud]

It came out of a 1993 chev truck. I had it rebuilt by a shop in Spokane. The torque converter was remanufactured by a second shop. So the same one for the 93 chev. It had a 6.5. This is a bad story. I planned on a super write up only to get it running and forget about it. I was essentially taken for 2K. Rustystud, you warned me about what to look for in a questionable shop. When I got there trans in hand, all the signs were there. I continued onward with hesitation. The guy lied to me and in the end I got back a trans with a cracked case. It sat under a bench for a couple months till I could tackle it and discovered a crack that I swear was not there beforehand. They told me to take a hike. I almost threw it through their front window. I decided it was better to walk away. I found a replacement case and discovered it was cracked in the very same spot. A mounting ear. That California shop stood behind their ebay purchase and sent me a new case with a brand new better rear bushing in it. They were great. In short I bought manuals, watched videos, bought one critical tool for a case change (H tool for end play measurement) and went after it. I found dirt, shavings and chinese parts. I took pictures of all of it. It was a bad experience to say the least. I got it all done after ordering quality kevlar bands and proceeded to get it going. It has worked great. You warned me. I had high hopes. That was wrong there.

Sorry that you had to learn this lesson the hard way about transmission shops. But now you know, now you really know !