I know this is a shot in the dark, but has anyone ever done a 6.5 to Cummins conversion? What cost range would I be looking at for a project of this nature? I would prefer the Cummins 12v as i understand they have better fuel pumps for veggie. I have seen adapter plates that allow the cummins block to work with the 80E tranny and the manual.

It's been done many times. You need to convert to a solid front axle to handle the weight. I don't think I'd attach a 4L80 to a Cummins.

Nick

It's been done many times. You need to convert to a solid front axle to handle the weight. I don't think I'd attach a 4L80 to a Cummins.

Nick
the 4l80e works great behind the cummins, FAR superior to the dodge auto. requires a stand alone tranny computer and an SAE bellhousing adapter (or find a box truck with an auto, has the cummins 4bt and depending on the year either a th400 or a 4l80e) and sell that 4bt and everything you dont want from it.

I think he's talking about swapping in a 5.9. How long do you think a 4L80 would last behind that?

Nick

I understand the dodge auto tranny is pretty bad compared to the 80E. So i was assuming the 80E would be better? Am i wrong thinking this? Yes, im considering buying a 6.5 that needs a new motor, and throwing in a 5.9. i know i need a tranny adapter plate, (found them) and motor mounts etc. i can handl eit costing a bit more than a 6.5 swap, but its its too expensive then nevermind. Also, if that turnes out the case, i assume a marine block (the one with more HP and touque) will fit? it comes with 6.5L MARINE DIESEL LONG BLOCK (REMAN) WITH 18:1
PISTONS, VALVE COVERS, HEADS, OIL PAN, HARMONIC
BALANCER, TIMING COVER

I think he's talking about swapping in a 5.9. How long do you think a 4L80 would last behind that?

Nick
thats what i said in my post, just mentioned that you can pick up a 4l80e with the cummins adapter already attatched if you find a box truck with an auto (the 4bt and 6bt have the same bellhousing bolt pattern).

the best auto to put behind the cummins 6bt is the allison obviouslly, but after that is the 4l80e. one of my friends back in midland put a cummins 12 valve to 4l80e setup in his ranch truck with a tranny cooler and a deep pan, last i heard from him he had 140k miles with no engine/tranny issues. spends most of its time pulling a 10-17k pound load.

if you can find a cummins 6bt for a decent price then it could be cheaper than replacing your long block with a marine motor (and yes the marine motor will bolt right into place).

sweet. that answer a lot of questions, ill do some research into placing a Cummins in the 6.5 bay.... thanks!

Do a search in the 6.5 forum, JK auto just did his 95 SUBURBAN. The 4L80E is a nice tranny, but cost effective wise a 47RH DODGE tranny is normally easier on the wallet. The 4L80E I don't think would hold in stock form anyways. And the aftermarket can correct all of the DODGE issues that were there. And there are different input shafts available to adapt your GM transfer case to the DODGE tranny so you can keep the stock speedo.

The IFS holds up just fine, there are many conversions out there with zero problems with the IFS and 6BT's backing them. I'm currently considering this option as well myself. I have a 6.5 that I am afraid has block rot beyond repair. So I've been doing considerable research on this myself. You can also do a google search. TDR has alot of info on conversions as well, but it is a pay site if you want to post or see everything.

The IFS can handle the weight? As usual, the mags were wrong. That's good to hear because the IFS rides so nice.

Nick

http://www.dieseltruckresource.com/dev/index.php its all about cummins and some swaps. http://www.cummins-conversion.com/photos/index.php

The best trans to put behind the Cummins is a 48re...much better than the previous Dodge trans. They still have a bad rep, but they really arent as bad as everybody thinks they are. Get a good rebuild and itll take anything you can throw at it. The Allison has way too much computer crap on it, and Im not all that convinced its much stronger than any other pickup trans. Swap in a 12 valve and a rebuilt 48re and youll be more than happy with it. Why deal with stand-alone ECMs and all that BS when you dont have to??

I've done the conversion or actually Las Vegas Cummins did it for me. In 85 put a warmed over new 6BTAA Cummins in a 84 GMC 6.5 4X4 Dually, with 4l80E trans, and Gear Vendors put a test dual OD behind it. I ran it 9 years and 400,000 miles, and it has been 12 years since I sold it, and it has gone another 500,000 miles beyond that, all without any engine problem. Nor Gear Vendor OD problem. BUTTTTTTTT, I lost a 4l80E transmission every 35 or 40,000 miles, for several years, and finally started changing out converters (the problem) every 30k miles. I had every kind of converter maid in the damn thing, and they still would blow, taking the trans with it. I was towing heavy (43 Enclosed race car trailer, triple axle, 25 to 29,000 CGVW), most of it in the desert. Great conversion for towing. Getting a trans or a converter to hold up was the only problem. Now, if you put the Allison behind it, then you'd be talking!!

SUNCOAST now offers a fully built 4L80E, so this would probably hold up to a mild 5.9L CUMMINS. I know that there is a DMAX powered truck backed up by a 47RE because the ALLISON couldn't be built up to hold up. I believe it was a member here that did the swap. Not to mention the sheer size of the ALLISON 1000 is huge and wouldn't clear most transmission tunnels without modifications for a swap. Now the AISIN that DODGE is using looks promising. The 68RFE would be nice as well, but the gear ratio spreads aren't very even in it.

Just to keep the record straight, 4L80E wasn't produced until '92 - what trans did you use B4 that, between '85 and '92?

You do not need to do a solid axle swap although that would improve the truck a lot. CrewCab59 on here has done some and can offer lots of answers. I'm doing a 67 Chevy right now but it's a nv4500.

Just to keep the record straight, 4L80E wasn't produced until '92 - what trans did you use B4 that, between '85 and '92?
what auto did gm use? the th400 was the heavy duty auto, 700r4 was the light duty. the 4L80 came out in either 91 or 92, then became electronic (4L80E) in 94.

GM Diesels had the T350, 700R4 in the 1500's, and T400 in the 2500's-3500's thru '91 - the 4L60E was thru '94 in the 1500's, discontinued in '95 for the 4L80E - 2500-3500's had the 4L80E from '92, as did some of the gasser's (patooie!), notably the 454 - there was a stand-alone TCM for the 4L60E and the 4L80E behind the Diesels till '94, due to the mechanical injection pump - after '94 the PCM handled engine and trans chores

The 4L80E has always and only been fully electric, needing a Transmission Control Module for the valve body and the PWM TCC

The GM oem late '91-'93 stand-alone TCM is the module the aftermarket speed shops sell with their 4L80E conversions, with some enhancement to the firmware for improved shifting characteristics and TCC control.

Note: when purchasing a truck that is not in it's current model year, WYSIWYG takes precedence

wow, im getting a lot of good feedback! thanks guys. id love to plug an Ally into the truck but just dont have the buget. i wouldnt mind putting in a gm rebuilt 80E, or better tranny for about the same cost. or a well built 80E as long as its not too expensive. im trying to stay fairly close to what it would cost to replace a 6.5. only on rare occasions will i be pulling a race trailer (8 to 12k) lbs. the rest would be daily driver and a boat or pop-up. ill do some research on the 47re. any opinions? is it expensive?

You are correct - senility is wonderful. The trans in my 84 was a Turbo 400, not a 4L80E. The 4L80E was in my 93 with a Peninsular 300HP engine and also would not hold for a lot of towing. 3rd rebuild finally held. In the Turbo 400 behind the cummins, it was not the trans, but torque converters. Sorry for my mental mixup. What do you expect from a guy who is as old as dirt.

ATS, DTT, Goerend, PATC, Suncoast, etc - for simplicity, I'd stay with the 47RH\48RE, check with PATC for DIY upgrades - the 48RE is the last upgrade of the old 727 Torque-flyte, has electric TCC, OD, and governor, easily managed with switches - the 47RH can take the 48RE mechanicals for high output, but has the mechanical governor, so shifting is purely automatic, only needing TCC and OD electrics, like the 4L60E

The 4L80E has specific programming to allow it to survive behind the 6.5TD and the 454\502, such as dropping TCC each time the throttle is released - that's to protect the hollow input shaft from the torque-reversal going from on-throttle to off-throttle to on-throttle - many broken input shafts resulted from wrecker-service and dump-truck vehicles - couldn't take the low-rpm torque - of which a Cummins has plenty of, and then some - mild tune = 750ftlbs

No prob, Gardner - me, too - they say three things start to go the older we get - one is memory, but I can't remember the other two.........

I've also been doing a search on this swap for my truck seeing as how my engine just took a poop, anyways, its alot cheaper to go with a 47RE tranny compared to a decent torque converter and adapter plate for the 4l80E, not to mention a standalone controller unless you want to take all of the electronics off of it and have switches to lock the TC and manually shift it....