2013 1500 - swap 65RFE for 66RFE?

[1SLwLS1]

I have a 2013 Ram 1500 2WD Sport that I bought new in 2013 and has around 166K mi on the transmission now. I wish I would've waited 6 months for an 8-speed but I needed a new vehicle and no dealers had any 8-speeds in stock early 2013 MY.

Background: Truck has been daily for the past 8 years and has been a great truck, all things considered. Last year I started adding mods, out of necessity and once started, I couldn't stop - been able to hold off several years. I had a Vararam from a few years ago since the factory clips on the stock airbox broke but was stock otherwise. I had lived with the exhaust manifold leaks for a while but finally repaired those and while I was in there, Matt @ Moe's added some ARH 1 3/4" LTs with catted y-pipe. I had a hemifever tune on it, added an ARH cat-back due to some rattles in the factory exhaust, etc. This last summer I had a tick develop and oil life reduce drastically - ended up having a seized lifter roller. Instead of simply repairing the top end, the engine was tired and the rings were a bit loose, I opted for MMX's 392 with mild NSR cam, ported 6.4 manifold, etc. The local tuner used HP Tuners so that was swapped over from DS as well (poor choice on local tuner). While the engine was out, went ahead and put in a ~3200 stall. I knew the transmissions wouldn't last long in this configuration but I figured if I babied it I could at least get a year or so out of it, but I only have 3 weeks in it with the new engine, making about 420 at the wheels (heavy 22" hellcat replicas in 3rd gear) and I go into limp mode anytime I need to get into OD gears with the dreaded P0734/P0735 codes.

I would love to attempt an 8-speed swap (or any custom setup) but we just sold our house this past summer and are in the process of buying land and building so we are in a rental and I cannot attempt anything too crazy until I have a shop again.

I don't like the idea of putting another 65RFE back in due to the weakness of the clutches and the special driving requirements needed to make it last. I also hate the gear spacing of the 65RFE and I am looking at different options. Jasper wants $3500+ (parts only) for a remanufactured 65RFE transmission (recommended by local transmission shop - Houston area). The 66RFE has a bit higher power rating and a little bit better gear spacing but if it was an easy swap, I feel like all of the 65RFE crap threads I have read, would've stated the 66RFE replacement as the obvious choice, but that hasn't been the case.

What am I missing that makes this swap undesirable? I have read about the PCM issues but with HP tuners (see attached screenshot), 66RFE is a selectable transmission from the Trans Type drop-down and it would appear that the trans gear ratios are editable. I believe I would need to swap the tail-shaft from my 65RFE and possibly a new driveshaft (splines on output shaft different?) - what else would I need? I am not sure on the torque converter, I have read that it is the same converter but have also read that the 66RFE torque converter is recessed in the case but on the 65RFE it sticks out (maybe I am confusing that with the 68RFE?) which if that was true, it would have to be a different torque converter since the 65RFE and 66RFE share the same case. Would I need a different flex plate or anything? I assume I would need to take it a transmission shop for the relearn process or something...?

I have scoured many threads over the past several months on transmissions options, any help or guidance is appreciated!

 

[TheEnder]

I have a 2013 Ram 1500 2WD Sport that I bought new in 2013 and has around 166K mi on the transmission now. I wish I would've waited 6 months for an 8-speed but I needed a new vehicle and no dealers had any 8-speeds in stock early 2013 MY.

Background: Truck has been daily for the past 8 years and has been a great truck, all things considered. Last year I started adding mods, out of necessity and once started, I couldn't stop - been able to hold off several years. I had a Vararam from a few years ago since the factory clips on the stock airbox broke but was stock otherwise. I had lived with the exhaust manifold leaks for a while but finally repaired those and while I was in there, Matt @ Moe's added some ARH 1 3/4" LTs with catted y-pipe. I had a hemifever tune on it, added an ARH cat-back due to some rattles in the factory exhaust, etc. This last summer I had a tick develop and oil life reduce drastically - ended up having a seized lifter roller. Instead of simply repairing the top end, the engine was tired and the rings were a bit loose, I opted for MMX's 392 with mild NSR cam, ported 6.4 manifold, etc. The local tuner used HP Tuners so that was swapped over from DS as well (poor choice on local tuner). While the engine was out, went ahead and put in a ~3200 stall. I knew the transmissions wouldn't last long in this configuration but I figured if I babied it I could at least get a year or so out of it, but I only have 3 weeks in it with the new engine, making about 420 at the wheels (heavy 22" hellcat replicas in 3rd gear) and I go into limp mode anytime I need to get into OD gears with the dreaded P0734/P0735 codes.

I would love to attempt an 8-speed swap (or any custom setup) but we just sold our house this past summer and are in the process of buying land and building so we are in a rental and I cannot attempt anything too crazy until I have a shop again.

I don't like the idea of putting another 65RFE back in due to the weakness of the clutches and the special driving requirements needed to make it last. I also hate the gear spacing of the 65RFE and I am looking at different options. Jasper wants $3500+ (parts only) for a remanufactured 65RFE transmission (recommended by local transmission shop - Houston area). The 66RFE has a bit higher power rating and a little bit better gear spacing but if it was an easy swap, I feel like all of the 65RFE crap threads I have read, would've stated the 66RFE replacement as the obvious choice, but that hasn't been the case.

What am I missing that makes this swap undesirable? I have read about the PCM issues but with HP tuners (see attached screenshot), 66RFE is a selectable transmission from the Trans Type drop-down and it would appear that the trans gear ratios are editable. I believe I would need to swap the tail-shaft from my 65RFE and possibly a new driveshaft (splines on output shaft different?) - what else would I need? I am not sure on the torque converter, I have read that it is the same converter but have also read that the 66RFE torque converter is recessed in the case but on the 65RFE it sticks out (maybe I am confusing that with the 68RFE?) which if that was true, it would have to be a different torque converter since the 65RFE and 66RFE share the same case. Would I need a different flex plate or anything? I assume I would need to take it a transmission shop for the relearn process or something...?

I have scoured many threads over the past several months on transmissions options, any help or guidance is appreciated!

View attachment 229406

You mine as well buy another truck unless you have some serious sentimental value with that truck if you’re even going to CONSIDER swapping an 8 speed into it, lol.

(The 8 speed swap is anywhere from 10K-15K.)

Regarding gear ratios - yes, on the 65RFE they’re not exactly desirable. But, regarding reliability and durability, you can correct this yourself for 25% of the time you’d spend trying to swap a 66 into your truck.

If Jasper doesn’t include any upgrades with the 66RFE you buy, then expect failures not now but down the road soon.

Keep in mind, ALL of these transmissions have the dreaded OD clutch failures, and the only way to cure that is with Sonnaxes oversized OD clutch drum. The valve bodies on these transmissions are also notoriously weak and are part of the OD clutches burning up as well, they’re made from very weak aluminum and are working over their maximum pressure ratings nearly all of the time. They have a history of warping, cracking, etc. So get a billet VB + raise the line pressure with your tuner.


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[1SLwLS1]

You mine as well buy another truck unless you have some serious sentimental value with that truck if you’re even going to CONSIDER swapping an 8 speed into it, lol.

(The 8 speed swap is anywhere from 10K-15K.)

Regarding gear ratios - yes, on the 65RFE they’re not exactly desirable. But, regarding reliability and durability, you can correct this yourself for 25% of the time you’d spend trying to swap a 66 into your truck.

If Jasper doesn’t include any upgrades with the 66RFE you buy, then expect failures not now but down the road soon.

Keep in mind, ALL of these transmissions have the dreaded OD clutch failures, and the only way to cure that is with Sonnaxes oversized OD clutch drum. The valve bodies on these transmissions are also notoriously weak and are part of the OD clutches burning up as well, they’re made from very weak aluminum and are working over their maximum pressure ratings nearly all of the time. They have a history of warping, cracking, etc. So get a billet VB + raise the line pressure with your tuner.


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Why would there be extra time adapting the 66RFE? Do you know some of the hurdles involved?

Jasper is quoting the 65RFE with their vague general upgrades, not sure if better components are actually being selected.

Are the 66RFE internals not better (marginally) than the 65RFE internals?

I cannot find anything on Sonnax's website of an oversized OD clutch drum for the 66RFE or 65RFE, only the 68RFE. Can you provide more information about this oversized OD clutch drum?