6spd to 8spd Upgrade possible?

Does anyone know if it's a fairly easy swap to change out the 6 spd auto to the 8 spd auto? Would you need a different ECU/PCM, or just a retune? Any info you can provide would be much appreciated.

Edit: What is the designation of the 8spd in the 1500 series? I know the 6spd is the 65RFE.

Nobody has done it yet

Hemi450hp said:

Nobody has done it yet

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Why do you think that is? Is the PCM and ECU integrated into one unit? Are there too many differences? Seems like this would be (in theory) a good upgrade.

Not counting the transmission itself, at a minimum it would be a PCM, TCM, associated wiring, drive shaft, mounts and probably a slew of other items. You would probably need a crash donor to pick apart as needed for the unexpected things.

Something like this is like people wanting to do auto to manual swaps or 2WD to 4WD, it is just way easier and cheaper to just trade for what is already built the way you want it.

its still way too new for this to be a cost effective swap. right now it would be cheaper to buy another truck.

Hootbro said:

...it is just way easier and cheaper to just trade for what is already built the way you want it.

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Short of spending a lot more money or losing some of my favorite amenities, there's nothing around that matches my truck within reason. I have to have the back up camera and I have to have limited slip. Everything remotely near me is $7k+ more (and no backup camera or LSD). I'll stick with my 6spd.

it would be a heck of a lot cheaper and easier to add a backup camera and lsd then to attempt a 6spd to 8spd conversion.

DannyMK2 said:

it would be a heck of a lot cheaper and easier to add a backup camera and lsd then to attempt a 6spd to 8spd conversion.

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Most likely, but then I'd have to go through the hassle of buying another truck, and in all honesty, do I need an 8 spd that badly? Hard for me to justify. I really like my truck.

I've been wanting this for a few years now.

You can actually find the ZF trans at a reasonable price but making it work. That's a different story. lol

I agree Hoot, you are going to want to donor truck to swap stuff you might know you needed.

There probably is some out there for 5-6K but I would rather buy a new truck unless I planned on keeping the 8speed swap truck forever.

nickpohlaandp said:

Most likely, but then I'd have to go through the hassle of buying another truck, and in all honesty, do I need an 8 spd that badly? Hard for me to justify. I really like my truck.

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Dont take this the wrong way, but you have started quite a few threads about the lack of performance and transmission options since joining. If you want to make the reliable, big power you have talked about, then yes, you do need a better transmission than your current 6sp.

My truck is a testament that you can make power and go fast on a 5/6sp truck, but I am extremely careful about how I drive it. Very few people would have the self control to make the power that my truck makes and not use it on the street. The 8sp transmission is the answer to that problem that allows you to make decent power and drive it however you want, whenever you want.

At this point in time, a new truck with an 8sp is a better option than trying to swap an 8sp in your current truck.

Hemi450hp said:

Dont take this the wrong way...

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Not taken the wrong way whatsoever. I appreciate your input.

Honestly, I think I'm being more of a worry wart than anything. I don't beat on my truck by any stretch of the imagination. I just read things and it gets my head rolling, and for me, that's not always a good thing.

I initially joined this forum with the intent of getting info toward doing a Procharger install. At this point I've pretty much abandoned that idea and decided to keep my truck N/A and do a few mods for a little more power. Like I've said before, this is my daily driver and camper hauler, not a dragster.

I've ceded to the realization that I'm not going to have a daily driver, camper hauler, street burner... that's a stupid thought, even more stupid as I sit here and see myself type it out.

I guess it's just been too long since I've been down the 1320 and I've got the itch. I've got a 30' x 40' shop going up and should be finished next week. I think I just need to get something to throw a bottle on with some big pills just to get the itch out of my system for a little bit while I collect my thoughts and decide what I really want to do for a "fun ride".

All that said, I think I'm pretty comfy with my 6spd. I've towed the camper across the country and back, done my share of "aggressive on ramp acceleration merging", and I haven't had problem #1 with my truck. It's been a great vehicle. 42k on the odometer and going.

Mostly, I'm just here to learn, and when crap pops in my head, I post it.

Right on. The 6sp will handle a good bit of power as long as you drive it right. Those WOT hits coming up an on ramp can be dangerous at higher power levels though, so be careful of that as you continue modifying the truck.

Hemi450hp said:

...Those WOT hits coming up an on ramp can be dangerous at higher power levels though, so be careful of that as you continue modifying the truck.

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I'm curious as to what you mean by this. Your truck is running in the 11's with a 6spd successfully, and I'm sure it's not doing that by you letting off the throttle between shifts. How exactly am I supposed to drive it? Seriously, I'm not being a smartass, I'm puzzled.

I don't think I've ever had my truck over 100, and if I have it was momentary at best. When I say "aggressive on ramp merging" I'm talking about laying into it up to about 75-80mph. I don't go from 40 and hammer down without letting the trans get into lower gear first.

Then there's the light to light blast, which could be considered the same as running in the 1/8th or 1/4. From a dead stop you lay into it with WOT and let the trans shift how it wants to. Is this bad for the trans? If so, how should I be shifting?

nickpohlaandp said:

I'm curious as to what you mean by this. Your truck is running in the 11's with a 6spd successfully, and I'm sure it's not doing that by you letting off the throttle between shifts. How exactly am I supposed to drive it? Seriously, I'm not being a smartass, I'm puzzled.

I don't think I've ever had my truck over 100, and if I have it was momentary at best. When I say "aggressive on ramp merging" I'm talking about laying into it up to about 75-80mph. I don't go from 40 and hammer down without letting the trans get into lower gear first.

Then there's the light to light blast, which could be considered the same as running in the 1/8th or 1/4. From a dead stop you lay into it with WOT and let the trans shift how it wants to. Is this bad for the trans? If so, how should I be shifting?

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The WOT downshift through 4th gear is the biggest issue. When you're pulling onto a highway on the onramp you're in 5th or 6th, and when you stomp the skinny pedal it has to downshift through the sequence which will go to 4th then to 3rd (if required) and as it passes through the 4th gear the 2p clutch pack is the weak link of the trans. If you do it often enough the clutch pack slips just a little and it takes almost nothing to really burn the frictions and warp the spacers.


A straight WOT run is fine with the stock 545/65 as long as you keep it below ~130mph where it will shift into 4th gear which is again WOT on the 2p clutch pack. Just let it shift how it wants or you can manually shift to get it running to higher rpm. High stall converters have had some issues in the past but those were hitting the trans at 4000+rpm.


The way to drive the truck properly is to manually downshift to 3rd before laying into the pedal and to keep it out of 4th gear at WOT. It handles part throttle in 4th gear just fine. We have had some people toast the 2p clutch with stock power just with the way they drive then you've got guys like Matt and I who have kept a stock trans behind decent power. My '07 was head/cam/spray with a stock trans and could do 230km/h, and the '09 with the F1-A is running a L&M trans and tune with no issues for 3 years.

nickpohlaandp said:

Most likely, but then I'd have to go through the hassle of buying another truck, and in all honesty, do I need an 8 spd that badly? Hard for me to justify. I really like my truck.

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Have you ever test drove an 8 speed?

My brother had a 2012 6 speed and when i got my 8 speed, it was a world of difference.

charonblk07 said:

...as long as you keep it below ~130mph where it will shift into 4th gear...

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Are you talking about it shifting into the first overdrive at ~130? 4th gear is the 1:1 ratio. I don't see how shifting into 1:1 would be an issue. I could see how shifting into OD at WOT could cause some problems thought.

charonblk07 said:

...The way to drive the truck properly is to manually downshift to 3rd before laying into the pedal and to keep it out of 4th gear at WOT...

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Again, I'm afraid that there might be some confusion with which gear(s) you're referring to. I understand that these are 6 speed transmissions, but they really only use 5 speeds depending on the situation. Gears #2 and 3 are both second gears, so it would be more accurate to call the gears 1, 2, 2p, 3, 4, 5, with 3 being your 1:1 and 4 and 5 being the overdrive gears.

Is the idea that you guys are trying to convey is to a) do not downshift at WOT from OD (or really at all), and b) do not go WOT into OD?

nickpohlaandp said:

Are you talking about it shifting into the first overdrive at ~130? 4th gear is the 1:1 ratio. I don't see how shifting into 1:1 would be an issue. I could see how shifting into OD at WOT could cause some problems thought.



Again, I'm afraid that there might be some confusion with which gear(s) you're referring to. I understand that these are 6 speed transmissions, but they really only use 5 speeds depending on the situation. Gears #2 and 3 are both second gears, so it would be more accurate to call the gears 1, 2, 2p, 3, 4, 5, with 3 being your 1:1 and 4 and 5 being the overdrive gears.

Is the idea that you guys are trying to convey is to a) do not downshift at WOT from OD (or really at all), and b) do not go WOT into OD?

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In the 545 you shift to 3rd, in the 65rfe you shift to 4th. You want to be in the 1:1 gear, it's the 0.75:1 1st OD gear that's the issue in both transmissions. It gets annoying/confusing when dealing with the 65 because unless you're in ERS it shifts the exact same as the 545. The 2p gear from the 545 is now the 3rd gear in the 65 but is only used in ERS; it's only a computer based difference that allows the use of the 3rd gear in the 65 even though it was still used in the upshift in the 545, you just couldn't select it with the 545.

charonblk07 said:

...It gets annoying/confusing when dealing with the 65 because unless you're in ERS...

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What's ERS again? I read about it somewhere but I can't remember.

OK, wait, ERS, Electronic Range Select. So when I have my shifter in "D" and let the trans shift on its own, it basically shifts 1-3-4-5-6. The only way I would see 1-2-3... is if I had it in ERS and selected 1 then 2 then 3 and so on... correct?

Here's a question. When I engage ERS by selecting the "-" to show "4" displayed on my console, that will make it so the transmission will not shift above 4, my 1:1 gear. However, while in this mode, will it shift 1-2-3-4, or will it still skip the "extra" second gear and go 1-3-4?

nickpohlaandp said:

OK, wait, ERS, Electronic Range Select. So when I have my shifter in "D" and let the trans shift on its own, it basically shifts 1-3-4-5-6. The only way I would see 1-2-3... is if I had it in ERS and selected 1 then 2 then 3 and so on... correct?

Here's a question. When I engage ERS by selecting the "-" to show "4" displayed on my console, that will make it so the transmission will not shift above 4, my 1:1 gear. However, while in this mode, will it shift 1-2-3-4, or will it still skip the "extra" second gear and go 1-3-4?

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in drive, it shifts 1-2-4-5-6. if i remember correctly its going to skip 3rd when you have 4, 5 or 6th selected. only way to get 3rd is by selecting 3rd and then selecting a higher gear when in 3rd, or by using tow/haul mode.