66RFE TROUBLE

[theviking]

What difference do you notice with the new upgraded torque converter? Was there something that you noticed wrong with the oem that made you feel the difference? I’m getting ready to upgrade my valvebody and solenoid pack and just curious about the torque converter.

Best way I can describe it is to say with the stock converter it always felt like some sort of torque management was active. The truck just wouldn't launch hard when you punched the gas. With the new converter it just GOES. There is no delay at all in comparision. Really makes the truck more fun to drive, especially when you are trying to get your point across at a stoplight

I went with a 2600 stall because I do tow with my truck as well. Matt/Moe's suggested a 2800 stall if I towed less frequently. With the 2600 stall I have had zero issues, even towing heavy loads.

 

[70UTE]

I’m me of the lucky ones that does not have the inline thermostat on my cooler lines.

Having just gone through a trans rebuild I think there are reasonably priced upgrades which address most of the common issues. I see a lot of big dollar 68RFE trans builds available but seems like the diesel guys blow those up just as easily. In my case I wore out the overdrive cluches and 5th/6th started slipping.

Personally, I would upgrade the valve body (accumulator pistons, springs, seals, etc) and channel plate to handle increased line pressure. Sonnax and other companies make a variety of components to handle this. Overdrive clutches are the primary weak link for sure, but there are a number of upgraded friction plates available. My shop added an extra clutch without having to purchase an aftermarket housing kit. I purchased a Mag-Hytec pan since it holds extra fluid and has a drain plug.

IMO the stock converter is junk, at least as far as drivability is concerned. I purchased a 2600 stall Edge converter from Moe's and it's been one of my favorite upgrades. Night and day over the stock converter.

was there any programming involved for the new stall speed?

 

[buckeyexx]

Best way I can describe it is to say with the stock converter it always felt like some sort of torque management was active. The truck just wouldn't launch hard when you punched the gas. With the new converter it just GOES. There is no delay at all in comparision. Really makes the truck more fun to drive, especially when you are trying to get your point across at a stoplight

I went with a 2600 stall because I do tow with my truck as well. Matt/Moe's suggested a 2800 stall if I towed less frequently. With the 2600 stall I have had zero issues, even towing heavy loads.

Ok gotcha. That makes since. Mine doesn’t seem to have that issue or maybe I just haven’t tried to launch it hard enough from a stand still to notice it. I went from a 3.73 in my last 2500 to the 4.10 in my power wagon and it feels stronger off the line to me but I know it just the gearing.

 

[theviking]

I’m me of the lucky ones that does not have the inline thermostat on my cooler lines.

was there any programming involved for the new stall speed?

No, it's all plug and play.

 

[Hemi395]

In my opinion,the 8HP trans isn't any more difficult to service other than having to fill it from underneath and raising the rear so that the trans is level
In fact,the 8HP has an actual drain plug in the pan vs none on the 66RFE,making it a bit easier and cleaner
Cost to service is much higher with the 8HP,though

The 545/65/66/68RFE has a dipstick to check the fluid level. Only need a funnel to fill fluid.

The 8HP45/50/70/90 requires you follow this checklist just to CHECK the fluid level. Filling fluid requires a pump of some kind while under the vehicle.

I sorry, the RFEs are just easier to service.

 

[gtomike60]

The 545/65/66/68RFE has a dipstick to check the fluid level. Only need a funnel to fill fluid.

The 8HP45/50/70/90 requires you follow this checklist just to CHECK the fluid level. Filling fluid requires a pump of some kind while under the vehicle.

I sorry, the RFEs are just easier to servi

I'll still take the 8HP over either of the 2 66RFEs that failed in my truck
I have a jack,and a scan tool to check the temperature
I also use Amsoil fluid in the squeezable pouches,so I don't require a pump to fill it

So,it takes a little longer to fill it,but how often are you changing the fluid and filters?
The extra few minutes it takes every 40-50k is worth it for a better transmission

Also,realistically,how often do most people typically check the trans fluid in their vehicle?
When they go for a long trip,or if they have a leak,right?

 

[Hemi395]

I'll still take the 8HP over either of the 2 66RFEs that failed in my truck
I have a jack,and a scan tool to check the temperature
I also use Amsoil fluid in the squeezable pouches,so I don't require a pump to fill it

So,it takes a little longer to fill it,but how often are you changing the fluid and filters?
The extra few minutes it takes every 40-50k is worth it for a better transmission

Also,realistically,how often do most people typically check the trans fluid in their vehicle?
When they go for a long trip,or if they have a leak,right?

I have all that too, but all I need is a rag to check my level.

I change my fluid every year and filters every other year. Also have a MagHytec pan that has a drain plug that makes fluid changes as easy as an oil change.

You're right, the typical person doesn't check their trans fluid or even know it exists. However pulling a dipstick to check the level before a long road trip is way easier than doing a 15 step process requiring a scan tool.

 

[Burla]

Yeah, my rfe runs a lot cooler as well. I wouldnt trust the 8 speed in real towing, neither did fca as they didnt have one available for a long time after the 1500's got them. At least the rfe is very easily buildable, get a plate- tune for pressure, call it a day.

 

[theviking]

Yeah, my rfe runs a lot cooler as well. I wouldnt trust the 8 speed in real towing, neither did fca as they didnt have one available for a long time after the 1500's got them. At least the rfe is very easily buildable, get a plate- tune for pressure, call it a day.

My understanding is the wait had more to do with the prawl/parking system changes necessary for HD truck applications. Regardless, the 8HP70/75 is worlds above the 66RFE in terms of actual feel and drivability. One of the nicest automatics I've driven. The 66RFE by comparison feels prehistoric and the gearing is far from optimal for a gas engine.

 

[mtofell]

The 66RFE by comparison feels prehistoric and the gearing is far from optimal for a gas engine.

Oh man.... is this ever accurate. As a guy who's suffered through towing 11K+ in the mountains with my 66rfe and had two failures (not towing-related) I'd roll the dice with a tranny designed and built by Yugo... even if it meant having to stand on my head while being ear-screwed by a ferret to check the fluid.

 

[Hemi395]

My understanding is the wait had more to do with the prawl/parking system changes necessary for HD truck applications. Regardless, the 8HP70/75 is worlds above the 66RFE in terms of actual feel and drivability. One of the nicest automatics I've driven. The 66RFE by comparison feels prehistoric and the gearing is far from optimal for a gas engine.

Agreed, the 8 speed is a superior transmission.

The discussion was about which one was easier to maintain and that is hands down the RFEs.

 

[theviking]

Agreed, the 8 speed is a superior transmission.

The discussion was about which one was easier to maintain and that is hands down the RFEs.

My comment was in response as to why they didn't put the 8 speed in HD trucks sooner. Yes, I did then elaborate on why I think the 8HP trans are a much better choice regardless of maintenance.

 

[deputy25]

My 66RFE rolled over and sank (again) on Friday. This time my wife and I were towing my CJ-5 on a trailer to West Virginia for a group trail ride. The truck went into limp mode in the mountains about 100 miles from home. Temp was in excess of 205 before we safely got off the road. Truck was towed home (my son retrieved the Jeep). A few hours after it was delivered to my home, I started it up and it ran and shifted normally. It remains parked at this point, this is our third time disabled while towing. Dealer says no codes, can’t do anything without codes. The truck is under warranty but we can’t get anyone to address the problem. It’s very frustrating. We like the truck and want to keep it but our patience is wearing thin and our summer is vanishing. Anyone have any ideas on how to prod FCA (or whatever they are called this week) into action? Truck had the trans line thermostat replaced and fluid and filters changed two weeks ago. Since it was overheated again it likely will need the fluid replaced again.

 

[buckeyexx]

My 66RFE rolled over and sank (again) on Friday. This time my wife and I were towing my CJ-5 on a trailer to West Virginia for a group trail ride. The truck went into limp mode in the mountains about 100 miles from home. Temp was in excess of 205 before we safely got off the road. Truck was towed home (my son retrieved the Jeep). A few hours after it was delivered to my home, I started it up and it ran and shifted normally. It remains parked at this point, this is our third time disabled while towing. Dealer says no codes, can’t do anything without codes. The truck is under warranty but we can’t get anyone to address the problem. It’s very frustrating. We like the truck and want to keep it but our patience is wearing thin and our summer is vanishing. Anyone have any ideas on how to prod FCA (or whatever they are called this week) into action? Truck had the trans line thermostat replaced and fluid and filters changed two weeks ago. Since it was overheated again it likely will need the fluid replaced again.

Sorry I can’t help you prod fca but I would almost guarantee you are having solenoid pack and or valvebody issues. If you can get them to do something I would have both done. I just swapped mine out of my 66rfe two days ago. I wasn’t having problems with mine but I know the issues they will and can cause so I swapped it out for a sonnax upgrade. It’s an easy job to do yourself if they won’t warranty it but it’s not cheap or really expensive. With fluid, filters, solenoid and valvebody it was around 650-700 bucks. What was the failure the first time it happened?

 

[mtofell]

My 66RFE rolled over and sank (again) on Friday. This time my wife and I were towing my CJ-5 on a trailer to West Virginia for a group trail ride. The truck went into limp mode in the mountains about 100 miles from home. Temp was in excess of 205 before we safely got off the road. Truck was towed home (my son retrieved the Jeep). A few hours after it was delivered to my home, I started it up and it ran and shifted normally. It remains parked at this point, this is our third time disabled while towing. Dealer says no codes, can’t do anything without codes. The truck is under warranty but we can’t get anyone to address the problem. It’s very frustrating. We like the truck and want to keep it but our patience is wearing thin and our summer is vanishing. Anyone have any ideas on how to prod FCA (or whatever they are called this week) into action? Truck had the trans line thermostat replaced and fluid and filters changed two weeks ago. Since it was overheated again it likely will need the fluid replaced again.

I've lived through two 66RFE failures and can tell you codes are scarce. I agree with @buckeyexx that your problem is likely the weak valve body. Going into limp mode should leave some stored codes that are deeper in the system than what we see but maybe not. My first failure was just kind of out of the blue but my second one gave me some insight into how these trannies crap out. Basically, hard acceleration at the 2-3 shift would cause it to go to limp. I'd get big clunks when dropping into third and then into limp mode. Obviously, all failures are not created equal but absent a code and with a warranty I'd go out and drive it like you stole it and get a video/pic of being in limp mode. In my experience dealers want to help but they have to have some proof/evidence of a problem.

 

[quickster2]

My 66RFE rolled over and sank (again) on Friday. This time my wife and I were towing my CJ-5 on a trailer to West Virginia for a group trail ride. The truck went into limp mode in the mountains about 100 miles from home. Temp was in excess of 205 before we safely got off the road. Truck was towed home (my son retrieved the Jeep). A few hours after it was delivered to my home, I started it up and it ran and shifted normally. It remains parked at this point, this is our third time disabled while towing. Dealer says no codes, can’t do anything without codes. The truck is under warranty but we can’t get anyone to address the problem. It’s very frustrating. We like the truck and want to keep it but our patience is wearing thin and our summer is vanishing. Anyone have any ideas on how to prod FCA (or whatever they are called this week) into action? Truck had the trans line thermostat replaced and fluid and filters changed two weeks ago. Since it was overheated again it likely will need the fluid replaced again.

Was the temp 205 before or after the limp mode? Reason I ask mine rarely goes above 172 and then only by a couple of degrees even towing 10K+ loads in 90 degree heat throught the hills of KY.

 

[jaflowers]

My 66RFE rolled over and sank (again) on Friday. This time my wife and I were towing my CJ-5 on a trailer to West Virginia for a group trail ride. The truck went into limp mode in the mountains about 100 miles from home. Temp was in excess of 205 before we safely got off the road. Truck was towed home (my son retrieved the Jeep). A few hours after it was delivered to my home, I started it up and it ran and shifted normally. It remains parked at this point, this is our third time disabled while towing. Dealer says no codes, can’t do anything without codes. The truck is under warranty but we can’t get anyone to address the problem. It’s very frustrating. We like the truck and want to keep it but our patience is wearing thin and our summer is vanishing. Anyone have any ideas on how to prod FCA (or whatever they are called this week) into action? Truck had the trans line thermostat replaced and fluid and filters changed two weeks ago. Since it was overheated again it likely will need the fluid replaced again.

Drive it under full load again till it either dies or goes into a bad mode and drive it right into the dealers shop. Three times and no codes, drive it till it blows.....then it'll be easy for them to find the issue.

 

[deputy25]

The truck didnt run hot until the limp mode stuff started. It was usually topping out in the 160s towing in warm weather. It has 45,700 on it and has been problem free till now. We were towing our 30 ft. travel trailer that scales at about 6500 loaded when the truck would shift from 1st to 4th (limp mode) in tow haul. After it sat for a while in normal mode it would operate normally. Dealer would scan it, no codes, no repairs needed. We finally got video of it banging its way into limp mode this past Friday. It still runs at normal temps. One of my coworkers has a 2017 2500 that had the same symptoms with no codes. Same dealer took his in, diagnosed it as valve body/solenoid, repaired it the next day. No problems since. His was not under warranty,, and his bill was 3K+. Mine is under warranty and they cant seem to do anything to repair it/honor their warranty. Seems like they are trying to run the clock out. It’s covered till 60K or summer 2025 whichever arrives first.

 

[deputy25]

Spoke with service manager this AM. They are replacing the valve body, solenoid pack, and trans cooler. Apparently the video shot by their sales rep accomplished what "no codes" couldn't. Hope to have it back later this week.

 

[deputy25]

My wife picked the truck up late afternoon while I was at work. Dealer replaced the valve body and solenoid pack, input clutches, trans oil pump, trans cooler, fluid and filters (again). I took it for a short ride this evening and it seems to be back to its old self. The mechanic at the dealership left a message that he'd like to speak with me tomorrow. I have a number of questions for him as well. I'll be doing some light towing this weekend, then hauling our travel trailer (30 ft. 6800 wet ) next week in the mountains.