Answers Please..

[Barry]

My '06 bolt action Cummins is closing in on 200K(194K and climbing) I have always bought 6 speeds in all my trucks knowing that the 48 trannie was the weak link.



Now, I am considering an automatic for the first time. What I really want is an Aisin but the chances of finding one is very slim. So, my fellow TDR brothers, would you give me some feedback on the 68RFE:



1) What do you think is the life expectancy of the unit?



2) Have any design problems surfaced?



3) Is the 4:10 gears the ideal rear end ratio?



4) What could I do to insure long life to the unit?



Thanx in advance for your comments... ... .

 

[Simplysmn]

Well I have a 08 with a 68 Rfe with 410's and love it max I have hauled was 25,500 and even with a 50 ft wedge behind me you could tell it was there but it still clinbed the hill's without a sweat running down road at 70 mph is roughly 2000 rpm's . Haven't had any major troubles with truck and I'm working on 87,000 in 3 yr's most of the time is spent in town

 

[Barry]

Thanx,

The RPM report is interesting. If one had a 3:73 gears, then would towing in 5th and coming home empty in 6th be a plan?

 

[Hoefler]

Not sure about the above RPM reported, I was running about 2050 at 70 with 3. 73's with my 08. Pulled my 40' fifth wheel quite well, ran 6th gear all the way on the interstates. Averaged 9. 4 mpg on our 3300 mile trip to Mt. Rushmore to Cody, Wy. to Yellowstone through the Big-Horn Pass to Jackson Hole over the Teton the to Cheyenne then back to S. W. Mo.

 

[mpaulson]

I'm at 127,000 on mine and not a single problem and I've got my truck chipped and am pulling heavy, wind dragging loads al the time. I've been up in the 38,000 lbs range quite a few times also. I'm no light foot either and the transmission seems to be keeping up with me. I average about 24000k a year with the holiday rig and deck on which is a 24,000lbs and major wind drag. I run in 5 gear when loaded and do what ever speed I want on any mountain.

 

[Jim W]

I don't have the mileage that must users have on my truck. I do pull a 5er about GVW of 11,000 LBS. My truck; 6. 7L with a 5"TBE, Smarty S67, 14ME software, 68RFE auto, Mag-Hytec trans pan and diff covers. Stock size tires with 3:73 gear set front & rear. I normally run in 6 gear when i tow on flat land, doing about 1500 to 1600 RPM's at 60 MPH. In the mountains I may have to dropped down to 5 gear to keep the EGT's down and doing approximately 60 MPH at 1,800 to 2,000 RPM's.

My trans pan temp is never above 180F with an ambient air temp of 90 F out.

The 6 spd auto's with the 4:10 gear set is rated to tow more than the 6 spd manual trans, for what every that is worth to you.

Jim

 

[Barry]

Thanx for all the feedback. I would prefer the Aisin trannie but I am beginning to weaken on the 68RFE.



I really think I would buy another manual before I bought a 48 RF.

 

[TulsaOkie]

just replaced the transmission at 335k, 68rfe is the best around. A little maintence goes along way... .

 

[EricBu12]

335K in 3 years?!! you a hotshot?. .

Have 15K on my 09 and no problems. the only thing is make sure the tow/haul switch is off before going downhill otherwise it will try to actively slow down and downshift when you dont want it to. . Also, when it shifts down, it unlocks revs up and then settles down to lock to climb. . kinda annoying. If you downshift to 5th before the hill it helps... Other than that, I have not had a problem with the 68RFE.

 

[HBarlow]

335K in 3 years?!! you a hotshot?. .

Have 15K on my 09 and no problems. the only thing is make sure the tow/haul switch is off before going downhill otherwise it will try to actively slow down and downshift when you dont want it to. . Also, when it shifts down, it unlocks revs up and then settles down to lock to climb. . kinda annoying. If you downshift to 5th before the hill it helps... Other than that, I have not had a problem with the 68RFE.

I tow 100% of the time using the Tow/Haul mode and my exhaust brake is also activated 100% of the time.

Turning off the Tow/Haul mode before descending a grade will eliminate one of the great advantages of having the T/H mode and exhaust braking integrated with the automatic transmission.

Unwanted downshifts can be prevented by 1) disengaging cruise control before beginning a descent, 2) using the accelerator pedal carefully (ie don't completely lift your foot unless you want exhaust braking), 3)and selecting the right gear.

 

[tp0d]

Harvey, you make some good points, but the Tow/Haul mode has really jacked me around a coupla times, and I dont use it anymore...

Biggest issue is downshifting on a hill... I tried using the go pedal to 'drift' a bit down a hill, but then when you let off, the damn thing shifts TWICE down. I`ve seen a bit over 4krpms like this, and a solid WACK to the drivetrain. . Dont want to leave parts on the road.

Would really like to have a switchable downshift option on the tow/haul. Love it on the upshift, it holds the shifts later, and I seem to get better fuel mileage with tow/haul on. . But them whacks to the transmission/driveline are the killer... ohwell, nuthins perfect. .

I`ve settled to using the manual up/downshift on the shifter. . works good, unless I forget to shift back up to 4-5-6 and revv the crap outa her lol. .

ymmv

-j

--edit-- maybe its the Pittsburgh hills here that drive her nuts, i dunno... we do have some nice long hills tho

 

[HBarlow]

I'm surprised to hear what you guys are reporting.

I have no experience with the ISB6. 7 pickups so don't know how they operate. My truck is a cab and chassis with Aisin. Perhaps the ECM/PCM programming is different for my "work truck" than your pickups.

I know that the gear ratios of the Aisin are a little different and my truck has a 4. 10 rear end. As I stated above, I tow 100% of the time using Tow/Haul mode and normally tow at 62 to 65 mph, less in towns and cities when speed limits are lower. The Aisin does what I want and expect it to do within reason.

 

[Hoefler]

I run with tow/haul and exhaust brake engaged 100% of the time. Part of my start up ritual. I have never had a problem with the down shift and tow every day in the Ozark Mountains in SW Mo. Like Harvey has said, it is all in the throttle control. Very light pressure on the accelerator, just enough to get it of the return stop, will keep the exhaust brake off. Take a little practice, but it becomes second nature real quick.

 

[HBarlow]

I run with tow/haul and exhaust brake engaged 100% of the time. Part of my start up ritual. I have never had a problem with the down shift and tow every day in the Ozark Mountains in SW Mo. Like Harvey has said, it is all in the throttle control. Very light pressure on the accelerator, just enough to get it of the return stop, will keep the exhaust brake off. Take a little practice, but it becomes second nature real quick.

Good. That's what I wanted to hear.

 

[Hoefler]

I run with tow/haul and exhaust brake engaged 100% of the time. Part of my start up ritual. I have never had a problem with the down shift and tow every day in the Ozark Mountains in SW Mo. Like Harvey has said, it is all in the throttle control. Very light pressure on the accelerator, just enough to get it of the return stop, will keep the exhaust brake off. Take a little practice, but it becomes second nature real quick.

 

[Hoefler]

I run with tow/haul and exhaust brake engaged 100% of the time. Part of my start up ritual. I have never had a problem with the down shift and tow every day in the Ozark Mountains in SW Mo. Like Harvey has said, it is all in the throttle control. Very light pressure on the accelerator, just enough to get it of the return stop, will keep the exhaust brake off. Take a little practice, but it becomes second nature real quick.

 

[Barry]

To the high mile users with 68 trannies... ... ... ...



What sort of preventive maint. are you following?



I think the first thing I would do is change the trannie pan to allow for fluid changes... ... ... ... . And a trannie temp guage.