Ford F-350 Shudders and Strains

[AlmostRetired]

I have questions for Ford Super Duty owners. Hauled our 2012 Bighorn 3185 out to South Dakota's Black Hills over Labor Day. The camper weighs 12200# loaded for the trip as verified by scales. TV is a 2008 F-350 diesel CC with 78K miles. It is still under the 100K drivetrain warranty.

I had the cruise set at 60 mph and the tow/haul switch engaged. The transmission temperature gauge was normal and had not been doing a lot of downshifting. As I began climbing a 6% grade, the truck downshifted once and everything was fine. A few seconds later it downshifted a second time and you would think the world was coming to an end. You could feel the truck shudder and almost hear the transmission slipping. I tapped the brakes to disengage the cruise and once the fuel supply was reduced, the truck recovered. I hate to admit it but I did recreate the scenario again. Mid-October I am traveling to North Carolina and back to Minnesota and am concerned about the elevations going East.

My questions are: 1. Am I abusing this truck/transmission by expecting too much from it? 2. Is there anything I should ask the dealer to investigate while it is still under warranty? 3. Do you have any constructive advice base upon personal experience. Please resist the name-calling...my wife has that job!

 

[truknutt]

IMO, the root of the problem appears to be that you were attempting to ascend a 6% grade with the cruise on.

 

[AlmostRetired]

Fair enough. However, if the truck is rated to haul loads heavier than what I was asking it to do, why does the tranny slip when giving it fuel under load? I understand having the cruise on is just like flooring the accelerator. Big deal...assume the cruise was off and I just floored the pedal. The transmission slipped going up the grade until the fuel supply was reduced. This is the issue I am asking for you guidance on. Suggestions?

 

[Bob&Patty]

2 questions. Was it hot outside? Are you sure that it was not the fan clutch engaging?? A fan clutch will draw lots of power from the engine and it sounds like the trans is slipping. Our D/A will do the samething on a hard pull when its hot. I do use the cruise but I will help by pressing on the throttle a little.

 

[lwmcguir]

Another possible item to look at is the solenoid valve that controls the torque converter lock. It may be weak but you should see a message in the console regarding this. Have you changed the transmission filter lately? Would be good to take a close look at the filter and the fluid to see if you have any noticable issues that might indicate larger problems.

 

[Rrloren]

Is the truck stock ? I have had the same problem hauling my Sundance when I had the power turned up too much and had low rpm's with torque convertor locked up. Downshift to increase your rpm's.
By the way when mind slipped it felt like I was running across those speed strips you find cut into the roadside.

 

[TeJay]

Hi,
I have a little experience with automatics so here goes. First you said, " Almost slipping." No dealership will accept that phrase towards diagnosis. They need something more definite. When an automatic or standard transmission looses the grip on the clutch discs the engine can't transmit power to the drive axle and the engine RPM's will increase. It's no different than slipping on ice or snow. The shuddering does indicate that there is intermittent slipping of the clutch discs. It's shuddering because you get grip and positive lockup then it slips again. This repeaded over and over causes the shuddering. The engine rpm's are the real indicator, at least to the dealer. Now why might it be slipping?? There's really only one thing that can cause it to slip and that's not enough hydraulic pressure against the clutch discs. Lower hydraulic pressure can be caused by two things. Either not enough fluid or leaking hydraulic seals. What ever the reason the only fix is to completely rebuild the transmission. Once clutch discs begin to slip they very rapidly burn through and are destroyed. If you pull the dipstick and smell the fluid it should have a burnt smell. Just changing the fluid will not repair or fix the burned clutch plates. Using the cruise control was not the problem. I don't like to use the cruise pulling up a grade because I can use a lower gear and simply slow down a bit so the truck does not have to work so hard. If I were cruising at 62 and hit a grade I don't like for the truck to try and keep it at 62 so I disengage and slow down. If you were using your cruise at say 45 while climbing the grade that also OK. You were simply using your truck as a camper hauler and that's all. They are designed to pull loads. If you were pulling within your weight limits they should rebuild it without any question.
Best of luck and I hope this helps some.
TeJay

 

[AlmostRetired]

Thank you for your comments. It was not hot - 72 or so and all guages were normal. I could not say for sure it wasn't the fan clutch since this is an issue I have had zero experience with. I would be surprised if it was the clutch only because the decrease in pulling power was so pronounced.

 

[AlmostRetired]

Wow TeJay! Sounds like you know your stuff and I appreciate the time you took to post such a comprehensive response. I'm taking the truck to the dealer next week for an oil change and routine maintenance and feel as though I can better discuss the issue now. Thanks again!

 

[codycarver]

I hear shuddering and I think drive line so I would check the U-joints just to eliminate that. I can't imagine how you would be abusing your truck if you stay in the weight ratings. I pulled those same hills and the Big Horns last weekend. Just for the record this is the first Auto trans I've had in over 25 years so I'm still getting used to the feel of it. The trip over the Big Horns (7% grades) was in auto tow/haul, it did down shift to 5th a few times and seemed to rev. I attributed this to an aux. fan The trans slipping did pop into my head but no shuddering at all, no lose of speed and the temp. barely got over 200 deg.

 

[Bob&Patty]

You may have a trans issue. But, I do know when my fan clutch fully engages there is a noticable power loss. If you have a trans issue, it might show up with a ford dealers scan tool. It might have set a trans code. If it did not set a code, then it will be hard for them to duplicate. Like was said...pull the dip stick and smell the oil. If its brown and smells like paint varnish...then its burning. It could be the torque convertor clutch that is failing also. Burnt clutchs wont last long. Good luck.

 

[brianharrison]

I agree with TeJays comments. I pull with the same truck (stock program). However I also have the benefits of an Edge Insight connected to the OBD2 port so I can see actual temps, load calculation, and whether or not the torque converter is locked (I put all these on one screen). My trailer weighs 12,000 on the trailer axles and 3000 on the kingpin (total 15,000).

You should get the tranny serviced by a competent tech - I have spent the money with a Ford dealership to do a full service with fluid change for my tranny. Eliminate any tranny possibilities first.

My shudder was due to driveline angle - with the 3000 pin weight my 350 (with camper option) squatted about 4 inches and changed the driveline angle. Couple that with an increased torque required scenario - up a grade and downshift to higher in the power band - I also experienced axle wrap (torque on axle "twists" it a bit) compounding my driveline angle issue. There are lots of discussions on the Ford Forums (here is one) about air bags helping, changing out driveline and carrier bearing (we have a two piece driveline) to beefer one, adding traction bars to prevent axle wrap, etc, etc.

My solution was to add air bags to fix the squat issue (i like my headlights aimed down the road; not up into the sky when loaded) which removed that concern for driveline angle. THis off loaded my springs so they could help prevent the axle wrap at high torque situations. Finally I drive the truck through the shudder point (ie no cruise) by decelerating or accelerating through it, similar to TeJay. The result is I rarely experience the shudder issue any more.

Hope this helps.

Brian

 

[TandT]

I hope this is an easy fix for you.
No matter what your outcome, I will never pull a significant grade with the cruise control on, as TRUKNUTT already stated.
I learned the hard way, when on several occasions my trans slammed into a lower gear trying to keep up with the speed request I had dialed in. Sounded like something was going to break. My trans slip alarm went off and scared the heck out of me.
Instead I take the cruise off and just drive the truck the old fashioned way on hills. No other problems after that

 

[rebootsemi]

Still under warranty good load the Sundance up and take it out and see if you can make it repeat the problem, sounds crude but probably would be best if the trans just blew up, just kidding. If you take it to the dealer they will never be able to make it repeat the problem (no load). On our F450 service trucks they used to just eat auto trans. With the Dodge I hardly ever let it shift itself down, I know when it wants to shift so I just roll out of the throttle and hit the button down a gear and roll back in the throttle. The next truck will have a 6 spd manual trans in it. Trouble with auto trans is you can't work the diesel hard enough. Just two cents worth.

 

[SouthernNights]

Had the same problem and at first thought the same thing about the transmission and torque convertor. Several trips to the dealership with test drives including with the trailer and hooked up to a computer at least proved it was not the trans or convertor. I could duplicate the problem with or with out the cruise. All it took was the trailer hooked up and a slight rise like an overpass on the interstate.

I started thinking it was drive line angle and found this TSB. http://ww2.justanswer.com/uploads/erc53/2010-05-02_225458_driveawayshudderf350.pdf Although this bulletin is referring to taking off from a stop, it was enough to convince dealership I was having this problem. On down shift, you still get the wrap up of the rear just like on take off. When the front off the pinion came up, the angle (or lack of it) changed enough to cause the vibration.

 

[Bob&Patty]

I had the same issue as Larry. Had driveline shake from stops when pulling. GM makes wedge type shims to install between the springs and the diff housing. With the shims you are able change the angle of the pinion either up or down. We installed them to angle the pinion down more to put more angle at the pinion when pulling the BH. Problem went away. BTW, now that I think about it, when my engine did start applying more torque as the RPM's dropped pulling a hill, I did get a very little driveline vibration. I could hear and feel it. Next time you are hooked to your BH, crawl under your truck and look at the angle of the pinion and the driveshaft. Almost straight or straight is not good. As mentioned axle wrap can cause all kinds of issues. It will change the pinion angle and can cause driveline shake.

 

[porthole]

So exactly which super duty do you have? Makes a difference.

2011's are well known know to have a shudder at lower speeds, especially from stop to about 15-20mph. But it can be felt in any of the lower gears.

That fan clutch i s something you may never hear under normal driving and moderate towing. Add a 12K trailer and a long pull up a hill and you will see gradual increase in temps, but not a big jump. At the right temp the fan clutch will kick in and make a lot of noise, and it is pulling a lot of air, which means it is sucking up some of the ponies being produced.
I've heard number as high as 60-70 horsepower to run the clutch.
If your truck is newer model, a slipping trans will generate diagnostic codes. If it is slipping, the PCM will reduce fuel in an attempt to stop the trans from slipping ("de-fuel") - less fuel - less power = less work.

BTW, the cruise is not the culprit. I use mine all the time and always have since cruise was first available.

 

[lwmcguir]

Regarding the 2011 Ford Truck shuddering at slow speeds, the latest computer update appears to have helped this a lot. We barely notice it now and do use the cruise when towing almost all of the time.

 

[porthole]

Which update, the one for trans shifting? That helped my trans to shift better (already shifted pretty good) but did nothing for the low speed shudder.

 

[lwmcguir]

I dont know which ones the Dealer flashed. Left it there and picked up after hours. They just noted that it was updated. It does shift smoother and barely shudders now at low speed. Still shifts better if you have a bit of throttle rather than just loafing around. Next time I am back at the dealer I will find out what they changed. This was just a couple of weeks ago so again not sure when they actually were available. I do have one other little quirk and that is the computer trip calcuator shows about 10% more fuel consumption than actual. Verified this over 4 different trips. It was a good surprise but would like it to be a little closer.