Sudden Acceleration in Reverse

[GBlaksley]

Bought a 2012 3500 SRW in October. Currently has just under 2000 miles. Twice in the last two weeks when backing out of the garage with my right foot on the brake, the back wheels started to spin in the gravel. First time, it dug two, six inch deep trenches. It really took me by surprise. I don't think the RPM went up very much, as there was not a real noise increase. Today, it did it again, but I was much quicker to get it out of gear. Still didn't notice how high the RPM went. I am a right foot braker, so I know I didn't step on the accelerator. Also, I tried to put my foot on the brake pedal and accelerator at the same time. It is very difficult to do. I do have the adjustable pedals, but can't imagine they would have a thing to do with it. Checked the floor mats and they don't seem to be anywhere near the pedals.



Anybody have any ideas?

 

[TWood]

I have experienced a similar thing 2 to 3 times in my 2010 truck. Most of the time you put it in reverse and it just slowly idles out of the garage but a few times it has lunged out of the garage. I dont know why but i just make sure I have my right foot firmly planted on the brake. It has only happened a few times so I havent really worried about it. It almost seems like somehow the torque converter is locked when you put it in reverse. I dont know if that is possible, it doesnt seem like it could be but i dont know.

 

[retirednak]

Gonna sit on the fence and watch this one,been thinking of a new truck.

 

[cerberusiam]

Sounds like a TC problem. Have been more and more of these issues showing on the TC's. Essentially, the sprag clutch in the stator is malfunctioning causing the TC to have no stall. With a TQ engine and a low ratio tires spin in the traction is low. Otherwise it wants to lunge.

 

[RonD]

My 2012 has never done that, mine is the Max Tow, so I think the T/C is not the same as the non Max Tow

 

[RustyJC]

My 2012 has never done that, mine is the Max Tow, so I think the T/C is not the same as the non Max Tow

My 2011 350/650 has never done it, either.



Rusty

 

[GBlaksley]

It actually did it again this morning, before I was out of the garage. It squeaked the tires. I had the presence of mind to look at the tach, and did not see a rise in RPM. This time, rather than slip it in neutral, I pushed very hard on the brake. It was all over in a second, and things went back to normal.



Thanks for all of your replies.

 

[Wingate]

Goerend... Calling dave Goerend... time for a converter since the dealership is gonna have it out anyway!!

 

[Bob4x4]

Had an 06 just today converter issue. T/c would load the engine so hard it was building boost with no pedal applied. The description on the repair order was interestingly worded.

 

[cerberusiam]

Had an 06 just today converter issue. T/c would load the engine so hard it was building boost with no pedal applied. The description on the repair order was interestingly worded.

Did it take the rpms all the way to defuel at 2100? That really freaks the drivers out. :-laf

Exactly what did the description say? This could be interesting. Oo.

 

[SPucillo]

Bought a 2012 3500 SRW in October. Currently has just under 2000 miles. Twice in the last two weeks when backing out of the garage with my right foot on the brake, the back wheels started to spin in the gravel. First time, it dug two, six inch deep trenches. It really took me by surprise. I don't think the RPM went up very much, as there was not a real noise increase. Today, it did it again, but I was much quicker to get it out of gear. Still didn't notice how high the RPM went. I am a right foot braker, so I know I didn't step on the accelerator. Also, I tried to put my foot on the brake pedal and accelerator at the same time. It is very difficult to do. I do have the adjustable pedals, but can't imagine they would have a thing to do with it. Checked the floor mats and they don't seem to be anywhere near the pedals.

Anybody have any ideas?

Have you changed the trans filters? If the TC is not at full pressure the clutch will engage. Typically it is the little spin on filter with a leaking back flow valve that will let the TC drain in to the pan. If you let it idle longer the TC will fill up and you will not have a problem.

 

[GBlaksley]

SPucillo,



I'll bet your on to it. I have had the truck since October, and haven't been driving it much. I think that each of the three times this has occurred, the truck has sat for a week or more. I have driven it every day this week, and nothing has happened. Can't see that I would need a transmission filter with only 2000 miles. Is that spin on filter inside the transmission or on the outside?



Thanks.

 

[kkelley]

Until you get it isolated... try letting the truck idle for a minute or two before putting it in gear. Also, back into the garage to see if you can induce the issue in drive as well.

 

[HBarlow]

Goerend... Calling dave Goerend... time for a converter since the dealership is gonna have it out anyway!!

Have the aftermarket transmission builders like Goerend and DTT moved into producing parts and modifying the six speed automatics now?

 

[cerberusiam]

Have the aftermarket transmission builders like Goerend and DTT moved into producing parts and modifying the six speed automatics now?

The 68RFE, yes. They had to because the trans will not hold the power. Can't sell high performance transmissions without fixing the issues. The 68RFEis no better than the Ally 1000 once the power goes beyond stock managed levels.

 

[HBarlow]

What about the computer controls? A former TDR member named Rowdy2 who I never met but lived not far from me had a very highly modified 6. 7 in an '08 a couple years ago. He predictably destroyed the 68RFE in a short time and had it built as a performance transmission. IIRC he reported here that the computer overrode the new clutches, etc. and made it shift like an OEM 47/48 anyway. He disappeared not long after that.

Does the aftermarket now have the capability to make them last behind a modded 6. 7?

 

[cerberusiam]

Does the aftermarket now have the capability to make them last behind a modded 6. 7?

Sure. Not "now have", but, "have had" since about 6 months after the 68RFE released and the builders got them to repair and upgrade. Suncoast and H&S have had shifting programs for years now, probably others. They even use them to keep the stock transmissions running longer with power upgrades.

Fully 1/2 of a performance rebuild is shift algorithm changes. Without the programs the trans just destroys itself with the crappy OE algorithms, even with upgrades. To fully exploit the shifting changes there are hard parts that need upgraded because they won't take the stress of the changes for long, if at all.

 

[HBarlow]

Thanks for an excellent explanation. I'm glad to know those things although I don't own one. Owners of 68RFE equipped trucks should probably consider upgrading their transmissions if using any type of power adder.

I think the former TDR member had a local yokel in a fast rebuild shop for ordinary light duty automatics rebuild his blown 68RFE. It probably didn't last long.

 

[SPucillo]

SPucillo,

I'll bet your on to it. I have had the truck since October, and haven't been driving it much. I think that each of the three times this has occurred, the truck has sat for a week or more. I have driven it every day this week, and nothing has happened. Can't see that I would need a transmission filter with only 2000 miles. Is that spin on filter inside the transmission or on the outside?

Thanks.

GBlaksley,
Any luck with just letting it idle for a while longer?

 

[NIsaacs]

Sounds like a TC problem. Have been more and more of these issues showing on the TC's. Essentially, the sprag clutch in the stator is malfunctioning causing the TC to have no stall. With a TQ engine and a low ratio tires spin in the traction is low. Otherwise it wants to lunge.

My Brother-in-law had this happen twice, scared the crap out of him, 2012 3500 SRW. I remembered this thread so I told him I would read up on it and advise him. It happens after it sets for a few days. Kinda crazy and dangerous



Nick