So I test drove and almost bought a GMC Duramax last week since my frustrations with my truck's constant front end death wobble issues are wearing me out.

One distinct thing I noticed when I drove the GMC was the lack of power compared to my 2012 F250 Diesel. The GMC was a slow surge of power and the Ford is a throw you back in your seat kind of power.

I am not an expert at all so can someone explain to me why the Duramax is so sluggish compared to the power stroke. I can't imagine the small difference in HP & torque creates that big a difference in take off power.

 

The power curve can be tuned in many ways (pwr vs. rpm, throttle position, ect.) to give a different experience given the same peak hp number. The manufacturers chose different schemes.

 

My Duramax buddies always tell me that the Allison tranny takes so much less power away from the engine that the combo is far superior to Ford and Dodge. But then one of them just had to buy a programmer and tune his Duramax.
He is always tinkering with something. I really struggle with the low hanging DEF tank on the GM twins.
Sorry to hear about your death wobble issues. I have not experienced them with either of my Superduties.

 

Thanks. Yes it's something very different in the power. Well I had a signed contract but luckily they didn't have the truck in stock so after a few days I requested a cancellation and they let me out of it. I've decided after four different attempts from Ford without total success on the front end shimmy that im going to put an aftermarket fix on it. The rest of the truck has not given me any issues and is such a blast to drive. That's why I backed out on the GMC. I'll fork out some money to fix the front end and keep my favorite truck

 

I understand about the power difference. While a 2012 PSD and 2016 DMax are very close power wise, it is all in the delivery. I hate the pedal response the DMaxs have. They are a very "fine tuned" power train though. Tough to beat the run of success they have had. The 6.7 should be around long enough to match it. Hard to beat a setup that has been somewhat unchanged since 2001.

 

I think this sums it up. My son had a 2011 and now has a 2015. Seems like you have to floor the GMC to wake it up vs the much more responsive ford pedal. Wouldn't trade my 2012 for anything GM offers.

 

Exactly!! I've grown quite used to being able to blast past someone on the freeway even if I'm already going 70 mph!

 

I drove a Cummins back in 2011 I think it was, and I felt the same sensation. I knew the power was there but it didn't feel the same and took more work to get it. I know the I-6 is a different animal anyway, but still.

I had a dura max back in 2005 I think it was, it did a great job really. Funny thing, I went to ford due to the front suspension woes of the gm, and also the seemingly steady issues with the engine. Mostly injectors. The 2008 SD was my first after using GM trucks for 5 years. I found the sd to outperform in every way with exception to the seat.

 

My truck is my first Ford diesel. My son has had a few DMax's and has an '05 2500 right now. If my truck has a front end wobble then I don't notice or know what I'm looking for, I do get some vibration at certain speeds but it's the whole truck and I can't tell if it's road or truck related.

My Ford needs to be pedaled to spool the turbo if I want to pull out and go, from a standing stop I can't just stick my foot down hard but maybe that's just the 6.7, my son's Dmax's don't do that but then they've all been tuned.

 

My '15 Ram is the same experience. The torque management to adjust how the power is delivered to the drive train is much more active on the Cummins and the Duramax. I think there is a lack of confidence in the transmission. People rave about the Allison, but I know plenty of guys that have transmission issues with Allisons. The 68RFE transmission in the Rams has been a weak point for a long time as well. The more I research the 68RFE, the more I cringe. No way I'm tuning this truck with a built transmission in the shop ready to go.

 

My truck puts plenty of power to the rear wheels and if I push too much on the go pedal it will try to break the tires loose with my bumper pull trailer hooked up.

I haven't ever really tried to spin the tires but I'm sure it would get quite costly if I was into doing it.

As for highway driving, the throttle is super responsive and I have no problem dealing with high volume beltway traffic other than the rear end being a loong way back. The only real hiccup I notice is if I am running 55-60 and need to accelerate quickly. Sometimes there is a little lag while the computer decides if it wants to try to get the job done in 6th gear or drop down to 5th and glue me to the seat. It seems to be related to how fast and far I move the pedal. If I mash it down it just downshifts and takes off. If I sort of ease into it that is when it gets confused. I know...just mash it right, but that might put me in the rearend of the car in front of me before I can change lanes.

 

With a somewhat aggressive tune the Allison will start to slip 5 & 6 gears. My son had that on his last DMax although he also drag raced it a couple of times. I think this one is doing better as he's been easier on it and not as aggressive with the HPTuners

From what I know from the Dodge guys when I had my shop their trans won't support a whole lot more power than the truck makes stock.

 

The Allison is fairly hit and miss in my experience. Most that I've had experience are exactly as you describe, but I have a good friend in town that is running H&S tune and if he takes it out of the tow tune he starts slipping. He finds this to be "expected with a truck that makes so much power". I just laff.

The 68RFE is a weak link. They have made progress, but I feel that tuning my truck is a bad idea without a purple built transmission in my shop waiting for the call, lol

 

Glad you stuck with the Ford. Although overall I think the GM trucks are pretty decent, there are several things that turn me away from them - the square wheel-wells, the IFS on an HD truck, and generally the interiors. The current trucks have a nice interior, but the steering wheel is offset in relation to the seat and pedals - I couldn't stand that. The Duramax / Allison is a very solid combination, although the LML uses the same problematic Bosch CP4.2 pump we have.

It's funny how you guys speak of the Powerstroke being more responsive - the Duramax, even with less rated output, seems to match the Ford's street performance times. Probably the GM trucks weigh a little less, not sure.

I've long heard of this front end death wobble - never experienced it on 3 Super Duties. I did experience it on my old 1992 Range Rover which of course had solid axles front and rear. It can be a bit nerve wracking when it happens. The problem is 100% due to wear in the bushings of the various parts which locate the front axle. This would be the Panhard / track rod and radius arms. The radius arms are the long steel arms which mount behind the front axle; they connect the front axle to the frame and prevent the axle from moving forward or backward while still allowing suspension movement. The Panhard or track rod is a shorter steel rod which also connects the front axle to the frame and prevents side to side axle movement. It is connected to one of the frame rails on one end; on the other it is connected to the axle. The Panhard rod has a steel and rubber bushing on both ends. Over time, depending on use and how smooth your roads are, hot / cold cycles, etc...the rubber cracks, twists, hardens, and the steel elongates. The radius arms also have rubber and steel bushings on both ends - typically 2 bushings on the front axle end, and one on the rear frame end. Lifted vehicles suffer death wobble more. Many people think a steering damper solves the problem - not so. Yes, your tie-rod ends and steering box needs to be tight...but if my truck gets the death wobble, I will simply replace all the bushings at once. (Note - some are very hard to remove, dealer might be better option). I went through the mill with the old Range Rover before finally replacing everything and solving the problem.

 

I agree with what you said. The weird thing is Ford replaced the bushings and tie rods in May and July. In September it came back and in October they replaced the dampener saying they had fixed it. A suspension shop said the parts were all broke and had way too much play. This shop also told me Ford would say they are fine which they did in fact say. From October 22 to this week the truck drove fine but now I'm noticing the front end getting loose again hence my frustration and looking at the GMC. My truck is all stock with no lifts. My concern is do I have long term damage under my hood from this and how do I finally fix it? I have an extended warranty but it's only through a Ford dealer and the dealer says the truck is fine. Argh!! Oh and Ford has warned me that if I have any work done to it outside of their dealership that they will void my warranty on the front end. See how I'm trapped.