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cansled

Denali-Rough ride when towing

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Just took my first trip towing with my 2018 Denali CC and it rode much, much rougher than my previous 2015 LTZ CC.  I am pulling the same trailer with the same WD hitch.  All measurements done right with within the same specifications of the 2015 with both the truck and trailer sitting level.   The height the trailer dropped the rear 4-5 inches (700 pound tongue), exactly the same distance as my 2015 and NEVER had the same problem.  It rode like I had almost no rear suspension travel and the rear shocks were very stiff.  Every bump in the rear suspension was felt.  When I got out and jumped on the bumper there was very little up/sown movement.   It tracked great, no sway, and of course did not porpoise with the stiff shocks.  On a flat road it wast perfect.  Unloaded suspension functions normal.  Anyone have the same issue with this Magnetic Ride Suspension?

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Same diameter wheels on both trucks? I'd imagine 22's would be pretty bone-jarring in any case. Only other difference I can think of would be the magnetic shocks in the Denali.

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I don't have an answer for you, but I'm interested in this topic.  I want to think that its got something to do with the magnetic ride.  

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Yes same 22 inch wheels.  Had the same wheels on my 2015.  I am wondering that the weight of the trailer might put the shocks closer to the bottom of the travel increasing damping and stiffening the shocks.  The only thing I can think about is the magnetic suspension.  I wonder if put in a set of timbren helper springs on would increase the ride height putting the magnetic shocks back into their sweet spot.

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I purchased a 2018 GMC Sierra Denali to tow my 2018 Airstream FC 23FB. I towed my trailer from Colorado to Illinois. The tongue weight of my trailer was 467 lbs. The magnetic ride stiffens as the load increases. I found the ride to be very good and with my WD hitch, stable and firm. I felt no harshness to the ride. I am pleased with my towing experience. My mpg coming home towing was quite surprising. I believe the differences you feel in the new truck are shaping your views of the harshness of the magnetic ride. Once you have unloaded yor tow, take a short trip with just the truck to see if the firmness has subsided.

 

zoz

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It is perfectly smooth unloaded.  Loaded it is much harsher than my 2015.  My wife and daughter both noticed it and asked me what was wrong with the truck.

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I’m guessing your bottoming out the magnetic ride rods causing the mag ride to max out firmness if you read though some of the threads on here about guys lowering or raising the ass end of the Denalis they usually comment on how harsh the ride has become even going as little as 2”. There is sensors mounted to the frame?/rear suspension? with a level rod. The answer for them is to modify and/or buy a shorter/longer rod. If you can I would try to adjust as much of the weight of your trailer to the rear of the trailer to decrease tongue weight then take it for a test drive to see if it improves the ride.

 

Some old timer years ago told me the magic number for tongue weight is 200 pounds no less the closer to 200 the “better” the trailer will pull and oddly enough I have found this to be true, of course that is not always possible.

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Another possibility is U Bolts not torqued properly letting the axel twist. (Lash) This messes up the Magneride shock function big time.. Maybe more likely than the sag from tongue weight! 

 

My 2016 had issues that I first noticed on a section of rough freeway and then again towing about 3000 lbs. It was undulating & then vibrating like I had no shocks. There is no way to check torque since GM uses torque and angle to theoretically stretch the bolt so it’s unusable again. I decided that was the only possibility and made several trips to 2 different dealers. GM refused to replace them and I was told that very high tech equipment made it impossible to have incorrect torque & more BS. I went to a Driveline Shop and had them replace mine with 5/8” vs 1/2” stock so they were able to torque to 135# as I recall. Problem solved for just over $50 including labor.

GM has dealers screwed down tight on warranty-if it isn’t a part failure good luck although some dealers will eat some $ for a good customer. My original dealer spent some time with me but there was no place close to duplicate the problem ergo “working as designed”, ha ha.

Edit....Forgot to mention that I had a 2014 so I had a reference point. I did tow a Travel Trailer, maybe 7000 loaded and didn’t notice an issue. Only one short trip before I got my WD Hitch installed.

Edited by Ron.s

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Timbren helper springs came in today.  So I will try this out first to see if it brings the shocks back into the "sweet spot".  However, this bothers me as GM says the Magnetic Ride adjusts for all conditions, preserving the ride.  They also say 70% of Denali owners tow with their vehicle.  This should not be something I have to add, just to make it work right....especially since I didn't need it on the 2015.  I will keep you posted on the results.

 

Ron:  Is there a way I can check if the axle is twisting myself.  I might see if the dealer will let me hook up my trailer to another Denali and see if it feels the same.

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On 5/30/2018 at 6:59 AM, cansled said:

Timbren helper springs came in today.  So I will try this out first to see if it brings the shocks back into the "sweet spot".  However, this bothers me as GM says the Magnetic Ride adjusts for all conditions, preserving the ride.  They also say 70% of Denali owners tow with their vehicle.  This should not be something I have to add, just to make it work right....especially since I didn't need it on the 2015.  I will keep you posted on the results.

 

Ron:  Is there a way I can check if the axle is twisting myself.  I might see if the dealer will let me hook up my trailer to another Denali and see if it feels the same.

If you are adding another leaf spring it’s a Moot point since you will need new U Bolts. For the cost if it were me I would just have them changed. Just go to a “spring works” and have them make a larger U bolt. Most medium size towns have one-the commercial trucks keep them busy. They make them in minutes and normally charge by the inch. I think 5/8 will fit the GM brackets. In the quest for lower weight GM has made each part as light as possible.

I know some contractors use Air Bags rather than add another leaf. More expensive but you can adjust the height to fit the load.

There are several ways to test for axel wrap. I saw a YouTube video where a camera was mounted pointing at the axel and a horizontal line on the axel to show if movement. You can sometimes feel it when you get on and off the gas. It’s possible that you could see the movement by fastening a level to the axel and hook up the trailer to see what happens. May not be room to crawl back under. From your description it almost has to be the U Bolts or bad shocks. Some dealers may be able to test shocks but probably won’t under warranty and that’s not likely the problem. If you have axel wrap the movement can trick the shock into thinking that you are rebounding when the shock is compressing or the reverse. So it might be reducing dampening just when you need lots more.

Good Luck!

 

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Well put on the Timbren's and the ride quality when towing has dramatically improved.  The truck only drops about 2 inches with the trailer hooked up and I think that the Timbren's put the height in the 'sweet' spot for the Magnetic shocks as I could 'feel' the suspension working with a much softer ride.  Without the trimbrens the drop was much more significant, putting the shocks near the bottom half of their travel increasing the firmness of the shock.  Feels much more like my 2015 now.   Still have some fine tuning with WD hitch and more miles to compare, but I am much happier now.  IF that was the problem I am surprised as I thought the Magnetic shocks were BETTER, because they "can tighten and loosen when necessary, the system allows the best of all worlds: a firm, tight ride when cornering and a comfortable, loose feel over bumps."!

 

PS.....I have driven it for a week with timbrens installed, Going over railroad tracks and frost cracks on Michigan roads and have not noticed any change in ride quality when not towing. 

 

I will keep you updated once I put more miles on.  Thanks.

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Thanks cansled, I don’t know how I missed your post when I first started. I thought I searched!  

 

What a counsidence!  You and I have gone through the exact same thing except my Denali is a 17. 

 

Where did you get the Timbrens?  You said one bolt to remove them. I’m not familiar with what you are speaking of. I have read up on the air bags and maybe the Timbrens are better?  I will see if I can find some information on them. I assume they won’t affect warranty?

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Timbrens work in the same principle in that they raise the back of the truck to help level it out and take some of the sag off of the springs.  The main difference is that they are non-adjustable and replace the axle bump stops with a progressive style rubber spring that is attached with a bolt in the same location as the original bounce stops.  Unloaded they sit a couple of inches above the axle and do not make contact with the axle.  When you lower the camper they make contact with the axle padse and take some of the pressure off the springs. ... increasing ride height.   Some complain they notice a difference in ride quality unloaded but I haven't.  What I meant in my previous post was you could easily remove them for the winter or when you're not using them if you wanted to.

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The MR shocks are gonna increase damping to infinity - basically go solid - as they near the compression limit.

So it makes sense that timbrens or bags that minimize squat are gonna be a huge help.


Sent from my iPhone using Tapatalk Pro

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Digging this up because I've a 2017 Denali and thought about putting a small ultra light camper in the box and towing a 23ft snowmobile trailer.. about 2,000 lbs empty but more like 5,000 lbs loaded.  GM says not to put a camper in the bed.  I guess it would compress the MagneRide too much and cause some of the concerns mentioned by the OP.  I am wondering what the new 2020 model is like because I think that GM discontinued use of the MagneRide.  

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