Intermittent Slight “hop” at 72mph.

[Rileymk]

Hey, I’m new to the diesel world and also anything bigger than a 1500. I bought 2021 ram 3500 with 80k miles. I test drove it around the block but wasn’t able to get on the highway. It was one of the smoothest riding trucks I’ve driven, until… I drove home with it & brought it to 72mph and it drove smooth until it randomly started a very very slight hop but it’s noticeable enough to raise a brow and sip a coffee.. for a long road trip, it would get annoying. I gassed it from 72-80 and it went away immediately. I brought the speed back to 72 and there were no hops until the road got a little rough, then it started again. No shaking or wobble, just a hop that’s felt through the seats & console.Tire pressure is good. It’s intermittent but only at 72mph. There’s only a half tank gas, nothing in the 8ft bed and I wasn’t towing anything. Could it be a hop because the truck was so light?

Thanks!

 

[KYPOTLICKER]

Yes it could be a # of things. No weight in the bed, road condition, and or a tire out of round/balance
I always start with the cheapest easiest potential fix. Maybe rotate and balance tires to see if that helps with the issue.

 

[Dean2]

Agree. Cheapest option, don't drive at 72 mph, go below or above. However, hop, shake etc. at one specific speed is almost always tire balance or tire construction related. Cheapest place to start is to balance and rotate. I run my 2500 at 50 front 45 back empty, usingOEM size tires. Makes a big difference in ride and handling.

If you have any uneven wear or a pull you may want to get it aligned, but suggest you use the Thuren alignment specs. They work very well on HD Rams.

 

[crash68]

I bought 2021 ram 3500 with 80k miles. I test drove it around the block but wasn’t able to get on the highway. It was one of the smoothest riding trucks I’ve driven, until… I drove home with it & brought it to 72mph and it drove smooth until it randomly started a very very slight hop

Smoothest riding truck doesn't belong in the description of a 3500.. LOL
Does the hop coincide with any cracks/lines across the road surface? I've had this happen before with various heavy duty vehicles "not loaded" on what appears to be flat pavement.
As mentioned I'd start with reducing rear tire pressure and possibly shocks. It could be the alignment also, had one truck make loud noise going over the sealant filled sawcuts across the road(ball-joints were going bad).

 

[Tulecreeper]

Hey, I’m new to the diesel world and also anything bigger than a 1500. I bought 2021 ram 3500 with 80k miles. I test drove it around the block but wasn’t able to get on the highway. It was one of the smoothest riding trucks I’ve driven, until… I drove home with it & brought it to 72mph and it drove smooth until it randomly started a very very slight hop but it’s noticeable enough to raise a brow and sip a coffee.. for a long road trip, it would get annoying. I gassed it from 72-80 and it went away immediately. I brought the speed back to 72 and there were no hops until the road got a little rough, then it started again. No shaking or wobble, just a hop that’s felt through the seats & console.Tire pressure is good. It’s intermittent but only at 72mph. There’s only a half tank gas, nothing in the 8ft bed and I wasn’t towing anything. Could it be a hop because the truck was so light?

Thanks!

I've had my truck for almost 10 months and haven't had it above 65 in that time. And that's been like maybe 10 times. Speed limits in this area don't go higher than that.

 

[Rileymk]

Thanks everyone! I’ll post the update when I get it figured out. I did adjust the tire pressure down to 55psi on all fours for a more comfortable ride to see if that fixes it but nope it didn’t.

 

[RoadRamblerNJ]

As previously stated, most likely a tire/rim or a balance problem. Do one thing at a time so you'll know what fixed it.

I've put 60k on my '17 2500 6.4, CC, Long bed and never felt anything like you described. In fact, the only thing that bothers me is the intrusive speed governor that kicks in at exactly 104 mph.
Good luck.

 

[dputnam01]

The 57 Freeway in Orange County CA used to have me bouncing down the road in my long wheel-base Crew cab w/8-foot bed. The spacing and wear on the concrete slabs would have my butt bouncing out of the seat at certain speeds.

 

[Les_Garten]

Thanks everyone! I’ll post the update when I get it figured out. I did adjust the tire pressure down to 55psi on all fours for a more comfortable ride to see if that fixes it but nope it didn’t.

Here ya go

 

[jr27236]

I assume you purchased this truck as a private sale? As others stated. It can't hurt to take the truck to tire/mechanic center and have them spin up the tires to check balance. They will also notice any uneven wear indicating other issues. Also, when it's up on the lift, inspect the shocks and see if they're in good shape. If they're all rusted out and need to be replaced then replace them. have the mechanic inspect and check all ball joints and linkages, drive shaft u-joints. But it sounds like it's a 3500 hop to me. Pay more attention while you're driving and see if it is on the seams of the road as other stated also. Do you know any previous history or use of this truck? What services were performed (if any)?