[Pappagray]

Hey guys,

Just curious if anyone else with a lowered charger is experiencing a driveline vibration? From about 70-90mph while on throttle I have a vibration. Cars brand new, was fine prior. Its the definition of driveline vibration, but not sure how you'd even rectify that with the IRS

 

[Linda's Hell Cat]

@DGatzby I bet you could help and explain?

Linda

 

[DGatzby]

IDK. There are risks to changing the geometry. What all is modified? How much is it dropped?

 

[Pappagray]

It just has springs from eibahc thats it. Its a fixed IRS so its not like pinion would ahve changed. My guess is the axle shafts aren't happy?

MY Challenger HC was lowered the same way with no issues

 

[DGatzby]

I am thinking hard for ya OP. The angle on your CV’s changed, but those things are made for that. Several of us have seen problems with the CV boots on the pre-Demon/RedEye upgraded axles, so watch that. I don’t know what version you have.

Alignment is changed with lowering, so you may want to get all of that checked to verify something is not off the charts. Other than that an isolated vibration like you describe could just about run most of us nuts!

 

[Rockster]

Hey guys,

Just curious if anyone else with a lowered charger is experiencing a driveline vibration? From about 70-90mph while on throttle I have a vibration. Cars brand new, was fine prior. Its the definition of driveline vibration, but not sure how you'd even rectify that with the IRS

No experience with vibration that was not caused from basically tire imbalance. Will mention here my experience with other brands of cars with high performance and wide tires fitted is as the tires wear they can go out of balance.

In the case of two of my previous cars the rear tires would wear out at around 20K miles. I'd replace them and of course they'd be balanced. But the car manifested a bit of vibration. Not as much as before the rear tires were replaced but the car would not be as smooth as it would be after all 4 tires were replaced. To address this the front tires -- which would last 40K miles -- required balancing.

As has been mentioned lowering a car can affect the angle of the driveshaft and its u-joints and any half shafts and its u-joints. Ideally thee drive shaft and half shaft u-joints want to be pretty straight with as little deflection as possible. An increase in deflection at the u-joint is a power loss (the amount can be derived form a formula which I think it given in a Machinery Handbook). But along with this with the added deflection of the u-joints manufacturing quality that might have passed unnoticed as under normal circumstances the u-joints are not deflected that much and when they are deflected this condition is very brief.

Another explanation is if during the lowering if the drive shaft or half shafts were separated at the u-joints and these were not marked to ensure the u-joint flanges were bolted up the same as before, if the u-joints were not bolted up as before this can have the drive shaft or half shaft balance incorrect.

Last but not least just the fact the lowering changes the alignment could account for the vibration. I'd get the alignment checked and brought into spec and if the tires have experienced some wear have them balanced.

 

[baabootoo]

Steering wheel or seat? Let's narrow it down. WHICH Eibachs?

 

[Pappagray]

It absolutely is not a tire balance issue. I should say I do own two Tire/wheel shops that do full mechanical repair, this is absolutely a driveline vibrating that only happens when on throttle. It happens through the floor of the vehicle, only when on acceleration at those speeds.

Alignment is fine, I did it myself on my alignment rack.

Eibachs are e10-27-004-01-22 - lowered 5 Challengers/Chargers with the same spring no issues

I'm not the guy to comes to a forum to solve an issue that clearly needs to be inspected by a professional, but I am the professional and Cant wrap my head around it lol. Was hoping someone would have run into this before. The ONLY thing that makes sense to be is the CV aren't happy for some reason

 

[Pappagray]

No experience with vibration that was not caused from basically tire imbalance. Will mention here my experience with other brands of cars with high performance and wide tires fitted is as the tires wear they can go out of balance.

In the case of two of my previous cars the rear tires would wear out at around 20K miles. I'd replace them and of course they'd be balanced. But the car manifested a bit of vibration. Not as much as before the rear tires were replaced but the car would not be as smooth as it would be after all 4 tires were replaced. To address this the front tires -- which would last 40K miles -- required balancing.

As has been mentioned lowering a car can affect the angle of the driveshaft and its u-joints and any half shafts and its u-joints. Ideally thee drive shaft and half shaft u-joints want to be pretty straight with as little deflection as possible. An increase in deflection at the u-joint is a power loss (the amount can be derived form a formula which I think it given in a Machinery Handbook). But along with this with the added deflection of the u-joints manufacturing quality that might have passed unnoticed as under normal circumstances the u-joints are not deflected that much and when they are deflected this condition is very brief.

Another explanation is if during the lowering if the drive shaft or half shafts were separated at the u-joints and these were not marked to ensure the u-joint flanges were bolted up the same as before, if the u-joints were not bolted up as before this can have the drive shaft or half shaft balance incorrect.

Last but not least just the fact the lowering changes the alignment could account for the vibration. I'd get the alignment checked and brought into spec and if the tires have experienced some wear have them balanced.

New Tires, both sets of wheels net same result.

Car has a fixed diff, trans, and shaft position nothing would ahve change.

Axles arent removed or even stressed when removing springs from that back of the chassis.

No u joints to clock, as nothing is removed also,

Real head scratcher

 

[baabootoo]

My driver's side motor mount was bad and caused some odd things. A You Tube video showed a Hellcat rocking its engine with a bad one, which I thought didn't happen since the 60's. No lowering springs, but it is sagged a lot with 50K on the clock. I first noticed it with an odd oil leak under it. Yes, they have fluid in them!

 

[Pappagray]

I will check ti out, but the cars a 2022 with 600miles i suspect it SHOULD be good lol

 

[Rockster]

New Tires, both sets of wheels net same result.

Car has a fixed diff, trans, and shaft position nothing would ahve change.

Axles arent removed or even stressed when removing springs from that back of the chassis.

No u joints to clock, as nothing is removed also,

Real head scratcher

Hopefully, the new tires and wheels have been load balanced to ensure all tires/wheels are properly balanced.

Was under the assumption the car had the IRS but if not but rather if equipped with a solid rear axle then the lowering could not have the same effect as it would with a car fitted with an IRS.

I would not go to the expense of fitting an IRS, at least until the behavior with the solid axle is dealt with. The odds are the current axle setup is not causing the problem and installing an IRS with the current setup not right can make the situation worse.

With the lowering though alignment has almost certainly been affected. I'd have the alignment done. You may find to bring the car into proper alignment suspension components may have to be replaced to provide for the necessary adjustment.

Also, as I think someone touched upon, a careful check of engine and transmission mounts and where the suspension is attached is called for. A bad engine/transmission mount or a bad suspension mount -- or just something not reinstalled right during the lower spring install -- all have to be suspected until they can be cleared by careful inspection.

 

[Pappagray]

Your diluting this thread, these cars come stock with an IRS, talks of a solid axle are a null point. Alot of the suggestions you are making are misinformation, and mudyd up a thread like this for anyone else who finds it down the road. As stated above this a 2022 with 600 miles, problem happened directly after springs were done.

Also as stated the alignment has been done, by myself, on my own alignment rack. I own two tire and wheels shops as stated above.

 

[DGatzby]

@Pappagray did your car come with the new version of the axles? Or the original style HC and SP version? I have been thinking as hard as you. That is a tough question, with nothing else as a symptom.

 

[Pappagray]

How can I identify?

 

[Rockster]

Your diluting this thread, these cars come stock with an IRS, talks of a solid axle are a null point. Alot of the suggestions you are making are misinformation, and mudyd up a thread like this for anyone else who finds it down the road. As stated above this a 2022 with 600 miles, problem happened directly after springs were done.

Also as stated the alignment has been done, by myself, on my own alignment rack. I own two tire and wheels shops as stated above.

I apologize. I read IRS in your first post and saw your past cars and assumed the Charger in question was fitted with an IRS. The in a subsequent post by you I got the impression the car had a solid rear axle.

If the symptoms appeared right after the springs were replaced there's something the matter with the springs or their installation or the shocks are not up to the task of dampening the lowering springs which are stiffer. As an owner of two tire/wheel shop this can't be your rodeo.

 

[Pappagray]

Dampening would never cause a driveline vibration. Driveline vibrations are a result of poor geometry. The question is, part part isnt happy. IMPO it has to be the CV Shafts as that is the ONLY variable in this type of setup

 

[DGatzby]

How can I identify?

@BULL @TrackDay or anybody does the ‘21 Charger HC have the Demon/RE axles? If they are not the upgraded axles it could be the CV ‘s. They never vibrated, but some of us had torn boots which indicates some stress is going on after lowering. I know the new design with the much different CV’s seem to be holding up now. After that my friend, it does seem really strange, I can’t help.

 

[Xylander]

Any time you lower an IRS car, it shortens the life of the CVs. Some cars are worse than others. Widebody Hellcats are likely one of the worst as they're heavy and very high torque, combined with the long length of the axle half shaft, it imparts a lot of pressure on the CV and axle boot. In my experience, conservatively lowering an S550 Mustang reduced the life by about 50%. I've seen new GT500s get failed CV boots and start leaking in only a couple thousand miles.

I've commented on this topic before, and I personally would think twice about lowering a widebody Hellcat or Redeye. I don't know what the anticipated lifespan is on the CV boots on a lowered Hellcat widebody. I just know that it's short and I know people who have been through 3 sets in 20k miles.

If someone is made of money and doesn't mind having to routinely check the boots for leakage and replace them, then go nuts. But if a person doesn't want to do an axle job on a regular basis, I'd not lower it.

Me, I wouldn't ever lower a powerful RW drive car because it makes them slower. I could go into the physics as to why, but the short version is that most people use lowering springs and those tend to leave the shock in a compressed state which hampers weight transfer and adds additional rebound (wheel hop). So, you're left with a car that can't fully transfer its weight over the drive axles and the light rear end Hellcats are known for just gets that much worse. For me, function is more important than looks... so I wouldn't do it for that reason alone.

 

[Mattm400]

I agree with @Xylander, I agree both Charger and Challenger models look great lowered. But I'd never do it to mine, all the power & torque at different angles than what it was designed for. Plus the CV boot leaking problem. Something is definitely not happy on these cars when lowered, some just show it more quickly than others. Good luck.