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08 i have no idea, the car moves to the left under load

8K views 36 replies 8 participants last post by  ChuckWagon 
#1 ·
So I recently swapped over to my winter tires/rims from the drag setup. I live in NJ so it's just time to be ready for snow. Anyway, when on the drag radials, the car had a noticable sway when accelerating hard. I've driven cars on slicks before, and just attributed this to the bias ply wiggle that you get on that setup. It is what it is.

The problem is now that I've swapped the setup out, I still have a very noticeable sway when accelerating. Specifically the car twists towards the passenger side. The movement is very subtle, and only under hard throttle, but it's alarming to me none the less. It's almost like it gets up on top of the tire and rolls to the side. Very hard feeling to describe accurately I checked all of the carrier bushings already, and all look fine. I know my shocks are beat, and I def need to do an alignment for the front soon, but I don't really think that is the issue here.

For the record, the car is an 08 Rt Charger, with about 100k on the clock now. I have 300-400 passes on the car, street and track, with 1.6/1.7 60fts every time.
The car was babied by the original owner, up to 60k miles, and then I've driven the hell out of the car ever since. Previously I broke both half shafts, and split the stock convertor, then broke the input shaft on the trans. All of which was fixed correctly.

Anyone have any ideas where I should start looking under the car?
I'll have it in the air in a few days to try and nail down the issue, but I thought if someone could give me a head start, that would save time.

*Edit*
This is not a tire traction problem. It happens identically each time I accellerate, same manner, same direction. It's not a violent move, nor does it vibrate, shake, bang, rattle, or any other noise. It's more than the normal driveline twist under torque load. I just haven't pinpointed the issue yet.

 
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#2 ·
Would be cool if you have a vid from the track of the car launching. 11.48 is moving for that combo. 125-150 shot of gas?

I hope it is something simple like dead rear shocks though I agree getting her on a lift to check everything makes sense. Take a good look at the rear cradle structure
itself. Northeast car subject to road salt in addition to a ton of hard launches at the track. . .. . . .never know.
 
#3 ·
You wouldn't believe me if I told you what size the shot was on the nitrous system haha. The car has made too much power for the driveline for some time now, but still I persist.
I was hoping it was just rear shocks because I was finally going to break down and upgrade them from stock this winter, but I just don't think that's it, unless I broke a shock mount. But that or any other hard brake to a part would show up in different scenarios. Under normal driving conditions, it doesn't happen.
 
#4 ·
Well, I took a long look under the car tonight trying to find something wrong. I started in the back under the cradle......Nothing. Although there is some surface rust on some of the parts, nothing I can't sand off. All the bushings surprisingly look good, no play in any of the arms. Good on Dodge, because I beat this car haha.
Anyway, after not finding anything in the rear, I moved to the front on a hunch. Again everything looks top notch, except the driver side motor mount is clearly torn. Passenger side is fine. Although this is definitely an issue I need to fix, is this what I'm feeling in the car?
 
#5 ·
The driver side mount keeps the engine from rising up when accelerating. Even though it is broken, there should be a safety catch. In the old days motor mounts didn't have the safety catch and it scared the heck out of me when my 283 V8 lifted up and the fan hit the metal fan shroud in my 59 Chevy Impala!
 
#6 ·
I agree, and it's probably why it's only doing it under heavy load and in no other scenario. Time for poly mounts or solids.
 
#7 ·
I had a blown driver side motor mount and I never experienced pull to one side like you're describing. When i changed my rear cradle back a year ago, i had an alarming amount of serious rust on the top of my cradle and was quite surprised that nothing was broken. Maybe there is a cracked weld that you cannot see unless a load was put on it? It sounds like the alignment shifts under load which would mean something is moving for sure....and not sure a crack would open that wide and then close up again.
 
#8 ·
I can get behind that premise. I just couldn't find anything else that justified the movement under the car. Everything is tight and solid, and like I mentioned alot less rust that I expected to find on all the pivot points. I was planning on dropping the diff in a few weeks anyway to do some sneaky gear stuff, I'll find out for sure at that point.
 
#9 ·
So the issue is most certainly not just the motor mounts. Although that hasn't been fixed yet, I can tell after playing with the car that the movement is 100% originating from the rear of the car. I went over everything again this morning. Although there are a few busings on one of the trailing arms with a crack in the rubber, none of the bushings are blown, and I couldn't find anything that looked off.
Except, the passenger side front mount on the cradle looks farther away from the body of the car than the same mount on the driver side. I checked the bolt, it's as tight as I can get it with a 4ft breaker bar. The bolt only turned a quarter turn, and I don't consider that loose. Other than this I cannot find anything that looks bent or out of place, or cracked.
The first time I looked over everything with the suspension unloaded, and the second time I did it with full weight on the suspension.
I just don't know where to go from here.
 
#11 ·
I will try to take pictures tonight. It's super hard to get my phone up there to take it. The passenger side front cradle mount hangs about a 1/4 inch or more from the body, while the passenger side front mount sits closer to an 1/8 from the body. The rear on either side are identical or close enough that I cannot tell a difference. Other than this though the mounts look fine. The rubber looks fine, they're not brand new or anything but definitely not blown or cracked enough to create the shift I am feeling.
 
#12 ·
IIRC the cradle bolts are 133ft/lbs torque. Could be that the cradle.shifted with all the power you're putting down. Couple that with a little bushing wear from one or more bushings, and there you may have a couple degrees of play. Do you have an alignment shop you trust? Maybe have them check it to see if the rear wheels are in spec.
 
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#13 ·
Many years ago I had a 1995 Chevrolet Caprice with LT1 motor and 4L60E 4 speed auto.

The rear would squat a little and sort of shift to the pass side.

I don't remember which exactly bushing was bad, but only found out once a control arm was removed. I don't recall if I had to replace the arm or only the bushing.
With everything bolted up, everything looked good and felt tight.

It was only once the car was on a rack and we started to remove pieces is what we discrovered this.

I know the suspension is completely different on these cars but this is just a tip that you may need to disassemble the rear to figure out exactly what's worn out and how bad.
 
#14 ·
I had a 9C1 Caprice that suddenly began locking up the rear brakes on acceleration. It turned out to be a broken(!) trailing arm. Closer inspection showed a little rust in the crack next to clean metal so clearly it had been cracked for quite a while and I finally broke it. The brake lockup was due to the parking brake cable pulling tight as the two halves of the arm separated. :) You gotta wonder what the cops did to crack that arm but you find all kinds of odd things wiht former police vehicles. Anyway obviously unrelated to OP's post but it's an amusing memory for me...and a very easy fix.

Back on topic, I seem to recall a few members posting here that track their cars finding cracked/broken cradles, aren't the early years more susceptible to this? Memory is vague but I believe they said they couldn't tell until it was down out of the car.

Richard
 
#15 ·
I'm really trying to avoid dropping the entire cradle just to look for damage that might not be there. But it might be inevidable from the info I've received on here. I may look into getting a complete upgraded bushing set for the rear of the car, I think Petty makes one. That way I just change everything out to new and see what happens after.
More info on the problem though, it seems when extra weight is added to the car, the movement is much less noticable. For example, I had my gf in the car over the weekend and tried to get the car to react so she could understand what I was talking about. It went from doing it everytime I accelerated hard by myself in the car, to only doing it after 1-2 shift and much less of a movement with the weight. I will add that although I am a 6ft 200lb+ guy, she weighs 110lbs soaking wet, so the added weight shouldn't have made that big of a difference. But it does make me think it has to be something suspension related.
 
#17 ·
I agree, but upon inspection I cannot find a bushing that stands out. It's frustrating to say the least.
 
#18 ·
Could I have broken a body mount? Without being under the car, I couldnt tell you where the mounts are located, but maybe that's a possibility?
 
#19 ·
Because the movement in the car is always towards the driver side, meaning the car shifts the weight to the left, pointing the nose towards the passenger side, I'm led to believe this must be an issue located to one side of the car. If it was a carrier, or cradle issue, I would think the movement would shift to either side, depending on the situation, cornering, etc. Anyone agree?
HHP sells Energy Suspension bushing kits for the rear linkages in this car, and they're fairly priced. It might be worth it to just upgrade all the arm bushings and go from there. If it doesn't fix the issue, it would only improve the car, and further isolate the actual problem.
 
#20 ·
I guess it wouldn't hurt to put the car on a lift and eyeball the frame where the rear cradle mounts up. But, i would think a structural issue that big would be constant whether there was any weight in the passengers seat or not.

I wouldn't just focus on the rear of the car either. Eyeball everything up front to as maybe all that power is twisting something up front. My gut tells me to check the alignment first before replacing or removing anything. Then obviously have it done again after you do the work.
 
#21 ·
I guess it wouldn't hurt to put the car on a lift and eyeball the frame where the rear cradle mounts up. But, i would think a structural issue that big would be constant whether there was any weight in the passengers seat or not.

I wouldn't just focus on the rear of the car either. Eyeball everything up front to as maybe all that power is twisting something up front. My gut tells me to check the alignment first before replacing or removing anything. Then obviously have it done again after you do the work.
I know I need an alignment up front, as the camber is off slightly. But it's been that way for a while now, and was that way prior to this issue. I should mention the front sway bar has been removed from the car. But it's been off for years and this is a new problem. But that may be adding to the weight shift.
 
#22 ·
I've had my front sway bar off for a while now too and now I like corners lol.

Any change if you add weight in the back seat?
 
#23 ·
I've had my front sway bar off for a while now too and now I like corners lol.

Any change if you add weight in the back seat?
No, I have 2 young boys, 5&2, and their car seats are always in the back. Never noticed a difference with or without them in the car, although I drive much much more conservative when they are with me lmao.
However, I recently removed the spare tire & jack from the trunk, in order to move the nitrous bottle down out of the way. I did notice the movement more with that weight change.
 
#25 ·
Okay so I'm getting super frustrated at this point with trying to find an issue. On top of the original issue, now I have a constant vibration that is coming from the rear of the car. And from a stop, it almost seams like the brakes are dragging on the rear. I looked over the entire disk setup, and everything looks fine, I have ceramic pads, and drilled/slotted rotors. I have to assume both issues are interconnected in some way, or at least sequential parts, one causing the other to fail.
Could the E-brake be grabbing?
The only thing I can think of, is that maybe I broke some teeth off of the spider gears, or have a blown bearing in the diff, possibly causing the passenger axle shaft to move in and out?
But there is no grinding, or clunking, just a steady vibration.
I am lost here guys.
 
#26 · (Edited)
Frankly, I have never looked under my car at the driveshaft. But, if it uses u-joints like most driveshafts. the angles of the u-joints on both ends of the shaft have to be the same or there will be a vibration. this could be caused by worn bushings holding the differential housing. That is why CV (constant velocity) joints are used on the axles.

watch this

Drive shaft velocity - YouTube
 
#27 ·
That was easily the most informative video on driveshaft/yoke angles I've ever seen, definitely appreciate it.
From what I remember, the stock driveshaft on my car is a 2 piece design, with rubber couplers attached to either end. And the bushings holding my carrier look perfect and undamaged. I've seen cracked and blown bushings posted by other members on this site, and mine although original to the car, look to be without issue.
 
#28 ·
Okay so a bit of an update, I'm 90% certain I've sourced the cause of the vibration that I recently started feeling. It seems the driver side exhaust mount off of my trans has a destroyed bushing, allowing the pipe to move back and forth within the mount.

**I will clarify, because nobody else will have this mount on their car. I have 2in primary shorty headers to midpipes, and then dumps just after the trans mount. Because my exhaust ends so shortly, I miss all of the factory exhaust hanging locations. I had a local exhaust shop fab up supports, bolted to the trans mount. Nothing crazy, just a rod welded to the pipe, rubber bushing and rod bolted to the trans mount.**

Tonight I have plans of getting the rear of the car back in the air, and spending however long it takes to figure out the issue.

 
#29 ·
I was able to borrow some ramps from a friend, and get the car in the air with the suspension loaded yesterday.

Problem SOLVED...

Dont worry, I won’t leave you guys in the dark haha. With the car up, and the suspension loaded, it took 5 minutes to find the issue. I can’t believe I never noticed it on previous inspections. Passenger side rear toe link bolt sheared off, which accounts for every symptom I’ve seen from the car lately. Man, does it feel good to finally have the issue figured out. I’ll have to order a new adjustment bolt assembly, and bring it in for an alignment after installing. I appreciate all the help from everyone while I was trying to source the cause.
 
#30 ·
When you're fighting and issue like that, the most simple solutions aren't considered because it's "too simple" lol

I'd have never thought to tell you to check for that, and might we'll have overlooked it myself if the car was on MY lift unless you brought it in for an alignment.

Glad you found it and that it wasn't worse than it was!!

Sent from my XT1650 using Tapatalk
 
#33 ·
I literally went over every inch of the rear assembly multiple times, and never saw it. And when the car was lifted from the diff, with the suspension unloaded the bar was tight. It wasn't until having the car in the air on ramps to keep the suspension under weight that I noticed the play, and then the sheered off bolt.

I will point out though, that someone here commented earlier that I should take it to an alignment shop and go from there. I forget who gave that tip, but if I had listened, they surely would have found the bolt when trying to align the rear. So kudos to the member who offered that advice. I'm just stubborn and wanted to find the cause myself before handing over my car to a shop.
 
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#32 ·
Thank you! I'm still in disbelief that it was something so simple this entire time.

Does anyone have any recomendations on where to order a new toe link bolt? I was contiplating ordering two new bars to replace each side, but since I couldnt find any upgraded options as a replacement, only oem, I'll probably just sand down the surface rust and reuse the ones I have.
 
#34 ·
Real glad you found the issue.and that it was not something huge. If you can't find the bolt on someplace like Rockauto.com, maybe call the dealership. Can't be that expensive.
 
#35 ·
Tried Rockauto first with no luck. But I went on Mopar Part Overstock, and not only did they have the bolt assembly, they had diagrams with every single piece of the suspension assembly broken down so that I could be sure I got the right part. It did cost me $30 after shipping, but at least I know it will be right.
 
#36 ·
All has been fixed. Indeed was just the sheered bolt creating the problem. I installed the new camber bolt, set the alignment to mirror the driver side and tightened up. Car now drives perfectly straight, with zero pull to any side.
I appreciate all the help from everyone on here. I'm super glad this one is taken care of.

 
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