LX Forums Forum banner

Loud bang while driving now car won't move

26K views 20 replies 9 participants last post by  lgprops5 
#1 · (Edited by Moderator)
Driving to work this morning there was a loud bang and now the transmission doesn't work. Actually thought that I hit something. After the bang, when you give it gas, it won't move, but the engine is definitely under load when in gear. When I put it in gear from the park, there's a clunk and it feels like the transmission is engaging, but won't move, same in reverse or forward.

Does anyone have any thoughts on what this could be? Maybe just the torque converter, or the entire transmission, or the differential? The car is a 2005 300c and has 180,000 miles on it.

Thanks in advance for any input!!

Sent from my SM-N950U using Scat Pack Forums mobile app
 
#2 ·
Does it roll in neutral? If so any clicking noises from the rear end? How's the drive shaft? In neutral does it Rev freely?

Sent from my SM-N900V using Tapatalk
 
This post has been deleted
#3 ·
Was the car towed to a shop (as you mentioned it happened on the way to work)?

Like mentioned above could be a few things. If they put the car on a lift see if you can get a look before you are told you need a new transmission or other expensive item unless you know the shop involved.
 
#4 ·
I was lucky enough to actually coast it for about 2 or 3 miles to a parking lot right next to my work so it does roll quite well in neutral. Haven't had a chance to check anything out yet, but my wife is coming to get me so I can tow it to work so I can check it out. I'm hoping it's the rear diff because I have a spare, but I somehow doubt that's it

It does rev freely in neutral, but when in gear, it will only rev to 3 or 4k rpm and definitely sounds like it's under load. There has always been a clunk anytime I hammer on it and get a hard downshift. I thought it was motor or tranny mounts, but I changed those and it never solved the issue. Unfortunately there's no transmission dip stick, so I wasn't able to check the fluid yet.

Sent from my SM-N950U using Scat Pack Forums mobile app
 
#7 ·
Well I doubt it's the rear diff then. Cuz you'd hear it making crazy noise if it was broke that bad. However once Its up in the air id start with the rear and work your way forward. Spin a back tire and the other tire should spin in the opposite direction, spin both in both directions. If you don't feel or hear anything, check the droveshaf lt and ujoint.



The thing about this that is tripping me up, It rolls freely and revs freely in neutral, so that pretty much excludes the rear, and the torque converter or flex plate.


How did it coast in gear? At this point I'm thinking maybe a sprag in the transmission went out or something. I'd get it up on a lift and start spinning stuff by hand while it's in gear, if everything else looks good visually leaving the trans as the only thing maybe disconnect the drive shaft from the trans and turn the output by hand and see how it feels in neutral and first. Can also take the cover plate off the bottom of the bell housing to inspect the flywheel.


The bang noise, was it similar to as if on decel how the rear end suddenly has slack then doesn't when the transmission starts free wheeling? Maybe the trans locked up really hard and sudden, did you hear your tires screech at the same time? If it coasts fine cuz it can still freewheel and it revs in neutral fine because the clutch pack is disengaged on the input, then the issue is what's left in between.



Sorry for the slightly sporatic order of the questions, just a lot of things it could be and if something isn't visually wrong it could be a pain to troubleshoot, also check for cracks in the trans case, in the event a planetary gear set blew up.

Sent from my SM-N900V using Tapatalk
 
#8 ·
So I just went to check it out in the light before I get my truck to tow it and I put it in drive and revved it up and all of a sudden there was a bunch of clunking and grinding so I had my wife put her foot on the break and I crawled under it and the drive shaft is spinning and the rear diff is now clunking and grinding.

Seems strange that before that point there was no noise or anything else, but the engine would be under load when in gear?? I also ASSumed that since there was no noise, it couldn't be the diff. Must've blown up the gears maybe? I've had a rear diff go on my Ram before and the sound was similar when it failed, but there was hellacious grinding and crunching afterwards.

This is actually fabulous news, lol!! I have an SRT8 parts car that I've been planning on swapping the rear diff over, but haven't had time, now I don't have a choice! Looks like my weekend is all planned out for me now, lol! [emoji16]

Thanks for the lightening fast replies guys, much appreciated!!!

Sent from my SM-N950U using Scat Pack Forums mobile app
 
#10 ·
Huh. Interesting.

Be sure to take plenty of pics and keep us posted. I'm interested to see what the damage looks like. My 05 C has 150kish ~miles so I'm getting up there aswell

Sent from my SM-N900V using Tapatalk
 
#12 ·
Forgot that you can't just pop the cover off the diff on these, will post pics of the inside tomorrow after I get it out. Got the SRT cradle out and ready today.

Rear cradle 1 Rear cradle 1 - Album on Imgur

Rear cradle 2
Rear cradle 2 - Album on Imgur

I'm also doing the SRT8 suspension, Brembo swap all the way around at the same time, it'll be like a completely different car!

Sent from my SM-N950U using Scat Pack Forums mobile app
 
#14 ·
Yep, got everything all swapped over, but I ran out of time to do anything else. Still need to bleed the brakes, and get some exhaust reducer for the SRT cat back. Probably be Friday before I have time to pop open the old diff.

Ran into a nightmare of a situation that I wasted way too much time on! One of the welded nuts for the cradle broke off, and I ended up having to cut a hole in the trunk to access it, what a crappy design!!

Sent from my SM-N950U using Scat Pack Forums mobile app
 
Top