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:scared: I had my car up on a lift today and found the cause of the thump when turning hard in reverse. There is NO stop on the back when you turn the sterring wheel all the way. Going in reverse pulls the front wheel into the anti-sway bar. I could see where the wheel/tire rubbed the rounded section of the sway bar. The thumping part is the wheel weights hiting the sway bar. This can be very bad, as it may knock off a wheel weight or move it. Make sure to not turn too far when backing up!!
 

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Hi SRTEight
Thanks for feedback. Is this a SRT "feature"?.
What size wheel/tire combo u running?
 

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I've heard it and thought it was the tires contacting the pavement at that sharp angle. I'll check it when the wife gets it home. (if she gets home, its snowing here in IL.)
 

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Discussion Starter #4
Jaffa said:
Hi SRTEight
Thanks for feedback. Is this a SRT "feature"?.
What size wheel/tire combo u running?
The stock F1s - 245/?? can't remember right now. What ever stock is.
:pat:
 

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I don't believe I have ever had this problem, and I frequently turn sharply in reverse. If I don't get to work early, I end up having to park in the lot with only small-car spaces and I back into the space. Therefore I'm turning sharply in reverse.

I have the 4 season RSA tires and wheels. But aren't the front wheels the same regardless of which tire/wheel package you have?
 

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SRTEight said:
:scared: I had my car up on a lift today and found the cause of the thump when turning hard in reverse. There is NO stop on the back when you turn the sterring wheel all the way. Going in reverse pulls the front wheel into the anti-sway bar. I could see where the wheel/tire rubbed the rounded section of the sway bar. The thumping part is the wheel weights hiting the sway bar. This can be very bad, as it may knock off a wheel weight or move it. Make sure to not turn too far when backing up!!
Dirk,
great info!!!
Sincerely,
cbutler32
 

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Ukyo Yoshiro said:
is it like that only on srt-8s????:scared:
I have never noticed on my 300C Hemi. I find it amazing that the clearance would be that tight on a factory set-up.
 

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I'm not too surprised. SRT8 wheels have clearance problems on non-SRT8s, so there probably isn't a whole lotta room there.

Probably a good thing I went w/8.5" wide wheels for the front.
 

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It was my understanding the LX chassis was from one of the last E class Mercedes-Benz's. If so, did Daimler-Benz keep it stock? They never ran meats as big as the SRT8 especially with 20" rims. AMG may have, but AMG, the in house tuner may have modified them correctly. I have noticed some light chopping noise on tight reversing, but merely thought it was tire angle disagreeing with the pavement.
 

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patents

The front ends unique geometry is patented, I doubt they changed it much.

Note that my car doesn't exhibit this behavior even with 275/40 on the front.

Most people experiencing strange bumping while backing up are just feeling the wheels slipping on the pavement.

I truly believe the original poster was not correct in his assumptions.
 

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Hi guys,

I've had my SRT8 for about a week and heard the same thump twice as I was backing out of the drive (which has a high apron) and backing out of parking space (completely flat, new ashpalt). Both were pretty tight turns. Is there a fix or is it driver beware?
 

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SRH how cold was it outside when you heard the noises? Less than 40 or so, and there is no fix we just need warmer weather to return. We need that up here to get our stock wheels and big tires back on.
 

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it was about mid 50s at the warmest. the car had been sitting all night the first time and a couple hours the second. and i did have the stock 20s on.
 

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This problem is unique only to F1 tires in cool to cold temps. It is not a rubbing on the tie rods or anything of the sort. My car does it all the time in cooler temps or wet pavement with the F1's. When I put my snow tire package on, the issue automatically disappears. The tire compound in the F-1's wasn't meant for cold temps and the rubber hardens as the temps drop. When cutting the wheel hard in reverse, the tire is hitting the pavement at a less than optimal angle and the hardened rubber from colder temps starts slipping on the pavement, thus causing the unusual thumping sound. Nothing to worry about.
 
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