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2015 Pitch Black Scat Pack 6M
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Discussion Starter #1 (Edited)
I have 2015 M6 Scat Pack. Bought it in late Jan of this year with 44k on the clock, and I've driven it 4k in the past 5 months.

Previous owner did some mods to it - aftermarket mufflers (I think they are Bullets but pure guess on my part) and resonators removed, Mopar CAI.

I'm experienced with manual transmissions, I'm also experienced with finicky manual transmissions. On top of that, I'm old and boring AF and aside from making loud noises in the first two or three days of ownership, I drive it gently and without drama.

Anyhow, everything's dandy aside from a refusal to smoothly shift into reverse at random times. Roughly 25% of the time that I try to engage reverse, it will grind. Sometimes it is a quick grind before engaging, sometimes it takes me 4 or 5 attempts. It happens in cold weather and hot, and it happens when I start it first thing in the morning and when warmed up.

The only other shifting issue I have experienced with this car is an occasional difficult up shift, but a bit of extra force applied to the shifter usually cures the problem without any grinding or anything dramatic. Never needed to use both hands to shift when this happens, and the force required has never been anything too concerning.This happens rarely, and hasn't happened much since the weather started warming up here in Vegas over the spring.

Based on the short video below, which is an example of the most severe reverse grinding I've experienced, does anyone have any thoughts? I have an appointment with a local Dodge service department on the 9th of June, would like to get some opinions while I wait.

 

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Have you tried letting the clutch out before attempting to engage reverse? Also, your shift linkage or clutch may need to be adjusted, if this is possible.
 

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2015 Pitch Black Scat Pack 6M
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Discussion Starter #4
Have you tried letting the clutch out before attempting to engage reverse? Also, your shift linkage or clutch may need to be adjusted, if this is possible.
By "letting the clutch out", do you mean pushing the pedal to the floor and then releasing it back about an inch? If so, yes, I have tried that. I don't know if it has an effect, I haven't been able to pinpoint one action to take that would reliably resolve it after the first grind.
 

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2015 Pitch Black Scat Pack 6M
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Discussion Starter #5
It would appear that the reverse synchro is worn out.
I bought a MaxCare (Carmax, not Chrysler) warranty with the car, my biggest concern at the moment is that it might be diagnosed as a clutch issue and I don't know if it would be covered. There is no identifiable slipping in any gear, but I'm not driving it hard enough to see if there is slippage at higher RPMs.

If it is a reverse synchro, then I assume it would be covered without an issue. I'm not sure what kind of work a reverse synchro problem requires, and I'm hoping I don't run into any issues.

Thanks for the help!
 

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Not likely a clutch issue, I wouldn't hesitate to bring it in. But if it's related to cold trans/oil make sure you tell them that so they're able to duplicate it. I'm confident they'll get you squared away assuming they can duplicate it.
 

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Sounds like a clutch issue to me. That was the test we used to do... idle it for a bit then push the clutch to the floor and wait 5 seconds or so, go to reverse and if it grinds the clutch was toast.


Sent from my SM-N960U using Tapatalk
 

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either the clutch is worn down that the slave cylinder is near the limits of its range or the slave cylinder is worn and doesn't hold pressure effectively (clutch drags slightly)

extra effort required on shifting gear to gear is another sign of clutch dragging / not fully releasing. Effort should be equal from any gear to the next.

When its intermittent, that's a sign of problems with a hydraulic clutch setup.

That's the problem with not knowing how the prior owner used it, or was 'learning' on a manual transmission and has more than normal wear
 

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Discussion Starter #9
Update - I dropped the car off at Dodge store here in town on Tuesday. I had planned on having them fix three issues under the Carmax service contract: the AES is squeaking (an issue known by Dodge), the rear deck lid vibrates and makes the speakers sound blown out (I believe there is a TSB for this), and the reverse grind issue. The service advisor tells me that each issue they diagnose costs $150 unless I have the issue repaired. So I tell them to just do the AES and the reverse.

Yesterday the advisor calls me and tell me the AES needs to be replaced, $3500. The entire exhaust assembly needs to be replaced apparently. He tells me he will have a diagnosis on the reverse grind in 24 hours and that he will call service contract company once he has the diagnosis for both.

Today he calls and tells me service contract doesn't cover exhaust systems, so I owe $150 for that because I'm not paying $3500 to fix it. The trans needs to be torn down to diagnose, which will costs $1400 that I will have to pay if service contract ends up denying the claim. I can't risk $1400 simply on faith that Carmax is going to "do the right thing", so I owe an additional $150 because the repair on the trans isn't going to be done.

I asked the service advisor if, since there isn't an actual diagnosis on the trans, and since I already knew the AES was bad before bringing it in, if they could do anything regarding the $300 I owe. He said no problem and dropped it to $150. That was cool of him to do, I don't expect people to work for free and was willing to pay the $300 despite being very unhappy with having to do so.

There is a silver lining, sort of. A couple of days before dropping it off, I tried engaging 1st gear and then engaging reverse without letting off on the the clutch - this appears to alleviate the problem completely. Rowing the gears never helped, and engaging any other gear by itself never helped either. But there has not been a single grind since doing 1st-to-reverse. Also, I can cancel the stupid worthless service contract and get a refund of the $2600.

Chapman Dodge in Las Vegas - my only experience with them but a very, very good one as they had me by the short hair and let go instead of tugging.

The beast:
995579
 

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The AES valves and actuator springs are available separately.

If the butterfly valve itself is seized, then the cat-back portion would be replaced.

68420755AA (right side) / 68420674AA (left side)

actuator spring (68319331AA) if only the spring is broken, and valve is operational
 
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