Hey everyone,

I have been experiencing something very odd in my 05 Mustang GT. It is an auto trans and when I slow down to exactly 20mph and 10mph, there is an odd clunk noise and you can feel it slightly. This only happens once it is warmed up and seems to happen randomly. I can confirm that it is more likely to happen if I press the brake through these speeds (20mph and 10mph). If I do not brake to these speeds, for example, just let my car slow down to these speeds on it's own, it sometimes does not happen or is not as noticeable? Any idea what this could be? Every person that I run this by believes that it is weird and have not heard of anything similar. Could the tune that the car has be contributing to this? Thank you ahead of time!

 

Hey guys, does anyone have some insight on what this might be? Any help would be appreciated. This has me a bit worried.

 

these cars have a U-joint and two CV joints, could be slop in one, could be slop in the slip spline, could be excess backlash/low lube level in the rearend, or backlash inside the transmission somewhere, or a excessive pressure situation in the tranny from a sticky valve, or a bad upper or lower control arm bushing letting the rearend torque a bit, or as simple as a loose bolt(had a camaro I bought new, took me 5 years to find a klunk caused by a crossthreaded control arm bolt/nut- it chewed a slot in the subframe holes), or a bizillion other things...

best to get it up on a lift, check all the mechanical stuff for slop/klunks first, verify oil level ok, if nothing amiss, maybe get the tranny looked at...

going from drive to reverse while sitting still should replicate the noise if its in the driveshaft/rearend...

roll forward, stop abruptly, shift to reverse wile holding the brakes, then let roll backwards, stop abruptly should give the klunk if its a rear control arm bushing allowing the axle to torque up too much...

 

Thank for the reply! I have had the driveshaft looked at and I guess nothing is loose. I have read about the drive line slop on Mustangs and that it is normal? Could this be the case? It only happens when it warms up and has not necessarily gotten worse within two months. Also, the harder I stop, the harder the clunk, but sometimes it is pretty noticeable regardless. What do you think?

 

How many miles are on the Mustang?Transmission oil level good?


RedGT

 

Yes sir! The trans fluid was flushed last Saturday. I have about 69,600 on it.

FYI...This is a 2005 Mustang GT auto trans

 

It is possible that it is the solenoid pack.


RedGT

 

Thank you, I will keep this on my list of possibilities. Is that your GT in the pic? Nice! have you had any clunk issues? I hear that it is quite common in these cars because the drivelines have a lot of play in them.

 

Thanks and yes,the GT is mine,have no clunk in driveline.... 26500 miles on it has a have a 1 piece driveshaft.


Red GT

 

I have read multiple forums where they say that Mustangs are notorious for this. I will research the solenoid pack thing. I am having a trans shop look at it on Saturday. I just fear that they will need to some extensive testing and dismantling to find the problem all to find out that this is not critical and, in fact, normal. Hopefully it's nothing big. If there are anymore ideas/experiences to be shared, please feel free! I will keep everyone updated on this with hopes that it will help someone else as well.

 

I have done a lot of research regarding this issue. One more thing that I have come across is that these cars act like this and others have turned to SCT/Brenspeed tunes. Does anyone have an opinion on tuners firming the shifts on these cars? Could these tuners make the tranny perform better overall? If so, what tuners and what tunes?

 

Hey guys!

So I had it looked at. It's not the driveshaft and the tech said he didn't even notice anything during the drive (it is definitely there). I was told it seems to be normal, and if there is an issue it might be internal in the trans. They added that because it has been doing it for more than 2 months and has not gotten worse that they doubt that anything is going wrong with it. Thanks for everyone's information regarding this! I think it's just the normal slop in the 5r55s trans.

 

Hi,

I have the same issue on my mustang gt after a tune, it's is a SCT tune comes with a supercharger. I have noticed this since I get this tune on my car.
I did quite a bit research as well, and was told fine or they did not know why.
I thought it's is the tune push the trans downshift hard during drive(like break), since stock set up is pretty much like it does not down shift until you completely stop.

thank you

 

I know this post is 4 years old, but were you able to find a solution to this? I have a similar issue which is going on for about a year. I chalked it off as "normal" as well because it isn't getting any worse, however, curious on your outcome.