Popping noise from rear after lowering the car

[Dan12GT]

I recently lowered my car about a month ago now. Everything went smooth. I am on BMR springs and panhard bar to align the rear. Stock shocks/struts for now. I actually just 2 days ago was able to get back under the car and checked to make sure the bolts were within factory torque spec via a torque wrench. When I initially did the work I tightened everything basically as tight as I could get it with normal tools and then just recently torqued them within spec (didn't have a torque wrench at that time).

Now, I am hearing a popping noise when I hit large dips/bumps. I was not hearing this before torquing everything. It seems to only occur on larger bumps or dips, not on normal lesser bumps / dips.

I also noticed the panhard rod had leaked out a good amount of grease from the driver side poly bushing fitting on the panhard rod. Not sure if that was only because it was excess grease from initially pumping some grease in it or if I have a issue.

Also, I can't quite pinpoint where the noise is coming from exactly. It sounds to me it actually is only coming from the passenger side/rear.

Anyway, everything should be as tight as it should be. Just seems odd this is now occurring. Could the noise I am hearing be from hitting the bump stops? I didn't modify those at all, they are in their stock condition. Also, maybe is the noise coming from the panhard rod?

Thanks ahead of time for the help / advisement.

 

[92hatchlx]

Did you loosen the bolts when you re torqued them, or did you just check that they were at least at the torque spec. You could try tightening up your PHB a little more if you did loosen it. Most of the time, after lowering cars and adding a phb, people don't tighten their phb bolts enough and it will cause a clunking.

 

[cdog1157]

I've got the exact same thing happening with Steeda Sports and Tokicos. I thought it was the spare tire bouncing up and down but took it out and still happens. I'm pretty sure it's on both sides of mine. The tard that installed my stuff says the lca's are in a bind and I need relo brackets, but I'm thinking it might be the bumpstops since it only happens on big/hard bumps on whichever side hits first. If I ever get a day off then I'll remove the bumpstops to see if that fixes the problem. If not then guess I'll get relo brackets and lca's. Update if you find anything.

 

[Dan12GT]

Today 11:19 AM
cdog1157 I've got the exact same thing happening with Steeda Sports and Tokicos. I thought it was the spare tire bouncing up and down but took it out and still happens. I'm pretty sure it's on both sides of mine. The tard that installed my stuff says the lca's are in a bind and I need relo brackets, but I'm thinking it might be the bumpstops since it only happens on big/hard bumps on whichever side hits first. If I ever get a day off then I'll remove the bumpstops to see if that fixes the problem. If not then guess I'll get relo brackets and lca's. Update if you find anything.

I am kind of thinking the same thing as you cdog. You would think if I had something out of torque spec it would make noise more often. This is just me thinking it through but im wondering if now my suspension has now settled a bit more and it truly is hitting the bump stops and that is the noise I hear. I put a dab a grease on the stops and will check back later today to see if it transfers some grease to the frame rails. If so this might be my issue.

Also hey i'd be careful with the bump stops. I don't think you want to totally remove them, otherwise you would be banging metal on metal when you hit large bumps. I have heard of people trimming them down about halfway to prevent them from slamming all the time and actually improve some ride quality. I will probably do this if this is my case.

Today 10:47 AM
92hatchlx Did you loosen the bolts when you re torqued them, or did you just check that they were at least at the torque spec. You could try tightening up your PHB a little more if you did loosen it. Most of the time, after lowering cars and adding a phb, people don't tighten their phb bolts enough and it will cause a clunking.

When I torqued the nuts / bolts into spec I did not re-loosen them. I have the panhard torqued to 129ft/lbs (factory spec) So I don't think it is that. I will recheck the jam nuts though, that is one area I missed checking.

 

[NoSlo5oH]

I have been experiencing a similar problem with my 2013 5.0 ever since I installed my billet LCAs. Mine pops constantly during normal driving and it is very annoying. I have loosened and retorqued the bolts twice with a load on the suspension. I even greased the bushing faces and the noise is still present. I am in the process of working with the manufacturer to get the arms back to them for disassembly and inspection to see if they locate a problem. Please let me know if you come up with a solution.

 

[Grant808]

I suggest trimming the rear bumpstops or getting the softer FRPP units. With 1" drop P spings, I was making contact with the frame rail...the bumpstops cleaned off the road grime that was there before the install. I just trimmed mine, but will get the FRPP ones soon.

 

[stang8psi]

^ this on the k's i was hitting also. I just cut the bump stops down on the rear!

 

[ModularSpeed]

Trim the top level off the bumpstops. It is simple, and can be done with a knife, without even getting under the car..

 

[blackbeast12]

you need an adjustable uca and relocation brackets to dial in your pinion angle, I bet when you do that it will subside...keep in mind you had no issue before the install so its more likely your pinion angle being off causing the lca's to bind when extended thus making the sound!

 

[c. love]

It very well could be the spring itself. If its just when hitting bumps maybe not. But... I have seen lowering springs of any type when goin up driveways at an angle momentarily shift and make a popping noise. Honestly it was pretty common on a few of the cars i had springs on. Although less common ive also seen debris such as dirt and rocks get caught under the spring perches and cause the same type of thing. One more thing to check

 

[Alien STI]

Im stock with no mods and when i hit a large speed bump or bump in general to fast i hear the loud pop noise in the rear. Im at 2500 miles...

 

[Dan12GT]

Haha! So many ideas. I do appreciate it though, gives me things to check. I will be checking on the bump stops. I put some grease on the tops of them with the intent to see if any grease transfers from them to the frame rails. If so I will be trimming the bump stops. I also do already have some relocation brackets I got from a friend for when I do the lower control arms, I will be installing both soon hopefully.

 

[Ill_W1N]

I had the same issue, take your adj panhard off and see if your still getting the noise. Could just be the bushings. It was on my car.

 

[Dan12GT]

I'm wondering if they aren't properly greased too. I will remove the fitting and inspect to see if I have sufficient grease inside the bushing housing. I'll be under the car tomorrow re-checking things along with installing a BMR panhard brace.

 

[VETTEHUNTER]

Sub'n...Getting ready to lower mine...

 

[Roadhouse]

Did you loosen the bolts when you re torqued them, or did you just check that they were at least at the torque spec. You could try tightening up your PHB a little more if you did loosen it. Most of the time, after lowering cars and adding a phb, people don't tighten their phb bolts enough and it will cause a clunking.

Same thing happened to me after lowering. Be sure and tighten the panhard bar bolts. :thumbsup:

 

[Dan12GT]

I torqued them within spec, 129ft/lbs.

I will be under the car again tomorrow checking things and installing some more parts so I will give everything an extra torque down again.

 

[Dan12GT]

Update:

I was under the rear or the car again around x-mas time. I was installing a BMR panhard rod brace and LCA relocation brackets. I backed off all of the bolts I messed with during the install of the lowering springs from the previous install. I re-torqued the bolts (strut mounts, sway bar bolts, panhard, panhard brace, and control arms bolts) all to factory spec with a torque wrench.

I am still getting the popping or banging noise from the rear. Same noise as before. I also previously had put a dab of grease on my bump stops when I first noticed the noise. When under the car I had a good chance to look at the frame rails. My bump stops are indeed making contact with the frame rails. I can see some grease has transferred from the bump stops to the frame rails.

This is the only thing I can think of that is cause for the noise. It seems to only occur when there is a good amount of body travel where it would be expected to make contact with the bump stops. Like over large humps in the road where the body will travel up higher and comeback down harder.

I have BMR LCAs on the way so when I do the install I will chop the bump stops down a bit and see if this remedies the issue. Stay tuned.

Any other ideas are welcome as well

 

[alex12gt]

I had a poping/banging it was my sway bar end links were not tight and when i would hit a bump they would shift and hit the underside of the car i just hit the bolts with an impact and havnt had an issue since

 

[VETTEHUNTER]

How much of a drop did the BMR Springs get you... Was it more than the advertised 1.0"-F and 1.25"-R?... I wouldn't think you would be on the bump stops with only a 1.25" drop in the rear..obviously you are though since you have grease transfer, which makes me think you actually got over a 1.5" in the rear.