WM Caprice (AFM) twin 3 inch droning / options to remove drone?

Hi all,

Having taken delivery of my CapriceV, i had a twin 3 inch cat back exhaust fitted. The initial exhaust that they put on sounded fantastic, but droned pretty bad between about 1700-2000rpm. Another muffler was added, and this made the system much quieter, and reduced the drone for around town driving, but it's still quite bad between 1700-2000rpm. More specifically, when cruising between 100-120km/h... So it's not practical for family holidays etc.

On the advice from my exhaust shop, i'm letting the exhaust bed in, then we'll re-assess and see if it's droning as bad and then work out what can be done to get rid of the drone.

Just wondering what other Caprice owners have done with their modified exhausts to get rid of drone? I want to keep the twin 3 inch system, and i know that the system used on my car doesn't drone on utes, sedans and sportswagons. So, it's left me wondering what the major difference is with the LWB sedan (apart from length, perhaps it's that crucial?). One thought is that the tailpipes are longer, and perhaps the muffler could be moved closer to the rear of the car, shortening the tailpipes.

Another option is going to a remote muffler system so that when on the highway i can set it to quiet.

The drone is evident in 8cyl and 4cyl mode, and only changes tone slightly.

Has anyone here got a twin 3 inch cat back on an AFM statesman/caprice, and what exactly have they done to eliminate drone? I'd love for the first system to be installed again if we can find a fix for the drone, as it really did sound amazing.

Hoping to be able to take some options back to the exhaust shop with me so that we can work out what the best option is.


Cheers!

What 3 inch system are you using?

it's the Sureflo system with their anti drone pipes. I'm not sure if they'll be able to some how adjust the drone pipes, move the muffler or what not. Just thought i'd see if anyone else has a twin 3 inch on their caprice/statesman, and if they had to do anything else to their exhaust system to help reduce drone.

I'll know more in a week or so when i call Greg back and let him know if the drone has changed at all. Just thought i'd get feedback from any other members with a LWB car and 3 inch cat back.

In my experience droning doesn't get any better as the exhaust beds in. All that happens is that you get more used to the noise.

I have managed to sort out a couple of "droners" by screwing with AFM apply speeds & torque convertor lock up settings.

I too had issue with the "drone free" system from Greg. I had to swap to a quieter muffler to get acceptable cabin noise level (drone level is a very personal opinion) its amazing how tweaking tune can effect as stated ;) diff car and exhaust I'm referring to though.

Thanks for the info guys.

APS Luis - As much as i'd love a tune, i can't do too much just yet as i don't want to void the warranty. I'm guessing by playing with the lock up settings it will void my warranty...
I'm hoping that they can get rid of the drone without needing to change the mufflers, if not, perhaps i'll have to go with the remote set up so that i can still drive it on the highways. Around town it's not too bad, and i can certainly drive around it. Most of my driving around town is about 60-90km with a few 100km stretches. If i didn't require the car for interstate trips, then it wouldn't be such an issue.

I'll give Greg a call on my next block of days off work and see what can be done.

I'm not going to get a chance to get up to sureflo until later in the month due to easter etc, so do people think that laying down half an inch of rubber or foam padding in the boot and spare wheel area will help reduce cabin noise/drone? The car is ok to drive around town, but if this reduces the noise a fair bit on the highway, i might not even need to take the car back. Any thoughts on this?

Well, i had the remote mufflers fitted today...

The result? I haven't had a chance to drive it much around town yet, but it sounds a little quieter than the previous system, perhaps not as deep at idle (could be my imagination though)... At WOT it sounded pretty good... Not sure why it sounds more quiet, considering one of the middle mufflers was removed... Maybe it's just me, perhaps i got too accustomed to hearing the drone! I'll have to get my wife to take if for a drive so i can hear what it sounds like from outside the car..

The best part? Silence all the way home to Canberra! I had it set on quiet mode, and the only time you could hear a hint of anything was when AFM kicked in (the slightest of hums, barely noticeable even to me with the radio turned down)... I doubt most passengers would be aware of it. When set on quiet and cruising around it's almost like stock but with a hint of a V8 note when the foot is put down a little.

On medium around town there was no drone, with a decent V8 sound when you put the foot down. I'm not sure if it droned on the highway, maybe a tiny bit, i didn't really test it.

When set to loud, it doesn't sound much different to medium at idle. Infact, when cycling through quiet/medium/loud i could barely tell any difference at idle, but again, perhaps it was just me... It sounds louder and a little more angry at WOT. There's a hint of drone at certain RPMs, but mainly when AFM kicks in and cruising. From the small amount of driving i've done, i'd have to say that the drone is minimal when set to loud. There is also very minimal 'booming' type noise when set at loud.

Would love to hear it set to loud or medium with a set of headers/cats.

Apologies to those who were following my drone issues, as i've replied with the same post to several threads of relevance for those interested.

Glad to hear it killed most of the drone, I'm still in the process of sorting out mine :bawl:

Having spent a bit more time in the car, and cruising around the streets it's safe to say that there is basically no drone when set to loud (this might change on the highway). There is the smallest hint of 'booming', but this is removed completely when set to medium. The 'booming' on loud is barely noticeable.

I haven't tested it on the highway on loud, but i don't think the drone would be too bad when set on loud. This leads me to think that the biggest problem with my previous system was the muffler design.

Andrew, do you have J pipes on your system? I think one of the other issues with my previous mufflers was the twin inlet/outlet. The varex is single in/out.

Let me know if you are interested in having a listen to mine, or going for a drive. I know the varex isn't everyones favourtie muffler, but it's certainly achieved the result i required in removing the drone/booming.