I had a local muffler shop install Flowmaster super 40's on my 1978 f150 4x4. They sound good but I guess they don't last? The driver side muffler (dual exhaust), is now rattling after 2 weeks of use. It is 100% inside the muffler. It is very noticable at idle.... embarassing as it sounds like tin cans rattling against each other. Why is this already rattling? Is this common.... maybe weak internals on these Flowmasters?

 

I installed Flowmaster super 40 on my 69 2 years ago sounds great and no problems (these are the stainless ones)

 

wow im really surprised that its rattling like that, ive never scene a flowmaster come apart inside. I actualy just put 2 super 40 series on mine and it sounds good but just not enough rap to them so gonna put glass packs on it hehe.

 

i have heard of this happening. the welds came loose.my opinion, you are paying for the name. you can get a pair of force mufflers that look the same and built the same and sound badass for about 70 bucks from summit. i got them on my 5.0 stang with long tubes and they are wicked awsome.

 

Yeah, it's uncommon. They're on top of the business for a reason. I think I'd see if you can't have them returned. That shouldn't be happening, and isn't a normal occurence. Try 'em again, and I bet you'll be fine.

Ryan

 

Marketing is the reason. Quality is on par or no better than others.

 

i agree 100% with ken, theres nothing special about their mufflers, except the name stamped on them....i will be surprised if you get any kind of warranty

 

Did you get real FlowMasters (TrashMasters in my book, sorry) or knock offs as there are a lot of muffler shops selling them at a massive profit.
On knocks offs the cone breaks off the end covers a lot of times.
.....=o&o>.....

 

Yeah some muffler shops, especially the cheap ones, will use knock offs. I have a 40 series, close to six months now, sounds and works great. Never heard of one falling apart.

They are on top because they provide a quality product people reccommend to their friends because it's superior to others they have seen.

RP
Zach

 

I installed the Super 40 on my ranger and my dads f150, they sound great but performance blows .... i ended up replacing both of them with magnaflows .... sound great, not TO loud but a good rumble and performance was awesome.

but if it is messed up im sure flowmaster will do something or make the shop replace it ...

 

that must be with mine also. Either that or i have some slop somewhere in the clamps.

Oh well, i dont like the flowmaster. It only sounds good on my buddies '69 nova with A LOT of compression, not my ***** stock 302.

Time for true duals only cats or straight pipe...

 

A problem like that should be covered under warranty. If not by your mufflershop then give flowmaster a call. If the shop doesn't cover it, then it's time to find a new muffler shop. I've had Flowmasters on my last 3 trucks and I've never had any problems. It's the only muffler I would ever buy.

 

In my files there is a muffler flow test done on mufflers with a SuperFlow 110 Bench tester @ 5" water, all mufflers at 2 1/2" tn / out.
Results from notes I have on that file:

SpinTech Truck RV, the most quiet of their line.......165 cfm

(almost as loud at Edelbrock's 5510 stainless steel RPM mufflers, RPM's droned
a lot hence replaced with SpinTech's).


Hooker Arrow Chamber........................................145 cfm

Dynomax turbo............................................. .....135 cfm

FlowMaster 40 series..........................................11 5 cfm

FlowMaster 50 series...........................................9 0 cfm

SpinTech Sportsman Street.................................170 cfm

SpinTech Sportsman SCS....................................175 cfm

SpinTech Pro Street...........................................1 80 cfm

Borla............................................. ...................180 cfm

I was at a Western Street Rod show 10 years ago, pressed a program over the top of a cut open FlowMaster to get spacing and angles., In the sheet metal shop I made two mufflers, sounded and performed like original, worse than the short glasspacks. I have gone thur many mufflers free to test with band clamps from a muffler shop friend, this is why I now run SpinTech's Truck RV mufflers. They are built like a tank and perform to where I have exhaust vacuum pulses back to the O2 sensors at the collector flanges, fuel / air gauge flutters full scale unless I stuff the 4 1/2" tips with glasspacks and add back pressure.
Different motors, cams and compression will change the exhaust loudness as well tone, what sounded good like posted above on a chebbie sounded like crap on a Ford, so true.
.....=o&o>.....

 

" I have exhaust vacuum pulses back to the O2 sensors at the collector flanges, fuel / air gauge flutters full scale"

Just curious, what O2 sensors are you using, stock?

 

Bosch single wire O2's with AuoMeters fuel / air ratio gauge, switch under the gauge housing for left / right banks.
No "stock" O2 sensors on a 68 414 FE motor.
.....=o&o>.....