Stainless Works + False Knock

[Wally-Bob]

The problem presented itself during a current Dyno tuning session. The characteristic rattling sound is present when a rubber mallet is applied to the collector. Wedging a screw driver between the primary tubes near the collector and/or tightening a hose clamp wrapped around the 4 primary tubes causes the rattling sound to go quite. The primary tubes are in contact with each other at points as confirmed visually and by feeler gauge, both driver and passenger sides.

My questions for the forum readership are:

How many of you out there have experienced this?

What have you done repair/modification wise to resolve the problem?

It appears that Stainless Works now tack welds the primaries together as evident from newer product pictures on their web site. (Mine were purchased in the fall of '15) My question here is does anyone have positive long term results with these tack welds? My concern is eventual tack weld fracture.

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[mustang_guy]

I've heard of the knock from the AC bracket or bolt touching the SW/SP but not your specific issue. I've not heard of any issues with Arh or kooks. I don't believe I've heard any complaints with Texas speed's either.

You at least have a lifetime warranty I believe with the SW version should they need repair.

 

[Wally-Bob]

I've heard of the knock from the A/c bracket or bolt touching the SW/SP ...

I definitely took care of the A/C bracket when I installed, ground down the stud and bracket to ensure clearance, no contact marks present. Yep, lifetime warrantee but I haven't spoken to them yet. Will do 1st thing in the morning.

 

[mustang_guy]

It's a pain that you'd need to remove them for the repair but I've heard good things about their customer service, they are supposed to be a good bunch of guys. Sorry I'm unable to be of more help.

 

[veeefour]

My experience with false knock. Automatic transmission - bell housing shield!

[ame]

 

[Wally-Bob]

I spoke with Stainless Works. They were very responsive and did admit they have had a "couple" of headers that caused False Knock due to primary tubes vibrating together.

The also said they do not tack weld and never have to resolve the problem. Their approach is to grind the welds off on the manifold flange (cylinder head side) and "reform" the tubes to provide clearance so they don't touch. If they deem that the headers are too far off for rework to be successful, a new set will be provided.

I'll keep this thread updated with progress.

Has anyone else experienced false knock caused by header primary tubes in contact and vibrating?

 

[Kong76]

Not to derail but can you guys elaborate on this AC bracket/sw-sp.

 

[Crackerjack17]

Not to derail but can you guys elaborate on this AC bracket/sw-sp.

Stand beside passenger side fender and look down at engine and frame rail. See the big a/c line running along frame rail? There is a small bracket with a single bolt/nut that protrudes out and touches the s/w header pipe when the engine torques over.

And yeah I've been trying to find an intermittent knock that keeps pulling timing. And I notice it's more prominent at certain rpm's. Which is likely the resonance frequency of whatever is rattling. Never thought of the pipes touching. Thanks! Will look at them this weekend.

 

[Wally-Bob]

And yeah I've been trying to find an intermittent knock that keeps pulling timing. And I notice it's more prominent at certain rpm's. Which is likely the resonance frequency of whatever is rattling. Never thought of the pipes touching. Thanks! Will look at them this weekend.

The knock sensor seemed to be disturbed at multiple frequencies (comes and goes at different RPMs) in an evenly spaced pattern on the dyno data logger, so YES, I conclude also includes harmonics of the resonant frequency, OR coincidence of each touching pairs of primary tubes hitting its resonance individually without harmonics. Either way, both headers are NFG !

What was also observed is that the problem is worse when the headers are cold (at start up) and diminishes somewhat at high temperatures. (after heating them up with a high speed highway run) Unacceptable !

 

[Einstein_nikola]

I spoke with Stainless Works. They were very responsive and did admit they have had a "couple" of headers that caused False Knock due to primary tubes vibrating together.

The also said they do not tack weld and never have to resolve the problem. Their approach is to grind the welds off on the manifold flange (cylinder head side) and "reform" the tubes to provide clearance so they don't touch. If they deem that the headers are too far off for rework to be successful, a new set will be provided.

I'll keep this thread updated with progress.

Has anyone else experienced false knock caused by header primary tubes in contact and vibrating?

Did you ever sent them back, I got the same issue but with ARH

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