Thunder headers
Thread Starter
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Tourer
Joined: Feb 2016
Posts: 309
Likes: 39
From: Southlake Texas
OK. User caused. So what do I do to fix it?
I install the OEM gaskets and the header loose...I.e. the rear bracket is removed. As I tighten the flange nuts I jiggle the exhaust to ensure it seats fully in the gaskets. I tighten the nuts evenly across both heads as I snug the header. Once the flange bolts are torqued to spec according to the factory manual for a 99FXDX, I install the rear mount.
For one iteration I continued to re-tighten the flange nuts to spec every week...until a stud broke off. Now I only tighten them once and leave them.
So, what do I change to prevent cracking?
I install the OEM gaskets and the header loose...I.e. the rear bracket is removed. As I tighten the flange nuts I jiggle the exhaust to ensure it seats fully in the gaskets. I tighten the nuts evenly across both heads as I snug the header. Once the flange bolts are torqued to spec according to the factory manual for a 99FXDX, I install the rear mount.
For one iteration I continued to re-tighten the flange nuts to spec every week...until a stud broke off. Now I only tighten them once and leave them.
So, what do I change to prevent cracking?
Road Captain
Joined: Oct 2014
Posts: 570
Likes: 45
From: Rocket City
I was really interested in the red thunder until SDC, nautical, and dead beat customs stopped carrying them just as fast as they started carrying them still unsure what happened there.
Good luck OP sorry to hijack
Good luck OP sorry to hijack
Seasoned HDF Member
Joined: Dec 2010
Posts: 6,850
Likes: 1,389
From: Florida
The thunderheader install instructions say to tighten the front pipe first. Then the back. Then the bracket and then the mount on the pipe. The bracket that mounts to the trans has some wiggle room. Make everything mate like it want to for support
Last edited by misfitJason; Jul 7, 2017 at 06:12 AM.
Thread Starter
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Tourer
Joined: Feb 2016
Posts: 309
Likes: 39
From: Southlake Texas
What were you talking about "tower" gaskets on your previous post? Are those different than the OEM?
Thread Starter
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Tourer
Joined: Feb 2016
Posts: 309
Likes: 39
From: Southlake Texas
Another question...since I didn't install these originally, does anyone have a picture of the rear mount? If nobody else is having issues, then SOMETHING must be different on my installation. My rear mount is to an extension off the base of the oil sump and uses a rubber isolator. Does the factory thunderheader install use an isolator?
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Thread Starter
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Tourer
Joined: Feb 2016
Posts: 309
Likes: 39
From: Southlake Texas
Well, enough said...or rather not said. I'll be going back to singles. I'd be willing to bet most of you guys running the T Headers have cracks but haven't noticed it yet. Like I said, you have an aluminum motor and steel pipes, so there will always be a lot of heat induced stress where the pipes come together. I also don't follow the idea of 2-1 increasing power, since the firing order is so irregular on these bikes. If you time the pulses for one firing pulse, it would necessarily be off for the opposite firing pulse. Singles can be optimized for the displacement and RPM range desired.
At least that's where I'm coming from.
At least that's where I'm coming from.