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Thunderheader/drivetrain question

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Old Jul 25, 2022 | 03:17 PM
  #1  
sweatin_dad's Avatar
sweatin_dad
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6th Gear
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Default Thunderheader/drivetrain question

Last night, I yanked the thunderheader off my 94 and put it on my 84. It didn’t quite fit.


this bike is pretty tall. I like that about it. I’ve noticed that places that sell thunderheaders list 84-86 and 87-94. What is the difference in those two? Is the early pipe angled outward more?

I’ve noticed some differences in the two before. My 94 seems to have the drivetrain further to the right than the 84 does or maybe it’s more narrow. Both of those seem unlikely to me, though. I have another pipe I wanted to try, but it has a transmission mount and would take quite a bit of modification to fit. Is the transmission case different?
 
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Old Jul 27, 2022 | 11:48 AM
  #2  
Craigny's Avatar
Craigny
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I believe the early models like the '84 have a higher seat position, at least I think that's what my wrench said to me when I first got my '84...frame slightly different or something that was changed by like '90....i'm sure the guru's here will be able to tell you exactly....definitely some differences in the trans.....the 84 was the first year for the Evo and I believe some Shovelhead tech is in there...more so with the clutch....I believe

Here's an older thread that may answer some questions.
https://www.hdforums.com/forum/prima...fferences.html
 
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Old Aug 3, 2022 | 01:26 PM
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Solid_Knowledge
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[QUOTE=Craigny;20740746]frame slightly different or something

Frame dimensions are the same. Difference is in the exhaust mounting tabs. OP should use some washers/spacers to angle out the exhaust pipe slightly and call it a day. TH's are the coolest of the cool but I've mounted 4-5 on different bikes over the years and they all fit slightly different.
 
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