Evo rocker box misalignment
Anyone remember this?
The funny part is I think it actually worked for him.
https://www.youtube.com/watch?v=ZykR3yqQjqE
The funny part is I think it actually worked for him.
https://www.youtube.com/watch?v=ZykR3yqQjqE
HDF Community Team
Joined: Dec 2005
Posts: 5,374
Likes: 2,570
From: NC USA
Seen this many times, actually. And sometimes they'll run for years aligned then do it, sometimes right after install. MoCo sent out a notice circa 1991 that the issue would not be covered by warranty so long as they weren't leaking oil, so yeah, some new bikes had it happen from the factory.
Occasionally, you can loosen all the screws, align and carefully tighten them back keeping them straight as you go, but often as not, you get into problems with the fiber washers under the screws leaking afterwards so it's best to take them off, wash the parts (including the gaskets) in warm dishwater, rinse and thoroughly dry everything before you go back and replace whatever you got under the screws. Of course lay the covers/spacers on something flat to make sure they aren't warped and the gaskets aren't compromised. Just be patient and take your time - run 'em down till they touch then about 1/2 - 3/4 turn each alternating in a cross pattern until snug.
Do yourself a BIG favor and use these type washers on the screws if you take them out: They're called sealing washers and they will not leak or get loose. OEM part # 6589. James Gaskets use the same part number and they'll work but aren't the same quality.
Occasionally, you can loosen all the screws, align and carefully tighten them back keeping them straight as you go, but often as not, you get into problems with the fiber washers under the screws leaking afterwards so it's best to take them off, wash the parts (including the gaskets) in warm dishwater, rinse and thoroughly dry everything before you go back and replace whatever you got under the screws. Of course lay the covers/spacers on something flat to make sure they aren't warped and the gaskets aren't compromised. Just be patient and take your time - run 'em down till they touch then about 1/2 - 3/4 turn each alternating in a cross pattern until snug.
Do yourself a BIG favor and use these type washers on the screws if you take them out: They're called sealing washers and they will not leak or get loose. OEM part # 6589. James Gaskets use the same part number and they'll work but aren't the same quality.
Road Warrior
Joined: Dec 2007
Posts: 1,286
Likes: 64
From: SoCal
+1
The worst part of an Evo engine is the rocker boxes, specifically the center piece...stupid design.
I think there was an issue on some `89 year bikes where these parts were made from crappy material, the set on my Softail got so bad that when i snugged down the top covers, I could see inside the rocker area...
I don`t think they will move once everything is torqued down.
Anybody ever try the S&S two piece rocker boxes?
The worst part of an Evo engine is the rocker boxes, specifically the center piece...stupid design.
I think there was an issue on some `89 year bikes where these parts were made from crappy material, the set on my Softail got so bad that when i snugged down the top covers, I could see inside the rocker area...
I don`t think they will move once everything is torqued down.
Anybody ever try the S&S two piece rocker boxes?
What I don't like about the S&S boxes is the chrome.
I am not a fan of chrome on aluminum.
Seasoned HDF Member
Joined: May 2008
Posts: 21,026
Likes: 12,548
From: South Carolina
Anyone remember this?
The funny part is I think it actually worked for him.
https://www.youtube.com/watch?v=ZykR3yqQjqE
The funny part is I think it actually worked for him.
https://www.youtube.com/watch?v=ZykR3yqQjqE
Club Member
Joined: Apr 2011
Posts: 5,776
Likes: 7,811
From: SE Louisiana
Seasoned HDF Member
Joined: Jun 2010
Posts: 9,324
Likes: 3,869
From: Upstate New York
'89 EVO. Could not get the rocker boxes to stop leaking. Replaced gaskets a few times, no dice. Then I honed the gasket mating surfaces of the rocker boxes flat on a 1' square piece of glass from the hardware store with some fine sandpaper taped to the glass. It took a bit of work but I have been 100% leak free for about 5 years now and cost less than $20.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
The Best and Worst Harley-Davidson Moves of 2025
Verdad Gallardo
Another source is the stone tiles they sell at Lowe's or Home Depot. They're 1/2" thick marble or granite, 12" square and polished to a perfectly flat mirror finish. I've used a couple of these for all kinds of jobs whether fitting a bridge saddle to a guitar or leveling mating surfaces. Everyone should have one.
Another source is your local granite countertop fabricator. They just throw their sink cutouts into the trash, and are happy to give you one.
Ultimate HDF Member
Joined: Jul 2014
Posts: 5,649
Likes: 430
From: MASS_hole
Not familiar with how these center rocker frames feel. But based off the video, it’s plain to see and understant why the MoCo originally designed them thattaway. Most as a gasked like application, with no squish ability. So it suffices me to conclude that proper alignement is crucial.
My final thought on them as far as their intended ourpose goes is... WHY?
So glad they abandoned them
My final thought on them as far as their intended ourpose goes is... WHY?
So glad they abandoned them