Cross threaded dampers,

GWoods

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I am working on a 83 XS that has sat since 85, after it was rear ended, while pulling the forks apart both dampers were extremely hard to get the bolts out, and now after I got them apart and cleaned the bolt and dampers look like they were cross threaded, the original owner only rode the bike about 2,600 miles so I don’t think the forks were ever serviced, I’m thinking about running a tap into the damper and buying two new bolts, anyone run across something like this?
 
Well, the bolts are usually hard to turn out the whole way because the factory put some sort of thread locker and some sealer on them. Maybe that's all it was?
 
You are talking about the damper rod allen bolts, right? That sit right at the bottom of the fork sliders?
It seems very unlikely that those can be cross threaded. If I remember correctly, these are fine pitch thread, not regular coarse thread metric. Maybe someone installed bolts with the incorrect thread pitch?
 
Well, the bolts are usually hard to turn out the whole way because the factory put some sort of thread locker and some sealer on them. Maybe that's all it was?
That’s what I originally thought, but the first 5 or 6 threads are pretty much smashed flat and will not start threading into the damper
 
You are talking about the damper rod allen bolts, right? That sit right at the bottom of the fork sliders?
It seems very unlikely that those can be cross threaded. If I remember correctly, these are fine pitch thread, not regular coarse thread metric. Maybe someone installed bolts with the incorrect thread pitch?
That’s what my thoughts are!
 
The last threads under the head of the bolts would not have been threaded into the damper rod. So checking the pitch there should be possible.
It seems the oem bolts should be 10x1.25, but I may be wrong. (Could they be 10x1.0 ?)
Anyway, an M8 bolt is 1.25 pitch, and an M6 is 1.00, and can be used to check thread pitch if you do not have a thread pitch gauge.
 
That’s what I originally thought, but the first 5 or 6 threads are pretty much smashed flat and will not start threading into the damper
If they are that bad then there won't be any metal to re tap. You would therefore be relying on what was left to retain the bolt.
Perhaps a helicoil would be the way to go?
 
Yes, maybe someone used replacement bolts with the wrong thread pitch. A standard M10 thread pitch is 1.5mm. These are a fine thread, probably a 1.25 pitch. I have some in my spare fork parts box I could check .....

l9B6mvN.jpg
 
Okay folks, I’ve found the problem, thanks for your input! It appears that someone had replaced the bolts with the wrong pitch, dampers are 10m x 1.0 but someone during the bikes 2 years of use before it was crashed and stuck in a shed, installed a pair of 10m x 1.25 bolts, my specialty hardware store had the proper bolts now I hope I can rethread the dampers
 
Yes, I just checked one and it is a 1.00mm pitch, the finer of the two M10 fine pitches .....

xuxvGNt.jpg


Here's a standard 1.50mm pitch bolt pictured with it, quite a difference .....

POqqA3C.jpg
 
As we all know, the devil is in the details. I like 5twins picture, which shows 2 essential tools for anyone working on old bikes. A thread pitch gauge, and a thread file. Nothing wrong with the old pocket knife either
 
Yes, I love my metric thread file and have fixed many a bolt with it. What seems to need it a lot are the axles. They take a beating, literally, and often have somewhat buggered up threads. I fixed several with my thread file and the nuts spin on and off very nicely now.
 
I like 5twins picture, which shows 2 essential tools for anyone working on old bikes. A thread pitch gauge, and a thread file.

Surly the most essential tool is a brain with a bit of common sense? :eek:
If it won't fit then there is something wrong so forcing it in won't solve the problem. :( :redface:
 
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