Aw Shooooooot! Rear Shock Mount Stripped Thread!

Taffy

Taffy

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Jun 28, 2019
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Wales GB
Thought it was going too good to be true. :(

A few niggles, on the way, in putting my pan back together after fitting a new swingarm, new alternator, new tyre, and check pads.:)
Today was checking and double checking...final drive alignment, moly paste here, moly grease there, checking and checking, torque settings and order of fitment...all good to go. I have never done this much before.
Got to lower shock and whilst tightening it up, and.....nowhere near the correct torque value, I felt it give way like a piece of cheese! :poop::poop::poop::poop::poop::poop::poop::poop::poop::poop::poop::poop:and
:poop::poop::poop::poop::poop::poop::poop::poop:again! Demoralized in an instant

I haven't even looked at the damage yet as I am just too pi**ed off. The bolt is staying in position until I have a plan. Somebody please tell me that I am just making a drama out of this and there is a fix somewhere, relatively straight forward, Pleeeeeeeeeease!:):):):):). I have search on the site but no specific results coming back with my situation.

As ever, grateful for hints, suggestions and or ideas.
Cheers
 
Is what stripped a threaded hole or a threaded bolt or stud?

Can you post a close-up pic of what's left?
 
I had to pull up a picture to remind myself what that rear shock lower mount looks like. IIRC, that threaded hole in the final drive case is a through hole, so it may be possible to find the same size bolt, only a bit longer and place a nut and lock washer on the other end. That might also involve reaming the hole slightly larger to accommodate sliding the new bolt through.

Just my wild guess at a solution for you, as buying a whole new drive case, or even a used one in good condition, would be crazy.
 

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The clevis mount places only shear forces on the bolt. There is no force toward pulling the bolt out.
 
I'll start off by saying I have no direct knowledge of this clevis on the 1100's final drive. However, @Bush said the bolt has a long shoulder which goes through the bushing on the bottom of the shock. If this is the case, then the threaded section that stripped is on the far side of the shock. Will a helicoil's OD be smaller than the ID of the shock's bushing? Will the helicoil slip into the clevis area so that it can be driven into the once threaded section?
 
Heli-coils are lower cost than the Time-insert, fun part of heli coils is getting the tap to cut the thread straight in the hole,most important to get it staight. The shoulder on the time insert may be to large to fit through the hole in the final drive.
 
@SMSW. Yes, that is correct. The bolt doesn't clamp anything. It is just a stud which is screwed in at one end only. The other end is supported by the hole in the bracket. It may be possible to helicoil it from the other side, if you can get at it.

Aagh no. Just looked at the only photo I have that shows it. It is a blind hole.

1718836023461.jpeg
 
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I'm pretty sure it's a blind hole (like Heathy said) and the stud is a fancy doo dah which uses a low torque value. It is a bit fiddly to start the stud in and I suspect someone at some time has struggled or simply overtightened it. Easy done.
From memory the outside hole is a larger diameter so you may be able to repair the threaded portion but the pumpkin will probably have to come off. I suppose it might just be the stud, but I doubt it.
You can find pumpkins on ebay in the UK cheaply enough, this may be the way to go unless you fancy doing the thread insert fix.
Good luck.
Upt.
 
Some will say use a Helicoil. Their ok but can screw when you don't want them to. At the shop I manage use Jergens Thread repair inserts. As close as you will get to being a permanent repair.
1718840183641.png
 
tnbill said:
not sure where you get this from i have done a LOT of heli coil repairs with no issues and you find them in a lot of aviation.
Click to expand...
Yes, unfortunately. The trim wheel bolt on the 737 aisle stand uses one. I don't know how many I have had to replace because it comes out with the fastener or gets dislodged during installation of said bolt.
 
Time-Serts work well, but not in all applications. Sometimes their flange can cause an interference problem. I doubt that it would be an issue for this repair, but that is not always the case.
jfheath said:
It may be possible to helicoil it from the other side, if you can get at it.

Aagh no. Just looked at the only photo I have that shows it. It is a blind hole.
Click to expand...
Easy enough to drill right through if one wished to attempt a thread repair from the inboard side.

Easier still to drill right through and then file the inboard round boss just enough to have a flat large enough to accept a lock washer and a nut. Then get a longer shoulder bolt of the OEM size and tighten it all up.
Looks like it would be easy enough to do in place but the step holder would likely have to be moved out of the way to allow drill access.
 
The simple part is to use a bolt of the pumpkin thread diameter, but longer, and use a nut on the other end. But then you'd need to find a collar with an I.D. of the bolt, and O.D. of the shock mount hole.

here's what I'm talking about:

https://www.ebay.com/itm/2259678618...MIm_n866LphgMV4tXCBB0FaAMmEAQYAiABEgLV4PD_BwE

BTW, shame on Honda for not using a bolt/collar arrangement like this in the first place.
 
Andrew Shadow said:
Easier still to drill right through and then file the inboard round boss just enough to have a flat large enough to accept a lock washer and a nut. Then get a longer shoulder bolt of the OEM size and tighten it all up.
Looks like it would be easy enough to do in place but the step holder would likely have to be moved out of the way to allow drill access.
Click to expand...

yeah, that's what any normal person would think, but here's the bolt the geniuses at Honda decided to use for this oh-so-complicated application:


the threads in the pumpkin are smaller diameter than the bolt diameter through the shock mount hole.
 
dwalby said:
yeah, that's what any normal person would think, but here's the bolt the geniuses at Honda decided to use for this oh-so-complicated application:


the threads in the pumpkin are smaller diameter than the bolt diameter through the shock mount hole.
Click to expand...
Not a big deal.
True that a shoulder bolt of the correct shank diameter will have a thread diameter that is to big for the newly drilled through hole of the inboard mount. The threaded portion of the shoulder bolt can easily be re-threaded to a smaller size to match the original hole diameter of the inboard mount.
 
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