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Rev 3 - Skid Plate Rear Bolts


mcman56
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Do the rear mounting holes on a 2008 Rev3 have helicoils from the factory (steel thread type coils)? Mine has them but I can not get them really tight.

On one side, it will get fairly tight and then the bolt threads strip. On the other side, the threaded coil worked its way out over time. Is there a solution?

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Maybe they were Helicoiled originally, but once the working part is stripped/damaged, even a longer bolt will only contact with a few threads. From what I remember, the rear bolts are angled into the frame, with a special M8 bolt with a small hex head. So if you tap out to M10, the larger head may protrude beyond the bottom of the bashplate. You can carefully pick out the end of the coil with something like a scriber then pull the wire out with pliers, then fit a new insert.

If you have a friend with a Helicoil kit, it is easy to use the Helicoil drill/tap and fit an M8 Helicoil, then you are back to standard.

I bought a recoil kit years ago -one of the best tools ever bought!!

Make sure that the bashplate is straigthened out so there is a little tension in it as possible before refitting, and locktite the bolts in.

Hope this helps!!

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Maybe they were Helicoiled originally, but once the working part is stripped/damaged, even a longer bolt will only contact with a few threads. From what I remember, the rear bolts are angled into the frame, with a special M8 bolt with a small hex head. So if you tap out to M10, the larger head may protrude beyond the bottom of the bashplate. You can carefully pick out the end of the coil with something like a scriber then pull the wire out with pliers, then fit a new insert.

If you have a friend with a Helicoil kit, it is easy to use the Helicoil drill/tap and fit an M8 Helicoil, then you are back to standard.

I bought a recoil kit years ago -one of the best tools ever bought!!

Make sure that the bashplate is straigthened out so there is a little tension in it as possible before refitting, and locktite the bolts in.

Hope this helps!!

The threads that hold one of the M8 helicoils are stripped. They are pretty close to an M10 so I would have to go to M12 for a good thread. There is not a lot of meat around the hole and I may not be able to open the skid plate holes that far either. If I drilled through for bolts and nuts, the far side is not flat to accept a nut. With some creativity, it may be possible to make a special shaped spacer to go between the nut and uneven shape but it would not be easy. I wonder if it will need to be filled with weld and redrilled? Based on the design, I doubt I'm the first with this problem.

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The threads that hold one of the M8 helicoils are stripped. They are pretty close to an M10 so I would have to go to M12 for a good thread. There is not a lot of meat around the hole and I may not be able to open the skid plate holes that far either. If I drilled through for bolts and nuts, the far side is not flat to accept a nut. With some creativity, it may be possible to make a special shaped spacer to go between the nut and uneven shape but it would not be easy. I wonder if it will need to be filled with weld and redrilled? Based on the design, I doubt I'm the first with this problem.

Agree that M12 is far too big to go to.

I have a v-coil set which must be very similar to Helicoil and the tapping drill for the M8 v-coil is 8.4mm od. If you have to got to M10, the tapping drill for the M10 v-coil is 10.4mm od, so it still may be possible to fit an M10 bolt.

Good luck!

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  • 2 weeks later...

Agree that M12 is far too big to go to.

I have a v-coil set which must be very similar to Helicoil and the tapping drill for the M8 v-coil is 8.4mm od. If you have to got to M10, the tapping drill for the M10 v-coil is 10.4mm od, so it still may be possible to fit an M10 bolt.

Good luck!

The holes were about 1.5 times as deep as the helicoil so I tapped them as deep as possible with the helicoil thread. Rather than installing up near the top per instructions, I installed the helicoils as deep as possible in the hole and was able to get good torque on the bolts. So far, it has held for one ride so maybe it will be OK. Is there a torque spec for these?

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Glad to hear that you found a fix without resorting to going out too big.

The helicoil thread is as long as a normal thickness nut, and a normal nut is design to be able to take the force exerted by the bolt, ie the bolt would snap before the thread pulls out of the nut!

So providing your bolt goes fully into the helicoil, it should hold ok.

If you are using a longer bolt, obviously the bolt should be a few mm shorter than the depth of the hole plus the thickness of the bashplate, otherwise the bolt might bottom in the hole before the bashplate/frame connection is tight

One thing about putting the helicoil right at the bottom of a blind hole is that you might not be able to knock the tang off or get the bolt thread fully into the helicoil, But one thing about helicoils, you can always pick them out and fit another if you are unhappy with the position. If you calculate that you have about a nut thickness of bolt thread in the helicoil it should be ok.

With regards a torque setting, I don't know one, but from previous experience, I normally put Blue, medium strength (removable) Loctite and as tight as you can go with a normal length 10mm spanner is adequate. And check the tension regularly as banging the bashplate causes movement and slackens the bolts.

Hope it continues to work!

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  • 1 month later...
 

My 2012 EVO had a Helicoil on the left side and none on the right. I had to replace the Helicoil because it was working its way out.A new one went right in and is still working good. My bike also has Helicoils in 2 of the 4 sub frame mounts and fron skid plate mount from the factory.

Fantastic Bike.

Ralph

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