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Stripped threads


frankd

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I was installing the clutch slave cylinder on the 83, and when I went to snug up the bottom bolt, the threads in the block stripped. Any ideas how to fix them good enough to tighten up the bolt?

 

I checked and it looks like there is about 1/8" or a bit more of good, unused threads left down in the blind hole, so I may try and see if I can find a bolt that is a little longer and see if there is enough left to hold. I don't think a heli-coil would be very easy to install. The female threads in the block are about 6" inside of the bulge in the stator cover, so I'd have to find a way to extend the installation tool. Also, the threads don't start at the surface, they are recessed about 1/8" so that the bolt will act as a pilot bushing also. The next best alternative that I see is to tap it for a larger bolt, probably a 1/4"-28 and open up the hole in the cylinder a bit. The Yammie bolt is 6mm or .236". I'll still have to come up with a way to extend the tap though. I haven't looked on the Grainger site yet, but do they make a tap extension so you can reach into recesses? Anybody ever have any luck with Devcon or something like this?

 

Barb and I are leaving on the 89 Thursday, so it'll be sitting for a bit.

 

 

Frank D.

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Hey Frank,

I have seen this before. I have had real good luck tapping the hole 1/4-28. You don't even need to redrill the hole. A 1/4 drive ratchet with a (I think a 4mm socket) will fit the top of a 1/4-28 tap. You may need a short extension, or a deep well socket to get in there. Turn the tap about a 1/4 turn then reverse the ratchet to clear the chips. If you get heavy handed with that ratchet Frank, and break that tap, you will be in a world of trouble, so "easy does it". Lube that tap with WD-40 or even better cutting oil. Do not dry tap that hole. When you install the new SAE bolt I would use a S.S. Allen Head Cap Screw and put anti-seize on it. This can be done with a little patience. Good luck with this project. :thumbsup2:

Earl

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Another option is make a stud for the application. Instead of using a bolt where your pulling the threads out, get a longer bolt and a nut. Thread the nut on so when you cut it off it will straighten the threads. Cut it off mount whatever and then thread the nut. If you dont have cleaence issues that is. Typicaly if you have it threaded all the way down and you just need to snug it up this will work. If its a head bolt or something like that well then you have to go the helicoil or thread-zert route.

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If I remember correctly, a stud won't work because it will get in the way to remove the cylinder. I have tapped that particular hole to a 1\4-28 and it works very well,,,, at least Wizard765 hasn't complained in 2 years.

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Hey Frank,

I have seen this before. I have had real good luck tapping the hole 1/4-28. You don't even need to redrill the hole. A 1/4 drive ratchet with a (I think a 4mm socket) will fit the top of a 1/4-28 tap. You may need a short extension, or a deep well socket to get in there. Turn the tap about a 1/4 turn then reverse the ratchet to clear the chips. If you get heavy handed with that ratchet Frank, and break that tap, you will be in a world of trouble, so "easy does it". Lube that tap with WD-40 or even better cutting oil. Do not dry tap that hole. When you install the new SAE bolt I would use a S.S. Allen Head Cap Screw and put anti-seize on it. This can be done with a little patience. Good luck with this project. :thumbsup2:

Earl

 

 

:sign yeah that: and the next time don't torque the cap screw down to 50ftlbs. 10ftlbs or snug will be adiquate.....

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My brother once had stripped out the threads in a V6 block and he used this stuff and never had a problem after that. He used the release agent on the bolt threads filled the hole let it set. Once it was hard he unscrewed the bolt and the threads held under 35ft. lbs of torque.

Loctite Form-A-Thread repair kit

[ame=http://www.amazon.com/Loctite-Form-A-Thread-repair-kit-grey/dp/B000WSEUII]Amazon.com: Loctite Form-A-Thread repair kit, grey - 4.8ml: Sports & Outdoors@@AMEPARAM@@http://ecx.images-amazon.com/images/I/31UAMyXc8GL.@@AMEPARAM@@31UAMyXc8GL[/ame]

 

Loctite® Form-A-Thread® Stripped Thread Repair, makes reliable thread repairs without drills, taps, tools, or inserts. Restores worn, stripped or damaged threads and eliminates future corrosion, galling, seizing, and rust. Allows up to 128 ft. lbs. of torque between -65°F to 300°F. Permanently repairs stripped threads and fasteners in five minutes (up to SAE Grade 5 English and 8.8 metric).

Edited by PGunn
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The way I have always done stripped bolt holes is to install a HeliCoil. It is a thread replacement device that you drill out and tap the hole for the Helicoil to be installed. This lets you use the original size bolt.

You can pick up a kit that will contain the Coil, Drill bit and tap. They are available at most Auto parts stores. If unsure what size you need take a bolt with you and match up.

 

The link below is a site that gives good info on use and installation

http://www.repairengineering.com/helicoil.html

 

 

 

 

Best to You

Edited by DMW
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Earl always has good advice and several others on this one. I think I want that thread repair and Heli-coils to put in the garage. Getting heavy handed with these bolts can really lead to trouble. I've learned to try and check tourqe specs for them. Kic got into trouble with the valve covers not long ago but with help from here got thru it. Ain't this PLACE GREAT!!!

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While Heli-Coils are great, they are also very expensive to get the kit. It can be hard to justify the cost for a single repair. In the metric sizes that we would be likely to use. it is $40 - $60 per thread size for off brand and $70-$100 for genuine Heli-Coil brand. Once you have the special tap and installation tool for a thread size then you can use all of the different types and lengths of inserts for that specific thread. I often start out with the off brand tools and then get the genuine coils to use for the actual repair.

 

There are situations that will easily justify $100 for a thread repair if the part being repaired is either very expensive and/or very difficult to replace.

 

I am slowly building up an assortment of Heli-Coil sizes. I do not have all of the sizes yet but some day I will.

 

There are applications where I design a part (usually aluminum) to have a Heli-Coil right from the start because the Heli-Coiled hole is stronger that the original thread size.

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I posted this on a similar thread on another forum here on Venturerider.

 

Needed new threads put into a set of used saddle bag side rails I bought, asked the srvice manager at the local Yamaha dealer if he could put in a Helicoil and he they do not use them , instead they use something called a Time Cert, new to me, but works well.

See link http://www.timesert.com/

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  • 2 weeks later...
  • 11 months later...

I have used the Time Sert to replace the stripped threads on a bikes drain plug. They make these thread inserts for all types of applications including oil drain plugs and spark plug threads. They are a complete threaded insert not just separate threads like the helicoil. They cannot be tightened too far in or come out as they lock into the hole you tap. I HIGHLY recommend them BUT they are very expensive ($100.00 for the kit to repair the drain plug on the bike but they come with the drill bit, counter bore tool, inserting tool, and 5 inserts in the size) The repair in the aluminum case of tghe bike where the drain plug is went very well, was easy to do and was a permanent repair leaving steel threads instead of the aluminum that were from the factory and best of all....no leaking oil!

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