75 MK3 ES stripped CC threads (Epoxy or Helicoil)

[click]

Hi Lads,

Re: 1975 MK3 850/900 ES

Doing a few small bits getting the Norton ready for the summer :mrgreen:

I had an annoying leak coming from the inner chaincase to CC joint & decided to check the 4 studs which hold the inner case in place.

One of the studs was loose & the threads have been stripped in the CC might have been done by me or the previous owner!!

The threads still have a little bite, I was hoping to get away with some plastic metal/epoxy to hold the stud in place so I can at least nip it up a little bit (I believe the torque for these studs are 4-5 ft/lb?) so just barely tightened up.

If I decide to do the 'proper' fix & use an insert (helicoil etc.) what size do I need? I'd like to use the original stud. It's a pain on the ES to strip all the primary 'junk' off to remove the inner chaincase cover to get at the CC holes so I'll avoid this if I can :roll: )

Thanks in advance

Happy New Year to one & all :mrgreen:

 

[comnoz]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

 

[Hobot]

I've had good success in buggered small case threads with the epoxy thread maker, made to flow into the thin gaps and set up likely stronger than the alloy itself. If the studs don't need to be removed just allow case to slip on/off then I'd not grease/oil the stud but let it set up permanent and might do the others too.
I don't like JBW that thin as gets both soft and brittle bits with that much engine heat unless ya filled hole and retapped it once JBW really sets up over some days and heated to cure hard. I tried to remake similar size hole threads on alloy chain saw cover holder to have heat and vibes destroy thin JBW with the weakened surrounding alloy. You already mentioned the next level escalation that would better please other more proper Nortoneers more.

 

[click]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

Jim,

Thanks for the reply.

Already had a helicoil!!! I didn't think it was possible to strip them!! unless you 'REALLY' wrenched down on them!

I've never done any type of insert before so bare with me!!

If there is already a helicoil which has stripped it's thread, how do I get this out before I install the time sert?

Also is it possible that the hole for the helicoil is too big for the time sert or can you get time serts with different outside diameters?

 

[click]

I've had good success in buggered small case threads with the epoxy thread maker, made to flow into the thin gaps and set up likely stronger than the alloy itself. If the studs don't need to be removed just allow case to slip on/off then I'd not grease/oil the stud but let it set up permanent and might do the others too.
I don't like JBW that thin as gets both soft and brittle bits with that much engine heat unless ya filled hole and retapped it once JBW really sets up over some days and heated to cure hard. I tried to remake similar size hole threads on alloy chain saw cover holder to have heat and vibes destroy thin JBW with the weakened surrounding alloy. You already mentioned the next level escalation that would better please other more proper Nortoneers more.

hotbot,

Thanks for the reply. I'll have a think before I make a decision, I know the 'correct' way of solving this is to use an insert but I'm trying to avoid a complete strip of the primary drivetrain, which I already did before last summer when I replaced all the ES 'bits' + rubber seals etc.!

I think I'll wait till next year to make a decision :wink:

 

[pete.v]

Thanks for the reply. I'll have a think before I make a decision, I know the 'correct' way of solving this is to use an insert but I'm trying to avoid a complete strip of the primary drivetrain, which I already did before last summer when I replaced all the ES 'bits' + rubber seals etc.!

I think I'll wait till next year to make a decision :wink:

I think it is best to wait to do it proper.
I used threaded inserts not only on the primary inner threads but also on the the drain plug (72) . I know the drainplug does not apply to you but thread inserts are much beefier, offer real dependability and are available at the hardware store. They were the EZloc with the pink stuff around the ouside. I removed the pink stuff and used JB weld.

I know many people add inserts to where ever they can.

Keep in mind that threaded insert are neither timeserts nor helicoils. If there is meat to support these, it is a straight forward process reguiring no special tools, other than taps.

 

[Hobot]

The thin type tread makers would likely soak in behind-around the heli coil to stablize it too. On my 750's I like to replace bolts with studs I red loctite in. I'd try thread locker 1st and if that didn't work then take apart engine to avoid swarf inside and remake the area by JBW tapped or Timeset milling drilling fitting. I don't know ES clearances but could also just go up one size bigger fastener hole. I've heard of some setting bike on side to let the drilling fall out w/o extra work taking engine out or apart.

Scan these for sense to go by.
https://www.google.com/#q=epoxy%20threa ... cification

 

[click]

Thanks for the reply. I'll have a think before I make a decision, I know the 'correct' way of solving this is to use an insert but I'm trying to avoid a complete strip of the primary drivetrain, which I already did before last summer when I replaced all the ES 'bits' + rubber seals etc.!

I think I'll wait till next year to make a decision :wink:

I think it is best to wait to do it proper.
I used threaded inserts not only on the primary inner threads but also on the the drain plug (72) . I know the drainplug does not apply to you but thread inserts are much beefier, offer real dependability and are available at the hardware store. They were the EZloc with the pink stuff around the ouside. I removed the pink stuff and used JB weld.

I know many people add inserts to where ever they can.

Keep in mind that threaded insert are neither timeserts nor helicoils. If there is meat to support these, it is a straight forward process reguiring no special tools, other than taps.

Thanks for the info. on the threaded inserts, they seem far less scary than helicons :lol:

Just have to find a supplier in Ireland or the UK!

 

[comnoz]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

Jim,

Thanks for the reply.

Already had a helicoil!!! I didn't think it was possible to strip them!! unless you 'REALLY' wrenched down on them!

I've never done any type of insert before so bare with me!!

If there is already a helicoil which has stripped it's thread, how do I get this out before I install the time sert?

Also is it possible that the hole for the helicoil is too big for the time sert or can you get time serts with different outside diameters?

There is a lot of vibration at this point so helicloils can fail. Time serts are larger OD than a helicoil so they are a good repair.
It should not be difficult to get the old helicoil out. If the thread has pulled it is likely part way out now. Jim

 

[click]

The thin type tread makers would likely soak in behind-around the heli coil to stablize it too. On my 750's I like to replace bolts with studs I red loctite in. I'd try thread locker 1st and if that didn't work then take apart engine to avoid swarf inside and remake the area by JBW tapped or Timeset milling drilling fitting. I don't know ES clearances but could also just go up one size bigger fastener hole. I've heard of some setting bike on side to let the drilling fall out w/o extra work taking engine out or apart.

Scan these for sense to go by.
https://www.google.com/#q=epoxy%20threa ... cification

Strip the engine :shock: :shock: :shock:

I've come across info. on this site about pressurising the CC and using lots of grease + having the large CC filter in the bottom gives you a better chance of finding any 'bits' that might get away from you!

Swingometer is leaning more towards the insert than using some goo :roll:

 

[click]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

Jim,

Thanks for the reply.

Already had a helicoil!!! I didn't think it was possible to strip them!! unless you 'REALLY' wrenched down on them!

I've never done any type of insert before so bare with me!!

If there is already a helicoil which has stripped it's thread, how do I get this out before I install the time sert?

Also is it possible that the hole for the helicoil is too big for the time sert or can you get time serts with different outside diameters?

There is a lot of vibration at this point so helicloils can fail. Time serts are larger OD than a helicoil so they are a good repair.
It should not be difficult to get the old helicoil out. If the thread has pulled it is likely part way out now. Jim

Thanks Jim,

Pity Concord is gone, I could get you to pop over work on my bike and be back in time for supper :mrgreen: :mrgreen:

 

[comnoz]

I normally pressurize the crankcase with a blow gun directed into the breather hose to tap them. That way the chips blow out as they are cut. Grease just seems to make a blob that may drop into the cases.

If a couple chips get in the case they will be in the sump screen next time you remove it. Yeah yeah I know -that's bad.

 

[Hobot]

Actually from couple events direct experience of alloy chips going through pump its a non issue as pump chews em up and spits out with mere surface burnish evidence. It takes harder steel or brooze cam washer tabs ingested to chip pump teeth somewhat but still not enough to bother full supply oil pressure. Screen catches anyway if one installed. Air pressure is good idea of course if a good size compressor available. Could also fill with oil or diesel and let the drain out keep the chips flowing outside.

 

[lcrken]

If there is already a helicoil which has stripped it's thread, how do I get this out before I install the time sert?

Also is it possible that the hole for the helicoil is too big for the time sert or can you get time serts with different outside diameters?

The normal way to remove a helical insert is with a triangular shaped tool that you use to unscrew the insert. See picture of extraction tool part way down this page.

http://www.helicoil.in/helicoil.htm

Lots of good info on Timeserts here:

http://www.timesert.com/index.html

Be aware that the standard 5/16-24 Timesert uses the same tap size as the standard Helicoil, basically a 3/8-24 tap (.370" major diameter for Helicoil, and .368" for Timeserts), so if the threads for the insert are pulled out, you may have to go to an insert with a larger outside diameter. I've replaced plenty of Helicoil inserts with the same size Timeserts with no problems, so that might work for you. If not, Timesert makes oversize inserts called Bigserts, where the 5/16-24 size uses a .470" major diameter tap.

Ken

 

[comnoz]

I guess I have never had a time sert with that small an OD.

I normally use these.

http://www.mcmaster.com/#90248a078/=q0tzgf

They are 1/2-13 OD. Jim

 

[DBowden]

click:

Have you considered the keensert? I like them because of the 4 "stakes" that are used. When the stakes are tapped into place there is no way for the insert to work loose. Take a look at this video: http://www.youtube.com/watch?v=XyCTh23Z6o0

 

[lcrken]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

Jim, I think you are using "time sert" as a generic term for solid inserts, while I assumed you were referring to the Timesert brand of insert. I'm a real fan of Timeserts for places where there isn't enough material to drill out for the larger OD inserts (e.g. cylinder base holes in crankcases bored out for 920 engines). One of it's virtues is that it will replace wire inserts like Helicoil without drilling the hole larger, as long as the threads are reasonably good. If there is room for the larger inserts, like the E-Z Locks you use, I would assume they have more pull-out resistance, if that is needed.

Ken

 

[comnoz]

You will need to install a time sert with a 5/16-24 ID. They had a helicoil in them from the factory. Jim

Jim, I think you are using "time sert" as a generic term for solid inserts, while I assumed you were referring to the Timesert brand of insert. I'm a real fan of Timeserts for places where there isn't enough material to drill out for the larger OD inserts (e.g. cylinder base holes in crankcases bored out for 920 engines). One of it's virtues is that it will replace wire inserts like Helicoil without drilling the hole larger, as long as the threads are reasonably good. If there is room for the larger inserts, like the E-Z Locks you use, I would assume they have more pull-out resistance, if that is needed.

Ken

Yes I was talking generically.

I have used inserts with the timesert brand some years back. Obviously they must have been the bigserts that you were talking about as they were larger than a helicoil.

Are the small timeserts you are talking about still a solid wall insert? If so I presume they would have the same thread pitch on the ID and OD.

For an fine thread insert used in aluminum I prefer a course thread on the OD. They have better holding power in aluminum. That requires a thick wall insert. Jim

 

[click]

Thanks for the links to the other types of inserts.

As always with this forum I'm getting an education :lol:

 

[lcrken]

Yes I was talking generically.

I have used inserts with the timesert brand some years back. Obviously they must have been the bigserts that you were talking about as they were larger than a helicoil.

Are the small timeserts you are talking about still a solid wall insert? If so I presume they would have the same thread pitch on the ID and OD.

For an fine thread insert used in aluminum I prefer a course thread on the OD. They have better holding power in aluminum. That requires a thick wall insert. Jim

Yes, the standard Timeserts are a solid wall insert, and the external threads are the same pitch as the internals. They get pretty thin between the threads. I agree with you about using coarse threads in aluminum, but sometimes there just isn't enough material. And in many cases the fasteners aren't stressed enough to worry about thread form. I still use Helicoils for things like timing cover threads that strip, but try to use Timeserts or other solid insert for real load bearing threads. I have Helicoil, Timesert, Sav-A-Thread, and Key-Lock inserts in my parts collection, and have used all of them on Nortons somewhere in the past. I've even made my own inserts a couple times when nothing else was available, but I'd much rather buy them than make them. The last time I made some custom bronze inserts I scrapped more than I made. Trying to get the internal and external threads to line up with each other properly is no easy thing, at least for me.