Can anyone tell me where I can get a reconditionning kit or components for iron head headbolt threads, i.e., coil and tap? Also, since I suspect that this hole may already be too large to re-sleeve, can anyone tell me what classic or modern-size replacement bolt could be used to enlarge the hole and, in that case, what the torque should be for the new bolt, if the rest of the head bolts remain the standard size?

email (option): jonny.rudge@verizon.net

hi john,how big is the hole now?and where are you based. reason im asking, ill have a look what ive got in the morning.the hole in theory should only be 3/8''diameter if you've stripped out the threads, if its bigger let me know. cheers rick

email (option): richardholt@rocketmail.comhi hans

please look on the technical section, all the info is on there

email (option): davmax@ntlworld.com

The bolt appears to be 3/8 BSF (20 t.p.i.) but the problem is three-fold. First, even though the bolt shaft measures pretty close to 3/8, it had so much rust on it that I can't tell how much material I removed when I wire-brushed it. Second, the bolt was being held on by LOTS of thread lock or some other unidentified junk, and it was the only one of the 10 that had this problem, so I am sure this bolt would have been way too loose, otherwise the person who put it on (not me, of course) would not have used so much. And lastly, there is about a half inch of "good" thread at the bottom of the bolt but the threads above that are truly mangled, almost as though they had been ground off. I don't know how this happenned as it pre-dates my first removal of the head. I have plenty of spare standard head bolts and I'll try first to fit one of them when I put it together. The questions I posted are in advance preparation of the day when I find out that I can't torque it down to spec, or try to torque it and end up stripping the rest of the threads in this hole.

email (option): jonny.rudge@verizon.net

Sorry, Dave, I did check the technical section of the web site before I posted, but I didn't find anything relating to torquing of non-standard head bolts or anything about where to get a thread repair kit. If I missed it, I'd appreciate you pointing them out to me. Thanks in advance.

email (option): jonny.rudge@verizon.net

hijohn,if you go to the website home page and click technical info then when the page appears click the third line down , cylinder head bolts,the bolts are numbered.you can tell everybody whch bolt you are talking about by numbering it.firstly if you are not sure it is stripped, i would get a 3/8 bsf plug tap and clean out the hole ,then blow it out with an air line or an empty squeezy bottle to see how bad it is.it may be the bolt was knackered when it was fitted,there are two lengths of head bolt fitted,the wrong length bolt may be in the wrong hole.you may be able to deepen the hole ,depending which one it is and tap it deeper and fit a longer bolt.as for torque settings, a torque wrench was not a standard m20 toolbox component,a little double-ended box spanner about 5''long however was and if you can strip a 3/8''bolt with that yuo must be charlie atlas cheers rick

email (option): richardholt@rocketmail.com

John, if you want or need to go down the re-threading route then you can buy a Recoil 3/8" BSF kit (part number 30060 or 30068) for around the £30 mark. You'll also need a correctly sized drill bit (can't tell you what size, but it will be shown on the packet). Google for suppliers or see Lawson-his.co.uk for instance. If you can discover the drill size and acquire that first, you can check whether the hole is too big to repair "like for like" (i.e. the drill bit just drops in) but normally this isn't an issue. Any insert ought to be able to take at least as much tightening torque as the original thread.

ChrisJ

Hey Jonny,

I have all that in stock. Taps, dies, and helicoil kits. 3/8 BSF (55 degree Whitworth thread)

www.britishtool.com (my site needs updating as all my new M20 stuff is not on it.)

I also have thread charts of all the British sizes of fasteners you can download.

Cheers,

Robb

email (option): britool51@hotmail.com

Hi Robb,
Do you have a new website of is it done? (Down?) Link doesn't work.
I also have a bad head bolt hole that needs repair, though my issue is it seems to have had a broken off bolt, drilled and tapped to a smaller size bolt. I'm holding out that I MAY be able to reclaim the original threads if I can get the remnants of the old broken bolt out.
PS did you send the rear wheel gauges we discussed?
Vincent

email (option): vinver-at-ns.sympatico.ca

The next convenient size up from the 3/8" bolts would be 10mm (with an insert)..Of course that would require a 17mm socket to remove the bolts from there on...or you could go 7/16", either BSF or UNF...With 7/16BSF you may have trouble getting the bolts and with UNF you are again looking at a non standard socket size

The tapping drill, tap and insert to repair a 3/8" thread are reasonably oversize and I usually find that if it is just a stripped bolt, even if the thread has more or less gone, you will still have the material to do the repair by this method...Ian

email (option): ian@wright52.plus.com