Who makes high grade 26 tpi allen head bolts?

jseng1

jseng1

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Someone in UK must stock high grade 26 tpi allen head bolts. 2-5/16” (2-1/4” min) underhead length and 1-5/8” underhead length. Who?
 
Probably not what you are looking for, but I use high grade metric M10 x1 allen head bolts, = 25.4 TPI.
(Alu barrel)

Who makes high grade 26 tpi allen head bolts?

I prefer to use 5 bolts of the same length,centre bolt with spacer.
 
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I had to make a 3/8" UNF 2 3/4" long cap head bolt by cutting down a long 3/8" BSF cap head bolt and screwcutting the thread on it (this was to repair a Hytork hydraulic tightening head) We didn't have the correct length cap heads in stores. It would have delayed the job (boiler feed pump rebuild) if we had to wait for the correct bolts.
Be aware, 10.9 cap bolt material is tough stuff, Luckily i had the gear (large MT4 tailstock die holder) and was able to screwcut under power. Used Rocol cutting paste as its the best i have found.
I know the purists will say the thread should be rolled, but it works.
I doubt you will find any suppliers of off the shelf CEI threaded cap bolts. The market for them will be tiny.
The long extended through cap bolts that Merlin used on the DOHC head were screwcut from longer ones, and that was 45 years ago... Interestingly the short head bolts were 3/8" UNF cap bolts tapped into the barrel casting. I think they had access to raw barrel castings and machined them to there own spec, ditching the CEI thread and using UNF instead
 
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3/8" diameter.
High tensile strength (grade 8 would do) 26 tpi allen head bolts. 2-5/16” (2-1/4” min) underhead length and 1-5/8” underhead length. Socket head cap screws.


similar to
Who makes high grade 26 tpi allen head bolts?


I asked the UK ARP people at the link in the previous thread if they have anything at all in any type. We'll see if they answer.

Ludwig - the long centerbolt with spacer is a good idea.
 
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British Standard Cycle Thread 8.8 should be available. If not could you make your own? Buy in long 3/8" 8.8 cap screws with the unthreaded length long enough to suit your bolt and cut the BSC threads yourself.
 
jseng1 said:
Someone in UK must stock high grade 26 tpi allen head bolts. 2-5/16” (2-1/4” min) underhead length and 1-5/8” underhead length. Who?
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Try Namrick ( based in Brighton ) . They do mail order etc…able to supply all manner of threads, lengths etc.
 
dobba99 said:
Morning Jim
How many do you need?
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Depends what's available. Please describe in a PM.

MarshG246 - ARP bolts are great but I want to check into a more economical alternative. So far it doesn't look like it exists.
 
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I went through this same search a few years back, and had no luck. There seems to be a reasonable supply of BSC/CEI 3/8" 26 tpi hex head steel bolts, but I couldn't find anything in socket head bolts. ARP were willing to make them to order, as they do the 12-point head bolts they make for CNW, but I would have had to order enough to make it worth while for them, and I didn't want to do that. They were also, as Jim just mentioned, quite expensive. But the quality is as good as it gets. I've used off the shelf, high strength ARP fasteners as head and cylinder bolts for Commandos, but it does require thread inserts to accommodate the SAE thread pitch.

Ken
 
Unfortunately Andy Molnar who is making Alloy cylinders now uses an odd 3/8" 20 tpi for the head bolts (BSA A10 head bolts I think). Would have been nice if he made them for 16 tpi like Maney did and the Maney thread worked just fine with a strong alum thread pitch. That makes it two different types of Brit threads required for todays Norton cylinders - neither of them are available in high strength socket head that I can find. The 3/8" 16tpi high strength was easy to find.
 
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Jim, I wouldn't use a 3/8" cap head Allen bolt for cylinder heads if I were you. Depth of the hexagon hole is less than 5mm, unsuitable for a high-torque bolt in standard form.
I've never seen standard cap head Allen bolts used on cylinder heads. Application of high torque requires a large head for safe tool interaction.
I'd stick to hex head (BS, DIN 931, ISO 898-1, SAE J1199) or flanged 12-point head (SAE J58_201502) if I were you.
For cylinder head bolts, I recommend metric class 10.9 or a corresponding imperial class of high tensile strength (150 000 psi).

- Knut
 
Just as an additional bit of info on this subject, a decade or two ago I used to import, modify, and then sell alloy Commando cylinders from D. M. Robertson. They were drilled and tapped for 10 mm x 1.50 mm pitch threads. They came with metric 12.9 grade socket head (colloq. Allen Head) cap screws that took an 8 mm hex key. I sold a lot of them over the years, and never had a problem with the socket not being sufficiently strong for torquing them to specification. This is a snip from one of my early adds for the cylinders. I should mention that the cylinder through bolts were the same as stock 850 items, i.e. 3/8 inch 16 tpi socket head cap screws. Only the head bolts were metric.

Who makes high grade 26 tpi allen head bolts?


So that's another option in place of the 3/8-16 SAE cap screws I've been using, but it does also require using thread inserts.

Just to be clear, I no longer sell these cylinders.:) I quit selling them shortly after Steve Maney started selling his own alloy cylinders. They were much better quality than the DMR cylinders, and I was tired of having to do additional machining on the DMR items to make them fit. In any case, that's now ancient history. I closed out the Left Coast Racing business a couple of years ago.

Ken
 
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