UMS 115-9 radial

[Stuart Atwill]

Hi, I have posted in the Technical help required but basically I need the above engine repaired as a bolt has sheared in the crankcase. If you know of anyone that could help, that would be great thanks.

[IAN TURNEY-WHITE]

The method I use to remove a sheared off bolt is with a small sharp centre punch , locate the centre of the remaining bolt and tap the centre punch with a hammer
You will need a stud extractor , this has a tapered left hand "thread" plus a sharp good quality drill ,tungsten if possible , diameter to suit the beginning of the tapered edge of the thread extractor
You then need to drill a hole in the centre of the remaining bolt , imperative that you keep checking you are drilling into the centre and the drill is parallel to the bolt,
not wandering off course, keep drilling until you just exit the end of the bolt , you will feel it with your drill . difference from the steel to the alloy crankcase, do not dill any deeper
Then with the stud extractor securely gripped in a tap holder , screw the stud extractor into the bolt but rotating it anticlockwise , it will cut its own thread and at some point grip the bolt and as you continue turning it it should unscrew the broken part of the bolt .
If its reluctant you may consider carefully applying heat to the area around the broken bolt from a small blow lamp but be very careful you do not cause any heat damage to the engine.
I have also had some luck with drilling a small hole in the bolt , again parallel to the bolt and then lightly hammering in the square ended tang ( handle end ) of a small file into the hole and with a small wrench turn the file anti clock wise removing the broken bolt.
Hope the above makes sense/helps
Good luck Ian Turney-White

[IAN TURNEY-WHITE]

Stuart, Just seen your original post , which makes my reply a bit irrelevant
Wonder if you could abandon the original tapped hole ( doubt you will be able to get the broken screw extractor tip out ) and drill another hole adjacent , fitting a recoil thread insert in the crankcase

[Stuart Atwill]

Thanks for your reply Ian. I don't think there is room for a separate hole. When this happened before, I was able to extract the two bolts, one of them had rounded out so I had to use a recoil for that which was very successful.
I think it's odd that mild steel bolts were used for this purpose, i.e. no grade marks on the heads of the hex bolts.
Where the front of the crankcase is bolted to the body of the crankcase, most of the bolts have grade marks but some don't, does this seem odd?
Would replacing the crankcase body be a practical solution?
Thanks again for your help, I will persevere.

[IAN TURNEY-WHITE]

Stuart , bolts , allen bolts tend to be in various grades ie. 8:8 , 10:9 , 12:9 , 12:10 , the higher the number , the stronger the bolt .
On allen bolts ( and bolts ) its normally stamped on the face of the bolt head
If its not stamped , then I would be suspicious of the bolts strength , maybe worth a look at all the bolts and replacing them with say 12:9 allen bolts ?
Soft bolts could stretch, sheer or come loose
Regards Ian Turney-White

[Stuart Atwill]

Thanks again Ian.
If I manage to extract the offending bolt I would like to replace all of the other unstamped bolts with the correct grade, I do worry though that other bolt heads might sheer off too.
It seems odd to me that good grade bolts were not used during manufacture. This is an early production model, about 2018 if I remember correctly, perhaps I should take it up with UMS.

[IAN TURNEY-WHITE]

Stuart , If it was me , I would contact the firm , a friend had problems with a slightly bigger version from the same manufacturer , they supplied improved components
Regards Ian T-W

[Stuart Atwill]

Thanks Ian,
I sent a message to them yesterday, nothing so far, fingers crossed.