4 replies to this topic

[Shaggy33]

Finally got round to attempting to repair stripped thread in rear trailing arm mounting plate. Now I might not be the sharpest tool in the box but what size thread are the bolts in these holes?
I thought there were 5-16 so I bought that size helicoil kit but when I fit the repair coil a 5-16 bolt doesn't fit, it's too small so bolt just slides in and out. I might not be the sharpest tool in the box but not the bluntest, what the hell is going on?..?
x

[MatthewsDad]

I've checked the kit I used for the same job and it's 5/16 - 24UNF. Are the bolts definitely 5/16?

[Shaggy33]

Well that I was led to believe and told....the other bolt that is fine is 5/16 so yep it's definitely that size. I've just taken an m8 (the nearest to 5/16) and it threads suspiciously well into one of the spare coils.....
I would have thought the tap is correct size as the coil threaded ok into the hole bit perhaps the Id of coils are m8. It would be just my luck to have been sent a repair set labelled 5/16 which are in fact m8...!
I wouldn't say the m8 is a perfect fit but it certainly holds if I try and 'slide' bolt off the coil whereas 5/16 slides off.
Any reason why I can't redo the hole m10?

[Spider]

The loose coils when not fitted in to anything, ie, loose from the pack, will just about fit any fastener around 8 mm / 5/16" dia.

 

Have a look at the tap that's with the set, it should be marked with what size repair it is for. It does 'look' to be a for a fine thread and I see the Inserting tool - for what ever it's worth - is marked 5/16-24 which is 5/16" UNF, however, as this is only the inserting tool it will fit anything 5/16" / 8 mm, it is not an indication of the tap size and form.

[Shaggy33]

Thanks Mokespider. I didn't realise the coil would compress as it gets threaded into the hole, makes sense now you say it! I thought I wasn't getting purchase on the new 5/16 bolt but it doesn't help when you can get socket head anywhere near the bolt head due to arm being in the way so a, not totally convinced that the 5-16 bolt won't be a snug fit when pinched up.
I've ordered some Allen head 5/16 bolts so I can actually tighten the damn things...