9 replies to this topic

[Shaggy33]

Well I knew it would happen eventually! Whilst fitting rear cones and shocks I managed to strip the thread of one of the bolt holes that holds the rear arm mounting plate in place. Its one just above the actually swing arm as opposed to the ones that go underneath.

Can I re-tap this with a metric tap, in other words is the subframe hollow behind that bolt hole or is into solid metal when bolt hole ends.

 

Any advice appreciated 

[RedRuby]

I am pretty certain that they are captive nuts, ie nuts welded on in the box type section

[Shaggy33]

Ok thanks so a re-tap may do it
So annoyed with myself

[Spider]

As Red Ruby has said, they are a welded captive nut. I heli-coil them, then it uses all standard fasteners.

[xrocketengineer]

This is the Heli-coil trick:

http://www.theminifo...il#entry3336546

[tiger99]

In any case if a 5/16" UNF thread has stripped you would need to go to M10, as M8 is too close to 5/16", and there isn't enough metal, nor probably clearance for the larger head. (Or try getting an M9, probably in the same parts bin as hen's teeth...) So you need a 5/16" UNF Helicoil or a new captive nut welded in.

There are other issues when substituting a UNF bolt by metric. The coarser thread means a deeper root and therefore reduced cress section and tensile strength, while the coarser pitch means less clamping load for a given torque. They should not be substituted on stressed parts without doing the necessary calculations, which are rather complex as you need to determine the actual dynamic loads.

[Shaggy33]

As ever incredibly helpful info, thank you and I echo someone on the helicoil thread, why haven't I used one before!
I'll give that a try.

[cal844]

Had this happen, we managed to weld another nut on top of the stripped one

[A-Cell]

Occasionally this happened during assembly in the factory. To this fixing, also to the heel board. The captive nut was stripped as the bolt was inserted using the "windy gun".

The repair process in the rectification area at the end of CAB1 was to "squirt" a bit of mig weld into the weld nut thru the hole, then drill and tap it 5/16 inch UNF and fit another bolt.

So that is another way of recovering the problem.

I have gas welded them in the past in service, also used bronze weld.

[A-Cell]

Also done on heel board fixings