7 replies to this topic

[Stevie W]

Good afternoon all

 

Hope everyone is enjoying this fab weather!!!

 

Anyway, to the matter in hand, as the title suggests, I have a real problem with the lower offside radius arm bracket thread in the rear subframe.

I bought the subframe donkeys years ago at Stanfoord Hall, it was second hand, but a genuine item. 

 

During some recent freshening up of my Mini in the vain hope of getting it on the road this year, I had to replace the perished radius arm bearing seals (only 2 years old).

When re-attaching the radius arm bracket the lower bolt wouldn't tighten up. Now I replaced this bolt some years ago and helicoiled the threaded hole as the thread had stripped. The only helicoil I could get hold of at the time was a metric one, slightly larger than the 1/4" UNF (M8 I think).

 

The problem I now have is this thread has gone and it looks like the helicoil has come loose or broken up so the resulting hole is too large to do anything more with. In fact a 5/16" UNF is a rattling good fit in the hole   . 

 

I'm planning to whip the subframe out over the next couple of weekends and looked at the cost of a new genuine 'frame...£400!!

The only option I can think of is to get a workshop to drill out the hole large enough then weld in a 1/4" UNF nut, grind back and then I can repaint the 'frame....unless anyone has an alternative???

 

Cheers muchly,

 

Steve.

[Spider]

The Thread size is actually 5/16" UNF.

 

The Root Nuts that are fitted are fairly 'chunky'. If it were me and I couldn't helicoil it, I'd drill & tap it 3/8" or 7/16" UNF, fit a bolt with high grade loctite, cut the bolt flush, then drill & tap 5/16" UNF. When doing the final marking out, I'd fit the bracket back in place as a guide.

 

Alternatively, if you have access to a lathe is to make the insert complete with internal thread, then fit (with loctite), using a 5/16" Bolt with a Locknut to help get it in.

[Stevie W]

Good morning Moke Spider,

Many thanks for the advice. I hadn't thought of your drill/tap and loctite in a larger bolt then grind flush and drill/tap back to standard size. That does sound a very good idea.

I'll get the subframe out and see what I've got to play with.

Cheers, Steve

[Spider]

Hope that does the trick and at a tad less than 400 quid!

 

Us convicts have be inventive from time to time.

[Stevie W]

Ha Ha......I'm sure it will do the trick......now you've mentioned it, it seems the obvious and welder-free way of doing it!!
And yes, a darn sight cheaper than 400 squids!!
I've got a good set of imperial UNF taps and a decent drill, so that's the way to go.....subframe to be whipped out next weekend
 
Thanks again, Steve.

Edited by Stevie W, 20 April 2015 - 08:10 PM.

[jime17]

Ha Ha......I'm sure it will do the trick......now you've mentioned it, it seems the obvious and welder-free way of doing it!!
And yes, a darn sight cheaper than 400 squids!!
I've got a good set of imperial UNF taps and a decent drill, so that's the way to go.....subframe to be whipped out next weekend
 
Thanks again, Steve.

Did this work?

Im interested to know.

[Stevie W]

Hi,

 

Did find another way of doing this repair. Spider Mokes was a good idea but there didn't seem enough "meat" on the captive nut to do this.

I partially welded up the hole on the damaged thread (partially filled the captive nut hole) then drilled and tapped it instead. Seems to be ok....

 

Cheers, Steve.

Edited by Stevie W, 15 May 2015 - 07:31 PM.

[cal844]

Hi,
 
Did find another way of doing this repair. Spider Mokes was a good idea but there didn't seem enough "meat" on the captive nut to do this.
I partially weld up the hole on the damaged thread (partially filled the captive nut hole) then drilled and tapped it instead. Seems to be ok....
 
Cheers, Steve.

Thats another way of doing it, we just welded a new 5/16ths nut to the frame