Spare wheel retaining bolt

[JohnLiddle]

Greetings,

I am trying to tidy up a few things on my son's 948 and I wonder if anyone can tell me the thread size of the bolt which secures the clamp against the spare wheel?

I have a bolt, but it does not seem to be the right thread (or of course the thread in the captive nut is bu**ered).

Either way, I would like to clean up the thread in the nut and fit a correct bolt.

TIA,

[dave flint]

HelloJohn,
I had a similar problem with my 1964 Minor. I bought a new bolt from a well known 'Moggy specialist' and although it was the correct diameter the thread was completely wrong - UNC I would guess. The tapped hole in the boot floor looked perfectly OK and not damaged. I tried many different bolts that I 'had in stock' and the only one with a thread that allowed good engagement was the spindle from a pedal bike (British cycle thread?). On consideration because the 'nut' is in fact a tapped pipe - the true thread may just be a British Standard Pipe thread. To solve my missing bolt I used the old bike spindle and locked the ball cone with its locknut to creat the bolt.
Let us know if you can identify the true bolt and a supplier.
Regards Dave Flint

[bmcecosse]

I imagine it will be 3/8" UNF .

[dave flint]

Hi John/bmcecosse,
It's not that obvious to be UNF - That was my first try.
Redards Dave Flint

[mike.perry]

Depending on the chassis no there was a change from BSF to UNF thread

[JohnLiddle]

Thanks to all for the replies so far.

The bolt I have (which has a T-bar fitted to it - is that correct?) appears to be 7/16" 18tpi, which would make it a BSF thread, but it does not want to engage very far with the thread in the body. There is no guarantee of course that it is the correct item!

Mike Perry - do you know when the change from BSF to UNF took place?

Regards,

[bmcecosse]

The bolt has a head to be unscrewed with the wheelbrace.....

[IaininTenbury]

Unless its a Series 2 or earlier when you have a convenient knurled wheel on the end of the bolt to turn by hand.
I didn't know there was a change to unf sizes, I'd have assumed that they were all bsf till the end like the rest of the bodywork bolts. Be interested to know when this happened.

[JohnLiddle]

Hi again.

I have tried the bolt that I have (which is 7/16" BSF) in my daughters 1970 1098 and IT FITS!

Since the bolt was missing from her car I have left it there - so that is one sorted.

All I have to do now is find out what thread I need in the 1960 948.

Could someone with a similar age 948 try measuring their bolt? Overall diameter and threads per inch will probably be enough to identify it.

TIA

[mike.perry]

I had a play with my 52 MM and 68 Traveller. The MM was definately 18 TPI. 7/16 BSF. The bolt thread on the Traveller was bxxxxxxd but when the threads were cleaned up it was also 7/16 BSF but would no longer fit the Traveller which also had a damaged thread in the hole. This was cleaned out with a tap from underneath the car and was fitted with a 20 TPI 7/16 unf bolt.
The heads of both bolts were 3/8 Whit.
There was a change of bolts at 451178 from a bolt with a long hex and plain shank to a flat hex and fully threaded. I don't know if the threads changed at that time

[JohnLiddle]

Mike,

many thanks for your response - I am beginning to wonder if the problem lies with the thread in the hole in the boot floor - I will try cleaning it up and see what happens.

Regards,

[mike.perry]

If someone has forced a 7/16 BSF bolt into a 7/16 UNF threaded hole it will have damaged the hole thread. Get a 7/16 UNF starter tap and turn it in from underneath the car. You will need to use a small spanner as there is not room for a tap wrench. Finish off with the middle tap
Sorry can't remember the names of the different taps