Steering relay bottom plate threads on chassis

[Webley1991]

I am referring to the threaded holes on the chassis where the bolts that hold the steering relay bottom plate screw into.

What are these threads formed into?

On the galvanised chassis I bought, the holes seem to be full of zinc.

I would like to know if I need to drill these out and re-tap to a larger size. This is why I am asking what these threads are formed into.

Thanks for any info.

 

[oxides]

You'll need to run a tap through the holes to clean out the zinc- and I can't remember the size. Get a UNF set and see what size the bolts are with the dies. Don't overtighten the bolts 'cos I'm not sure there's much more than the thickness of the crossmember to screw into. If it all goes horribly wrong you can go up a size.

 

[Webley1991]

Thanks for the reply. The zinc appears to have completely plugged all the holes.

If it's only the thickness of the cross member that the threads are tapped into, I might drill them out completely and put some nutserts in.

 

[Blackburn]

Looks a fair thickness of steel in this pic original chassis
I would expect galvanise chassis to be the same thickness .Mine was Marsland and just had to run tap through to clean up.
If the holes are just full of zinc should drill out very easily

 

[oxides]

Looks a fair thickness of steel in this pic original chassis View attachment 55634
I would expect galvanise chassis to be the same thickness .Mine was Marsland and just had to run tap through to clean up.
If the holes are just full of zinc should drill out very easily

Ditto.

 

[Webley1991]

Thanks for the replies.

I drilled and tapped mine today to 5/16" UNF. There was a good 10mm thickness of steel there.

I think I will also replace the original steering relay ring with something a bit more substantial such as a square of 8mm plate with the correct size hole bored through it.

 

[Rubins4]

I'm trying to identify the part number for the relay retainer plate but the manual isn't very clear, is it 90624433 for a late series 3? Other than the bolts and washers, is there anything needed to secure the bottom of the relay in the chassis?