Which Bolts to use

**dickyjoe** · 2nd August 2010, 04:21 PM

Hi All,

I am planning a reburb of my 1984 110 Land Rover "Mongol", some of you may have seen it in the Nth East section of the forum.

Anyway I am looking at Galvanising the chassis and the firewall using the local company's who are rebuilding the army Land Rovers.

The question I have is what is a good type of bolt with a coating that I can use to use on the rebuild. What would work best with contact with galnanised steel and aluminium. I am rebuilding this truck to last me so I don't want to be looking again at it in 5 years time.

My thoughts were ZINC coated bolts or even the cadmium plated bolts. I don't know enough about metals though.

Please Help!

Rich

**Blknight.aus** · 2nd August 2010, 05:16 PM

Id be looking at cad plating or a nickle based antisieze compound.

**JDNSW** · 2nd August 2010, 05:40 PM

Landrover decided this sixty years ago - galvanised (not zinc plated) bolts.

John

**dickyjoe** · 2nd August 2010, 06:19 PM

Hi Blacknight / John

Thanks for your input.

Which bolts are galvanised John?

I have had a look at cadmium plating kits online. Has anyone had any success with one of these?

Rich

**isuzurover** · 2nd August 2010, 06:34 PM

The bottom line is that the galvanised chassis will protect any bolts in contact with them from corrosion. I would be happy with zinc plated bolts - class 8.8 +

**JDNSW** · 2nd August 2010, 07:33 PM

Galvanised bolts suitable for all body bolts should be available in metric sizes, albeit you might have to get them ordered in and take a whole box. If in contact with a galvanised chassis, the galvanising on the chassis will protect the bolt in the immediate vicinity of the galvanising, but not, for example, the head or nut on the other side of the aluminium. Zinc plating will only protect for a short time in an adverse environment.

You should also use galvanised washers, although you will probably have to settle for zinc plated spring washers.

The original bolts used in Series 1 bodies were Sherardised, coated with zinc by a process of vapour galvanising. This has the advantage that the zinc is diffused into the steel, making them more durable and not significantly changing the dimensions (hot dip galvanising requires the thread to be cut deeper before galvanising, and often needs a die run over the finished bolt). However, it is a relatively labour intensive and hence expensive process, and as far as i am aware is no longer done on a commercial scale.

John

**dickyjoe** · 3rd August 2010, 12:45 PM

Thanks all for your help. This is going to make my truck last longer, which as I see it is a good thing!

**dickyjoe** · 5th August 2010, 03:57 PM

So put simply would Gal be much better than Zinc bolts.

It seems its much easier to get Zinc bolts over Gal. Would the Zinc bolts chew out the alloy or something?

Rich

**one_iota** · 5th August 2010, 04:23 PM

Rich,

Galvanizing applies the Zinc to the steel in a molten form where as Zinc plating applies the zinc electrolytically:

Galvanised Coatings - Zinc Galvanising versus Zinc Plating

So there will be no difference corrosion wise.

The benefit of galvanising is that the Zinc coating can be thicker and therefore can last longer. However as JD says, on a bolt this is problematic as the coating will "clog" the thread.

Zinc is close to Aluminium in the Galvanic Table and is probably and practically the best coating for a steel bolt going through an aluminium panel. However if you can seperate the materials with say rubber or paint all the better.

Happy to be corrected on this though.

In fact they now coat steel roof sheeting with a Zinc/Aluminium coating for corrosion protection.

**JDNSW** · 5th August 2010, 04:40 PM

Originally Posted by one_iota

Rich,

Galvanizing applies the Zinc to the steel in a molten form where as Zinc plating applies the zinc electrolytically:

Galvanised Coatings - Zinc Galvanising versus Zinc Plating

So there will be no difference corrosion wise.

The benefit of galvanising is that the Zinc coating can be thicker and therefore can last longer. However as JD says, on a bolt this is problematic as the coating will "clog" the thread.

Zinc is close to Aluminium in the Galvanic Table and is probably and practically the best coating for a steel bolt going through an aluminium panel. However if you can seperate the materials with say rubber or paint all the better.

Happy to be corrected on this though.

In fact they now coat steel roof sheeting with a Zinc/Aluminium coating for corrosion protection.

The difference in electrochemical potential of aluminium and zinc is still considerable, but it is less than steel and aluminium, and the fact that both zinc and aluminium form a hard insoluble layer of oxide is an advantage. But particularly if there is any possibility of movement on the joint, some form of insulation, at the very least paint, is preferred, since the aluminium will be preferentially attacked..

In galvalume, where sheet steel is coated with a mixture of zinc and aluminium, the function of the aluminium is to provide a much harder and hence more durable oxide surface, as aluminium oxide is more impermeable and harder than zinc oxide.

John

Thread: Which Bolts to use

Thread Tools

Which Bolts to use

Bookmarks

Bookmarks

Posting Permissions