Thread: Which Bolts to use

And so....

If you were doing up a Land Rover with or without a gal chassis and you had to purchase the bolts would you use Zinc or Gal? The local bolt man doesnt seem to have Gal but has Zinc and I was wondering if its going to make it that much better or maybe the difference would be negligable.

Rich

Originally Posted by VladTepes

How? By magic ? By setting a good example ?

Surely the fact the chassis is galvanised will limit/prevent corrosion *at the point of contact between bolt and chassis* but it's not going to protect a bolt from anything else - like rust from salt water etc.

Zinc corrodes preferentially. Any bare steel in contact with zinc will be protected for ~+/- 5mm either side of the contact, and further away will only develop light surface rust usually.

Steel boats have a few lumps of zinc screwed on their hull to prevent corrosion (but that is immersed in electrolyte).

The IIA dad and I built for him has all the steel body bits galvanised, but mostly standard bolts. It has been on beach /fraser etc fishing trips many times over the years. The bolts are fine.

If you can get them use cad plated hardware otherwise use paint to protect the surfaces.

Paint is cheaper and easily applied.

Lanolin/lanotech is another surface application which appears to have come into vogue more recently and appears to have got acceptance from many as it is natural and less harmful than the metal plating heavy metals and chemical used in the process of preparing or used as a medium to hold the metal in some solution in order to apply it.

I just use Grade 5 UNF zinc-plated bolts that you buy in boxes of 50 or 100. I've found over the years that when you go to enormous lengths to rebuild your Landie to be perfect, there's always something that doesn't quite go the way you planned and so it's never quite that perfect after all. And then other things come up and you don't care so much. So now I use what good quality stuff I can get and othewise don't worry about it.

Galvanised bolts are typically available in only softer grades like 4.6.
You have to go for zinc electroplate or cadmium plating in harder grades.

If I could get them I would use galvanised bolts in preference to zinc plated. The problem is that the plating is usually (not always) so thin that it is broken by casual impact, such as using a spanner or the nut running along the thread, so that it is easily attacked.

It is about four years since I did a body off repaint on my 2a. Where possible I used the original galvanised bolts, but had to replace some of them with zinc plated ones (could not get galvanised UNF bolts and did not want to use metric). The forty year old galvanised ones are mostly still OK. The four year old zinc plated ones are all rusty.

I cannot think of any of the body bolts where the grade of bolt matters, as none of them carry a lot of load - possibly the ones mounting the bottom of the firewall, but that is about it.

John

Originally Posted by JDNSW

I cannot think of any of the body bolts where the grade of bolt matters, as none of them carry a lot of load - possibly the ones mounting the bottom of the firewall, but that is about it.

John

All the body bolts are Grade 5 - which is ~ Class 8.8 in metric. Although that may be overkill, I wouldn't want to decrease the strength of the bolts. Most of them may be overkill, but a lot of them are small, and prone to snapping during removal.

"Structural" grade bolts are Class 8.8 hot dip galvanized

BUT

you may struggle getting them in the smaller sizes required and they will be the new fangled metric threads!!!

Galvanic Table (snipped)
Active (Anodic)

1. Magnesium
2. Mg alloy AZ-31B
3. Mg alloy HK-31A
4. Zinc (hot-dip, die cast, or plated)
5. Beryllium (hot pressed)
6. Al 7072 clad on 7075
7. Al 2014-T3
8. Al 1160-H14
9. Al 7079-T6
10. Cadmium (plated)

Clearly the best fasteners for the job at hand would be forged from Beryllium!!!!!! The list certainly makes Cad plated look the most logical choice being only just more cathodic than both the gal chassis and Al panels commonly available and easy to source in the correct sizes and grade. Zn plated bolts surface scratch to easily and generally hot dip Zn bolts (apart from structural) are generally low grade with poor tolerances.

Steve