r32 underfloor rails?

[Matvei27]

My driver's side under-floor rail had an unfortunate meeting with a wrongly placed jack stand.

How bad is this and can I get it repaired? How? 

[Duncan]

That is one of the straightest chassis rails I've ever seen on a 32.......next time put the stands where that seam is (forward of where you used), or spread the load a bit with a piece of wood along the rail

[Matvei27]

So, spray some undercoat to prevent rust and leave it?

[Duncan]

you could....but I cant see a dangerous amount of bare metal there.  If you look at other places like the spot welds where the chassis rails meet the floor you can see how a touch of surface rust can start over 30 years. It's not a dangerous rust risk like some places where water can pool and really eat into the metal.

If you are worried underfloor sealer (tarlike stuff) is available in cans, it resists stone chips better

[Matvei27]

This is what I was referring to:

https://www.amazon.com/3M-03584-Professional-Rubberized-Undercoating/dp/B002H9CMCQ/ref=sr_1_1?ie=UTF8&qid=1539126833&sr=8-1&keywords=3m+rubberized+undercoating

Is that different?

[GTSBoy]

The rail itself is fine to be left like that apart from rust considerations as mentioned above.

Sadly, the dent is big enough that it would fail a roadworthy.  So if this is an issue where you live, it would want to be fixed.  I had to pull all similar dents (much closer to the front end of the rail) out of mine to make sure it was going to pass Regency when I did my engine conversion.  We made a special tool that we could insert through the holes near the front to help with this.  That option would not be possible with the dent shown in your photo.  Too far back.  It it must be repaired, then you will be cutting metal out and putting straight stuff back.

Simple rule.  Chassis rails like that are not strong enough for chassis stands.  Too much point load on too thin a section of metal.  Even the doubled up seam that Duncan pointed out is not strong enough.  The only place designed to hold the car's weight is the jacking point under the sill.  This doesn't help, if you're jacking there you can't put a stand there too.  The only solution is to use stands that can fit under the lower inner pivots of the front suspension arms.  I had to grind the edges of the tops of my chassis stands to make them slim enough to fit in there.  Those points are hard enough and strong enough to hold the weight.  The only time this is no good is when you need to pull the lower arms off - then you can find an alternative way, probably involving the jacking points.

If you have to put chassis stands under the rails, then you need to use load spreaders, but this must be done safely, which is quite difficult.  Just putting lumps of steel/wood between the rail and the stand is not safe.

[niZmO_Man]

I wish my "rails" were that straight.

[Matvei27]

I'm not in a location where the vehicle has to be inspected.

So my question is more like does this affect handling, alignment, or structural integrity in any way such that it would be better off fixed?

Or, is it just cosmetic?

And, for rust prevention, is that 3m stuff I linked the right idea or do you mean something else by undercarriage coating?

[GTSBoy]

53 minutes ago, Matvei27 said:

So my question is more like does this affect handling, alignment, or structural integrity in any way such that it would be better off fixed?

Or, is it just cosmetic?

The rail is not bent.  The bottom of it has been pushed up which has pushed the sides out, but the position of the rail's centreline (left-right) is probably in exactly the same place as original and the height of the floor/straightness of the weld line along the rail/floor joints are probably not altered at all.  The rail might have slightly less strength against deformation (say in a frontal collision) than it used to, but that change would be quite small.  But this is the reason that they are defectable here in Australia with that sort of damage.  In reality, it is pretty much just cosmetic and nearly every other Skyline on the roads is in a much worse condition.

53 minutes ago, Matvei27 said:

And, for rust prevention, is that 3m stuff I linked the right idea or do you mean something else by undercarriage coating?

No.  That rubber stuff is not "rust proofing" in that you would not put it on bare metal.  it is meant to be put on top of properly prepared and rust-proofed steel, to provide an additional physical layer of protection over the chemical protection layer.  If you have damaged coating on that part of the rail and you want to protect it again, you will need to hit with some protective primer and/or underbody sealer/paint and only then consider the rubber shit.

Edited October 10, 2018 by GTSBoy

[Matvei27]

any product recommendations? something like POR-15 or?

[GTSBoy]

That's the Rolls Royce way to do it.  Even a quick flick with a wire brush and a spray with some rust primer from a can will do the job though.