Powder Coating in Chassis Holes! Help

[Gt6ball]

Hi all, I had my chassis Powder Coated a long time ago and have just comes to bolt the Body to it. I went to check the bolts fit first and the holes are full of Powder coating so I can get to the threads and hence the bolts won't go in - think I'll learn something from this!

 

Anyone any ideas how to get the threads clean. I would prefer not to tap new threads and I can't get a dremel in the holes as they are to small.

 

Any help would be appreciated!

Thanks

Stephen

 

 

[NonMember]

Run a tap through them. You're not "tapping new threads" - if the tap is the same thread as the one under the coating then it'll just cut away the coating and clean the thread up.

[Mjit]

The people powder coating your chassic SHOULD have plugged all threaded holes, if not all holes with bungs before spraying the powder to prevent this.  As they didn't you'll need to get yourself a set of imperial taps and dies and re-tap them as NonMember has said.

The process I'd follow is:

1. Start by using a parts manual to work out which nuts and bolts go where.
2. If you have a bolt to do in a painted hole start by grabbing the dies and find the one that matches the bolt. Assuming you were sent the correct bolts you now know the correct thread size, avoiding any miss-prints, etc.
3. Swap that for the corresponding sized tap and start running it in the painted thread with little or no pressure, though maybe a little more pressure to intially break the paint surface.  Running the tab through the paint surface should be easy and the less pressure you're using the more likely it is to catch the existing thread, rather than try to cut a new, cross one.  If you're needing to use any real force/facing any real resistance the tap's probably trying to cut metal, not paint, so abort and try again.
4. Usual rules apply - screw the tap down one-and-a-half turns/back off half a turn/down one-and-a-hald/back off half/... till your out the other side or bottom out/run out of thread (sudden big increase in effort required to go any further.

[RogerH]

......and than ask yourself the question  -  why did I get the chassis powder coated. Doh!!

 

Roger

[ahebron]

17 hours ago, RogerH said:

......and than ask yourself the question  -  why did I get the chassis powder coated. Doh!!

 

Roger

I have asked myself that same question a few times!
And not doing it again.

Looking at something like this for the next one

Adrian

 

[Nick Jones]

Loathe powder coating. Always fails in the end and flakes off - but only after fostering  particularly malignant rust under it first.

Etch prime, zinc primer then paint for me.

Nick

[ahebron]

I am dealing with parts that were powder coated back in the 90's and its not good.
Spider rust on the chassis that had to removed and sprayed.
The worst is cast steel/iron items like hubs that have rusted underneath the powdercoating.
These are all on a car that has not been finished since the late 80's.
 

[Colin Lindsay]

16 minutes ago, Nick Jones said:

Loathe powder coating. Always fails in the end and flakes off - but only after fostering  particularly malignant rust under it first.

+1 to that. Hate the stuff; looks good for a year or two then falls off in large flakes and the metal behind rusts like billy-o.

[RogerH]

The major problem is if it does 'not' fall off.

The rust continues under the paint skin year on year. Eventually you have a hollow paint shell (perhaps a bit of imagination there).

The point is that it does not actually protect the metal. Being quite hard it can easily chip - moisture enters - rust is let loose.

 

Roger

[Mjit]

Powder coating is about the best way to apply paint to protect metal...IF it's done correctly.  More often than not it isn't.

[Gt6ball]

Thanks  guys, did as you suggested last night with the tap and all is good with all bolt threads now clear.

 

Really impressed with the Powder Coating but get the feeling you guys are against it 😀😀😀

 

thanks again and and will be back with more questions I’m sure

 

stephen

[Colin Lindsay]

47 minutes ago, Gt6ball said:

Really impressed with the Powder Coating but get the feeling you guys are against it 😀😀😀

 

Long experience, Stephen. Looks good for a short while, but when it starts to crack and moisture gets in under it, then bits start to fall off, and you can't touch in the rusty bits with paint since you can't match the coating with a brush.... lots of trouble. Here's hoping you're spared any bother, you might just be lucky!

[NonMember]

As Mjit said, if powder coating is done properly you shouldn't get any of that bother. My Spitfire's chassis was powder coated 25 years ago and is still immaculate. Granted it's spent most of the intervening time in a series of damp barns and somewhat less damp garages, rather than being driven, but so far my experience has been good.

[SpitFire6]

1 hour ago, Mjit said:

Powder coating is about the best way to apply paint to protect metal...IF it's done correctly.  More often than not it isn't.

Agree.

I have worked with Fusion Bonded Epoxy coatings for over 25 years. If the substrate is good the coating will last years. Underground.
It would disbond if hit with a hammer, but liquid paint is not much better. It weathers in sunlight. Prone to disbanding on sharp edges.

Liquid paint is more forgiving.
 

Think I would use a specific liquid coating on chassis.
Mine is galvanised.

Cheers,

Iain.

[ahebron]

5 hours ago, SpitFire6 said:

..........

Mine is galvanised.

Cheers,

Iain.

How did that all go, I had though about it but that was all
Any twisting?
I am aware of Landrover chassis being galv-ed but they are a bit more robust.
You would want to make sure the chassis is perfect before dipping.

[SpitFire6]

7 minutes ago, ahebron said:

How did that all go, I had though about it but that was all
Any twisting?
I am aware of Landrover chassis being galv-ed but they are a bit more robust.
You would want to make sure the chassis is perfect before dipping.

Hi,

 I was told it was dipped & where the coating has flaked off the zinc is present.

Around 500c I believe.

Been on the car for ten years now. Drivers side outrigger lasted 8 years.. Plated now.

Cheers,

Iain.

[Peter Truman]

Our Spit Mk2 chassis is powder coated (Red) over 20 years ago, and it still looks original it is checked periodically  and any stone damage painted with epoxy paint.

We do live in Aus the car s always garaged and seldom taken out in the rain! so there are few negatives.

Do remember that the powder coating only protects the outside or sprayed surface of the chassis the inside still needs protecting.

Peter T