Bodyshell preparation

[COLIN STUBBS]

im reshelling a race car and have a mint unrotten road car shell to start with thats stripped out. whats the best/easiest/most cost effective way to get all the clag/sealant/underseal off before i start welding? had a price on acid dipping but very expensive!would you go for shot/grit blasting or does it have to be the scraper and wire brush???????

[cannardd]

I'd try soda blasting.
Not sure if it will shift underseal though, but worth asking.

Sand blasting can be far too aggressive.
Acid dipping can be very risky too, you can very easily end up with a bodyshell with panels that resemble a doily!

[Al Weyman]

Blasting would be the way to go if you can afford it IMO.

[terence]

If you take the blast route make sure who ever does it is not an animal with the pressure.Ive seen quite a few shells effectively ruined by this prosess. If you can stretch to it ,go for soda dip,before the shell goes though score all underseal with a decent blade. One other problem with blasting is that it will take forever to get all the grit out from all the box setcions etc.One other thing if you have it blasted,is to find someone who uses wallnut shells instead of grit.

[StephenRae]

It is uneconomic to remove underseal or any kind of 'rubbery' stonechip by shotblasting, the friction tends to melt it not move it.

[vaughan jones]

wire brush on a angle grinder,noisy but cheap and effective

[1200Datto27]

Dry ice is wonderful for removing sound deadener and underseal, just put it on top of the area that you are working on, wait a minute or two, and then just lift the stuff off the metal. I did a whole Impreza shell in 3 hours.

[terence]

Originally Posted by StephenRae

It is uneconomic to remove underseal or any kind of 'rubbery' stonechip by shotblasting, the friction tends to melt it not move it.

It does depend on the type of grit used.

[TEAM78]

Use a hot air gun and a paint stripping scraper to scrape all the stuff off, can be done in a day. The effort involed though in shell preparation makes it uneconomical to go doing this as the return in performance isnt noticable unless the car is extremly sensitive coupled with a very sensitie driver, Id be surprised to see an effect on the lap time although I appriciate theorectically it should.

[vaughan jones]

i dont removing the underseal makes the car faster,it makes it easier to weld etc,also the old engineers adage what looks better often is applies.

[greenamex2]

Originally Posted by vaughan jones

i dont removing the underseal makes the car faster,it makes it easier to weld etc,also the old engineers adage what looks better often is applies.

I removed about 3 or 4 Kg of underseal from my Corolla. It may only make a few hundredths difference but worth having and sort of free.

[terence]

One other method,if you have access to a decent compressor, is a thing called an MBX, this is a rotary wire brush,very effective in removing sealant from all the seams .You will need to clean all of these in order to get a good clean weld If seamwelding.

[crogthomas]

Another vote for the Dry ice to remove sound deadening. Sort of.
I've never used it, but just wait until winter when its nice and cold, (about now is good) and smack the floor from undearneath with a hammer. The sound deadening just shatters and flies off.

A wire brush in an angle grinder seems the most effective at removing seam sealer (and bits of loom nearby).

Underseal is the most difficult. Hot air gun and scrapper is cheap, but still hard work.
The alternative might be one of these companies that puts the whole shell in some sort of oven and burns everything off it? Anyone used this?

[zefarelly]

Originally Posted by crogthomas

The alternative might be one of these companies that puts the whole shell in some sort of oven and burns everything off it? Anyone used this?

most larger towns and cities have council estates on their outskirts where you can get that done for free, no oven required !!!

[terence]

Thats not funny! The only problem with this service is you never get your wheels back!

[COLIN STUBBS]

ah! thanks for the advice. im thinking if getting al weyman to give it a large smack with a camaro...... that might shake it off. seriously,iv found a guy that knows how to blast shells properly,and local to me so might not have to spend christmas day with hot underseal dropping on me head!i realise it wont gain nothing in lap times,but i need it seam welding properly so need the lot off.and i want it to look right when its done. thanks again.

[275 GTB-4]

Originally Posted by crogthomas

A wire brush in an angle grinder seems the most effective at removing seam sealer (and bits of loom nearby).

Ask for a twist knot wire brush....then get some very good eye, face, mouth, body and hand protection They fairly rip any thing off in their way.

[Al Weyman]

Originally Posted by terence bower

One other method,if you have access to a decent compressor, is a thing called an MBX, this is a rotary wire brush,very effective in removing sealant from all the seams .You will need to clean all of these in order to get a good clean weld If seamwelding.

I have one of thise I bought for my vinyl shop but as you say terence change the head and they are a great tool, bit expensive though, here are some shots I posted on a signmakers site of the machine being used. My machine is an electric version incidently and is available from Jaguar Signs.

Here is the tool being used on the roll cage of my Penske IROC.





Oh and Colin, happy to oblige anytime:-)

[terence]

Glad your sorted,have fun!

[1200Datto27]

Originally Posted by 275 GTB-4

Ask for a twist knot wire brush....then get some very good eye, face, mouth, body and hand protection They fairly rip any thing off in their way.

Definately need protection with twist wire brushes, I have pulled the wires out of my body numerous times using them. They are worse at sheeding wires when used in a tight space as well.

[greenamex2]

Funnily enough I have just been using a wire brush attachment on my angle grinder without wearing gloves.

My left index finger is now a few grams lighter.

Ouch.

[terence]

Originally Posted by Denis Bassom

Funnily enough I have just been using a wire brush attachment on my angle grinder without wearing gloves.

My left index finger is now a few grams lighter.

Ouch.

Bet you wish you,d been reading this beforehand!

[greenamex2]

Would still have done it, but just kicked myself even harder after!

[tzei]

A few car shells have been blasted with very hot high pressure water. Takes everything off.

[Chris Y]

...including the metal