Underseal & Stonechip

[Jozi]

I'm close to needing to underseal and stonechip my shell, what have you used?

I thought I had it figured out and ordered this: Dinitrol 445


Only to realise stonechip is not underseal BMW have their own underseal

but only no2 above (51910427674 - Undercoating, black) was available. Having got this it's not quite what I was expecting and looks that bit different to the original stuff


I had found a dintrol underseal that was resin based, dries elastic and is NON bitumen based. There's also a 3M product but it's very expensive and also maybe Bilthamber Dynx UB/UC

So what to use and where? Unfortunately I now have both the BMW and Dinitrol stuff listed above which I should probably use! I was thinking stonechip in/around the arches and underseal everywhere else under the car?

[Brianmoooore]

DO NOT under any circumstances put that bitumen based muck anywhere near a BMW!!!!
This stuff is for stretching a couple more MOT passes out of some scrapyard dodging heap from some lesser manufacturer, and shouldn't go anywhere near a 'quality' vehicle!
It works for a couple of years, then begins to lift, trapping water behind it, resulting in rapid corrosion of anywhere that there's a nick in the original BMW underseal. I've currently got an E30 cab in the workshop for restoration that someone has 'treated' to this stuff, and have already spent many hours and several litres of white spirit removing the stuff, muttering evil thoughts towards whoever put the stuff there while doing so.
The 3M stuff you have found is a two part polyurethane sealer, very similar to the OE stuff, but single pack polyurethane stuff is also available and cheaper.
IMHO, you should be using polyurethane in and around the arches and for patching the OE stuff, and using stonechip on the sills and lower valences at both ends of the car.

[Jozi]

DO NOT under any circumstances put that bitumen based muck anywhere near a BMW!!!!

Don't worry, won't let it near the car with the amount of work going into it I was fortunate to only have a little bit of it to clean away but even that caused grief!

I rang the shop I got the Dinitrol stone chip of earlier today and they reckoned the stonechip would also be fine in the arches, they said "area's of high abrasion" for stone chip.

The tech data sheet for 445 says this:
Spray is a synthetic resin/plastic-based product with anti-drone
effect for stone chipping and bodywork protection.
It can be used as underseal?

The other Dinitrol product I couldnt think of earlier was Dinitrol 447
is a black or grey, fast-drying, rubber and resin based auto-body protection agent.

I've fired of an email to dinitrol to see what they say, for now though it's bmw underseal (prob dont have enough) on the body, stonechip on the sills & valance.

[stew72]

A good stonechip will work fine if theres something good underneath it. In the past I've used a 90% zinc rich primer from the witham group under a good quality stonechip and its proved very good.

See here http://www.withamgroup.co.uk/sitefiles/ ... EDUCED.pdf

[mikeyh]

Sorry to hijack your thread

I'm also looking for some stone chip that has the same textured look as the oem for my rear valance. I've had to get a patch put in and i'm wanting to try blend it in

[lion_yo]

What is bitumen based stuff?? I have Bilthamber is that okay to use?

[Finto_316]

Jozi ill be getting some epoxy mastic as underseal then mayb estonechip on top, Its used for oil rigs out at sea . Jon Miller the restores in clare cant praise it enough http://www.classiccarworkshop.ie/contactus.html , Ill be getting it here http://www.rust.co.uk/epoxy-mastic.cfm

[spook]

Some awesome resto work going on in that workshop Flinto

[Finto_316]

I tried contacting him for a respray , engine rebuild and leather re trim but no reply. Would of liked to see how much he would of charged

[polsta]

Jozi ill be getting some epoxy mastic as underseal then mayb estonechip on top, Its used for oil rigs out at sea . Jon Miller the restores in clare cant praise it enough http://www.classiccarworkshop.ie/contactus.html , Ill be getting it here http://www.rust.co.uk/epoxy-mastic.cfm

that sounds like good stuff

[bimanut]

[quote="lion_yo"]What is bitumen based stuff??

I`m assuming they mean waxoil underseal?

[Jos]

Jozi ill be getting some epoxy mastic as underseal then mayb estonechip on top, Its used for oil rigs out at sea . Jon Miller the restores in clare cant praise it enough http://www.classiccarworkshop.ie/contactus.html , Ill be getting it here http://www.rust.co.uk/epoxy-mastic.cfm

Jotamastic 87 - same stuff, loads cheaper. Also do an 87GP with added glassfibre for very high abrasion areas, not tried it though. Takes 2 weeks to cure in outside temperatures!