Underbody sealant on the chassis?

[matt 74]

Appreciate that the prefered method to maintain minimum corrosion on the chaasis is to prepare the surface and repaint if required with smoothrite and waxoyl. It is apparent that the chassis is particularly vulnerable especially in the hard to reach areas, of say, the internal box section of the wishbones.
In light of this wouldn't underbody sealant stand a better chance of keeping the corrosion at bay compared to smootrite?
Interested to hear if anyone is using it, perhaps not on all of the chassis just the most vulnerable areas - appreciate that cosmetically it might not be quite as appealing however neither are some rotting chassis' that i've seen!.

[taylormj4]

Hi Matt,
I'd go for underseal with waxoil over hammerite as a matter of course actually. Haven't had goo experiences with hammerite products, they form a really good solid barrier against water etc, right up to the point where it detaches from the chassis....rather like the stuff that TVR put on originally, or worse still it sits there trapping moisture against the chassis, actually speeding up corrosion!

I use a red oxide, zinc based primer (after cleaning up with a wire brush etc) and then wack on the underseal.

Cheers,
Matt

[griffter]

The key to rust prevention is complete, airtight coverage - and keeping on top of it at least once a year. I found I could force a paint brush into most places - you're right about the wishbone box sections, particularly at the 'point' of the V on the bottom wishbone. My tactic here was to spray in waxoyl at every angle. Same tactic employed for the rae upriaght. Another hard to reach part is the tops of the outriggers. Some people have managed to pass a paint-soaked rag over the top of the tube and then 'floss'. I preferred to trust to waxoyl (actually tetroseal/syl sp? - more expensive but IMHO better) again, which 'creeps' into any areas you miss.

I found pressure washing (careful where you spray it - avoid electrics/brakes) was effective at clearing muck, but on exposed chassis tubes ie those to be painted, wire brushing / scraping was required.

Basically it's easy enough to quickly clean up and paint the chassis, but takes a lot longer to do a thorough job and get to all the awkward parts.

[spend]

griffter said:

...quickly clean up and paint the chassis, but takes a lot longer to do a thorough job and get to all the awkward parts.

Too right, this is why every time you drop the prop / diff / manifolds... you have to expect to take at least a few days in the middle of the work to get to grips with the chassis parts that you can't normally reach. TBH I think a major benefit of doing some major jobs yourself is that you will take the time and clean up the chassis (and other peripheral bitty jobs) that a professional probably wouldn't - unless you asked for a complete restoration...

Dave

[griffter]

spend said:

griffter said: ...quickly clean up and paint the chassis, but takes a lot longer to do a thorough job and get to all the awkward parts. Too right, this is why every time you drop the prop / diff / manifolds... you have to expect to take at least a few days in the middle of the work to get to grips with the chassis parts that you can't normally reach. TBH I think a major benefit of doing some major jobs yourself is that you will take the time and clean up the chassis (and other peripheral bitty jobs) that a professional probably wouldn't - unless you asked for a complete restoration... Dave

Agree - my 'three day jobs' normally end up three weeks! I actually did the chassis tubes under the manifolds with a long screwdriver (to scrape), a small mirror (to look at the top surface from underneath the car) and paint brush taped to my long screwdriver!! I also used a cut down paintbrush in the palm of my hand from underneath. But I'll never really know how good the job is 'til the manifolds come off...

Take the time to do it right, and do it once (hopefully).