Rusty Rockers - Replace or Fill?

[Apodman]

I've got two pretty good sized holes forward of my left front jack point. I'm starting to grind, sand and prime a bunch of smaller rust spots on the body in anticipation of a paint job this summer. I've been thinking that I would fill the holes with bondo, then seal and cover with paint and undercoating.

Now I find that for $62 a whole replacement steel rocker panel is available from Mill Supply in Cleveland ( http://www.rustrepair.com/app2/onlinecat.htm?p=sm ).

Has anyone tried going this route or know of someone who has? Obviously there is still cutting-out, cleaning-up and welding to do, but at least there's peace-of-mind knowing that there is steel where there might have been bondo.

Any successful bondo stories out there? It could be cheaper and quicker, but how does it hold up?

Thanks in advance for any help.

Alex

[dpatterson]

Well a rocker (or "sill" panel as we prefer to call it in this part of the world) is structural. Bondo is ok for cosmetic repairs but obviously its not doing much for you structurally. So it really depends on the size of those two holes (and whatever else is lurking in disguise under the paint). You will have to judge for yourself.

A couple of little holes - well, maybe no big deal if you rust treat them properly (ie grind ALL the rust off so that you have shiny steel and then treat with rust convertor) and cover them with bondo. Paint it well and it will probably last 5+ years, maybe. On the other hand some people are content to just scratch some of the worst rust out, slap bondo over the top and then coat with stoneguard etc to hide the result. This effort usually falls out on the driveway within 6 months.

If they're big holes then perhaps you should consider getting some patches welded across them and then dressing them with bondo. I wouldnt be going for a whole rocker replacement if I didnt have to (and I recently had both sills, along with a helluva lot of other steel, replaced in a 350SL so its fresh in my mind) - its a lot of work to cut out and then refit the full panel and the car needs to be properly supported or you will have panel fit problems for sure. Its a job for an experienced panelbeater, not someone at home with a $200 mig from Home Depot - IMHO.

My choice would be grind it clean, assess the extent of the holes then and just locally patch them. Cheap and effective.

Originally Posted by Apodman

I've got two pretty good sized holes forward of my left front jack point. I'm starting to grind, sand and prime a bunch of smaller rust spots on the body in anticipation of a paint job this summer. I've been thinking that I would fill the holes with bondo, then seal and cover with paint and undercoating.

Now I find that for $62 a whole replacement steel rocker panel is available from Mill Supply in Cleveland ( http://www.rustrepair.com/app2/onlinecat.htm?p=sm ).

Has anyone tried going this route or know of someone who has? Obviously there is still cutting-out, cleaning-up and welding to do, but at least there's peace-of-mind knowing that there is steel where there might have been bondo.

Any successful bondo stories out there? It could be cheaper and quicker, but how does it hold up?

Thanks in advance for any help.

Alex

[alabbasi]

I actually bought my rockers from MB and paid a lot more, the following day I found that rust repair site..... Alas, what can you do.

You can see some pictures of the work in progress on my 450SEL on http://alabbasi.net

[Mark DiSilvestro]

Whatever repair you decide for the rockers, I suggest if possible, first enlarging the biggest rust-hole enough to get a small vacuum cleaner hose in there and clean out as much of tha accumulated sand, dirt, rust-flakes, compost, dead insects etc... I recently removed about 30 pounds of debris from the rockers on a '73 450SL. Strangely, the rockers on this car were still intact, but the ends inside the wheel-wells had rusted open, creating convenient access holes to run my small shop-vac hose the length of the rockers.
You should treat the inner cavities with some sort of preservative - Waxoyl, POR-15, etc...
Awhile back, someone on this Forum posted about a rustproofing made from sheeps-oil.
In the past, I've had good results applying 90 weight gear-oil in rusty crevices inside my cars, but it does stink!
If you're going to weld, the weld areas should be pre-treated (I think there is something called 'weldable primer' or some other chemical) or they will rust again, that much faster.
If you weld, you'll need to apply whatever inner preservative you choose afterwards - maybe by pumping/spraying in through drain holes or making a small access hole in each wheel-well that can be sealed with a rubber plug.

Happy Motoring, Mark