Chassis Tube Clean Out

[Rick Iverson]

Gents:

I am in the process of the second total ground up rebuild of my car. I removed what I believed was the factory belly pan by drilling out the rivet heads, and did the same in the last rebuild.

In doing so, the crush end of the rivets are trapped within the walls of the chassis tubes. My concern is, track time will cause this debris within the tubes to vibrate, thus removing chassis material in acting as an abrasive.

Presumably, I need to drill holes in each rail length large enough to extract the debris with a magnet, say 0.3125”. And do these larger holes need to be plugged? And if so, how?

[racpercival]

Anxiously awaiting the solution also!!!

[lowside67]

In my opinion, the abrasion effect of aluminum rivet heads bouncing against a steel tube will be extremely minor and probably not measurable even in 10 times the lifetime of the car. On the other hand, a hole drilled in it definitely is. If you were to drill that hole, you must certainly weld it up again.

-Mark

[cliff]

Most of my chassis tubes have one larger hole at one end. I put an air blast in the rivet hole on the other end of the tube and you would be surprised how much of the rivet remains come out.

[10rmotor]

I wouldn't worry about aluminum rivet heads inside a steel tube. If anything, the rivet heads are going to be abraded as they're softer than the steel. But if that excess weight and presence bothers you, a small hole at one end and air on the other should blow most of them out. The hold should definitely be welded back. A small punch out can be welded in to fill the hole. Or just welding rod.

[Rick Iverson]

Gents:

The rivets are aluminum AH64H closed end blind rivet with a countersunk head from Hanson rivets, but with a steel mandrel. Given enough time, it will be steel to steel.

I believe RP once reported the rivets merely secured the pan in place until the epoxy sets. And therefore, I believe opening one (1) hole on each rail to extract the debris is reasonable, say 0.3125”.

The other question is, location. Since the chassis bottom has, say, 320 holes in it, my thought is interior lateral. Semi protected from WX, and can be capped. Thoughts?

[Richard Hybels]

I heard ftom a reputable source that a World of Outlaws chassis was DQ’d because it had been sandblasted many times causing the walls to be thinner than spec.
so I would not sweat rivet heads doing any damage in the next 10-15 seasons.

[BeerBudgetRacing]

Most of my chassis tubes have one larger hole at one end. I put an air blast in the rivet hole on the other end of the tube and you would be surprised how much of the rivet remains come out.

I used a combination of things to move the rivets toward a vacuum at one end. I too had a couple spots in the chassis tubes that were large enough to extract the rivets.

Cover all the existing holes with tape and the suction does pretty well. Rotate the chassis at an angle too.

One of those long magnetic part retrieval tools worked too. I think there was only 1 cross member that I could not get to.

Just be persistent.