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914World.com _ 914World Garage _ Trailing Arm Question ...

Posted by: SirAndy Aug 6 2005, 02:58 PM

while working on assembling my new (to me) trailing arms i noticed that on one arm there are 4 "drainholes" (for the lack of a better word) while the other one doesn't have any.

they both came of the same car and the holes do look stock ...

why would one need "drainholes" on a trailing arm?
if the welds are OK, there shouldn't be any water getting in there to begin with, right?

btw, the one with the holes is the drivers side arm ...
Andy

Posted by: pete-stevers Aug 6 2005, 03:07 PM

it won't get wet if you keep it on jackstands.....
who drives in the rain anyhow?

Posted by: davep Aug 6 2005, 03:15 PM

Don't know why the four holes are there. I recall most of them having holes.

Posted by: neo914-6 Aug 6 2005, 04:11 PM

They are there to lighten the arm and compensate for driver weight.

Posted by: MattR Aug 6 2005, 04:13 PM

Is it possible one side is early and another is late?

Posted by: Eric_Shea Aug 6 2005, 05:38 PM

Some have holes and some don't.

Posted by: cdmcse Aug 6 2005, 06:04 PM

Mine were the same way, drivers side had holes passenger side didn't.

Posted by: SirAndy Aug 6 2005, 06:10 PM

QUOTE (cdmcse @ Aug 6 2005, 05:04 PM)
Mine were the same way, drivers side had holes passenger side didn't.

ok, here's a WILD guess ...

notice how on the drivers side, the trailing arm has an additional tab on the underside?

how about the holes were added to equal out the weight?
Andy

Posted by: URY914 Aug 6 2005, 06:19 PM

Those are pre-rust holes.

The allow the early start of rust formation.

P

Posted by: SLITS Aug 6 2005, 07:18 PM

If they are sealed tight, under severe stress in a corner, the box distorts and creates high pressure inside which will lead to an exploded trailing arm. The holes relieve the built up pressure to avoid a dastardly incident.

this is also the fix for high altitude driving as the trailing arms were built at near sea level.

Posted by: Travis Neff Aug 6 2005, 10:02 PM

Y'all are nuttier than squirrel turds. Everyone knows the driver side holes are to weaken the drivers side to offset the passenger side hell hole/suspension console when it rusts out and breaks.

Posted by: balljoint Aug 7 2005, 06:32 AM

I have no holes in my '71 trailing arms, but they are there in the '74.

Posted by: J P Stein Aug 7 2005, 06:51 AM

My best guess.......not as much fun as these others.
Vent holes.
Prevent blow back / prevent a vacuume froming due to the heat from welding heat....just in case one of those lousy welders gets a perfect seal.

Other than that, I haven' a clue.

Posted by: Racer Chris Aug 7 2005, 07:15 AM

Look again at the ones without holes. They may be there but plugged with putty.

Posted by: SirAndy Aug 7 2005, 12:32 PM

QUOTE (Racer Chris @ Aug 7 2005, 06:15 AM)
Look again at the ones without holes. They may be there but plugged with putty.

nope, they were blasted to the bare metal before the powdercoating ...

no holes ...

so, next stupid question then, should i drill similar holes in the 2nd trailing arm as well?
Andy