http://community.webshots.com/script...bumID=42267828

Photo album with shots of my SLP Y-pipe and tunnel brace install.

Background:

Got a used SLP Y-pipe from a dude, SLP sez
it's supposed to bolt right up.

It does, to the stock -exhaust- stuff. But
then you can't get the tunnel brace back on,
without some bad banging. The brace will force
the pipe up too close to the the driveshaft,
causing some hard scrubbing of the balancing
weights under hard braking, and some banging
in reverse (vibrational, interference).

Rework:

I spent several nights trying things to fix
the interference problems.

Shimming the brace down is ineffective, you
can't get enough height with the stock bolts.
Longer ones might help some, but a lot of
space needs to be added for a hang that's
quiet over all vehicle maneuvers (hard stop,
hard go and road bounce).

I ended up beating the brace in two sessions,
the first wasn't a severe enough beating to
get its mind right. I used a 2-lb baby sledge
hammer and my 6" bench vise.

I marked up the region of the brace that was
interfering with the pipe and went to work on
the lip that sticks up and hits it. First I
rolled the outer edge under and down. The metal is
fairly mild and if you hit with a dragging
motion it will curl under nicely. Getting the
lip collapsed is necessary to take the stiffness
out so you can flatten it down.

After I got the metal curled under as far as it
would go, I then laid it flat on a board and
beat the lip as flat as I could. I returned to
the vise and worked on curling it under some
more, to get more lateral clearance to the pipe,
and finally did another flat beating to get a
little more vertical drop (more arch).

This left it looking pretty scabby, so I put
a couple of coats of POR Chassis Black on it
to make it less noticeable to the dealer
service dudes.

The beating work got it close to working but
after reattaching I still has some light banging
in reverse w/ brakes on; engine mount torque
compliance. So removing it again, I took a
heavy ball pein to the Y-pipe in the areas where
I saw it close to the brace. It only needed a
localized 1/4"-at-deepest dimpling; this should
not be a performance impact.

Taking the brace on and off so many times, I
managed to cross-thread one of the front captive
nuts on the brace. The steel is way too soft, the
bolts can only be torqued to 20 lb-ft and are
just waiting to yield. So I hogged out the two
captives to 3/8", and used some -real- Chevy
bolts I had off some earlier project cars. These
took all the torque I could give them with the
big ratchet. Fairly awkward getting the lock
washers and nuts onto the bolts, up on top of
the trans brace; that's why the cheesy captive
weld-ons are used. But it's doable if you have
long skinny fingers and some patience. And an
offset dogbone 9/16" wrench for the top work,
'cuz the nut is down inside the brace stamping.

Bottom line, no more banging. Have noticed a
few creaks when I steer hard, and at low speed
braking or shifting F/R with the brakes on.
This sounds like it's from the front end, I don't
know for sure if this has to do with making the
brace slightly less stiff (by flattening the one
rib and arching it) or if it's just the car
loosening up (2500 miles on it now).

I also tried the SLP convertible replacement
tunnel brace, and could not get it to fit the
mounting holes, and the Y-pipe was in a bind
between the upper "spider" and the lower, sedan-
style tunnel brace stamping. So I'm running with
the free rework, and no more troubles.

 

Tried the washers, but couldn't get enough
drop. The middle has to come down at least 3/8",
that's like an inch of washers at the back. I
guess you could stack enough of them up with a
long bolt. I thought that might add more "give"
to the whole arrangement, having it up on stilts.
But I reckon mine also compromises rigidity.

The link works when I try it... ???

 

The link may work for you but I don't think it will work for anyone else, It reads (Error- You do not appear to be the owner of this album. Make sure you are logged in.)

 

slp makes new brace for convert.

 

I bought one of the SLP braces. Tried real hard
to make it fit, but just not right. I'd rather
return it than hack on it. Also not that sold
on its actual bracing properties, after looking
at how it's made and how it's attached. I guess
it's better than air. Not convinced it's any
better than the banged-on stamping. Even if all
6 of the bolt holes lined up at once, and it
didn't bind the pipe.

Maybe this link works for other people, for the
stock-brace-abuse pix.
http://community.webshots.com/album/42267828Hxlyau

 

Holly cow you did a lot banging on that tunnel brace, I think I would have gone with washers to lower the brace. I did a y-pipe install on a friends SS and just went to AutoZone and got longer bolts, BTW your webshot doesn't work.

 

I cut mine and later got rid of it. Flimsy POS.
Try a driveshaft loop crossbar if you want some extra side to side rigidity.