Help Please with Rear Heat Shield On Valence

asphaltgambler · 08-13-2006, 09:04 AM

Have an '85 Targa that I'm restoring. Just replaced the rear lower valence with a nice used undamaged piece.

Problem: There is a heat shield that covers the inside portion of the rear bumper area. The lower portion of the OE valence had three blind studs that secured the lower part of the heat shield.

My new (used) valence does not have any blind studs there. I do not really want to drill and mount bolts /screws as they will show from the outside. The heat shield only uses three screws for the upper mounting. If I go ahead and install as is there is no way to secure the lower part.

Can I just 'toss' the shield? Or is it really that effective and I must keep it? I am installing a hot-rod 3.4 with B&B complete set up no cats.

Anyone run into this or have a solution??

Thanks!!

Zeke · 08-13-2006, 10:41 AM

My one and only thought on this is if you have to paint the new (used) valence to match, can you not weld studs on first? Maybe I don't know exactly what a blind stud is, but I'm thinking a bolt or machine screw with the head ground down and tacked 3-4 sides to the sheet metal on the backside. One tack at a time with ample cooling between should result in minimun warpage. That would be taken care of easily when prepping for new paint.

I would have suggested epoxy, but that is affected by heat.

asphaltgambler · 08-13-2006, 11:15 AM

The valence is already installed and the paint is flawless. Don't want to change that.

Blind studs are tack welded to the back side of the panel so not visible from the outside.

widgeon13 · 08-13-2006, 11:50 AM

Other than the fact that the valence and heat shield were originally held together by the blind studs, why do the two need to be held together? When I removed my valence to paint it there was a lot of stones and dirt between the two pieces of metal. Do the studs hold the heat sheild in place? I thought it was also bolted to the inside of the bumper higher up. Don't think there is much that can be done now that the valence is painted.

Jim Sims · 08-13-2006, 12:06 PM

"paint is flawless"

Without the heat shield there is a good chance it won't be flawless for long. Even with the heat shield this area gets cooked.

asphaltgambler · 08-13-2006, 01:12 PM

To secure the bottom portion of the shield it should be bolted to the valence or it would (I assume) rattle.

The B&B muffler is a lot thinner and not as close to the rear area.

????

Jim Sims · 08-13-2006, 01:38 PM

Maybe you could support the bottom of the heat shield with compressively loaded "stand-offs" mounted on the shield and projecting from both sides. Have one group loading against the valence and another group loading against something inboard (muffler?). Make from all-thread rod; stainless steel would be best for poorer heat conduction (desirable in this case). Adjust by having a nut on either side of heat sheet panel. If using stainless use anti-seize compound on the nut threads.

asphaltgambler · 08-13-2006, 02:47 PM

Yes that is an idea. I was looking more though whether anyone just removed it with no ill effect. IE: paint bubbling

klaucke · 08-13-2006, 02:50 PM

My car runs no heat sheild w/o any ill effects. However, I am using a Bursch muffler w/ early style exchangers. I think you could probably get away w/o the shield, but you may want to keep it just to be safe. Perhaps you could make a small "L" bracket that is held to the muffler w/ a large hose clamp, and secure the shield to that.

randywebb · 08-13-2006, 03:12 PM

I think Bill Verberg posted that was no problem unless you had a turbo. Dunno what muffler config was involved but the context was a FG rear piece -- that would have lower heat conduction to the paint than a steel piece altho it might melt itself...

asphaltgambler · 08-14-2006, 06:27 AM

Bump - Anyone

wcc · 08-14-2006, 06:38 AM

My '85 had a busted up rear valance with OEM exhaust. When I got around to it I removed the valance. Mine didn't have a heat shield in there. Then I changed my muffler to a Borla and cut the aftermarket valance for the outlets and installed. It's been like that for a few years now and no problems. So I'd toss the sheild cause it's fine without it IMO.

charleskieffner · 08-14-2006, 08:27 AM

glad to hear you got the valance on. since i went to RUF rear bumper we added a heat blanket and used large hose clamps to hold in place. maybe that will be simple cure. my fiberglass bumper in just 30 mile drive was very hot, so we added heat blanket.

asphaltgambler · 08-14-2006, 09:16 AM

Thanks all

greenie2 · 08-14-2006, 09:39 AM

I just replaced my rear valance on my 85 last week.

I bought a genuine Porsche part from from the dealer, it had no "Blind Studs"

I think on later runs of this part they must have found them unnecessary. The heatshield & valance are "as stiff as a four Viagra night with Sheryl Crowe" ( this from Car & Driver this month )

911pcars · 08-14-2006, 01:03 PM

Quote:

Originally posted by Jim Sims
Maybe you could support the bottom of the heat shield with compressively loaded "stand-offs" mounted on the shield and projecting from both sides. Have one group loading against the valence and another group loading against something inboard (muffler?). Make from all-thread rod; stainless steel would be best for poorer heat conduction (desirable in this case). Adjust by having a nut on either side of heat sheet panel. If using stainless use anti-seize compound on the nut threads.

Here's my parallel Jim Sims solution from a few years ago. Flat aluminum bar bent to fit under the muffler straps as well as stand off from the muffler. A formed-to-fit piece of sheet metal flashing material bolts to bracket and floats between muffler and rear valence/license plate panel. Creates two air insulation spaces so paint doesn't bubble from the heat. Unfortunately, I created the bubbles prior to installing the shield.

Sherwood