"vestigial" exhaust system donut hangers

re 1997 riv L36

on the front of the center resonator there is a unused stainless bracket.
it is correctly shaped to accept common rubber exhaust donut hangers.



the image also shows the floor pan has 2 adjacent hooks that are shaped to accept rubber exhaust donuts.

this exhaust system is factory original, but there is no rubber installed at the center resonator.
also
the Factory Service Manual shows nothing at the front of the center resonator for L36/L67,
but page 6F-3 indicates these hangers are used by the L47 engine [ Olds V8 ] at "View A":




it appears that common $4.00 rubber exhaust hanger donuts would fit correctly.



questions:
has anyone installed donuts at the front of a Riviera resonator ?
.and/or.
anyone encountered a Gen8 Riviera with rubber isolators installed there ?

are these exhaust hanger tabs there because the Riviera floor pan is the same part number as Aurora pan ?

Lmck3 wrote:

re 1997 riv L36

on the front of the center resonator there is a unused stainless bracket.
it is correctly shaped to accept common rubber exhaust donut hangers.

the image also shows the floor pan has 2 adjacent hooks that are shaped to accept rubber exhaust donuts.

this exhaust system is factory original, but there is no rubber installed at the center resonator.
also
the Factory Service Manual shows nothing at the front of the center resonator for L36/L67,
but page 6F-3 indicates these hangers are used by the L47 engine [ Olds V8 ] at "View A":

it appears that common $4.00 rubber exhaust hanger donuts would fit correctly.

questions:
has anyone installed donuts at the front of a Riviera resonator ?
.and/or.
anyone encountered a Gen8 Riviera with rubber isolators installed there ?

are these exhaust hanger tabs there because the Riviera floor pan is the same part number as Aurora pan ?

The hangers that go there are small dogbones not donuts, I have them on my Riv.

I'd say it's unlikely that your exhaust is factory original; the original is one welded piece from the downpipe connector to the muffler tips, including the cat. IIRC Walker or Arvin was the OE and your replacement is probably from an OEM, they would have all the dimensional data and identical parts.  Also, there were different styles of factory replacements made.  IIRC yours looks like one of the no-CAT factory replacements that was available for the Rivs.  When I got my replacement exhaust the no-CAT factory replacements for the Riv were no longer available so I got a complete exhaust made by GM ostensibly for the 2005 Park Avenue Ultra. There were none available at the time so it was made for me at Wixom (see https://en.wikipedia.org/wiki/Wixom_Performance_Build_Center).   Service manager quietly noted on the order that it was for a Riv, I paid in advance,  and wouldn't you know it arrived with all the mounts in the right place and new dogbone elastomeric straps to hang it up.  The CAT bung was not in the right place exactly but I extended the splash shield with a piece of flashing, and the cat was smaller (much smaller - newer technology) and closer to the front so I made and installed a heat shield - more flashing - for that too.  The PAU exhaust is stealth quiet and breathes very well, got rid of the 2500-3000 RPM flat spot I had on acceleration.  I miss the burble but not that much, car drives better.

The OE dogbones are made from a high tech black elastomer that looks like rubber and lasts for-flipping ever; even junkyard ones would work 110% fine. They should be available from the dealer for short money or from a junkyard -- the kind of thing that many pick-n-pulls will let you have for very cheap or free.

I found one of mine missing and the other broke in half but still hanging there a few years ago.  I replaced them with the donuts and it was a very tight stretch, obviously because they aren't right.  One only lasted a few months and broke.  I did replace that one again but they both are cracking and look pretty aged from being stretched.  Might find the correct ones for it now that I'm thinking about it again.  Does anyone have part numbers of the correct hangers?

the hangers are called INSULATORS on my pars fiche from 2001... for the 97 (98 different)

fronts were GM p/n 25609451 list $7.39

rears were GM p/n 25609452 list $6.31

an insulator's not shown on my fiche for the hangers in the very front. So if they used those insulators they were generic "shop supplies."

I forgot to come back to this after I did some research. It looks like hose hangers were no longer installed starting in 1997, per service bulletin #60-66-03.

stydel311 wrote:

I forgot to come back to this after I did some research.  It looks like hose hangers were no longer installed starting in 1997, per service bulletin #60-66-03.  

They were only removed for "exhaust noises". In my world, that means that stupid people expect a car to make ZERO noise. They remained in use on other platforms for quite some time. Apparently Pontiac/Chevy owners didn't have an issue with the "noises".

________________________________________________________

#60-66-03: INFO. - ELIMINATION OF FRONT EXHAUST HANGER INSULATORS - (Sep 3, 1996)

REVISION: 09/03/96

THIS INFORMATION WAS PREVIOUSLY SENT AS A DCS MESSAGE AND IS NOW BEING ISSUED AS A DEALER SERVICE BULLETIN. PREVIOUS DCS MESSAGE NUMBERS WERE: BUICK 96-22 OLDSMOBILE 96-162 **********************************************************************

SUBJECT: INFORMATION - ELIMINATION OF FRONT EXHAUST HANGER INSULATORS (RUBBER O-RINGS)



MODELS: 1997 BUICK PARK AVENUE/ULTRA, RIVIERA 1997 OLDSMOBILE AURORA



THE ABOVE LISTED MODELS ARE BUILT WITH THE FRONT EXHAUST HANGER INSULATORS (RUBBER O-RINGS) REMOVED (SEE FIGURE 1). THESE INSULATORS (RUBBER O-RINGS) HAVE BEEN REMOVED TO IMPROVE THE LEVEL OF EXHAUST NOISES. THE HANGER BRACKETS WELDED TO THE BODY AND EXHAUST ARE STILL PRESENT ON THE VEHICLE. DEALER TECHNICIANS MAY NOTICE THE ABSENCE OF THESE INSULATORS (RUBBER O-RINGS) AT THE REAR OF THE CATALYTIC CONVERTER. DEALER TECHNICIANS SHOULD NOT INSTALL INSULATORS AT THIS LOCATION AS THEY HAVE BEEN REMOVED TO REDUCE EXHAUST NOISES. THE BRACKETS WILL BE REMOVED FROM THE VEHICLE UNDERBODY AND EXHAUST ON FUTURE BUILDS