Exhaust replacement questions

[KDirk]

The 91 Reatta I recently bought may need exhaust system work sooner than later, so I have a few questions.

I know the stock exhaust has been discontinued, and that there is a Camaro exhaust system that apparently is a good fit. My questions are:

1. What year Camaro exhaust setup works on the Reatta?

2. Any particular brand? This seems to be a contentious subject amongst a lot of people, with personal preferences running deep. I'm thinking Magnaflow, but am open to suggestions.

3. I've seen a conversion to dual rear pipes on at least 1 Reatta. Since the lower rear bumper valence has only one cut out for the stock tail pipe setup, is a matching cut made on the other side, or is the exhaust installed low enough to clear the bottom of the valance panel extension? Also, is a single resonator/muffler used with the split to duals on the outgoing side or is it dual from the cat back?

Would like some clarification so I am ready to do this when the weather gets decent.

Thanks,

KDirk

[D-a-n-i-e-l]

What part of the exhaust are we talking?

Autozone has a direct fit cat. any thing else I would just have a muffler shop do, unless you have a welder and pipe bender.

[KDirk]

I'll be looking to replace from the cat back. Actually, right now the car has no cat. Previous owner must have removed it (catalyst probably broke apart and clogged the exhaust)and just put in a straight pipe. Was clearly done by somebody with proper tools and equipment because they did a nice job.

That said, the exhaust is just a bit noisy. Probably the lack of the cat, which I may put back in, even though I am exempt from emissions testing in Missouri for anything 1995 or older. May also be some debris in the resonator from the cat going bad.

So, my main concern is the proper pipes from the cat to the muffler (which can be fabricated), the muffler itself, and whether to keep a stock style muffler (two pipes on drivers side) or go to a single pipe on each side as I have seen on a couple of other Reattae.

Any input?

KDirk

[jonlabree]

First

decide whether you want to look stock or cool.

[KDirk]

Jon,

Quite honestly, I'd prefer stock. I don't really need a performance look exhaust to stroke my ego <chuckle>. Besides, it will cost less to go with a stock style setup, the money saved can be spent on other more worthy work on the car, like repainting the hood and front bumper to get rid of the rock rash.

What I'd like to know is whether there is a consensus on who makes the best muffler suitable for the Reatta, and a part # for it if there is a preferred supplier. I've used Magnaflow parts in the past on other vehicles and was satisfied, but thought I would get input from those of you who have done exhaust work on a Reatta first.

The pipes etc. are easy, I'll have these fabricated.

KDirk

[jonlabree]

Well, Stroke your ego with this:

There are no stock parts fo the exhaust.

Riv comes closest

[KDirk]

Jon,

That's why I'm asking if anyone has a preferred exhaust setup they have used to replace the stock parts. I know factory parts are NLA, was just hoping for some guidance on what brand and part number has been successfully used with good results. A stock-looking setup with the pipe(s) on the drivers side only is fine, doesn't need to be fancy.

KDirk

[Guest MauiWowee]

1. Keep in mind that the pipes on a '91 are larger than '88-'90.

2. Check Greg Ross's posts from the last few months. He modified the rear pan for dual outlets and posted pics. There is also a discussion of alternate mufflers.

Good luck.

[jonlabree]

The man doesn't want dual exhaust, as he put it.

don't really need a performance look exhaust to stroke my ego

[KDirk]

Maui,

Thanks, that gives me a starting point. For the record, my remark about not needing a dual exhaust to "stroke my ego" was intended to be humorous, in case anyone misinterpreted that. I didn't mean to sound like a pretentious rectal cavity. Oops, there I go again.

KDirk

[Guest steelfoot427]

try the exhast from a 91 riv. you might have to take a few inch's out of a pipe or 2 but it's the close's to it

[Barney Eaton]

Attached is a typical Camaro muffler system from a catalog.

On the Camaro the exhaust enters the end with two pipes.

On our cars it enters on the single end and has two exits on the same end. Most muffler catalogs indicate the muffler can be used either way.

So you can use the Camaro muffler to operate the same as the original Reatta or if you wanted the "dual exhaust" look, you could plumb it like the Camaro.

[Guest Greg Ross]

Remember, the '91 Reatta had a 2-1/2" diameter exhaust system. As suggested, if '91 Riv parts are still available that would definitely be the place to start if you're staying "stock". And getting pipes bent to properly to fit the Reatta from the Cat back is not that simple. There's some nasty routing under there, even installing factory original parts it's a challenge getting it right so it doesn't contact the floor pan/ transfer noise, fits within the heat shields, etc. "I SPEAK HERE FROM EXPERIENCE!

You didn't mention which portion of your exhaust system is rough. You're right about added exhaust noise without a cat. converter. If that's all you need, look at aftermarket ones, they can readily be cut in. Caviat is, on "high mileage" cars the pipe in the mid pan area around the cat will be noticeably thinned from the high temperatures and will be more difficult to weld if just installing a cat.

[KDirk]

Randy, Barney, Greg:

Much thanks here. This is the kind of info I was hoping to find. This is where guys like me who are new to the Reatta experience truly get their money's worth with interest out of a resource like this forum, so to speak.

Since stock stuff is no longer available, except maybe Riv parts as already stated, I appreciate anyone who can speak from experience so I know what NOT to do, and to plan for unforeseen difficulties, like bending and routing the pipes.

Regarding the noise, I think it is probably just a heat shield or something loose. Had it up on the rack Sunday night, couldn't pin down anything loose by poking around. Also hard to tell inside the car, and too cold this week (so far) to spend time outside listening to it.

I am worried that if the cat blew up (probably why it was removed), the muffler may contain some residual debris from that event. This may be contributing to the noise I am hearing.

I am not adversed to going with the Camaro style setup, just not sure I see the need to do so. Obviously, it will add cost to the project, but it does have it's benefits, in looks and performance.

Right now I am just hoping to get rid of the vibration noise on acceleration. Unless the muffler proves to be full of catalyst chunks, the major work can wait a while. I have more pressing items that I would like to tackle first, mostly suspension related; it's a bit noisy too.

Thanks again,

KDirk

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Right now I am just hoping to get rid of the vibration noise on acceleration. </div></div>

My car has the same problem. If you find the cause, please post the cure here.

[Guest Greg Ross]

If it's resonance into the floor pan you're hearing you first need to look at the hangers. There is a pair of them mid-ships, as I recall just behind the Cat (or where it should be) The muffler is also on a pair of them, if any one of these is gone the weight of the exhaust system is going to swing it to a new neutral point and can have it rubbing in any number of places.

Next place to look for contact is the heat sheild at the 90 degree corner under the passenger seat. Particularly if these's been any work done on the system, like splicing in pipe to replace a burned out Cat, the length could be wrong and when hot (expanded), or cold you can have the pipe contacting the heat shield.

The Riviera model is a longer wheel base, think in terms of a stretched Reatta! In the case of exhaust parts all you'd end up doing is shortening one or both pipes, most likely around where the Cat is mounted.

A blown catylic converter will likely have just spewed out the catylist, and it would most likely just blow out the exhaust. Having loose parts get back to the muffler isn't very likely. Many cats just eventually rot out. The stainless steel from repeated heat cycles just erodes away until it holes thru.

Same can be said for the muffler, stainless lasts a long time but will eventually corrode away.

One other possibility besides the Camaro type muffler (A-M tend to be loud!) is to go to a muffler or aftermarket/ automotive shop and look at their catalogs for "1-in/ 2-out" mufflers of a length similar to what's on your car now. Again, the '91 Reatta has a 2-1/2" diameter system ('88 to '90 were 2-1/4") so you be looking to match the inlet size and then look at the size of the stock tail pipes to size the outlets. It's quite conceivable to salvage the twin tail pipes and have them reinstalled on the new muffler.

Speaking of egos! muffler shop installers can do anything!!! Least that's what they all tell you!

[Barney Eaton]

Greg know his exhaust, also FYI the stock Reatta mufflers (not counting the end pipes) were 22.5 long for the 1988-1990 muffler and 24.5 for the 1991 muffler.

[Ronnie]

My exhaust noise sounds like sheet metal buzzing as I accelerate but I can't seem to locate it. There are so many sheet metal heat shields that the possibilities are endless.

[KDirk]

Greg-

Floor pan vibration crossed my mind, but all hangers are in place, and in good condition. I will give it a thorough test once things warm up here.

Ronnie-

This is kind of what I am getting too. Not really bad, but a little obnoxious with the radio off. I hope that I can track it down, you make it sound like it might be a PITA.

In any case, my determination will whip this problem eventually.

[Roadster90]

I have had a Phantom Bzzzzzz since I bought my coupe in 2002.....was determined for a long time....I still have the Phantom Bzzzzzzzz ....

[Ronnie]

I have tried to find the noise two or three times. I have checked the hangers as suggested earlier and mine seem to be in good condition.

I made a little difference in the noise by clamping the heat shield to the front exhaust manifold with a radiator clamp. I couldn't get my hands to fit well enough between the engine and firewall to clamp the heat shield to the rear manifold.

Another thing that helped some is to put a small crease, in each side of the large sheet metal shield that protects the center console area from the exhaust heat. The crease forms a rib running at a 45 degree angle in order to make it a little more rigid. If you want to try it you can use long nose channel locks (like welders use) clamped to the sheet metal at an angel and then slightly twist by inserting a long screwdriver in the handle of the channel locks to use as a lever. If you wanted to get a little more professional you could remove the shield and use a bead roller like the stock car guys do to make the sheet metal more rigid.

Despite that I still hear buzzing noises when I accelerate that I would like to find and eliminate. If any one finds a better way to stop the noises please let me know.

[Roadster90]

Thanks for the info Ronnie.... I had thought about the possibliity of the misc heat shields causing the noise, but they seemed fine when I checked them (several ... maybe 4 years ago)...doesn't mean they are fine though. My bzzzzzing is intermittant in nature....there is no rhyme or reason much less a pattern to the noise. I will wait to warm weather....and hopefully a rack somewhere to look with your suggestions again....

I would really like a simple drawing of your "crimp" or crimping of the sheet metal if possible?

Thanks,

Nic

[Guest imported_blazer1997]

KDirk

If still have my cell number give me a call. Monday evening at Autozone this guy came over, and started talking about my reatta.

Then he started talking about his reatta he just traded in.

Next question I had was it white, and traded at SamSwope?

Answer was yes. I have his name, and cell number if your interested.

He also spoke of everything he had replaced. Might be of interest to you.

Larry

[Guest Greg Ross]

On a rack, or on your back with the car elevated start by giving the whole system a couple of shakes. If it's contacting the floor pan/ heat shields you should definitely hear it. No luck there, start at one end or the other, which end doesn't matter. using the wooden handle of say a hammer rap on the pipe, muffler, heat shield what ever you have access to and listen for the buzz. One heat shield you likely can't even see easily is on top of the catylic converter. It's been years but as I recall it's part of the cat, not even attached to the body.

Have to work your way along and be patient, you should find it!

If you find the pipe is touching anywhere it may me necessary to renew the hanger donut rings, they get tired and stretch with age. If you still have contact you may have to get more brutal and impose some more serious persuasion. It may be necessary to adjust the shape of the system. eg a 2 X 4 as a lever and bend a bit where necessay. Don't use a hammer, it leaves dents and scars painted panels!

As mentioned, a hose clamp strategically placed around manifold shields can quiet them down if that's what you happen to find. Spot welds can easily have failed after 20 years or the aluminum has corroded around the support stud.

[Ronnie]

Greg, thanks for the tips. I intend to try find all the noises before I give up.

You did remind me that I had to remove the mesh cover on the converter the first time I was looking for the noise. It was loose on the top of the converter. Before I removed it I tried to crimp it on better but I could never get it tight enough that it didn't rattle. Maybe a loose covering on the converter is the source of the noise others are hearing on their car. That would be the first place I would look.

[KDirk]

Ronnie,

Thanks for the additional info. I will look at crimping the heat shield like you described. A sheet metal guy I work with should have the tools to do this up nicely.

Greg-

If I may, I am going to appoint you the resident exhaust expert of the forum! After seeing your custom setup and the advice you have provided you clearly know what you are doing. I will print this thread and keep it handy.

When the weather improves I will go over the thing with a magnifying glass and a stethoscope if I have to. Little things like this buzz just bother me, since there's really no good reason it can't be eliminated.

Nic-

Please update this thread when you have checked yours out, maybe we can all learn something valuable from a collaborative effort on this. I will do the same.

Thanks,

KDirk

[Roadster90]

I will contribute a little something here...not sure how important it is but anyway:

I replaced the two rear exhaust hangers....they definitely made a difference as at the time, when taking off from a stop I was hearing a clunk...pipe was hitting the "framework". Anyway, the local dealer couldn't make up his greedy mind on how much to charge me (I bought one at a time) per hanger....one was 17.00 and the other 19.00. Needless to say, they will never see any more of my money. I investigated several GM vendors on line, and found them as low as 8 or 9.00 + shipping.

There are also generic hangers available at all of the aftermarket jobbers, but they are all smaller in thickness, or height, and are not the same material (some softer and some harder)...not a big deal (maybe around a 1/4 of an inch), but when there is a noise and the idea of bending and twisting the exhaust pipe brackets to help eliminate the noise doesn't excite you, it may matter