87 GT V6: Exhaust donut and pipe flare questions (Page 1/1)
Signupacct APR 10, 01:51 PM
I did review some of the archived discussion threads related to the flexible exhaust joint, however not sure that they produced the information I was searching to find

First someone else in a thread discussion mentioned the lack of flaring on the end of their pipe. He was going to make a reverse flare and the forum members waived him off that idea and suggested he go to a muffler shop to see if the flare could be restored.

I have a similar issue in that my pipe also does not have adequate flaring to make an effective seal against the donut. I will either go to a muffler shop and see if they can increase the flare shape or order the cat delete pipe from the fiero store.

my question since the pipe on the car looks oem and not altered or tampered with is the lack of flare at this point the result of constant shifting around on the graphite donut or did previous owner alter the pipe in away that is not noticeable. If it is wear than should I expect this wear to occur in the future?

Second question: on my crossover or as I refer to it as a y pipe, there are two nuts that are square and are welded to the exiting side of the pipe. in the process of removing the spring bolts one of the welds broke and the nut began to spin freely. Eventually I got cut the bolt with sawsall. Would it be okay to put a nut back on with a lock washer rather than reweld a new one in its place. The fiero store rep said they welded those on for ease of installation and no other reason. My engineering sense is that nylox would not stand the heat, and a lock washer might not be strong enough for the vibration. and will be a constant maintenance item to check the tightness of that spring bolt.

Suggestions and feedback are welcome

and third question relates to the donut. I ordered a donut from the fiero store and also from autozone and both appear identical in that both come with a metal sleeve. The fiero store rep said that earlier models are to use it with the sleeve and the later models not. without the sleeve it fits loosely on the y pipe and with the sleeve it has to be pressed on as there is about a 1 and 1/2 mm difference. The fiero store rep said it should collapse and seal without the sleeve and with the sleeve it should not take up any additional space between the joint and cause issues with getting the spring bolts into the correct place.

Feedback is welcomed

[This message has been edited by Signupacct (edited 04-10-2023).]

sleek fiero APR 10, 02:47 PM
Hi Don't use a lockwasher. instead use swedge nut which will not vibrate loose. they are only designed to use once or twice so keep a few spares for future use. My 85 does not use any doughnut on the joints just metal flair on metal taper. sleek
My system is totally aftermarket system so is probably totally different than yours.

[This message has been edited by sleek fiero (edited 04-10-2023).]

Signupacct APR 10, 10:00 PM


has anyone used flexible pipe in place of the the spring bolts and donut ?

this is the 4" length one but they have different lengths also

see attached pic
Signupacct APR 10, 10:05 PM
is this what you are referring to ?

[This message has been edited by Signupacct (edited 04-10-2023).]

sleek fiero APR 10, 10:24 PM
No swedge nuts have dimples forced into the sides of the m that cause an interference fit to the bolt threads. Your rocker arm nuts are swedge nuts.
Signupacct APR 11, 01:12 PM


now that you have used swedge a second time I know it is not a mispell or auto spelling correction error

not finding in a google search

perhaps you can send a link to a supplier


thanks in advance

Joe k
sleek fiero APR 11, 04:36 PM
Hi Joe; different manufactures' use different terminology but it's an all metal locknut. when they forge the nut they swedge dimples in to it to create a slight interference on the threads to stop the nut from working loose.

[This message has been edited by sleek fiero (edited 04-11-2023).]