Exhaust Collector Stud Orientation

[nobbyv]

This is a really basic question, but I want to be sure to get this right the first time:

My '97 2.3L needs a new exhaust. I bought a shiny new Dynomax cat-back system and a Walker downpipe/cat. I pulled the rusted old system off last weekend, so am almost ready to go. However, the bolts that were holding the downpipe flange to the collector/header flange were very rusted (surprise!) and one broke while I was removing it.

I understand originally there were studs here, not bolts. I went to the local parts place and measured the existing bolt on their gauge and got what I believe are the correct replacement studs: Dorman/HELP 03129 exhaust flange studs, which are M12-1.75 in 62mm length.

I just want to be sure I have them oriented corrected when I go to install them, since I don't have the old ones to go by. So there are two parts to the stud, a short threaded part and a long threaded part, separated by an integral washer-type thing. I *think* what I want to do is thread the long threaded part of the bolt through the top side of the collector flange, bottoming them out on the integral washer thing. Then, slide the downpipe flange onto the remaining exposed part of the long threaded side, and use the nuts to hold it on (obviously, installing the correct donut gasket between the collector and downpipe flanges).

Is this correct? If so, why is the shorter part of the stud even threaded? Is that so I can get a nut on there temporarily to help bottom it out on the collector flange? Or do I have the studs completely backwards?

 

[RonD]

The short part with threads goes in from the bottom, the shoulder is there so it tightens to the collector.
The longer threads are what the exhaust pipe plate goes on and nuts to tighten it down.

At the end of the long threads is a fitting for tightening the stud to the collector, I just use a double nut instead

 

[nobbyv]

Thanks Ron, just found this pic (which is actually a 3.0L from a Windstar, but close enough), and of course you're right: the short part gets threaded through the bottom of the collector flange to the shoulder.

Thanks!