Hi Flo Cat installation problem

[John Baird]

I'm putting hi flo cats on my Gen V. Cant get the clamp holding the header collector and the hi flo cat back on right. I have spent hours on this and can't get it back together. I know how it is supposed to work, but can't get it done. Access and vision is nearly impossible. Can't get the two seated in the clamp and tightened up correctly. Help!

[Gen5snake]

Yep...I know what you're talking about. The clamps provided are...well...there's no other way to put it...crap...not usable for this application (at least the ones that came with my high flow cats). The threaded stud is just not long enough.

I reused the factory clamps....if your factory clamps are shot, order some new OEM units.

[SRT BILL]

I recently installed a high flow cat system also and had trouble with the same clamp. Take snake's advise it's good.

[John Baird]

Thanks Snake, I ordered two new clamps. When putting the hi flo cat and the exhaust collector together with the clamp; do you put the clamp on the collector first, then try to fit the cat into it, or visa versa? Do you leave the long bolt on the clamp or take it off and try to put it on later?

[Scott_in_fl]

John, as you've noticed, this is easily going to be one of the more infuriating events of your week. I had one side go on with only about 20 minutes of fiddling, but another side that not only took forever to get on, but took forever to remove (the clamp).

Snake's advice on using the OEM clips is the right way to go. You also need room to work. A lift would be optimal, but I did not have access to one. I mated the pipes, and then rolled the clamp over the flanges with the nut already on the bolt but backed off as far as possible. For this to work, you need to have both pipes aligned perfectly.

If the car is up high, one person could hold the cat aligned in place, while another messes with the clamp. That would also allow you to keep the bolt out of the clamp because you would have two hands to screw the bolt onto the nut once the clamp is seated. But to do all of this yourself is agonizing. Good luck!!

[Gen5snake]

I mated the pipes, and then rolled the clamp over the flanges with the nut already on the bolt but backed off as far as possible. For this to work, you need to have both pipes aligned perfectly.
!

That's exactly what I did. If I remember correctly, I assembled the exhaust first, then hooked up the rear clamp...and that helped alight the flanges up perfectly up front. I think I also put a shim at the 90* part of the pipe up front to help keep the flanges aligned.

I found a pic...I thermal barrier'd the entire exhaust except the cat.

IMG_E2114.jpg

[John Baird]

How do you keep the clamp wide open while you put the two together? It's almost impossible to reach way up in there when everything is in place.

[Steve M]

When I did it many years ago, I got the pipe in place, and then put the clamp over everything...it should pull far enough apart to do that. As long as the clamp isn't tightened down any, you should be able to still make adjustments by smacking it with a rubber mallet as needed.

I also had to use an exhaust pipe expander on one side of mine because it flat out was not going over the flange on the manifold properly. Just expanding it a bit made all the difference.

[Gen5snake]

Look at the clamp on the far right side of my picture, zoom in. The threaded part of the clamp is like a T on one end. I unhooked it at the T end, kept the nut on at the threaded end and spread the clamp over the pipe, then slipped the T portion back into the clamp. This way you're not screwing around trying to get the nut back on and the whole thing falling apart on you again in the process.

All that said, I remember going mental trying to use the clamps with the kit...that nut would barely get on the first thread...while trying to squeeze that clamp tighter to expose more threads...then the whole thing would fall apart. It was a cruel joke.

[Steve M]

I'm surprised they are coming with clamps now...when I did mine, I had to reuse the factory clamp. Which is perfectly reasonable, because they are reusable clamps.

[John Baird]

The hi flo cat tube fits over or into the exhaust collecter tube before you seat the clamp ? I thought they just butted together inside the clamp?

[Steve M]

I'm not describing it well enough, so here's a picture:



The belled out part of the high flow cat should sit flat against the flange from the manifold, which requires that the inner diameter of the tube clears the short part that extends from the exhaust manifold into the high flow cat tube.

One of mine did not clear that short section of the exhaust manifold on my car, so I had to expand the high flow cat tube a bit so it would slip over. The clamp won't fit in place properly unless you can get them to butt up next to each other with no gaps.

[John Baird]

Great illustration! One more question. Do you put the clamp on the exhaust first, then push the cat up to it and try to pull the clamp back over the cat. Or do you put the clamp on the cat first and push it up to the exhaust, then try to push the clamp over the exhaust flange? I've tried both ways.

[Steve M]

I think you could go from either side if you pre-position the clamp with the same probability of being able to get it in place.

What I remember doing (and again, this has been years, so my memory has faded a bit) was putting the cat pipe in place, and then putting the clamp over the entire assembly. That requires that you remove the nut from the v-band clamp so that you can open it up to put it over, and then pull it back together enough so you can get the nut started on the t-bolt. I don't think you can spread the clamp enough with the nut installed to clear everything needed to get it in place. I don't remember this part being particularly hard, but all installs are different. I had a hell of a time getting my side sills off, so my problems started much earlier in the process.

[John Baird]

I made it! I ended up using the clamps that came with the cats. What a job. After you learn all the little tricks of getting around in there it's not to bad.. Thanks to everyone for their help, I never would have made it alone.....John

[Steve M]

You'll forget all the bad stuff in a month or two. Enjoy the extra sound, and less heat!