HMF Exhaust Pipe Melted CV Boot Cover

[Xmarduk]

First off, just want to say I love these pipes. I simply want to get the message out there to precaution those who install these to check for clearance and address the issue before it costs you a CV boot cover or worse---an axle like it did me.

When I initially installed my HMF Performance Series Dual Exhausts on my 2012, I failed to check the clearance between the exhaust pipe and the CV boot covers. The passenger side was A-OK, however, the driver side pipe (not the silencer/muffler) was pressing directly onto the CV boot.

I would imagine it only took one ride for this to melt and expose the bearings. BUT, I was unaware that this even happened until weekend before last when the rear axle began to pop----this being maybe 7-8 rides after the fact. So, needless to say it's ruined more than just the boot, my bearings are trashed from the exposure.

It was quite the pain getting the axle out honestly. Had to remove the exhausts in order to unbolt the rear differential to swing it to one side in order to remove the axle. We didn't know enough about the rear torsion bar in order to know if it was completely unloaded with the wheels hanging down. It might have been easier to slide the trailing arm to one side in order to get the axle out. Maybe someone can chime in.







The fix: After getting the new axle installed we put the HMFs back on to see about getting some clearance from the CV boot. We bored out the bracket mount holes first to allow us to raise up the pipes about a quarter inch but raising the rear of the silencer didn't do much for the clearance of the pipe and the CV boot.

We noticed the most gain of clearance between the two by pressing DOWN on the rear of silencer itself when the bolts were just only inserted into the frame---not tightened down. So, to get more play, we removed the rear bolt in the top of the frame mount. The remaining bolt served as a pivot point. One man pressed down hard, the other rear top frame bolt into place and tightened it down and then tightened the other bolt serving as the pivot point. It worked.

This gives enough space to wrap the pipe without worry of the CV boot touching or eventually wearing a hole in itself or the wrap and the problem starting all over again.

[miller48]

WOW that is still very close and may get the rubber very soft?

[XTCntn]

Sorry to hear of you troubles, X
I can't see where you're going to be able to sit at idle for very long on that boot or run for an extended period of time with the exhaust that close. That rubber and grease is gonna heat up fast and when it does, it's going to be like chewing gum. Even though the shaft is turning, it still don't have much time to do any cooling with such a small diameter of surface that is rotating. And, that boot changes in relative distance away from the exhaust when that trailing arm travels up and down.
Just My .02

[SANDSTAN]

I would think X with both exhausts that close also to the rear diff, you could have issues there after along hard ride... I would keep an eye on that rear diff oil also besides the cv's and boots, good luck...

[Xmarduk]

So, you all think even with the exhaust wrap on there it'll still cause extreme heat problems? I'm thinking of rolling the pipe----or rather beating the pipe so that it forms an arc right above the boot so it has some additional clearance. Thoughts?

[Xmarduk]

Bump for thoughts on heat wrap?

[XTCntn]

The heat wrap helps a whole lot, but when you "mud up" the pipes, the "cured mud" from the heat is going to be an abrasive right next to the boot. I didn't realize just how close the pipes would be on the exhaust that runs through the lower bed box. I'm probably wrong (as usual) but I wouldn't like it that close and have to constantly watch and worry about it.

Do you have a fuel ratio controller or know for sure that it's not running a bit lean? Not that it's going to make a major difference, but the pipes will be hotter, if not running the correct air/fuel ration, even that far back from the header pipe.

[Rod]

I would make the pipe and take it off and cut away about 1/4th of the bottom of the pipe closest to the CV about 4 inches long and weld in a piece of flat in the void to get more clearence. Then wrap the pipe, yes this may create a little more back pressure but I doubt you would ever be able to "feel" any performace change.

[jhquad]

You might want to contact HMF and see if they will help you out or have any suggestions. If they get or may have been getting enough complaints maybe they will redesign the pipe or come out with a heat shield that will better protect the CV boot. Doesn't hurt to try anyways, there are still some companies that care about their customers & their product.