Exhaust support?

[beeman]

Is anyone aware of a good option to support mufflers like in this picture I attached? Kind of like the FFR Kooks mount but weld-on instead of clamp-on. Basically a vertical rod (red) into a bushing (blue). Thanks!
Dave

[David Ferguson]

How about if you used traditional rubber exhaust hangers. You just need to make the welded on rod for the chassis positioned above the welded on rod from the muffler . That would provide the support needed for the weight, but allow the movement needed for heat expansion.

[beeman]

How about if you used traditional rubber exhaust hangers. You just need to make the welded on rod for the chassis positioned above the welded on rod from the muffler . That would provide the support needed for the weight, but allow the movement needed for heat expansion.

Not a bad idea, I just want to keep it as subtle as possible...

[cob427sc]

You definitely need some sort of rubber isolater as the exhaust is going to move differently than the chassis. Might be better if you support the mufflers off of the transaxle somehow rather than using the frame. I can't remeber on my early GTM build but as best I can remember and looking at photos the Kooks didn't have any rear support.

[beeman]

How much movement would I expect at that location?

[VRaptor SpeedWorks, LLC]

Yes, you will definitely want to mount them to the transaxle so that the exhaust can move with the engine/trans. Movement will depend of what you're using for motor mounts. If you're using the OEM donor motor mounts, there's quite a bit of movement at the exhaust tips. I normally leave 5/8" clearance all the way around the exhaust tips to the "trim"...whether that be exhaust trim panels I designed or the FFR perforated mesh.

You won't need any rubber hangers as long as you mount to the transaxle since everything can move together as a unit. Maybe you can copy some ideas from this?

https://vraptorspeedworks.com/mendeo...ting-brackets/

[crash]

I just built two new exhaust systems using expansion joints and solid metal supports. You still need to allow for things to move a bit, and I would never put rubber on an exhaust system. I know that a lot of OEMs do, but my exhaust gets a lot hotter than most OEM setups. I use expansion joints, exhaust springs, and all stainless steel hose clamps to help position the exhaust while letting it still move around just a bit. You can see three different versions here that have been on the FFR PDG GTM race car over the years. #1 is the most recent design where the sway bar has been relocated above the exhaust. No real good pictures of where the system sits on the support at the rear, but I will see if I can get a better shot of that this afternoon.

[crash]

Here is a pic of my rear mount. Nothing fancy, but has done the job well. The mount that you see below this one that is welded to the frame is used when we have sound restrictions and have to run an exhaust system with a muffler, which ends up sitting right on the rear framework. That is why this open exhaust system mount is bolted in and removable. Because the muffler is entirely stainless steel and packed with stainless steel "scrubble" it doesn't even get hot enough to discolor the paint on the frame even though it is sitting right on it.

[beeman]

Thanks for the input. Maybe instead of mounting it to the gearbox subframe, I'd be better off mounting it to the g96 gearbox itself. This would be a solid mount without bushings, or would bushings protect the gearbox aluminum better? I can't imagine drilling a pair of holes in this flange on the gearbox rear support would compromise the integrity of it?

20240627_160607.jpg

[crash]

I see a steel support mount there for your gear box. I think I would probably make a small bracket that is bolted to that and supports the exhaust. Gravity is your friend, so if you can build something where the exhaust naturally wants to sit in the mount and stay aligned, that is best...but you still need to allow for some movement due to heat expansion.

I have modified Porsche gearbox housings previously and regretted it. I think I would stay away from drilling holes in the transaxle case if at all possible.

I will say that with the transaxle rubber mounted, if Shane has an option that uses the transaxle for support and doesn't require case modifications, I think I would probably go with that,

[VRaptor SpeedWorks, LLC]

The brackets I have available are to support the Kooks mufflers in their original configuration......to either a G50, G96-50 or Mendy. Since your transaxle is different and your exhaust layout is different, none of my brackets will help you. If there are no other bosses or threaded holes to mount to, maybe you could sandwich something in where the shift cable bracket attaches to the trans?