Exhaust Mounting Tabs Breaking

D

Dockmaster

Well-known member
Joined
May 5, 2021
Messages
832
Reaction score
679
My little Revo is breaking the tabs that bolt the exhaust to the frame. In the picture you can see the exhaust system. On the frame side of each muffler there are two tabs on each muffler and corresponding tabs welded to the frame. These are bolted with 1/4" bolts. Three out of the four tabs (2 on one side, 1 on the other) have broken off where they weld to the frame. I'll be welding the tabs back to the frame but wondering if they are breaking from thermal expansion of the exhaust system or just poor welds? I don't currently have a picture of the welds but will get one tonight. I was wondering if looking at the exhaust system alone if thermal expansion would be a problem and potentially breaking the mounting tabs? I would think the two bends in the exhaust pipe would be enough to give some flex but maybe not? Do I need to do something to allow for thermal growth or would you just weld the tabs back on? I'm inclined to just weld them back on and see if they hold. I'll probably tig weld them. 

Revo.jpg

 
Kraut_n_Rice said:
Are you sure the engine isn't moving?
Click to expand...
Don't think so. No sign of problems on engine or trans mounts. And I just had the trans out and back in so I had my hands on all those mounts and hardware. 

 
Closer pics and type of material would help.

generally i despise tabs, especially on stainless exhaust. Stainless has alot of built in energy and that gets released as it warms (thermal expansion). That energy needs somewhere to go, or it will rip itself apart.

stainless systems need slip joints, balls or bellows to assure no cracking. Hard mounting tabs will always break. They need rubber isolated mounts. Or better yet unwelded ring support clamps

 
Last edited by a moderator:
What about the engine mounts? Are they solid mounted or are there bushings? 🤔 I remember reading about engine flex at the mounts cause issues on solid mounts of any kind. 

 
Here are examples of a stainless system i did last week. The only support is a turbo support bracket; which mounts with rubber isolaters which absorb vibration. Every segment has slips to give energy somewhere to go

FFE7508C-3C2C-409F-AE72-C545E9E44658.jpeg

4F90A102-2A63-477A-9A05-FEE067439694.jpeg

50D4667F-3125-4999-8F61-7861734E95A8.jpeg

 
I thought about making some tabs with slots to allow more movement. But the clamp shown by @Sausage450r in that picture looks like a better option! I would prefer to not have to hack up the exhaust to add slip joints as I recently had the ceramic redone and that's not inexpensive to do. What is a good source for those clamp rings? Really appreciate the input here!

 
you would be surprised how much the rear part of the car moves independent of the engine.  it was super clear how much it was moving when I video taped the movement back there. 

these witness marks on my trunk are from the old engine covers Ive had on it over the years.  the large square one, was 3/8" away from the trunk & it still rubbed.  I ended up going 3/4" away from the trunk & putting a rubber grommet on it to make it less ugly.   I could not find a picture with the grommet material....

One of the guys in our group had the same problem.  he used hose clamps, but left them "lose" so it would simply limit how much the exhaust could move downward. 

image.png

image.png

 
Cookie said:
I always mount exhaust to the engine, never the frame. Far too much flex.
Click to expand...
It is mounted to the engine. The headers are the main mount and take all the weight. It is a mid-engine car so the exhaust is little longer and just needs some support near the end. 

 
how about to the trans?  I would think that would move less than the frame..

 
richard h said:
This is how I did mine. Mounted solid on motor and supported from the trans. Mid-engine and no issues.  
Click to expand...
I did the same on my mid-engine SU Sand Pro 2 and it worked great. 

 
Any of you who supported it from the trans have photos? Maybe your cars and exhaust were configured differently? The way my exhaust routes puts it pretty far from the trans. I'm having a hard time visualizing how this would work without some long bracket coming off my trans. 

 
You must log in or register to reply here.
Back
Top