33 Coupe Paint 9        8/13/05

I've been thinking about how the engine sounds lately and wondered what it might be like with a different set of mufflers. I only have a limited amount of room between the X members where the mufflers are (which is 4 1/2") and would have to buy something that would fit between them, so I started looking at what's out there. What I found were some made by Borla which is what I have now but a different model. The new ones are the XR-1 race versions and are very close in dimension to my current ones. After ordering them and checking them out, there are two things that are going to be a problem. First thing, the new ones have a center inlet and outlet but my old ones have a center inlet and offset outlet. The second thing is the new containers are 1/4" higher or taller than the old ones are.

At this point, I have to make a decision if I want to keep them or not because if I want to send them back for any reason, I won't be able to modify them in anyway so it was time to figure out if they were going to work or not. 

The first thing I did was test fit the mufflers to see if they would fit between the X member and sure enough, it was too tight. If you look below, you'll see the drive shaft hoop mounted on the top surface of the lower X member. That bracket is 1/4" thick so I thought by taking it out, that would give me enough clearance. Even after removing the drive shaft hoop, the mufflers were still to tight. Now I know that I could fix that but it would mean denting the outside of the mufflers to make a small amount of clearance in them. But if I did that, then they would be mine and I wouldn't be able to return them so I had to give that some thought. The next thing I checked was to see if the center outlet was going to be a problem or not. I did manage to install the exhaust system to where it looked like it would work so now the decision is, do I want to modify my drive shaft hoop and dent the mufflers? Well denting the mufflers would be easy but changing the way the drive shaft hoop bolted up is another.
 

 

 

What I decided to do was go ahead and change the way the drive shaft hoop bolted to the chassis so I made some new brackets. I tried to use the old ones but they wouldn't end up being long enough. One big reason for changing this is because if I ever wanted to remove the drive shaft hoop, I would have to also remove my exhaust system from the rear of the car up the this point. Notice where the two flat head cap screws are located on the brackets. As it is now, my mufflers cover these screws and I wouldn't be able to get at them so this would be a good fix. Now mounting these new brackets would mean locating them under the lower X member which is no problem, but how am I going to bolt them up without the head of a bolt or nut being in the way of my mufflers? 
 

 

 

After thinking about it for a while, I came up with this idea. By placing the head of the bolt under the chassis, the nut would have to be on top but that would end up just as bad as before. Now if I located the nut "inside" the lower X member, I would end up with nothing in the way. What I did was make two 3/8-16 X 5/8" diameter X .560 long nuts out of steel so I could weld them to the inside of the X member. I didn't want to weld under the car because that would mean touch-up paint time. 
 

 

 

What I did was open the existing 3/8" diameter bolt holes to 5/8" diameter (the new nut diameter) but only on  the top surface. The way I did that was with my right-angle die grinder and a carbide bit. By placing the die grinder through the top hole only, I slowly worked the hole open to the diameter of the new nuts. The nuts were going to rest on the bottom surface of the tubing and wouldn't be able to pull through. The length I made them were slightly lower than the top surface of the tubing so I could weld them and have the weld end up flush with the top surface of the tubing. 
 

 

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