Just noticed this: http://www.nasaproracing.com/rules/time_trial_rules.pdf

After installing a 3" downpipe I found that one of the two horizontal sub-frame braces wouldn't fit anymore so I had to upgrade to a brace that had a kink in it to accommodate the larger downpipe. This seems like a common problem with most downpipes, but I'd hate to have to take a +3 penalty for a brace that will offer little benefit.

Anyone else have this problem? What downpipes work with the factory braces?

 

I went through several braces, but found that the factory ones simply heated up and bent a notch around a vice works best and 0 points. Cheaper then trying to change downpipes and doable at home. Any shop should be able to help otherwise with it. But I also wrapped my downpipe (helps with oil temps a LOT) which added even more thickness, most "notched" braces weren't really worth the $ then for any performance gains.

 

I ground off about half the thickness on one of those cross members at Shenandoah where the entrance to a carousel had a steep angle (http://farm5.static.flickr.com/4063/...cb0e1a7397.jpg). So when the downpipe got in the way I ditched the OEM ones and took the chance to get a aftermarket brace. Now I gotta go looking for OEM bars again

 

Spacers...

 

Nice. Simple. I like it!

 

Spacers work well. I was able to use them on the eBay downpipe but just couldn't make it work after changing to a dump tube.

Honestly though, just throw the brace out. Here is my reasoning for this:

That boxed frame member has got to be super strong as it is (scientific, I know). And the moment arm from suspension movement isn't very high down that low.

Bolt bending is also increased significantly by adding spacers therefore reducing the load transfer abilities of the brace. And the spacers move the brace lower making it more susceptible to hitting stuff (this happened to me several times).

The holes through the brace are very sloppy. It would have to move significantly to transfer bearing loads into the bolt. And since the bolt is fully threaded (no smooth shank), it can't handle much load before galling the threads or digging into the brace.
Note: This analysis does not account for clamp-up forces applied by tightening the bolt. This will help, but the majority of the load needs to be bearing into the bolt.

And an added weight savings is accomplished by losing the brace.


Now, I'm sure the Mitsu Engineers added these braces for a reason, but I'm having a hard time figuring it out. I would really like/need to see some load analysis of the sub frame to figure it out.

 

i have a dp that works megan

 

Well, to add some scientific information to the discussion on the effectiveness of the brace, I'll see if I can do a session without it and compare the times/handling.