mikey_audiogeek

Hi Patrick, makes sense. Looking forward to 2015!

When do we get to see a match race against TonyG on the same track?

JustinL

Here's the one I've got for sale. $400+shipping, which is about half of what I paid for it. I offer no warranty what so ever (obviously) on this piece. It was never installed, just unpackaged. I'd recommend following some of the suggestions in this thread to beef it up.

I can't use this piece anyway with new rules in my race region that requires factory suspension subframe. It is the factory height roll center model that Bruce made.

67King

A little speculation and a little calculation......

Speculation. The banana arm is a lever. The sping is the fulcrum. Yes it transmits some force to the torsion bar pivot, but some will be transmitted to the torsion tube. I think Van's geometry was right, but I don't think it requires bumps. Just weight transfer will change the force on the tube. I think just travel is what causes the failure, and I'd speculate that the stiffer the springs, the worse it will be.

Calculation. Caveat, its been 20 years since I looked at this stuff, so I had to keep it simple, and not look at a four point bend calculation. Just a quick check of section modulus in bending. I'm not sure what the diameter of the stock torsion tube is, it is at least 3.5", but my caliper jaws aren't deep enough, so it may be greater. Don't know what wall thickness is, either. If I assume each has a 0.125" thickness, the round tube as more than 10% higher modulus than the 2X3, and well over twice the modulus of the 2X2. As modulus of a round tube is a function of r^4, but only t^3 of the square one, increasing the thickness will benefit the round tube more than the square tube. Source for calculations, http://en.wikipedia.org/wiki/Section_modulus.

I absolutely applaud Bruce for doing this. And if it were legal in SP3 I might be inclined to buy one, and make some changes. It really is a nice job. Very creative. It just stinks that it didn't work, and moreso it stinks that so many (both Bruce and his customers) have lost money on this. Unfortunate that a guy who is such an asset had this happen. Again, I really applaud the effort.

Max Energy

Bruce,
I am glad you are healthy again. If you would like to upgrade one of the T-Bar's I have one that has not been installed. The one that is in the car broke two weeks ago at the pivot point.
I am in Houston at least twice a month, let me know if you would like to get together.
Merry Christmas,
Max
maxenergy@***.net
225 573-0664

95ONE

I just sent you a text Max. Text back anytime.

Thank you Mr. 67King, but it's hard to think about any praise for anything right now.

67King

Show me someone who hasn't failed at anything, and I'll show you someone who hasn't succeeded at anything.

You might be able to make them work by making the side walls thicker. If you can package it, a round tube might work. The pivot point in place of the spring plate is the magic part of this thing, IMHO. I really hope you don't give up on this.

Max Energy

Great Quote!!!
Merry Christmas to All
Max

dand86951

++++++20

But saying the above never makes us feel any better when we do try and fail. All we can do then is learn from it and move forward. Glad your health is back.

vwmann1

95ONE.....I recently bumped your thread looking for more info on where I can get one or borrow one just to measure. can you please contact me so we can discuss the possibility of working something out?
cell: 773 841 0590
shop: 773 275 4832
email: Zach@vfc-motorsport.com

Thanks,
Zach

333pg333

Just poking around the car today and pulled the X member off. Here's a couple more pics showing a crack in the sheet metal itself and referencing the bend via comparison to the benchtop. We are possibly going to build something ourselves down here that will stand the extra G loadings that some of our cars are putting through these parts. If anyone is interested we could put together a group buy and ship them across. On a boat with a few people splitting costs should keep the price down a bit. Anyway, let me know.

Not trying to tread on your toes Bruce. I think perhaps we were all caught out by the stresses going through this part of the car. Especially with over 2 g's on longer corners.

Dutch944

Wauw.. There has been a huge amount of force on that Tbar!

95ONE

Wow. You were pulling some severe G loads. Man that is one wicked G loading car. Even still, using a thicker main bar would have prevented that. (hairline crack in the first pick above) Lesson learned. Clearly there are some crazy loads on your car and your bars have been through a lot of stress. The bend is from a completely different way than the others I saw though. I had my engineer buddy look at the pics and run his best guess FEA and it was the aluminum swing arm pivoting on the shocks and "pulling" the bar down most likely from curbing or hitting strong elevation changes. which I would consider a typical road race scenario. Very very interesting to see though. I've cut those "hooks" off of my torque tube a long time ago, but I had no idea how much those moved. But now that I think about how much the trans moves and breaks the CV axle from extreme angles, I'm thinking it makes sense now. Hrmmmm. I think simply removing the hooks might cure that issue. But alllll the other isssues.. ugh.

I've redesigned the bar for Eric, who, AMAZINGLY had his bar hold up until last season when he crashed into something and bent a bunch of stuff.I completely started from scratch (although it looks almost exactly the same) and designed his new bar to have a much beefier main bar. Huge spherical pivot bolts with fine thread (will not let go) I'm adding support tabs that everyone discussed, but Eric will have to Drill the holes to match his specific car. (best compromise) And a much more refined design on suspension geometry that will prettty much be impossible to tell the new bars from the old one, but still improved. Some had alignment issues and this should completely fix that.

I'm building and getting one to Weston Dallas Locally so he can beat the crap out of it. I'm going to ask him to TRY and Kill it. Hes such an amazing driver and all around nice guy, and he's always wanted one so now is the time to hopefully give him his wish. (since I had to redesign one for Eric, why not him) I wish I would have done this from the beginning. Hindsight and all.

I'm not really "back" and it made me sick to read this whole thread again. But Eric needed a replacement and I really really want him to succeed. To everyone who still had positive things to say so long ago in the past, thank you. For those that lost confidence and money and time. I have no words that can fix that, but I am much much better physically and can cartainly fix your bars for you much much faster now. Please send them to me and I will reinforce them everyway I can within 2 weeks. I understand that they're probably trashed by now, (4 years later) but if for some reason you still have one. Please pm me and I will forward you to my emai for quick and instant discussions.

rlm328

Where have you been, missed our discussions. Did you get your car finished? Last time I saw the car, it was being prepped for paint.

333pg333

Bruce, it's great that you're trying to make good on these. I think we were caught out on how much stress it would be under. It's hard to say exactly what was the reason for this particular failure. On that weekend we had a number of things go wrong. It's impossible to say what was symptom, what was cause. We went out on brand new tyres. I had had them skimmed and purportedly heat cycled but we found out very quickly that something was wrong. Paul did an oulap and came back in thinking the wheels hadn't been tightened. Turned out that the tyres were either so out of balance or just not round. We continued briefly before I think an axle or CV failed. (2014 so forgive memory). Then parts of the engine sheared apart and self destructed. The whole car was attacked by vibrations and harmonics so really hard to say what did the damage to the rear bar???

Eric_k

I got 3+ seasons of racing on the bar and never had any issues with its integrity. But, in October I hit a wall after spinning in the rain. That definitely bent it and a lot of other stuff. I didn't take it easy on it either, with 1200# springs, wing and decent power (although not compared to Patrick). Thanks to Bruce for stepping up to make me a new and improved one.