Tubular subframe benefits

[Indy Lonnie]

Went auto crossing a 2 weeks ago - found the limits of the rear suspension and the unpredictable feeling of lift oversteer. Got me thinking…

What are the benefits of the DF tubular subframe vs the stock setup? I need specifics like this thread for $3000.
https://www.dfkitcar.com/forum/index.php?threads/stock-rear-suspension-geometry.4205/

I let a national champion auto crosser take my car for a few runs. The first run, his first time in the car he set the third fastest lap time of the day. His second run he spun and said it gave him zero warning.

If the new tubular setup could help, I need to justify the cost.

 

[Desert Sasqwatch]

There are several suspension simulators available, some free, that can give you much of what you may be looking for. You just need to make accurate measurements of the dimensions the program requires to get usable values to help set up your suspension. VSUSP is a good one to use, if you don't have a purchased program.

Vehicle Suspension: Front View Online Suspension Simulator

VSusp (vehicle suspension): Front View Suspension Geometry Calculator/Simulator

www.vsusp.com

@Sebnuts did the work for the donor suspension values - know that the values he provided may vary slightly with differences in the strut used (donor vs. BC), set up ride height, etc. Every suspension setup will be slightly different. The biggest issue with the donor rear suspension is the pro-squat (anti-dive when it was a front suspension). The DF tube subframe reduces this to at least a slight anti-squat tendency. This itself is a big advantage over the donor suspension. Plus it weighs significantly less and definitely looks better than the Cobalt pieces. If you're looking for performance enhancement, just write the check and appreciate the time and test @Lonny put into developing this alternative.

@Sebnuts chose to design and fabricate his own custom rear subframe and suspension. Likewise, I'm doing the same, since struts have geometry limitations and require more compromises than designing and building a UCA/LCA suspension system. For all out racing performance, this is the best option. Oh, and changes to the front suspension geometry to incorporate anti-dive is also a significant benefit and has more effect in the handling of the car at turn entry. @Sebnuts did this - see in his posts - and I have this described in my build log too.

 

[Desert Sasqwatch]

Lonnie, if there are questions about the tube subframe under racing conditions, you may want to send @Justinreed7 an IM to see if can respond. He has the best insight to how much different the tube subframe and suspension performs versus the donor items.

 

[SmsDetroit]

I went from my first season with the stock subframe to the tubular subframe this year. It does make a big difference with bump steer and rear grip. It does not however get rid of the snap oversteer. I feel like i can drift it a bit more and control it but just a bit to far and around you go. Would i buy it again. Absolutely. There is no rear end wiggle on hard acceleration Either.

 

[Rttoys]

The biggest benefit is the rear bump steer like SmsDetriot said. Stock setup, the rear toe moves when the suspension moves. The new subframe eliminates that. Plus the solid control arms eliminate all other movement. There’s a noticeable difference in a race/autocross situation. I bought mine for this and to expand my options on the rear suspension, but I haven’t made much progress there. You will lose the rear sway bar but I without a front sway bar, that’s not a big deal. The other benefits out shine the sway bar. There are alternatives though.