Posting my reply to a TBar question for general discussion
Originally Posted by rogtsaamokin
Mark, I read your tbar thread about just touching the graphite and then coming up 1/8th so it just flops , how then do they adjust there tweak???
Thanks Roger T
Arh well.. interesting isnt it?
Well the bottom line is that they dont. Mick Farrell and Andy Griffiths are the two top drivers running in our nationals and I know for a fact that Mick does NOT tweak out his car.
This is also in line with looking at Frank Calandra's CRC ar the worlds. He runs the side springs quite a way off touch down... so also no way to tweak it out using the springs.
The idea is that losening off the rear tbar screws by 1/8th turn (or link car springs) will allow the car to be more stable over small bumps and the general changes in the carpet.
If you use my method in www.12thrc.com
to set up the front end, checking front axle height and spring preload, the main chassis will be level when the car is loaded up. If you set the t bar screws so that by eye the rear pod is level to the main chassis (take the motor out to do this the first time). Then it will all be spot on.
I dont use the coins anymore anyway. Like I have said my "the coin trick is not enough" comment, the coins tell you nothing about how the car is sitting on the springs. I am convinced many people have no idea what they are actually measuring when the coins drop.....
I am finding that keeping close tabs on any differences in ride height left to right is the best way of spotting "tweaks" in your setup.
If you allow the rear end to "just" float around the T bar then the attitude of the chassis is only a function of the front suspension and shimming of the king pins. This all assumes your chassis is not bent!
When I have done more work with the T bar car I will write all of this up on the blog.
Hope this helps.