306 Torsion Bar Setting

[stumpyjag 6]

hi all. 
 

I recently rebuilt the rear beam on my 306 DTurbo and set the distance between to shock centres at 330mm. This setting has left the car very low at the back compared to when I started. I know I can change the distance and raise the car but I hate doing things when I don’t understand the reason why. Does anyone know if the 330mm setting is a bit low and if so what would a more normal setting be. Many thanks for any assistance. 

[welshpug 1,621]

330 is standard height for the 20mm torsion bars that the sport  chassis setup uses, this is the gti6, s16, xsi, and the late DTurbo HDI.

 

the smaller torsion bars used were 19.3mm, I'm not sure what you would use to set these.

 

145mm from ground to jacking point front and rear is the dimension listed in Autodata for all 306's, not sure how accurate this is!

[jord294 87]

You very sure you set to 330? I tend to set around 328mm as a std setting

[stumpyjag 6]

Thanks for the advice. Well I hope I’ve don’t the right thing. I’ve raised it by one spline which gives me a dimension of about 342/343mm instead of the 330mm. I can’t make any sense of the 145 mm from ground to jacking point at all, everything I measure is over 200mm from the ground?? I have measured from the top of wheel arch to the top of the  wheel rim and the back is now about 10mm higher than the front, and that’s on a completely empty fuel tank. If my wife sits on the edge of the boot (won’t say her weight but she’s not that heavy)  the dimensions are identical back to front. Still not completely happy but it is better than before as with two people in the back it was on the bump stops and after all I have only gone one spline up so not much else I can do. Any further thoughts appreciated. 

[welshpug 1,621]

never do it by 'splines'   that is where you're going wrong!

 

pull the torsion bar out, set the distance you want, then refit the torsion bar, you will have to rotate the bar till you find the pair that slide in easily,  one end of the bar will engage 5mm or so before the other. 

 

 

changing from 330 to 342 will increase the ride height by 30mm.

[welshpug 1,621]

also never use the bodywork as the rear arches are lower than the front.

 

I highly doubt your jacking points are 8" off the ground, these are on the sills btw.

[stumpyjag 6]

Thanks for the reply. Everything you say makes perfect sense, thanks. I will double check the dimension from the sill to the ground again tomorrow but I’m sure it was much more than 145mm on the front which is standard set up. Thanks again. 

[stumpyjag 6]

One other thing do you think I should be checking front to back heights with a full tank?

[stumpyjag 6]

I think probably as you expected 342mm ended up looking a bit high so I have arrived at a final dimension of 335mm which looks and measures about the same as the front. Thanks for all the advice it was very much appreciated.