Dougs951S

I'm torn between going 28mm or 29mm for a mostly street driven car with that has 300# front coil-overs. I searched and read lots of info but I'm just looking for some new opinions.

300*.91 = 273# front effective
combined with 254# 28mm T bars =1.075:1 front/rear effective ratio

for reference, stock front/rear ratio is 1.08:1.
with 29mm bars the ratio becomes .93:1 which seems like it would oversteer.

LS1Porch

I have the 28mm rears with 300# springs. I also have 968 M030 sways and Koni yellows. It's a very nice ride for the street and feels very balanced on the track. The back end still dips a lot with acceleration, but i suspect that's a problem even with slightly higher rates.

Dougs951S

yes I suspect due to the geometry of the rear end that power squat remains an issue until you get into very stiff track car territory. I am running stock sways but if I feel I need more rear spring I will be adding the 5 way adjustable 968m030 sway with the stock turbo front. Just pulled the trigger on a pair of chromoly 28's. Thanks

86 951 Driver

How bad is it to change out the torsion bars? I have heard it is a huge pain in the butt.

Dougs951S

Eh, thats all relative. A big part too is if you are doing it with hand tools in a driveway vs air tools on a lift. In order to change them, you have to drop the whole rear suspension which can be a pain. You will likely end up having to drop it more than once because ride height in the rear is controlled by the clock position of the splined T bars and if you dont get the clock position right, you need to pull it apart, rotate them, and try again. You wont know if you got it right until you bolt it all back together and lower then car down onto the wheels. You also need to make sure you get both sides riding evenly. So you can see how it can end up taking all day, a lot of beer, and plenty of expletives. That being said, it isnt as bad as say, a clutch job. It is however pretty high up on my list of things I only want to do once.

car_slave

I run 275 front springs with rear 28mm bars on my 968 DE car. Sways are m030 front and 22mm Welt in the back. Car is VERY neutral. I've also run 250 front with 28 rear and full m030 bars. That setup had some understeer. So, you can run 300 with 29 rear bar and then adjust with rake and sway bars. If it's a street car I would keep it mild because you'll be driving in the rain. FYI - this is with stock wheel stagger.

Hope this helps.