I upgraded to bilsteins and H&R springs a while back and I have noticed something that I am beginning to move from the imagination category to theory.

Is the stiffer suspension going to be more particular when it comes to tire pressure? In other words, is it going to react more abruptly to changes in tire pressure than the stock suspension would?

Forgive my ignorance with this sort of thing.

 

Heirsh,

I'm not running my 964 on the track so I will only answer for street driving. The new springs and shocks did improve my car's handling but its never been "abrut". I am running the stock tire pressures on Cup-1 17" wheels (36 psi cold).

 

It will definitely work this way. The more compliance you remove from the system, the more effect adjustments will have such as tire pressure. If you have total slop, you can have things way out of adjustment and you'd never know the difference!

 

A stiffer suspension means less suspension travel. Less travel means less change in toe and camber due to geometry changes over the amount traveled and less change to the contact patch. It will feel different. It may affect how much heat you get into your tires, but I really don't think that it will make the car a lot more sensitive if you know what pressures work best.

I've been making pretty big changes in my suspension but I don't note any difference in tire pressure sensitivity. (I still have to be 25-27 lbs or I'll have "issues") I have been running the JIC-Cross mid level suspension. Due to problems with tire wear and getting the alignment dialed in I recently eliminated all the rubber bits from the rear (went full mono-ball and Heim joints). The rear sticks better but we think the camber changes due to suspension travel (and the cars weight) continue to cause excessive wear. It's back in the shop now to check the camber and toe change over the travel range and, if the hypothesis is correct, we'll go to more firm springs. At the same time I'm going to EVO uprights with a bump-steer kit and mono-***** up front to eliminate the play and get rid of the bump steer from the car being so low.

 

Thanks for the responses guys. I just drive it on the street, but I tackle corners fairly aggresively regularly. With the stock suspension i didnt notice the tires being off about 2-3 lbs each. Now, at least so far, I have. Ive got 1 tire that bleeds down faster than the rest. I didnt notice it on the stock suspension till it was high 20s psi, now I notice at 34.

Probably just the more sensitive suspension. Gonna take some time to get used to it I guess.

 

Sorry for the hijack...

Turtle's new Avatar is better - somehow nicely more menacing that the other pic. T8 TH?

 

I also installed Bilstein damper and H & R sport spring last month, I had my Porsche lower also. I found that 36 just too hard and lower the tyre pressure to 33 for street driving. I used to have 36/38 for my stock suspension.

Eddy

 

Hi Tom, I'm running the same suspension as you are with full monoballs and JRZ triples. I've not had any issues with excessive tire wear. FWIW, I'm running 600lbs front springs and 700lbs rear springs. What tires and alignment settings are you using.