New tires Vs. chassis ridgidity

[7391417]

I'm posting this in following to my last post on 205/50/15 tires. With the rapid expansion of tire technology lately I am concerned about the stress that todays High Perf. tires will exert on our 914's. My car is a solid, no structural corrosion 73. I have measured chassis flex with the roof off and a yard stick between the top of the window frame and the rollbar, and then jacking the car up and down in different locations. The amount of flex I get is about 1/16 - 1/8 of an in. at the extremes. Even though that is good, this car was still designed in '73 and todays cars are much stiffer. When I get my car repainted in the next couple of months I am going to have the Brad Mayeur chassis stiffining kit, GT stiffining and trailing arm stiffining kits all installed (I don't want a roll cage because of the space it takes up.) Please express your opinions on this subject.

[Dave at Pelican Parts]

I personally think it's a bit of overkill for a street car. I might think about the GT kit, just from reading about Don Haney's experience with his car.

He's doing a Six (nearly-GT) conversion, and so he added the GT stiffening kit. When the shop took the undercoating off so that they could add the kit, they found that the chassis was already cracking. And his car had a stock or mildly-pumped 2.0 in it, and as I recall a pretty reasonable street suspension.

The Brad Mayeur longitudinals will add a lot of weight to the car--they probably will get rid of almost all (or all) of the flex that you have measured. If you do want to get rid of that flex and avoid a roll cage, that is your best option.

I'm not sure I'd bother with the trailing arms. Most of the local racers don't seem to bother. Then again, the serious ones have the budgets to replace the arms every few years. Most of them also have a really big thing for saving unsprung weight. A lot of the weight of the trailing arm is unsprung.

Of course, it's up to you since it is your car.

--DD