Porsche says the GT4 is 10mm lower than the Cs With X73 Thus far my previous 981Cs with X73 scraped more than my GT4. With a fully adjustable suspension I find it hard to believe you can come up with a certain number. In the middle of my car the lip is 4 3/4 inches off the ground. Has anyone lowered their springs all the way down? If so how low is the front lip in the middle? Has anyone raised the springs to avoid scraping or are you thinking about it? If so how high to the middle of the lip? Personally I am going for the best of both worlds...not my DD but I like to go to autoX and plan on many more track days without trailing a car.

 

I didn't think the suspension is adjustable by height, is it?

 

I believe the struts are threaded for height adjustment, but your ability to do so is limited, particularly given the sensitivity of a strut based suspension to ride height for proper suspension geometry.

 

Correct....they are all threaded.

 

The coilovers are height adjustable, just like the older GT3s etc. Based on others' experiences with the older GT3s, these factory coilovers are generally quite ok within +/-5mm from the factory specs. I wouldn't lose sleep over it if 5mm helps you to get through your daily drive way. The roll center etc should still be well within range.

I would definitely keep it within +/- 10mm though. Anything more I think you probably need to do some "tuning"

The PCA video with TPC's Mike there mentioned that the wheelbase actually changes too when one adjusts the ride height. I suppose the change in wheelbase is relatively small? I'm a little surprised the wheelbase changes accordingly

 

My GT4 is noticeably lower than the Spyder with X73 I drove recently. However there is a tolerance on spring length, springs sag over time, and the GT4 is height adjustable, so not every GT4 will be lower than every X73.

If I wasn't tracking I'd consider the Spyder front lip and backing the rear wing off to match, understanding that the aero balance would be hard to maintain. Raising the car would be the next step, but even with an alignment the roll center would be thrown off so I wouldn't go far.

As I do plan to track I've simply left it alone. My car does scrape semi regularly, but no significant damage so far. I'm simply planning to change the lip as needed- to my thinking the cost is not completely unreasonable if you're careful.

 

If you change ride height you need to corner balance. Otherwise you end up with a three legged stool.
You can have the car level with the corner weights screwed up. carl
http://lshapedgarage.blogspot.com/20...asurement.html

 

I would like to lower my GT4 another 1/2" inch to close the wheel gap and dial in a little more camber via the drop. I'll probably be looking to get the toe links too so I might do a corner balance at West End with me in the car.

 

I measured mine today using the factory procedure from their measurement points. The service manual spec is X73 F=116 mm +_10mm R 143Mm+_10mm so the GT4 should be 10mm lower.

Mine was 113.88&113.08F 135.74&133.28R ..i have a custom made ride height gauge that i developed for when i was setting up my lotus. Accurate to .2mm(.008) and repeatable.

With the 10mm the height drop from the X73. The factory spec for the GT4 ride height is( F 106 +_10 = 96-116MM) (R133+_10=123-143MM) with less than 5mm difference side to side.carl

 

lets not get carried away with lowering now, there is a special place in hell for people who do this to their GT4