Lowering ... and loss of suspension travel question

[DKTZ06]

I'm contemplating which shocks to buy for my Z06 ... auto-x mainly with a couple time trials/track days possibly. Searched a bunch on shocks and lowering. The common concern has been about loss of suspension travel. Ecklers told me that the Bilsteins have a 3/4" shorter shock body. Read that the Koni SA's have a 1" shorter shock body. And then, I saw posts that claimed that guys were still having problems with the suspension bottoming out on the bump stops (after lowering the car).

So, my question is ... is there a good rule-of-thumb for how much suspension travel needs to be regained for ride height lowering? IOW, if I lower the car 3/4", how much suspension travel do I need to regain with aftermarket shocks?

[roadrash]

BUMP....Good question as I would be interested in the answer also.I want to lower my Z desperately,but I am afraid that I will mess up the handling by bottoming out.I have searched also and it seems that for some people there Z will bottom out and others it never bottoms out.

[RocketSled]

My 02 is as low as the factory bolts allow. I don't have any problems with suspension bottoming.

But...

The biggest issue is the chin spoiler, which bangs on everything. Sometimes, on steep driveway entrances, you can bang those steel tubes under the nose, or bottom out the body.

[BLU-BY-U]

I had mine lowered on the stock bolts and it doesn't bottom out. I hit the skirt occasionally, but thats why its there. It's cheap to replace and gives you a warning that you're about to screw up if you don't slow it down.

[Dr. Z]

My Z is lowered as much as possible with the factory bolts. I put in SA Koni's and was concerned about the little available suspension travel.
I've since autox and been to Sears Point a couple of times with no difficulties - an excellent upgrade.

Pete

[roadrash]

OK,thanks for the answers,so you can lower the Z to the max on the stock bolts and it won't bottom out.How much lower can you lower the car without it bottoming out? I mean if you get the bolt kit so you can lower the Z more is it going to hurt your handling.I'm thinking about like 1inch rear and 1.25 inch in front.Sorry not trying to hi jack the thread.

[DJWorm]

If you lower to the "factory max." using the stock bolts the shocks will be fine and marginally shorter shaft Koni's or Bilstein's will give you a slight edge.

If you lower greater than the "factory max." using aftermarket bolts then you will need short shaft and body shocks such as the Penske's or JRZ's to take maximum advantage of the lowering. If you retain the stock shocks in this condition they will bottom out and the marginally shorter Konis will hit the bump stops frequently.

I personally recommend Double Adjustable Penske's:
1. Mono Tube racing Shock
2. Reservoir equiped
3. Compression adjustable
4. Rebound adjustable.
5. Inverted design/mounting to save unsprung weight
6. Light weight
7. Revalvable
8. Totally rebuildable. They will outlast you and the car.
9. Easily Upgraded to tripele Adjustables
10. Easily Upgradable to Coil - Over
11. Can Be upgraded with "Third Spring" and Active Suspension
12. Great Factory Support
13. Excelllent Custom builds and valving from Guy Ankeney and Mallett.
14. With an on-Line downloadable Service manual and factory Support they are completely servicable and rebuildable by the owner/racer.
15. If you eventually sell the car they will add to the value or you can easily remove them and sell them outright or move them to your next car.

JRZ's and Moton's are equal in performance and features however are foreign made.

These shocks make it extremely easy to tune the car especially on a dual use car. For example......I use compression settings 1 & 2 (softest) for AutoX, 3 for street use, 4 for Interstate travel, 5 & 6 for the track.....Like the Ronco ad.....set it and forget it.
We dialed in the rebound settings by 1st setting them at mid range (12-14 sweeps). After a few weeks and a couple of skid pad sessions we determined more "turn in" in the front and went to a 21 setting, then with too much rear bounce we dropped the rear rebound to 9 sweeps. The rebound is now perfect for all the compression settings.
We can also easily soften up all 4 compression settings for a wet track and we can decrease the rear compression for a slippery hot track for better traction.

We have also used different compression settings to wheel jack on a raceway.

www.mallettcars.com
www.penskeshocks.com

[DJWorm]

Incidently, I recommend Harbar's Titanium lowering bolts

They also have a nice Locking Camber Plate, which is better than the T1 camber Plates.

Also, look for a front spring kit soon. Shhh

www.hardbar.net

[roadrash]

Thanks DJ,I'm not sure how low I want to lower my car now.I wanted to lower the car about an 1inch but that is lower than the stock bolts can go. I would just go out and buy the bolt kit but if lowering the car 1 inch is going to mess the handling up then I won't go that low.I want it to function not just look good. I guess I will have to go with the 15mm lower ,because I don't want to buy shocks for my car right now,and if I did I was considering on buying the 04 shocks,but that won't help any.

[DKTZ06]

DJ, Roadrash - I just spent the day chatting with a bunch of local auto-xers. Beth and Erik Strelnieks both commented that they didn't have problems with the '04 Sachs shocks bottoming out with their car lowered. Anywhere from 3/4"-1" is still fine for most of the shocks out there. Chris Ramey also ran on the Sachs shocks with comparable lowering.

With respect to which shocks to buy, my take is this ... if you absolutely must have adjustability, then get whatever you need. Penskes are a good choice, Koni 30 series or 28 series (big bucks) are also a good choice. JRZ and Moton make great products ... but not too many people have been able to win with them. Now OTOH, in my conversations with Erik, he seems to think the '04 Sachs shocks are very comparable to his Koni 28-series shocks. At $300 for the set, that's pretty darn good, IMO.

The only concern I might offer now is that after lowering the car, you scrape on everything. No big deal, if you ask me though ... that air dam is a consummable.