When lowering isn't wise to also cut the height of the snubbers inside the shocks to allow for more travel?

Yes but here’s the rub.

The rubber bump stops are highly progressive over-damped ‘springs’ over relatively short travel distance (say 10-20 mm).
If you remove sections, you gain travel before contacting the bump stop.
The downside is when you hit the bump stop, it is no longer as ‘progressive’ and the suspension ‘crashes’ into the stop.
This is both hard on the car and parts and is an even more sudden change to the handling.


The common mod for gaining suspension travel is shortening the shock absorber.
(This is all backwards/forwards depending on ‘normal’ shocks vs. Bilstein-type shocks.)
This is where you shorten the shock tube so the shock body has farther to go before it hits the rubber stop.
When you shorten a shock body, you must also shorten the shock piston (maybe just a bit more) so the piston & valve doesn’t bottom – ever.

In front, the downside of these shorter components is that it raises the side stress on the shock and shock tube when cornering and braking.
With extreme shortening, the rear can reach the suspension limit on rebound and cause increased inside wheel-spin.
Any shortening decreases the handling performance if you have your 911 leaping in the air over high speed bumps. :eek:
So long as you don’t go overboard (so low the pan is on the pavement), modest mods seem to last as long as OE parts.


An ‘easy’ front lowering mod is to reposition the spindle assembly higher on the shock tube.
The limiting factor here is the clearance between the ball joint nut and the inside of the wheel rim.
Our 911s still clear the 14” rims from the late ‘60s. Note the clearance to a 16” rim. Keep in mind the 15” spare wheel.

While drastic lowering can put the suspension in unusual curves for suspension (camber & toe) change vs. travel, stiffer springs limit the travel and reduce any effect.
Very low can also result in not being able to adjust to acceptable camber & toe settings without mods to the adjusting hardware and pieces.

With modified suspension, it is wise to assemble everything without the springs and sway bars.
This allows you to manually move the suspension through its entire range of travel (including hard against the bump stops) and ‘test align’ to confirm you can get correct settings.

Everything considered, a bit low works fine. :cool:
Too low is either a ‘disaster’ for handling or requires a bit of clever work.

Best,
Grady

As Grady alluded to, like most things with cars its a matter of effort/money spent. You can go lower than Euro (I have slightly with good results), but to do this with max results may result in recambered struts, raised spindles, camber plates, strut braces, modified ball joints, shortened shocks with modified bumps and bump steer kits. If Porsche maximized geometry at one height, then you must work to re optimize it as you move outside the original engineering sphere. Not original question at all, but can't overstate a great shock! The torsion bar cars were also designed with totally different tire construction with much higher slip angles originally. Michelin X and Michelin Pilots amazingly handle slightly different :D

Luke, well said.

What we all need to remember is an automobile, any automobile (including Porsche) is an engineering compromise.
There isn’t anything possible that is comfortable, long-lived, quiet, fast, street-legal and competitive in F1.
A stock 911 comes close if you move all the criteria toward the center.

With each of our ‘personal’ 911s, we get to make engineering choices, partially unconstrained by Porsche’s original design criteria.
Originally our 911s had to meet a LOT of conflicting engineering requirements:
Built and sold for a profit (or Porsche AG would disappear).
Comply with the various countries requirements.
Be competitive in the marketplace.
… and a LOT more.

High on that list are ‘coolness factor’ & ‘handling prowess’ that we discuss.

With deep pockets anything is possible.
Porsche will even do it for you (at a price).

There is also the ‘progress’ of technology. Tires, as Luke properly notes, are high on the list.
One challenge for out 911s is how to best make use of current tire technology.
Simply bolting on wide, low-profile ‘high performance’ tires doesn’t necessarily yield high performance.

Also here the economics of reality plays front-&-center.
This is where four torsion bars, appropriate shocks and some adjustment make a ‘world of difference’ in a 911’s appearance and handling performance.
All this, inch wider wheels and current 16” tires are still a very suitable ‘engineering compromise’.

Best,
Grady

PS: Not mentioned above are the real-world issues of speed bumps and curb-cut hazards to very low 911s.

PSS: It would be enlightening to retrofit to my SC 165/78SR15 X-Stops on 4½x15” steel wheels in place of the 245/50ZR16 Pilot IIs on 8x16” Fuchs, realizing that the current tires on a new GT3RS have similar (more?) difference in performance.
G.

I'm surprised that I haven't seen the measurement numbers posted in this thread. Place the car on a clean, level floor, set the tire pressures to factory spec, have the fuel tank half full, and get out a tape measure.

Measure vertically through each wheel center from the floor to the first body colored (painted) part of the car - the lowest part of the fender lip. The rear should measure 25", the front should measure 25.5". This is not the most perfect way to measure, but is easily done, and for the most part, will give you a good idea where your car is at.

My '82 (set to "Euro" height):

http://forums.pelicanparts.com/uploa...1336696999.jpg

FYI - Even with the spindles raised 33mm (dedicated auto-cross car), the 15" spare will fit with a 10mm spacer. Otherwise, 17" wheels are required.

Doesn't raising the front more than the rear put more weight on the front? This would be the preferred weight bias with these cars. I am at euro height but the front is slightly higher.

No, not really. Theoretically there is a small change but I doubt you could measure it.

JR

Here in San Diego the gangs lower their low rider cars.

They raise them up here in Bakersfield, and then add 26" chrome mags. Really stupid looking...nothing like a Nissan Altima so high off the ground it looks like a weird SUV.

personally I feel it's too lowed in the rear, or too high in the front. I like to have front fender is around .5" higher than the rear, or both equal.

[QUOTE] The rear should measure 25", the front should measure 25.5".

I went out and measured:
Front driver- 26 1/4"
Front passenger- 25 7/8"
Rear driver- 25 1/8"
Rear passenger- 24 3/4"

Pretty close to Mr. Zimmerman's recommendation. At first I was concerned with unbalance left to right, but thinking about it with me sitting in the car I wonder if it's good where it is at?

[QUOTE=DWeg1998;6744910] Well, there is only one way to find out! Starts with a C and ends with orner Balance!

G

[QUOTE=DWeg1998;6744910] [QUOTE=aigel;6746809] The recommendation to corner balance is a good one. I wonder if you brought the LF down to 25 3/4 if it would bring the RR up slightly. I guess it's possible that the front was left on the high side because of tire/fender lip contact, but your car is definitely too high in front.

In addition, I should mention that if your car has Bilsteins, always drive the car just before measuring. Bilsteins can lose a small amount of height, and then "pump up" after being used. If your car sits overnight, and you measure it in the morning it can skew your readings.

mine is the same way and I .plan on bringing the rear up. one mechanic says lower the front but i'm not. i want it leveled out

This is what I ended up with... Front was lowered a bit as well. Only mild scraping in. The front in bumpy tight corners.

Might be too low for some, but I kinda like it.


http://img.tapatalk.com/553e8864-2a1e-da7d.jpg

What is scraping? The front bottom of the car against the road or the tires / wheels against the the body?

You can't lower the car into the weeds without increasing the spring rate so it doesn't bottom out. I would deem a car unsafe that bottoms out while driving.

Sure looks like the goal here is looks more than performance - and you achieved a good look, judging from the picture.

Good Luck,

G