How much lower? - Rennlist - Porsche Discussion Forums

Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

How much lower?

Reply

Old 02-05-2018, 11:58 AM
  #1  
Socal_Tom
Addict
Rennlist Member
Thread Starter
 
Join Date: Jan 2015
Location: SoCal baby, SoCal
Posts: 672
Default How much lower?


My ‘87 sits a bit high to my eyes. I bought the Spring tool, so “just” need to find the time to go after it,

Any thoughts or coaching on how low without compromising daily driver use?

Thanks!


Socal_Tom is offline  
Reply With Quote
Old 02-05-2018, 12:13 PM
  #2  
Socal_Tom
Addict
Rennlist Member
Thread Starter
 
Join Date: Jan 2015
Location: SoCal baby, SoCal
Posts: 672
Default



Socal_Tom is offline  
Reply With Quote
Old 02-05-2018, 12:23 PM
  #3  
Speedtoys
Addict
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 8,712
Default

Measure the actual ride height.

Eyes are weird, they might like how it looks a lot lower, but it comes with a host of moderate to severe issues, esp with big wheels.
Speedtoys is offline  
Reply With Quote
Old 02-05-2018, 12:25 PM
  #4  
Jerry Feather
Addict
Rennlist Member
 
Jerry Feather's Avatar
 
Join Date: May 2008
Location: 2706 Skyline Drive, Grand Junction CO 81506
Posts: 4,392
Default

It looks like you are somewhere above the WSM specified ride height. I would first check the manual and measure what you have in comparison, then decide how much lower, if any, you want to go.

There are probably several threads on here about how much different from recommended ride height is feasible.
Jerry Feather is offline  
Reply With Quote
Old 02-05-2018, 12:42 PM
  #5  
Socal_Tom
Addict
Rennlist Member
Thread Starter
 
Join Date: Jan 2015
Location: SoCal baby, SoCal
Posts: 672
Default

Good morning, and thanks for the response.

Let me go measure here so I’m not just winging it, thanks!
Socal_Tom is offline  
Reply With Quote
Old 02-05-2018, 12:46 PM
  #6  
Rob Edwards
Archive Gatekeeper
Rennlist Member
 
Rob Edwards's Avatar
 
Join Date: Sep 2002
Location: Irvine, CA
Posts: 12,926
Default



Rob Edwards is online now  
Reply With Quote
Old 02-05-2018, 01:42 PM
  #7  
FredR
Addict
Rennlist Member
 
FredR's Avatar
 
Join Date: Jun 2005
Location: Oman
Posts: 4,944
Default

Tom,

When the 928 is set to factory spec it inevitably looks high because most of the ones on the road are lower than they should be so the correct one looks oddball. For whatever reason it seems the front springs sag more than the rear ones so front down *** in the air is probably how many end up. If you live in an area with lots of potholes then stick with what you have unless measurement tells you it is silly high.

Those of us who have spent time trying to tune the handling of the car end up with something ranging from reasonable to downright silly. I run mine at the bottom end of the allowable range [somewhere around150mm] and I try to keep the front/rear difference in ride height aligned with the factory numbers but then I have springs that re about 25% stiffer than stock. Just remember if you change the suspension collar height you change the alignment settings- mostly it is toe that is impacted and lowering causes toe-out and more camber. If you have of plenty of toe-in to start with maybe not an issue but if like me you run with minimal toe one has to be very careful.
FredR is online now  
Reply With Quote
Old 02-05-2018, 01:47 PM
  #8  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 16,571
Default

Hi Tom --

I'll toss out the observation that you are already at or near the bottom of the factory-recommended 190 to 170mm front ride-height range. And that ASSumes that you've managed to drive more than 100 miles or so since the car was last lifted off the suspension. The goal is to have the car high enough that the alternator and AC compressor don't become sacrificial parking stops or skid plates. As far as suspension geometry, static ride height goal has the lower control arm horizontal from centerline of inner bushings to centerline of lower ball joint. At the same time, the tie rods will be level, so there's minimum toe change as the suspension moves up and down from that static position. Experience has shown that having the shock working at it's design extension improves ride quality along with apparent handling (read: "feel"). Extreme cornering benefits from a lowered CG, stiffer springs and sticky tires, at the expense of ride comfort and tire wear.

My car came to me at 8 years old with about 20k on it and already-drooping suspension. In the first few years it was taking more and more care just getting into my own driveway at home. At about 5 years 20k of my miles I noticed that I was seeing inner-rib scrubbing from excessive toe out due to the sagging. So I raised the car back to spec height and all was well again for a while. Plus I could get into my driveway.

In the end, most owners decide on a ride height that "looks good" to their own eye rather than to a measurement. The cars sink slowly so we don't notice the change until we decide to correct for the sag, and suddenly the car looks off-road ready. After doing some modeling of the front suspension geometry as a CAD exercise, my conclusion is that the factory knew exactly what they were doing in the initial design height. Euro cars were reportedly delivered near the lower half of the design range, while US cars were higher per some of the "experts" over the years. The factory height numbers are the same regardless of market.

I keep the car now at no less than 173mm in front unloaded. I have it aligned perfectly at 175mm, and check the height a couple times a season to make sure it doesn't stray too low.

Don't forget corner balancing, especially since you've done so much suspension work on the cars. I have a 928 horror story for you sometime from an "enthusiast" owner from your SoCal neighborhood who stuffed his car after just tossing in new springs & shocks and not paying enough attention to all the settings.
dr bob is offline  
Reply With Quote
Old 02-05-2018, 02:01 PM
  #9  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 16,571
Default

Also--

The high-tech ride height gauge set that Rob displays is an authorized copy of a set I made for the 928. I used some handy plated steel gas welding rod, cut to length and tagged with the masking-tape flags and a Sharpie marker. They are calibrated against a handy metric scale (ruler) using a pair of lineman's pliers to adjust the lengths. Mine are carefully fitted into a caddie made from a scrap of corrugated boxboard, and are stored in a see-through case that looks suspiciously like a 1-quart Ziplock freezer bag. Total fabrication time -- less than five minutes. You can save some as Rob did by sacrificing some wire clothes hangers. They are a little softer and easier to cut, and already have a protective enamel coating on them to resist corrosion.
dr bob is offline  
Reply With Quote
Old 02-05-2018, 02:11 PM
  #10  
Rob Edwards
Archive Gatekeeper
Rennlist Member
 
Rob Edwards's Avatar
 
Join Date: Sep 2002
Location: Irvine, CA
Posts: 12,926
Default

The money I saved on using coathanger in lieu of welding rod allowed a splurge for some masking tape and a red sharpie for labels.
Rob Edwards is online now  
Reply With Quote
Old 02-05-2018, 02:28 PM
  #11  
Socal_Tom
Addict
Rennlist Member
Thread Starter
 
Join Date: Jan 2015
Location: SoCal baby, SoCal
Posts: 672
Default

Great discussion and information gentlemen, I will leave this alone for now.
Socal_Tom is offline  
Reply With Quote
Old 02-05-2018, 02:35 PM
  #12  
Ducman82
 
Ducman82's Avatar
 
Join Date: Nov 2009
Location: Rancho Palos Verdes, CA
Posts: 6,859
Default

on Social roads, stay stock man. my skid plates can attest to that
Ducman82 is offline  
Reply With Quote
Old 02-05-2018, 03:03 PM
  #13  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 16,571
Default

Originally Posted by Rob Edwards View Post
The money I saved on using coathanger in lieu of welding rod allowed a splurge for some masking tape and a red sharpie for labels.

Deviation from the standard blue tape with black Sharpie. Certain liberties and design deviations are allowed so long as they don't adversely affect the functionality. I depend on the bimetal (copper over steel) structure on mine to maintain a perfect thermal expansion profile. In your stable SoCal measuring environment, such concern is not nearly as critical. In fact, you could probably get by without any thermal correction at all.

dr bob is offline  
Reply With Quote
Old 02-05-2018, 03:22 PM
  #14  
davek9
Addict
Rennlist Member
 
davek9's Avatar
 
Join Date: Jul 2006
Location: Bloomfield, MI
Posts: 4,224
Default

^^^ well so much for using wooden dowels ^^^
LOL
davek9 is offline  
Reply With Quote
Old 02-05-2018, 04:18 PM
  #15  
FredR
Addict
Rennlist Member
 
FredR's Avatar
 
Join Date: Jun 2005
Location: Oman
Posts: 4,944
Default

Originally Posted by Ducman82 View Post
on Social roads, stay stock man. my skid plates can attest to that
Those sound more like anti Social roads!
FredR is online now  
Reply With Quote

Thread Tools
Search this Thread
Quick Reply: How much lower?


Contact Us Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: