Notices
964 Forum
Sponsored By:
Sponsored By:

Planning To Upgrade 89' C4 Wheels and Suspension

 
Old 05-19-2010, 03:56 PM
  #1  
colbychris
User
Thread Starter
 
Join Date: Aug 2007
Posts: 6
Default Planning To Upgrade 89' C4 Wheels and Suspension

I'm planning on upgrading the wheels and suspension of my 89' C4 which I track about 10 days a year but still want to be reasonably comfortable in when driving around town.

Any opinions on wheel diameter? Can (should?) I go with 18" over 17"? Can the rears safely accommodate 10" wide wheels with the help of spacers?

I've read 'Wringing Out I-III'. Does anyone have any recommendations on shock and spring combinations for my particular application?

Will a lowered 89' C4 be able to accommodate 18" diameter wheels, 8" wide in the front, 10" in the rear (with spacers)?

Please forgive my naivety, this is my first Porsche of which I've only owned for a few years, completely stock.

Thanks for your help.
colbychris is offline  
Old 05-19-2010, 04:15 PM
  #2  
Indycam
Super User
 
Join Date: Sep 2004
Location: not in HRM
Posts: 5,061
Default

Can O worms . Go as fast as you can on the stock rims and suspension . When you are faster than the stock rims / tires and suspension , then upgrade .
Indycam is offline  
Old 05-19-2010, 04:33 PM
  #3  
Greg964
User
 
Greg964's Avatar
 
Join Date: Mar 2007
Location: CT
Posts: 517
Default

My personal opinion is to stick with 17" wheels, makes the ride tolerable and tire replacement relatively inexpensive. For suspension I would go Bilstein HDs (make sure the rears are correct for your model year) and H&R springs. Get an alignment and corner balance and you should be in good shape. You can also get larger sway bars, Porsche used 22 mm front/20 mm rear for the C2/C4 M030 sport suspension. Stock for the 89-90 C4 are 20/18
Greg964 is offline  
Old 05-19-2010, 06:07 PM
  #4  
colbychris
User
Thread Starter
 
Join Date: Aug 2007
Posts: 6
Default

Originally Posted by Indycam View Post
Can O worms . Go as fast as you can on the stock rims and suspension . When you are faster than the stock rims / tires and suspension , then upgrade .
Upgrade to a different 911 or upgrade rims/tires? Been running in the White run group now for a couple of seasons, definitely faster than the stock set-up is allowing me...
colbychris is offline  
Old 05-20-2010, 12:30 AM
  #5  
kgorman
Addict
Rennlist Member
 
kgorman's Avatar
 
Join Date: Sep 2005
Location: Austin, TX
Posts: 2,417
Default

17 with ra1s
kgorman is offline  
Old 05-20-2010, 02:19 AM
  #6  
rotorheadcase
Addict
Rennlist Member
 
rotorheadcase's Avatar
 
Join Date: Oct 2005
Location: Nelson, New Zealand
Posts: 506
Default

There are plenty of opinions on wheel diameter... I have 18's and love them. Previously had 17's and noticed only a slight increase in ride harshness until...

I installed KW Variant 3 suspension and lowered it between RS and Cup height. Replaced the rear roll bar with a C2 bar. Now quite stiff and a little harsh for the average street driver but blindingly quick through corners and very neutral. I can squeeze 10' in the rear with the current ride height but i'm running a bit more negative camber on the rear approx 1.7 deg

In my opinion just the wheels themselves will not adversely affect your ride comfort but will give you a lot more predictable breakaway when the the rears start to slide.

Regards,

Neil
rotorheadcase is offline  
Old 05-20-2010, 07:56 PM
  #7  
joey bagadonuts
Addict
Rennlist Member

 
joey bagadonuts's Avatar
 
Join Date: Mar 2002
Location: Highland Park, IL
Posts: 3,606
Default

Originally Posted by colbychris View Post
Will a lowered 89' C4 be able to accommodate 18" diameter wheels, 8" wide in the front, 10" in the rear (with spacers)?
Whatever wheels/tires you choose, make sure you buy them, first, and have them mounted on the car when you install the new suspension and car lowered.

kgorman's suggestion sounds like a good one: 17's with RA-1's.
joey bagadonuts is offline  
Old 05-20-2010, 10:48 PM
  #8  
ACSGP
User
 
ACSGP's Avatar
 
Join Date: Mar 2009
Location: Singapore
Posts: 623
Default

Originally Posted by colbychris View Post
I'm planning on upgrading the wheels and suspension of my 89' C4 which I track about 10 days a year but still want to be reasonably comfortable in when driving around town.

Any opinions on wheel diameter? Can (should?) I go with 18" over 17"? Can the rears safely accommodate 10" wide wheels with the help of spacers?
Tyre sidewall does make a diff in ride harshness as you're losing a bit of "give" in the flexible rubber wall by going up 1".

But, from personal experience, if you lose weight in the tyres (i.e. the Conti CSC3s are one of the lightest in the class) and the rims (such as the OZ Allegeritas, which lose abt 8 lbs in weight each compared to Cup 1s), you can get a better ride despite going up 1". TireRack has a very good online tool to compare tyre weights.

My A6 went from heavy OEM Avus 17" rims to light MTM Forged 19" Bi-motos, and my ride improved. Really.

Incidentally, I've been in contact with OZ abt the Allegeritas in 18", and with DPE abt forged monoblocks in 17".
ACSGP is offline  
 


Thread Tools
Search this Thread

Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

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: