I wanted to share my experience with other owners as it relates to shock revalving and suspension modification.
My Laforza was first sold in 1999, but was basically the 1989 model. I purchased it two years ago with 18,000 miles and it currently has 19,500 miles. It was not in use for over a year while it received an engine rebuild and upgrade.
I had experienced the "nose dive" under hard braking that others have mentioned, although I did not find the stock brakes were lacking in stopping performance, as others have. With an upgraded engine and more power, I did feel there was more body roll in "aggressive" cornering than I liked.
I took the car to Quickor Suspension (www.quickor.com) is owned by Glen Rissenberger, who goes to the same Church that I do. Glen drove the car and felt he could greatly improve the handling. I told Glen to go ahead but I did not want a "stiff race car feel"; I wanted to retain a comfortable ride.
Glen felt there was too much "nose dive" under hard braking and also felt there was too much "body rebound" when driving at speed over bumps (actually some slightly raised railroad tracks where he almost got the car airborne in the front!). After talking with various shock manufacturers he decided to stay with original Bilstein shocks. Our first task was to see if the shocks were operating within the original specifications. Although they only had 19,000 mile on them they were 14 years old.
The shocks were sent off to Bilstein and I asked that all test values be recorded so that the info could be shared with other Laforza owners. The initial test results showed that all shocks were within the original specifications. Glen then asked that Bilstein revalve the rear shocks to stiffen them as much as possible. Listed below are the values for the rear shocks. The stock number is the actual number from testing my shocks, which they said was within original specifications. I am told these values are metric and measured in Newton's (@ .52 meters per second).
Stock Revalved % Increased
Compression 717 844 17.713
Rebound 867 1311 51.211
The fronts were revalved with values below:
Stock 1st Revalved % Increased
Compression 796 891 11.935
Rebound 1972 2353 19.320
While the shocks were gone, Quickor fabricated and installed a sway bar at the rear of the car. Dave, at Laforza, had told me a year ago that the stock rear sway bar had little affect on handling as they were too weak, which is why the cars were sold new without rear sway bars. I believe the diameter of the stock rear sway bars was ½". The rear sway bar installed was 7/8" in diameter.
The revalved shocks were then re-installed and the car tested. The "nose dive" was greatly reduced and the "body rebound" was cut in half, but Glen was still not happy with the front shocks, as he felt there was still too much " body rebound" when tested on the raised railroad tracts as before. The front shocks were sent back to Bilstein for revalving again to the values below (Please note - the 2nd revalving values are compared with the stock values not the 1st revalve values):
Stock 2nd Revalved % Increased
Compression 796 991 24.497
Rebound 1972 2548 29.209
After installing the front shocks and driving over the railroad tracks Glen was satisfied with the results. He felt the ride comfort would suffer from any further increase in stiffness of the front shocks.
Glen then moved on to adding an additional sway bar to the front. He retained the stock sway bar but added an additional one on top of the original one. The new front sway bar was clamped onto the original. After testing Glenn and was not satisfied with handling in corners with the new front sway bar. He then fabricated a second front sway bar with a slightly different design and larger diameter. The second design work well and was retained. The diameter of the second sway bar was 1 1/4".
The tires were replaced with stock sized Yokohama Goosanders H/T-S P265-70R-16S (because of their performance characteristic work in our wet, Portland, OR climate). The web site www.tirerack.com worked well for factoring in the handling characteristics that were most important to me to find the right tire for my needs.
I'm very happy with the results of the above changes, as the car handles significantly better in cornering and the "nose dive"has been eliminated. The car feels much more stable when driven at speed and traveling over bumps in the road.
I'm sure there are other equally good ways to arrive at improved handling, and I only offer what I did in the hope that others can benefit from it.
The costs were as follows:
R & R four shocks $ 75.00
Revalve four shocks by Bilstein 278.00
Freight to and from Bilstein 40.00
R & R front shocks for 2nd revalve N/C
2nd revalve front shocks 137.50
Freight to and from Bilstein 20.00
Rear 7/8" sway bar design, fabricate
and install 310.00
Front 1 ¼" sway bar design, fabricate
and install 310.00
Four Yokohama Geolandars H/T - S
P265 70R 16S 678.00
Total cost $1848.50
Quickor will sell the front and rear sway bars at $209.00 each and is looking at getting an exchange set of revalved shocks if anyone is interested in having theirs upgraded. You can reach Glen at 503 654-2175.
Oregon City, Oregon