I installed a class-II hitch and a Saris T-rax a few weeks ago...but with a bike on the rack and some stuff in the trunk, the car sags too much for my taste.
I remedied this by installing a set of Moog (TRW) cargo coils. $68 + shipping from partsamerica.com. I also ordered a new set of spring insulators from 50rest.com. $44 + shipping from 50resto.com
The original springs. Can you say destroyed spring insulators?
(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_004_small.jpg)
Below is a comparison of the new/old springs. Lucky for me the new springs are shorter. The spring rate increase is 50% according to Moog.
(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_011_small.jpg)
A comparison of the new/old spring insulators. You can see how the old insulators have compressed over the years. This is the upper insulator.
(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_013_small.jpg)(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_015_small.jpg)
Look ma, no hands (or dampers or springs). Due to 4-link's mega-bind I had to resort to pry bars and a BFH to coax the left spring out. The right spring came out much easier.
(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_016_small.jpg)
That's right purty.
(http://www.griffshp.com/belchja/forums/rearsprings/rearsprings_019_small.jpg)
I took ride height measurements to see what effect the springs/insulators had. I will redo these measurements in about a month once everything has had a chance to settle in.
The measurements were taken from the top of the LCA bolt on the chassis end.
Old Springs
No rack - 8.9375"
Rack (no bikes) - 8.6875"
Rack (2 bikes) - 8.4375"
[COLOR="navy"]Total Change = 0.5"[/COLOR]
New Springs
No rack - 9.6875"
Rack (no bikes) - 9.5"
Rack (2 bikes) - 9.1875"
[COLOR="Navy"]Total Change = 0.5"[/COLOR]
I used a tape measure so my accuracy is +/- 1/16". I was surprised the new springs seemed to have an equivalent rate to the old springs. I'd hazard a guess that 3/8" of the ride height increase is due to the new insulators.
I haven't driven the car enough to obtain any driving impressions.
You likely saw the same drop in height because the cargo coils would be progressive rate, meaning they have a similar rate to the original ones until a certain amount of weight is added, then they have a higher rate. You can actually see it in the spring - look at how much tighter the coils are at the top of the spring
I've been using Moog cargo coils for 15 years, Jeremy. Enough said...they are incredible, and really make these cars handle loads as they should have from the factory. I haven't noticed any more bottoming-out than the stock springs. Let us know how you like them.
The cargo coils and original springs have the same number of active coils, similar mean diameter, but different coil diameter (The cargo coil is much thicker).
This means the cargo coils have a much higher spring rate even before coils begin to close out (and increase the spring rate even further).