Zac88 Posted June 5, 2011 Share Posted June 5, 2011 So I dont know very much about damping ratios and such and how exactly they affect handeling. I'm looking for some info on which struts to buy depending on what type of springs I buy. Probably going for H-techs to lower just an inch and a little stiffer but I know stock struts wont be able to dampen them properly, why is this and can someone explain please? Link to comment Share on other sites More sharing options...
notthesnail Posted June 6, 2011 Share Posted June 6, 2011 Struts and shocks are basically oil filled tubes with a piston that moves through the oil. Attached to the piston is a set of discs with holes in them, otherwise known as valves. The valves are designed to allow oil to pass from one side to the other at a given rate controlling, or damping, the speed of the piston. The factory chooses a damping rate calculated to match the spring rate and provide the desired ride quality. The components are also designed to work within a given range of motion. When you change the springs, you are creating a mis-match between the springs and the struts, unless the springs were specifically designed to work with the struts on the vehicle. Stronger springs can overwhelm the valves, causing premature wear or distortion, which leads to underdamping and a bouncy car. Shorter springs can lead to the strut working over a shorter range, often bottoming the piston over large bumps. The H-techs offer 0.9" drop and a very small increase in stiffness over stock, so would probably work fine with stock struts, if they aren't already tired or worn. KYB GR2s would probably be a good choice for replacements. Eibach/Epic Engineering also fall into this category. For anything else (that doesn't require Bilsteins), your best bet is Koni yellows. They're designed to work with springs that drop more than 1" and they're adjustable to accommodate a range of spring stiffnesses. You can also get them customized (rears) from the factory to avoid the use of spacers if you're worried about the "saggy butt" seen with some springs. I'm going with Konis, and am looking for a set of Ion springs as my first choice. With modified rear shocks it won't matter if I find wagon or sedan springs, either. Second choice is Rallitek springs. This is based on a daily driver that I also autocross. For everything you never wanted to know about suspension tuning, check out this guy: Dennis Grant. Link to comment Share on other sites More sharing options...
Zac88 Posted June 6, 2011 Author Share Posted June 6, 2011 after doing alot of reading on here I think I might go with the Ralliteks, but they are made by eibach, so would I be good with KYB GR2's? Link to comment Share on other sites More sharing options...
notthesnail Posted June 7, 2011 Share Posted June 7, 2011 With the higher spring rate of the Ralliteks, which are different then the Eibach Prokit/Epic Engineering springs, you might find them underdamped with the GR2s. They'll probably hold up better than stock, but it's hard to say if they'll be ideal. Did you find the spring chart? Link to comment Share on other sites More sharing options...
soloz2 Posted June 8, 2011 Share Posted June 8, 2011 I have some Eibach springs and plan to install them along with KYB GR2 struts later this summer. Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
Zac88 Posted June 9, 2011 Author Share Posted June 9, 2011 wow so must springs are only .5 stiffer? So I would be much better just spending my money on very good struts such as bilsteins? Link to comment Share on other sites More sharing options...
cypher0117 Posted June 9, 2011 Share Posted June 9, 2011 if you're going to just buy good struts go for Koni's. They can be matched to stock springs or basically any spring available for the legacy Link to comment Share on other sites More sharing options...
smashcrunk Posted June 12, 2011 Share Posted June 12, 2011 Is it true that for the billstien HD's, you need to buy spec B upper mounts? This is what tirerack.com claims Link to comment Share on other sites More sharing options...
notthesnail Posted June 13, 2011 Share Posted June 13, 2011 You need SpecB upper mounts just for the front if you're using Bilsteins. Link to comment Share on other sites More sharing options...
mk6933 Posted June 13, 2011 Share Posted June 13, 2011 KYB GR2 is a replacement for stock strut. Stock strut is also KYB, but the GR2 is made to KYB specs, not Subaru specs, which means it will be a bit more stiff. Link to comment Share on other sites More sharing options...
AZP Installs Posted June 17, 2011 Share Posted June 17, 2011 Good info here about the KYBs and the Konis. I concur with the above posters MK6933 and notthesnail. -mike Link to comment Share on other sites More sharing options...
Zac88 Posted June 21, 2011 Author Share Posted June 21, 2011 so are stock struts adequate for stock springs or are they underdampened? Link to comment Share on other sites More sharing options...
goneskiian Posted June 21, 2011 Share Posted June 21, 2011 Most feel they are underdamped even for stock springs. Link to comment Share on other sites More sharing options...
cypher0117 Posted June 21, 2011 Share Posted June 21, 2011 I thought they were underdamped with stock springs, but they were livable and drivable. Once I put Eibach springs on (which are not that much more stiff than stock) they really felt underdamped. So much so that I didn't like the ride and I am sure i was constantly hitting my bumpstops. Koni's solved that issue and now I think it rides better than stock. Link to comment Share on other sites More sharing options...
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