Mach V Dan
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Posts posted by Mach V Dan
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If putting on the COBB Sport Springs which are suposed to lower 1.75" front and 1" rear. How necessary is it to also change the struts? I dont track my car or drive it too hard. Are the stock struts on a legacy wagon non GT good enough? Also are the cobb springs a good way to lower?
In my experience, the stock Legacy shocks are not nearly firm enough to control the higher spring rates of a lowering spring like that. I'd go with Spec B Bilsteins or Tokico HTS adjustables.
I can't comment directly on the Cobb springs -- I haven't used them. I had thought they were out of production?
--Dan
Mach V
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Does anyone know if these will fit the lgt, 2005 wagon?
Rota G-Forces, 18x8.5, +48 offset, 114.3 bolt pattern
Those wheels ARE available in 18x8 5x100, which will fit your car. We carry them...HERE.
--Dan
Mach V
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Sorry kind of a n00b question, but does lowering the car affect the size of the wheel/combo.
No.
The reason I ask is because I had rubbing issues in the rear of my 97 LGT. The rear tires would rub on the bottom of the spring/strut assembly. I should note that my stock tire size is 205/55/16 and the rubbing occured with a 205/50/17, but I now have 205/45/17 and they are running fine on stock suspension set up.Hmm. What wheels are you using? Sounds like the offset is not quite the same as your original wheel. The 205/50R17 is less than 1% larger in diameter than your stock tire, so it should not cause rubbing unless you're using a wheel that's got a different offset.
205/45R17 is 2.5% smaller than stock. As a rule of thumb, I suggest staying within 2% of your stock tire size so as not to change your gearing and your speedometer/tachometer readings too much.
--Dan
Mach V
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ok so I have located some resonably priced wheels and tires off of an 06 wrx. they are 17" and 5X100. I see no reason why they wouldnt fit but just wanted to make sure that something silly like the centering ring size or offset was screwy or dont clear the calipers(stock).
Offset and hub bore are the same, so you're fine there. I don't know for sure that they'll fit over the Legacy GT brakes, but they probably will. The stock WRX brakes for '06 are pretty big.
--Dan
Mach V
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would 17x7 45mm offset fit over an 08 legacy?
There's not enough information to tell. Some 17x7 +48 will fit. Some will not clear the brakes.
--Dan
Mach V
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It was my understanding that this thread was a general discussion of the pros & cons of different suspension modifications. Since Subarus do have MacPherson strut front suspensions I felt the write-up about sensitivity to ride height was relevant even if the write-up was originally done regarding VWs.
I appreciate the visual appeal of lower a vehicle as much as the next person but there are trade offs. I must have missed where you previously discussed what is an acceptable amount to lower. So I specifically asked the question how much if any can a Legacy GT wagon be lowered from stock ride height before the control arms are no longer level and the handling is adversely effected?
Between 1.0 and 1.5" would be the maximum I would lower the car without making any other geometry modifications. I would also advise stiffer shocks, especially if the car is at the lower end of that range..
True. As I mentioned, all lowering springs that I know of are stiffer than stock. And I'd advise a shock that has stiffer dampening to match.You say you are only recommending lowering the car the same amount the suspension might compress while cornering. But that means you would need to stiffen the suspension a considerable amount to avoid having undesireable suspension geometry while cornering.
Yep. There's no free lunch. Lower = shorter suspension travel = less compliance = less ride comfort.If the suspension is stiffen wouldn't that adversely effect its ability to deal with any bumps it encounters?
The best solution if you want better really-bumpy-road handling would probably be to have stiffer springs and shocks at the stock ride height. But nobody makes anything like that. So I'd say a good set of shocks (the Spec B Bilsteins or the Tokico HTS) and a set of mild lowering springs (JDM STi pinks, Swifts, Eibach) would be ideal.So I ask the question again how much is too much to lower a Legacy GT wagon for driving on NE roads when handling is more important than looks to the driver?
Additional frame stiffening, with strut braces and undercarriage braces, would also improve handling even with stock suspension.
--Dan
Mach V
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Dan,
Your link says these work on Impreza's and STi's. Will they work on Leggy's as well?
Yes. The Legacy front suspension is nearly identical to the WRX front suspension.
--Dan
Mach V
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But bashing/defending VWs is off topic for this thread.
Um...quoting someone's article regarding VW suspension on a Legacy suspension thread is off topic for this thread.
Have you even looked underneath a Legacy? Do you have any specific information about this specific suspension? Do you even know what angle the control arms start out at?
The small amount of lowering I'd recommend on a Legacy (an inch or so) would be no more than the car would go through while going around a mild corner. The car certainly doesn't go all out of control if the suspension compresses an inch during cornering. Plus, lowering springs are firmer than stock -- this reducing any increased roll tendency from the lowered roll center. And if you are really, really concerned about negative lowering effects, you can install roll center adjusters, which will space those control arms back up where you like them.
--Dan
Mach V
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OK, conceptually. What limits the amount of drop you can get away with and still maintain a good amount of travel?
These are two exactly counteracting things -- the more drop you have, the less suspension travel you have, unless you physically relocate the suspensioin mounting points. Even if you did that, you'd soon have clearance issues with the tires anyway.
I hear all the time about lowering and the geometry issues associated with this but nobody explains technically what happens or any solutions to the problem. What kind of parts would maintain adequate geometry while allowing for a good amount of travel at a lower ride height? Or is this not possible?There ARE some parts to try to correct some of the geometry problems -- Zero Sports has roll center adjusters to try to level out the front control arms, and I think Syms also has a tie rod version of the same thing. But neither of these addresses the loss of travel. Shorter travel means you MUST put stiffer springs and (ideally) dampers on to keep the car from bottming out. Stiffer suspension means less ride comfort, and less bump compliance.
Any lowering spring that claims to maintain as much ride comfort as stock is going to be prone to bottoming out.
So there you go...it's the same old answer: There's no free lunch. Everything is a compromise.
--Dan
Mach V
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I'd prefer that this thread continue to be about suspension concepts in general, names/functions/locations of suspension components, and understanding of how things work; there are other places to post specific part reviews.
--Dan
Mach V
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...all the info that I have been able to read has told me that switching to a bigger rear sway will increase oversteer, (which I want), and using a bigger front sway will increase understeer, something I don't want.
That's a generalization, but isn't always true. If the car is rolling a lot (which the factory suspension definitely does), adding a sway bar to the front can help to reduce roll and INCREASE grip at that end of the car. That will DECREASE understeer. This is because when the car rolls a lot, the front tire experiences positive camber -- leaning out away from the car -- and isn't parallel to the road. Reducing that roll will make the tire more parallel to the road during cornering.
So basically the effect of a sway bar upgrade is going to depend on a lot of other factors.
I have had MUCH better results on my cars (DSM, Legacy GT, Evo) with upgraded front AND rear bars. The car corners flatter and behaves more predicatably. THEN I can dial in oversteer/understeer behavior with tire pressure adjustments, alignment changes, end link changes, or other tweaks. (On the Evo, more front camber resulted in a HUGE increase in front wheel grip, and a big change in cornering behavior.)
In my experience, upgrading only the rear gave the car uneven front and rear roll stiffness, which made for a car that did not behave as predictably, at least from my perspective. But that's just my opinion. Plenty of other people seem to feel that a stock front bar with an upgraded rear is the way to go.
--Dan
Mach V
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1. These end links I keep reading about on the forum - WHAT DO THEY DO?!?! and are they necessary to upgrade with my swaybars (that better hurry up and get here).
They connect the end of the sway bar to the suspension control arm. Depending on the sway bar you get, you may need to go with a shorter end link to make everything work or fit right. But the stock links aren't bad, so there's no need to replace them if they're working fine. On the WRX, the rear links are a plastic C-shaped thing that's quite weak. Replacing those can help the car handle better.
2. I know you said they're essentially the same thing, but what is the REAL difference between shocks and struts? Also, are dampers something slightly different or is that really just another word for one of the above?Dampers are anything that dampens suspension movement, so shocks and struts are all dampers. A shock (short for shock absorber) is a device dedicated to dampening vibration, and serves no other purpose. It will not carry any sideways loading. A strut (usually we'd be talking about a MacPherson strut) is both a shock absorber and a structural part of the suspension, and will handle sideways loads at the same time as absorbing spring motion. The MacPherson strut basically replaces the upper A-arm, and serves as the steering axis as well.
--Dan
Mach V
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Are the OEM struts simple orifice compression/rebound dampeners? Do all coilover/aftermarket struts digressive (e.g. use shim stacks or position sensitive orifices)?
I don't think you can make any generalization about type or design of OEM or aftermarket shocks. There are as many shock designs as there are brands of aftermarket shocks. One thing that ALL non-coilover struts have in common is that they're sealed assemblies. They are NOT user-modifiable or rebuildable in any way. If they have adjustable dampening, you get to turn a knob, but that's it. And if the seals blow out, you throw the whole thing in the trash.
Coilovers have separate dampening cartridges, and those usually ARE rebuildable, but I don't know anyone who rebuilds them outside the factory themselves.
--Dan
Mach V
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speeds-yes. we (cycling guys) are referring to how fast or slow the strut is allowed to return to it's extended state.
i certainly get firm vs soft but, for example: is a strut set at full soft adjusted to slow the return rate of speed or is it allowing the strut to extend as quickly as possible?
You seem to be talking only about REBOUND dampening, and not COMPRESSION dampening. MOST adjustable automotive shocks that I'm familiar with adjust both at the same time. The one exception I can think of is Koni yellow shocks, which adjust only rebound dampening. To answer your question, a shock set at full hard will tend to resist motion of the wheel in either direction, and full soft would allow more motion in either direction.
oh yeah, you are the perfect person to ask about my current set up. i installed my swifts (on oe struts) last saturday and would like to minimize the bounciness and hopefully the jarring when hitting a pothole or similar. the bouncy part is the most annoying.I experienced that, too. The stock dampening is (I think) not firm enough to control the stiffer Swift springs to an adequate degree. A firmer shock, or an adjustable shock that will allow firmer dampening, will fix that.
yes, the tokico's are on my shortlist but at that point why not sell what i have and get megan racing coilovers? i'll end up roughly at the same $'s. what would be the downside?I don't have experience with MR coilovers specfically, but there are a few downsides to coilovers. One is simply the installation/adjustment hassle; if you have height AND dampening adjustment at all four corners it can be some work to get it all sorted out. Another is that many coilovers only allow the car to be a certain ride height, and no higher. If you don't want the car "dumped," you may not have a choice. Coilovers may also require a bit more care and feeding -- more cleaning to keep them from getting stuck permanently at one setting, and sometimes the shocks need rebuilding.
But if they're good coilovers, you may find you have a better/more adjustable suspension than with fixed-heigh springs/shocks.
--Dan
Mach V
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Um...fast and slow refer to speeds, in my book. I'm not sure what that means in terms of shocks. But automotive people almost always talk about shocks in terms of firm/stiff vs. soft. Firm being like a stick in peanut butter, and soft being like a stick in water.
Some very high-end shocks have different dampening adjustments for high-speed and low-speed shock motion. Most don't, though.
--Dan
Mach V
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BE is obviously the '00 sedan, and BH is well documented as the Wagon, so what is BA? Thoughts?
A typo.
--Dan
Mach V
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Which is a better first mod (aside from wheels and tires) if I’m looking to improve the suspension, cornering, and handling…
There's no one answer for that. It depends what you are looking for, and how much you want to spend.
Strut bars improve chassis rigidity. This has a positive effect on handling, although adding only front and rear strut tower bars won't have a dramatic effect. But strut bars aren't very expensive, weigh very little, and are simple to install, so the overall cost is also minimal.
Sway bars reduce body roll in corners, and can help move the car's at-the-limit balance more toward neutral (or even oversteer), compared to the Legacy's default understeer bias. But as I've said before, too much sway bar can make the car very snappy at the limit, and you can have some harshness when the car traverses a bump with one wheel -- your spring rate is effectively increased by the way bar during single-side suspension travel. Most aftermarket bars for Legacy aren't THAT much thicker than stock, so having too fat of a bar probably won't be a problem.
As for brand, you have many to choose from. Strut bars are going to be pretty hard to get wrong -- if they fit, they should work. But sway bar space is pretty tight on the Legacy, and many users of aftermarket bars have reported interference with the suspension, so choose carefully when considering sway bar brand.
--Dan
Mach V
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What are dampers, and what do they do?
Dampers = struts = shock absorbers ("shocks"). Three names for the same device. The shocks are paired with the springs, and serve to dissipate suspension energy, so the car does not keep bouncing once the springs have done their job.
--Dan
Mach V
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+48MM offset, technically it should probably be a little more because of the increased diameter ...
Wheel DIAMETER has nothing to do with the required offset. Wheel WIDTH will affect the offset -- a wider wheel will have to have a lower offset to maintain the same centerline position relative to the car. Hence skinny stock wheels (7" wide) with +54 offset, and fatter aftermarket wheels (7.5" or 8" wide) with +48 offset.
--Dan
Mach V
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Perhaps this discussion (the last couple of posts) should move to another thread. This thread is about suspension basics. Let's discuss relative merits of different cars/tires in a separate thread.
As to the Legacy's oversteer/understeer balance, I also find that the Legacy is more tail-happy than many cars. It can oversteer (slip at the back end of the car) on both power-on and lift-throttle situations. I have noticed that tire pressure can play a big part in this. Overfill the rears a few pounds, or underinflate the fronts a little, and the back will be more prone to sliding around.[/url]
--Dan
Mach V
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Where do struts come into all of this?
For purposes of this discussion, struts = shocks.
--Dan
Mach V
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I'm not sure the effect is as big as you're saying. Without trying to hurt my brain with physics, the weight still transfers forward, and the lack of dive affects that transfer subtly, but doesn't prevent it from happening. I think?
I certainly know that you would never want 50/50 bias in racing!
Oops, my theoretical example isn't quite right. To have a situation where you had no weight transfer to the front, you'd need a car that was all the way flat on the ground -- like a sheet of plywood. But if the center of gravity is above the ground, you'll always have weight transfer, even with a completley rigid suspension.
In fact, given a 3200-pound car with a 110-inch wheelbase, a center of gravity 25 inches off the ground, and a braking force of 1.0 G, I calculate a front/rear weight transfer that would effectively make the front wheels weigh 2327 pounds, and the rears weigh 873 pounds -- a 73%/27% split that is very close to all the bias on the braking systems we're talking about. Assuming the suspension allows the car to actually move, that weight bias becomes more front-weighted, although I admit I can't figure out how to calculate it right now.
--Dan
Mach V
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This is a great thread! praedet, kudos to you for assembling all the data.
I wanted to chime in with a couple of observations.
1. Calculations only get you so far. There are a lot of real-world variables that have an effect on braking, and many of them are going to play just as big a part as pad mu or the difference between 70/30 and 72/28 bias. In my experience, the best way to figure out what works is to come up with your best guess using the calcuations, then TEST that guess in the real world. If you tromp on the brakes and the rears go up in a cloud of locked-tire smoke...back to the drawing board.
2. Ideal brake bias is dependent on weight transfer under braking. If you lower your car, it's going to dive a lot less under braking, and if you leave the bias alone, you'll tend to lock up the front brakes! Imagine that you had a super-hard suspension with NO dive under braking. You'd want to have a 50-50 front/rear bias. If you put on firmer, lower springs, you'll want to try to move the bias towards the rear to keep the braking force consistent with the weight over each axle under hard braking conditions.
3. In my opinion, the ONLY reason (okay, the only non-appearance reason) to do a big brake kit on the Legacy GT is for TRACK USE. The car has plenty of brake torque, enough to lock up the wheels at any speed, at least one time. And the size of the rotors is plenty big to dissipate all the heat I've been able to make even on a twisty mountain road. But at the road course, the heat loads are much, much higher, and that's where a larger kit is going to be able to better dissipate that energy.
4. Somebody mentioned above that grippier pads would generate more heat. That's not the case! Stopping the car from a certain speed creates the SAME AMOUNT of heat no matter what pad you use. The pressure involved may be different -- the grippier pad will require less pressure from your foot -- but the heat generated is exactly the same.
My follow-up to these calculations would be to gather some empirical data. For those of you with big brake kits, how about some experiments with an observer (or maybe even a video camera) watching to see how the car behaves with the ABS off under hard braking? Do the fronts lock up first? The rears? Are they even? Does it change when the brakes warm up?
--Dan
Mach V
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Trying to fit 18" 5zigen fighters on a 2002 Leg GT Lim...will they fit with a 5-100 or 5-114.3 bolt pattern....if so, which tire would be best for city all-season use?
Use the search button, and read the FAQ threads. Your car has a 5x100 bolt pattern. As to the tires, there's lots of threads discussing them...
--Dan
Mach V
Mach V Dan's mega suspension guide
in Suspension/Brakes
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I'm not aware that the OEM endlink bushings are available separately; I think you have to get the whole endlink. You certainly do not have to change out front and rear at the same time. For that matter, if you're just replacing it with an OEM part, you could just replace the broken one.
--Dan
Mach V
FastWRX.com