Busted a strut clean in half

Pentalab

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My pass side strut (roush) broke clean in half... aprx 2" down from the Steeda HD strut mount. All I did was gently back it out of the driveway, and heard this gawd awful racket. I needed the car back on the road asap, as I'm looking after a sick friend....so had oem front struts installed.

Roush lowering springs used, 1" on the front...and 1.25" on the rears. 30% stiffer than oem.
Sure is a lot smoother now on some of our shitty roads around town with oem struts installed. The Roush struts were rock hard from day 1..installed Aug 2011. I couldn't get 1 mm of deflection, sitting above the wheel well ! Now I can push down on the top of the wheel well, with both hands..and bounce it a little. Still have roush rear shocks + springs, but the rear is not bad over minor bumps. ( the front was horrid over anything minor, miniscule, had to avoid man hole covers, etc. Speed bumps had to be taken at 0 mph. And don't even think about crossing a train track at any speed.

Roush used re-branded XXX for struts + shocks I believe...and I'm sure they are OEM length..which seems nuts, since then you just lost 1" of travel on the front..and 1.25" on the rear.

I saw Vorshlags .... 'Bilstein street pro' struts and shocks. I think these may well be the ticket..as they are shorter than OEM....and will /should work with any brand of lowering spring. Site sez on a 05-10 car ( mine is a 10) that GT-500 strut mounts ( or vorshlag caster /camber mount) must be used..since GT strut mount is not strong enough. Can my Steeda HD strut mount be used ? I don't see why not.

Ok, I know the Bilstein street pro struts + rear shocks are not adjustable, and I'm fine with that. What I don't want is a repeat of the Roush struts.... IE: rock hard for my taste. The roush setup was fine on the HWY..and local good roads. But a lot of local roads appear to have deteriorated in a lot of places.

Bone stock, the car would nose dive on braking...and front end lift /rear squat when you hit the gas..and also leaned on the corners. So the roush suspension package solved all of that...except the ride on anything less than perfect roads is not pleasant.

Also installed is Roush front + rear sway bar, whiteline watts link, some bracing here and there..and camber set to -1.5 deg. 275 front / 285 rears...all on 10" rims. Plus BMR adj UCA and BMR lca's...and BMR lca relocate brackets, middle holes used.

I'm tempted to use Koni yellows / D-specs, since they can be tweaked, but I fear they may be 1 step forward....and several back. A lot of folks using yellows /d-specs seem to leave em on.. 'full soft' for around town DD use..then tweak em for autocross, hwy etc.

I asked around town, but no one is using Bilstein Street pro struts and shocks. Too bad, I'd love to test em out. I dabble with autocross 1-2 times a year, if that. Zero road courses. Anybody here used the Bilsteins, with typ lowering springs... on less than stellar roads ??
 
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modernbeat

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If think if you search the Corner Carver section for "Vorshlag Bilstein" you will see many personal, first-hand accounts on their ride quality and performance.
 

2Fass240us

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I assume these were twin tubes? Given that you're considering a Bilstein monotube?
 

oldVOR

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Having had adjustable Koni's on a prior car and the Vorshlag Street Pro setup on a current car with both on FRPP K springs and driven many miles on the roads in my area, I'd go the route of the Bilstein's again without a second thought. The Koni's were nice however, I noted the damping start to drop off as mileage increased requiring more positive damping to adjust for the drop off. I've got about half as many miles on the Bilstein's at this point and have not noted any difference since new.
 

kcbrown

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My Koni yellows handle pretty well, but even on full soft my car rides like a damn brick.

I'd bet that it's your springs more than your dampers for that. I don't know how much your springs lower the car, but you might be in the bump stops for some of the larger bumps you encounter. The rates I've seen for the Steeda Ultralites aren't that much different from stock, but they lower the car quite a bit (1.25" up front, 1.5" in the rear, if I'm not mistaken).
 

Sky Render

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I'd bet that it's your springs more than your dampers for that. I don't know how much your springs lower the car, but you might be in the bump stops for some of the larger bumps you encounter. The rates I've seen for the Steeda Ultralites aren't that much different from stock, but they lower the car quite a bit (1.25" up front, 1.5" in the rear, if I'm not mistaken).

But, but, it's all about the STANCE, bro! :roflmao:

I've thought about changing my suspension up, but I don't really want to mess with it until I'm ready to drop coin on some good coil-overs.
 

Senna1

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I'm curious how high a rate Vorshlag think their StreetPro setup can handle and still be reasonable in a DD. BMR has some GT500 springs that approach 265 lbs/in in the front, and are the highest rate 'OEM style' springs for the S197 I've seen on the market.

On their site, they have the FRPP springs and Eibach Pros as pre-assembled options, which are 200 lbs/in or less, some significantly (11+ Eibach Pros, in particular IIRC). Not sure if they have a ranked preference for those, or simply offer them because they're available and people want them.
 

kcbrown

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I'm curious how high a rate Vorshlag think their StreetPro setup can handle and still be reasonable in a DD. BMR has some GT500 springs that approach 265 lbs/in in the front, and are the highest rate 'OEM style' springs for the S197 I've seen on the market.

I did that analysis here, based on Vorshlag's dyno plots. In short, it looks like they'll handle up to 525 lb/in up front.

They'll handle more than the Konis will, but the downside of that is that because they're not adjustable, it appears they'll be slightly overdamped for low speed motion of 200 lb/in springs, and even more so for OEM springs.
 

Senna1

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I did that analysis here, based on Vorshlag's dyno plots. In short, it looks like they'll handle up to 525 lb/in up front.

They'll handle more than the Konis will, but the downside of that is that because they're not adjustable, it appears they'll be slightly overdamped for low speed motion of 200 lb/in springs, and even more so for OEM springs.
Thanks for the link; I've used your dyno data for OE and Koni (with hysteresis averaged out as best I could) and the Bilstein plot together and I have trouble seeing it (see attached plot).

Based on low speed (2 in/sec) critical damping math, even the OE front damper 'looks' like it will handle a spring up to ~300 lb/in by the '65% rule'. Which I sincerely doubt in reality. Maybe because it blows off to only 7.5 lbs/in/sec between 3-4 in/sec velocity, while the Konis are nearly linear for rebound @ full hard. Bilstein is hardest in compression at all velocities, but softest in low speed (<1 in/sec) rebound, ramps up sharply until 4 in/sec, then blows off to something very close to the OE slope.
 

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Pentalab

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Just came back from taking the car for a rip. It just doesn't feel right...with oem struts + roush springs. Got out the tape measure..and the front is 1/2" higher than b4 ! Less rake than b4. Feels floaty. Front end is not quite stiff enough. Trade off between smoother ride..and handling. It doesn't nosedive though. The nose dive issue on the bone stock oem suspension is caused by back end lift. And I still have the roush rear springs + roush rear shocks in place.

Ok, roush sez their springs will lower the car 1/2" front + rear...IF used with oem struts /shocks. IF using roush struts /shocks, then the ride height is 1" lower front /rear. Mystery solved.

Ok, so what does roush do to their struts /shocks such that they reduce the ride height by an additional 1/2" ?? I don't have the roush struts anymore..they reside in the dumpster, long gone. Dumb move on my part, I could have taken some measurements on the good strut.

Looking at the graphs on the post above me, it appears the koni's have adjustable rebound only. The Bilsteins seem a little heavy on their compression. It would be interesting to know how the koni's / Bilsteins would affect the ride height, when used in conjunction with roush springs ? I'm gonna leave it for now, but I'm not a happy camper.

I could install new roush front struts... or replace all 4 x corners with koni....or Bilstein. But until I know how the koni /bilstein affects the ride height with roush springs, I'll leave it as is, till I get it sorted out.
 

kcbrown

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Thanks for the link; I've used your dyno data for OE and Koni (with hysteresis averaged out as best I could) and the Bilstein plot together and I have trouble seeing it (see attached plot).

Based on low speed (2 in/sec) critical damping math, even the OE front damper 'looks' like it will handle a spring up to ~300 lb/in by the '65% rule'. Which I sincerely doubt in reality. Maybe because it blows off to only 7.5 lbs/in/sec between 3-4 in/sec velocity, while the Konis are nearly linear for rebound @ full hard. Bilstein is hardest in compression at all velocities, but softest in low speed (<1 in/sec) rebound, ramps up sharply until 4 in/sec, then blows off to something very close to the OE slope.

The critical damping formula I'm using is this: CD = 2 * sqrt(SpringRate * SprungCornerWeight / 386.4) / (MotionRatio ^ 2)

For the front, the sprung corner weight I'm using is 945 lbs, with a motion ratio of 0.97.

For the rear, the sprung corner weight I'm using is 747 lbs, with a motion ratio of 1.0.

The Bilstein front rebound damping rate appears to be around 50 lb/(in/sec) between 2 and 3 in/sec (it actually looks a little higher than that). 200 lb/in springs in the front have a critical damping rate of 47 lb/(in/sec), so the Bilsteins appear to be past critical in that region.

50 lbs/(in/sec) is 65% of 77 lb/(in/sec). 77 lb/(in/sec) is the critical damping point for a 536 lb/in spring. I "rounded" to 550 in my message I linked to, which seemed like a reasonable thing to do given that the rebound damping rate appears to slightly exceed 50 lb/(in/sec).

What with the sharp elbows in the curve and everything, the speed range you look at matters a great deal. I was presuming that 2-3 in/sec is what mattered, but that might not be the case. But the main reason I used 2-3 in/sec for looking at the Bilsteins is that it's what I used when analyzing the Konis, and I wanted the comparison to be as direct as possible.

The stock dampers look to have about 40 lb/(in/sec) in that range. That's 65% of 61.5 lb/(in/sec), which is critical for about 340 lb/in. Yeah, it looks like the stock dampers would be able to handle that spring rate in that region.

But that region is only for handling. If there's not enough rebound past that, then the springs will overwhelm the dampers when going over bumps and the ride will suffer for it. The OEM dampers might be okay in handling cornering transitions with springs in the 300 lb/in rate, but I'd bet they'd do pretty badly if you throw some bumps in the mix there.

While the Bilsteins settle to rates similar to stock past 4 in/sec, the absolute force numbers past that are higher, and that'll contribute to their control over firmer springs. It's interesting to note that even on their softest setting, the Konis have firmer high speed rebound damping than the OEM dampers, and cross the OEM curve to boot, so the force numbers are higher past the intersection point, too.


These numbers can only tell you so much. Only driving the car with the setup in question will give you the complete picture (well, a more complete picture, at least).
 

kcbrown

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Just came back from taking the car for a rip. It just doesn't feel right...with oem struts + roush springs. Got out the tape measure..and the front is 1/2" higher than b4 ! Less rake than b4.
Feels floaty. Front end is not quite stiff enough.

Given the higher speed damping rates of the OEM dampers, that doesn't surprise me at all. Probably feels "rubbery" over bumps, too.


Ok, so what does roush do to their struts /shocks such that they reduce the ride height by an additional 1/2" ??

They probably locate the mounting points for the strut closer to the top. Overall length is probably shorter, too.


Looking at the graphs on the post above me, it appears the koni's have adjustable rebound only. The Bilsteins seem a little heavy on their compression. It would be interesting to know how the koni's / Bilsteins would affect the ride height, when used in conjunction with roush springs ? I'm gonna leave it for now, but I'm not a happy camper.

Konis lower the front by 1/4" without any other changes. Dunno how much Vorshag's Bilstein struts do the same.
 

ddd4114

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My Koni yellows handle pretty well, but even on full soft my car rides like a damn brick.
That's exactly what I thought of mine. When I first switched to MCS dampers, I doubled the spring rate, and it was actually more comfortable. However, I'm having a tough time beating my lap times from my Koni Yellow setup...
 

Sky Render

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Came back for carnage pics. Still disappointed.

Sent from my Samsung Galaxy Note 4 using Tapatalk
 

Wes06

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Exactly
Been looking for said busted struts but just seeing words
Boring
 

Pentalab

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Sri folks, no carnage pix, both front struts now reside in the dumpster. Suffice to say, the strut on the pass side sheared 2" down from the steeda HD strut mount, and I mean the main piston, and NOT the interface between piston + threaded portion at top. I'm just glad it sheared while I was backing out of the driveway...and not the hwy. So much for Roush struts.

While the ride is smoother with oem front struts + roush springs, after some more testing, the handling is not what I'm used to, and the ride height has increased 1/2" on the front. Too floaty, rubbery, nose dives more, way too much front end deflection, etc. Plus the roush springs /roush rear shocks are still there..so it's now a big mismatch.

Right now, I'm just pissed / livid.


I'm seriously thinking of going to the Vorshlag- Bilstein streetpro monotube suspension kit, complete with the Vorshlag camber / caster plates. But I'd like to use the new BMR handling springs, 240 lb/inch front LINEAR spring rate...... and 200 lb/inch rear DUAL-rate spring. I did read one posting where a fellow had a helluva time installing his BMR handling springs with his steeda HD strut mount. Top of the spring would not seat properly into the steeda HD strut mount.

As long as the BMR handling springs are compatible with the Vorshlag camber / caster plates..and also my steeda front STB, I believe I may well have an optimum setup for my requirements. My steeda front STB uses all 4 of the bolts of any strut mount..and not just the inner 2. There is a large hole in the middle of the stb, to get at the top nut of the strut. However, that large hole only allows for so much camber. Right now, camber is set for -1.5 degs..which is what I want for street use. I don't need any more caster adj, but that can be set to oem on the Vorshlag camber / caster plates.

Dunno if the above Vorshlag / BMR handling spring combo has ever been tried, but looking at all the data, I think the 2 would be compatible, like as far as front/rear spring rates ? Bear in mind that the BMR rear springs are progressive.

http://www.steeda.com/steeda-mustang-whipple-billet-strut-tower-brace-555-5726-whp/ Note hole in middle is raised quite a bit..and at an angle.

http://www.bmrsuspension.com/?page=products&productid=1462&superpro=0 Apparently these are typ slightly less than the advertised 1.5" f/r drop ( like by 1/4 - 1/2"..which suits me fine ) Click on features.

http://www.vorshlag.com/product_info.php?cPath=141_142_179&products_id=559
This package looks like the real deal..and no loss of piston travel with lowering springs.

http://vorshlag.smugmug.com/Product-Pictures/Bilstein-Shocks/i-t3XzfkS/0/XL/1_DSC8420-XL.jpg The piston on the Bilstein is massive...at 36mm. I don't think I would be busting it anytime soon.

I don't need coilovers, and the above proposal, IF it's all compatible, will meet my requirements. This will be the 3rd time I have had the suspension all apart..and I'd rather it also be my last. If I want a nice gloppy ride, I have a 2011 Fusion for that function.
 
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