[Julian2485]

What spring rates would you guys recommend for xi for street 4k/13k maybe ?

[Taskmaster]

Originally Posted by ajsalida

Why are you being such an asshole about this? Provide the stuff you say I'm not or STFU. Jeez....some people. Probably has a financial interest in selling cheap coil overs to noobs.

I'm being an asshole because you deliberately misinforming people.
Hear me out for a moment: How can you make such definitive statements of what is 'better' without having a way to substantiate that - it's bullshit.

You have literally no evidence outside of brand name, no first hand experience on this platform to make such a definitive statement, and you're upset with me for calling you on it?

So tell me again why the OP (or anyone for that matter) should spend $2500 for a kit that objectively might be better by the minuscule amounts, which honestly doesn't matter since OP isn't in competitive racing.

[Julian2485]

Originally Posted by Julian2485

What spring rates would you guys recommend for xi for street 4k/13k maybe ?

Anyone ?

[ajsalida]

Originally Posted by TheAxiom

I'm being an asshole because you deliberately misinforming people.
Hear me out for a moment: How can you make such definitive statements of what is 'better' without having a way to substantiate that - it's bullshit.

You have literally no evidence outside of brand name, no first hand experience on this platform to make such a definitive statement, and you're upset with me for calling you on it?

So tell me again why the OP (or anyone for that matter) should spend $2500 for a kit that objectively might be better by the minuscule amounts, which honestly doesn't matter since OP isn't in competitive racing.

OK I'll play. BTW I'm not upset, you are, and you're calling me out for stuff you aren't providing either, which makes you a hypocrite.

Maybe you have a reading comprehension issue. I am making definitive, objective statements about parts that have certain capabilities and features I consider essential to a track car. That cheap coil overs don't have. The (informed) opinion is whether those are important features to have or not, and I freely admit that is an opinion. I do own an XI and have modified it extensively. I don't want to put coil overs on that car. I am happy with a koni/eibach/ZSP set up.

And, in case you still can't read, I am NOT recommending OP or anybody else buy coil overs for this platform. I am actually saying don't do it. I am recommending if they still do want to they buy good ones that have capabilities cheaper ones don't, like being rebuildable and (at least) rebound adjustable. And I have recommended lower end coil overs for street use for people who have difficulty getting ride height correct on this specific XI platform because it seems to be so hard for some to get right.

If you have some objective measure or direct personal experience that supports your claim that non-adjustable non-rebuildable cheap no-name $800 coil overs are as good as 3k TCK/KW/Ohlins etc. FOR TRACK PURPOSES by all means put it up here. Not getting why you are so cranky esp since I am not even doing or saying what you claim you are so upset about.

My 335XI is not a track car, and never will be. It's a pig (4000 lbs) and has an AT. I live at 8k ft ASL my house has seen 10 ft of snow this season already WTF do I need coil overs for? You don't even need coil overs to run drivers schools and I said so. My point is simply if you want them be aware they are tools for people who know how to use them. So make sure you need them and then make sure you understand why. As such buy some good ones.

Now being a former serious track junkie, having set up lots of cars, even worked in the industry for years maybe some people might want to hear what I've got to say. Some might not but not getting all the hate. I do own an XI, I am familiar with its suspension quirks and there are a lot of them. It is a big heavy AWD car and if I were to even think about tracking it at much higher suspension loads I'd want a fairly high quality suspension on it. Because my life would depend on it. Literally. Just my preference.

Now why don't you tell us which cheap coil over kit you have on your XI and regale us with how well it does after thousands of track miles, and compare it to the expensive coil over kit you also ran for thousands of miles. Oh yeah, and the dyno plots. All 48 of them for the expensive double adjustables, too. Before and after 5000 track miles. Lap times too, cheap vs expensive would help, and notes on all settings.

JFC

[ajsalida]

Originally Posted by Julian2485

Anyone ?

Where did you get those numbers?

4k = 224 lb/in and 13 k = 728. That latter is pretty stiff for a street car. Are you running coil overs? If not you're going to have to pick something fixed from aftermarket.

This is a great thread for spring rates, all really depends on what you want to do and how stiff you can stand. Good discussion of motion ratios and wheel frequencies later on in it.

http://www.e90post.com/forums/showthread.php?t=85206

Some numbers from that thread

Stock 335i e92:

• Front: 145 lb/in
• Rear: 460 lb/in

Stock M3 e92:

• Front: 160 lb/in
• Rear: 550 lb/in

335i KW v3:

• Front: 260 lb/in (progressive average)
• Rear: 570 lb/in

335i KW Clubsport:

• Front: 400 lb/in
• Rear: 570 lb/in

M3 KW v3:

• Front: 285 lb/in
• Rear: 630 lb/in

M3 KW Clubsport:

• Front: 508 lb/in
• Rear: 800 lb/in

[Taskmaster]

Originally Posted by ajsalida

OK I'll play. BTW I'm not upset, you are, and you're calling me out for stuff you aren't providing either, which makes you a hypocrite.

I didn't definitively state if one product was better than another - we aren't the same.

Originally Posted by ajsalida

Maybe you have a reading comprehension issue. I am making definitive, objective statements about parts that have certain capabilities and features I consider essential to a track car. I do own an XI and have modified it extensively. I don't want to put coil overs on that car. I am happy with a koni/eibach/ZSP set up.

Consider essential why? What are the assumptions based on?

Originally Posted by ajsalida

And, in case you still can't read, I am NOT recommending OP or anybody else buy coil overs for this platform. I am actually saying don't do it. I am recommending if they still do want to they buy good ones that have capabilities cheaper ones don't, like being rebuildable and (at least) rebound adjustable. And I have recommended lower end coil overs for street use for people who have difficulty getting ride height correct on this specific XI platform because it seems to be so hard for some to get right.

Ahh, so being rebuildable and having rebound adjustment makes a product good? What about having good valving for the spring rates out of the box? Do you even know how much change is being made for per each turn of the knob? If you don't - how can you say it's 'good?'

Originally Posted by ajsalida

If you have some objective measure or direct personal experience that supports your claim that non-adjustable non-rebuildable cheap no-name $800 coil overs are as good as 3k TCK/KW/Ohlins etc. FOR TRACK PURPOSES by all means put it up here. Not getting why you are so cranky esp since I am
not even doing or saying what you claim you are so upset about.

This isn't about me, I'm not the one making baseless claims, using evidence I pulled out of my ass. You're whole premise is based on 'brand name.' Which is a shit way of evaluating products.

Originally Posted by ajsalida

My 335XI is not a track car, and never will be. It's a pig (4000 lbs) and has an AT. I live at 8k ft ASL my house has seen 10 ft of snow this season already WTF do I need coil overs for? You don't even need coil overs to run drivers schools and I said so. My point is simply if you want them be aware they are tools for people who know how to use them. So make sure you need them and then make sure you understand why. As such buy some good ones.

No disagreements here.

Originally Posted by ajsalida

Now being a former serious track junkie, having set up lots of cars, even worked in the industry for years maybe some people might want to hear what I've got to say. Some might not but not getting all the hate. I do own an XI, I am familiar with its suspension quirks and there are a lot of them. It is a big heavy AWD car and if I were to even think about tracking it at much higher suspension loads I'd want a fairly high quality suspension on it. Just my preference.

Now why don't you tell us which cheap coil over kit you have on your XI and regale us with how well it does after thousands of track miles, and compare it to the expensive coil over kit you also ran for thousands of miles. Oh yeah, and the dyno plots. All 48 of them for the double adjustables, too. Before and after 5000 track miles. Lap times too, cheap vs expensive would help, and notes on all settings.

JFC

That's exactly what I'm looking for - not some monkey behind the screen giving his opinion as if it was fact, when he's barely qualified to drive a car. Glad we are on the same page with expectations.

[ajsalida]

Originally Posted by TheAxiom

(clipped out cheap coil over deragement syndrome Coprophagia)

That's exactly what I'm looking for - not some monkey behind the screen giving his opinion as if it was fact, when he's barely qualified to drive a car. Glad we are on the same page with expectations.

Maybe I'm just an elitist. As I said I did work at a race shop for a bit. We cut open a lot of shocks (some that were not rebuildable) and you wouldn't like what you find inside. Entry level Koni, Bilstein were solid but nothing special. KYB of that era was junk, as was most OEM. On the higher end Penske, Ohlins etc. were extremely nice. KW didn't exist at that time. There was a level of quality of internal pieces (seals, reed valves, machining, pistons, tubes etc.) you saw repeatedly on high end you didn't on low end. We ran lots of shock dyno tests.

If you're looking for back to back track tests and dyno plots of cheap vs expensive coil overs, man I don't know where you'd find it outside of proprietary manuf data, which would cost a fortune to produce. Good luck though, not sure why you expect it or are so pissed off it isn't in this thread. Maybe go to a SCCA race prep forum. Manuf and teams tend to guard this data like state secrets though, so good luck with that too. And they won't be testing 1k coil overs. Or even 3k. You might ask one of your fave cheap CO manuf to provide it as a public service. There's a reason why pros pay $10k (and far more) for good shocks.

Anyway based on that experience, and bad personal experience with cheap shocks on race/track/street cars, I try to stay away from them and advise others to do so as well. It's an informed opinion, take it or leave it.

[Taskmaster]

Originally Posted by ajsalida

Maybe I'm just an elitist. As I said I did work at a race shop for a bit. We cut open a lot of shocks (some that were not rebuildable) and you wouldn't like what you find inside. Entry level Koni, Bilstein were solid but nothing special. KYB of that era was junk, as was most OEM. On the higher end Penske, Ohlins etc. were extremely nice. KW didn't exist at that time. There was a level of quality of internal pieces (seals, reed valves, machining, pistons, tubes etc.) you saw repeatedly on high end you didn't on low end. We ran lots of shock dyno tests.

If you're looking for back to back track tests and dyno plots of cheap vs expensive coil overs, man I don't know where you'd find it outside of proprietary manuf data, which would cost a fortune to produce. Good luck though, not sure why you expect it or are so pissed of it isn't in this thread. Maybe go to a SCCA race prep forum. Manuf and teams tend to guard this data like state secrets though, so good luck with that too. And they won't be testing 1k coil overs. You might ask one of your fave cheap CO manuf to provide it as a public service.

You're not an elitist, just the end result of good marketing. If you can come up with objective data that can quantify WHY said products are better, then you really don't have much more than your word.

That being said, I do think there is a difference between a high end coil over and an entry level model - I don't think this is necessary for the majority of people. (Hell, I don't even like 'adjustable') And for the record, many manufactures will provide you with a shock dyno for their off the shelf/revalved products. I remember when one shop was dynoing off the shelf Koni Yellows, and the valving was all over the place, and the variance from shock to shock was huge - compared to something like X brand (BC, Feal, etc) which show their shocks within range and valved appropriately for the spring rate.


It isn't as easy as saying X is better than Y. You running away when I challenge you on that proves it - You have a lot to learn (and I do too)

[ajsalida]

Putting all this unpleasantness aside, I figured some might not know what a shock dyno is and what it tells you. Here's an example pic of one, they all look more or less the same all though they can be cheap or super expensive with additional features



Basically you have a frame you mount the shock in (without a spring). Frame has a load cell that measure applied force, +/-. There is an electronically (hopefully digitally) controlled hydraulic (or electric) ram connected to the bottom of the shock, with position sensor either internal to the ram or external that measures how far the ram moves, and to help do closed loop feedback control of ram motion to force it to follow programmed wave forms under various loads the shock produces.

You send a sinusoidal waveform to the ram, then measure force and position times histories. You differentiate position to get velocity. Since the top of the shock is fixed, position sensor output is shock rod positon relative to the shock and so derived velocity is actual piston velocity in the shock. Then you plot Force vs velocity for the points you have. You get 2 quadrants of data, one for rebound and one for compression dierction.

Here's a random sample F-V plot I ripped of some website, various lines in a quadrant are different damping settings:



Here's the thing. This isn't like a chassis dyno where you get WHP and can say, oh yeah this or that mod gave me more or less HP so I will be more or less fast. Suspension tuning is a black art and highly subjective. Two different very fast drivers could have identical lap times in the same exact car with wildly different damping settings.

I mean it is informative if you know what you're doing and know what you want to do and how shock damping might fit into it, but it is not absolute and there are literally no "objective" data to say this or that damping curve will always make you faster (like a WHP dyno might). And finding somebody who can read one and translate it to repeatedly faster times for a given driver handling preference, that dude makes serious coin on F1, NASCAR, Indycar teams. They always have one shock guy. Usually such a team has a vast number of shocks with carious characteristics, a shock dyno in one of the team semi trailers, and that dude's job is to have dyno charts on all of them, he rebuilds them to spec sometimes, and he provides that data input the other dudes who do suspension tuning for specific tracks, weather, etc. Very big deal but shocks are only one small piece of a giant puzzle at this level.

What you really want is repeatable consistent data out of the shocks and evidence of any problems/deterioration, which is what the dyno provides, and then you begin to take notes and impressions of settings for all the tracks and various other tweaks you do for suspension (springs bars etc.). Dump it all into one big database. Like I said most teams this is super secret proprietary and obviously very time consuming and expensive to gather and keep up. A good shock dyno itself is not cheap either. The one I used was a 250k piece of hardware with all the data acq and other stuff. Not chump change, you can get them far cheaper but accuracy suffers.

Anyway if you can read F-V curves having them is helpful kind of generally but not so much specifically what to do next. And you're not going to see something like quality differences between low end and high end just off the curves. You might see some goofy stuff at low piston speeds like sticky seals or whatever, you might see big changes with temp as shocks get hot or oil foams in non-monotubes without floating pistons. But by and large you just see F-V. What you do with that is up to you, how much experience you have translating them to your car and whatever track situation you're facing.

[Taskmaster]

Originally Posted by ajsalida

Putting all this unpleasantness aside, I figured some might not know what a shock dyno is and what it tells you. Here's an example pic of one, they all look more or less the same all though they can be cheap or super expensive with additional features



Basically you have a frame you mount the shock in (without a spring). Frame has a load cell that measure applied force, +/-. There is an electronically (hopefully digitally) controlled hydraulic (or electric) ram connected to the bottom of the shock, with position sensor either internal to the ram or external that measures how far the ram moves, and to help do closed loop feedback control of ram motion to force it to follow programmed wave forms under various loads the shock produces.

You send a sinusoidal waveform to the ram, then measure force and position times histories. You differentiate position to get velocity. Since the top of the shock is fixed, position sensor output is shock rod positon relative to the shock and so derived velocity is actual piston velocity in the shock. Then you plot Force vs velocity for the points you have. You get 2 quadrants of data, one for rebound and one for compression dierction.

Here's a random sample F-V plot I ripped of some website, various lines in a quadrant are different damping settings:



Here's the thing. This isn't like a chassis dyno where you get WHP and can say, oh yeah this or that mod gave me more or less HP so I will be more or less fast. Suspension tuning is a black art and highly subjective. Two different very fast drivers could have identical lap times in the same exact car with wildly different damping settings.

I mean it is informative if you know what you're doing and know what you want to do and how shock damping might fit into it, but it is not absolute and there are literally no "objective" data to say this or that damping curve will always make you faster (like a WHP dyno might). And finding somebody who can read one and translate it to repeatedly faster times for a given driver handling preference, that dude makes serious coin on F1, NASCAR, Indycar teams. They always have one shock guy. Usually such a team has a vast number of shocks with carious characteristics, a shock dyno in one of the team semi trailers, and that dude's job is to have dyno charts on all of them, he rebuilds them to spec sometimes, and he provides that data input the other dudes who do suspension tuning for specific tracks, weather, etc. Very big deal but shocks are only one small piece of a giant puzzle at this level.

What you really want is repeatable consistent data out of the shocks and evidence of any problems/deterioration, which is what the dyno provides, and then you begin to take notes and impressions of settings for all the tracks and various other tweaks you do for suspension (springs bars etc.). Dump it all into one big database. Like I said most teams this is super secret proprietary and obviously very time consuming and expensive to gather and keep up. A good shock dyno itself is not cheap either. The one I used was a 250k piece of hardware with all the data acq and other stuff. Not chump change, you can get them far cheaper but accuracy suffers.

Anyway if you can read F-V curves having them is helpful kind of generally but not so much specifically what to do next. And you're not going to see something like quality differences between low end and high end just off the curves. You might see some goofy stuff at low piston speeds like sticky seals or whatever, you might see big changes with temp as shocks get hot or oil foams in non-monotubes without floating pistons. But by and large you just see F-V. What you do with that is up to you, how much experience you have translating them to your car and whatever track situation you're facing.

Bro, you need JRZs to do a HPDE once a year.

[ajsalida]

Originally Posted by TheAxiom

You're not an elitist, just the end result of good marketing. If you can come up with objective data that can quantify WHY said products are better, then you really don't have much more than your word.

That being said, I do think there is a difference between a high end coil over and an entry level model - I don't think this is necessary for the majority of people. (Hell, I don't even like 'adjustable') And for the record, many manufactures will provide you with a shock dyno for their off the shelf/revalved products. I remember when one shop was dynoing off the shelf Koni Yellows, and the valving was all over the place, and the variance from shock to shock was huge - compared to something like X brand (BC, Feal, etc) which show their shocks within range and valved appropriately for the spring rate.


It isn't as easy as saying X is better than Y. You running away when I challenge you on that proves it - You have a lot to learn (and I do too)

LOL so now you agree with me about high end vs low end? Again I do not even recommend coil overs at all! Just if you decide go that way for track purposes get some good ones. End of story. This is too funny. Post up some of this data you're claiming you've got, let's see it. Jeez did you have childhood trauma involving a coil over? Not getting all the hostility at all.

You can run bargain basement coil overs on your track car if you want, I just don't recommend it. Lot of other issues besides damping curves, quality of basic tube, valves hardware etc. There may be some new entrants to this field at very competitive prices, I suspect you may be involved in marketing them. That would be great. Why not give us your spiel devoid of all the insults.

[ajsalida]

Originally Posted by TheAxiom

Bro, you need JRZs to do a HPDE once a year.

Jesus Christ you are a fucking asshole, give it a rest.

[Taskmaster]

Originally Posted by ajsalida

LOL so now you agree with me about high end vs low end? Again I do not even recommend coil overs at all! Just if you decide go that way for track purposes get some good ones. End of story. This is too funny. Post up some of this data you're claiming you've got, let's see it. Jeez did you have childhood trauma involving a coil over? Not getting all the hostility at all.

You can run bargain basement coil overs on your track car if you want, I just don't recommend it. Lot of other issues besides damping curves, quality of basic tube, valves hardware etc. There may be some new entrants to this field at very competitive prices, I suspect you may be involved in marketing them. That would be great. Why not give us your spiel devoid of all the insults.

Originally Posted by ajsalida

Jesus Christ you are a fucking asshole, give it a rest.

So everyone who points out how full of shit you are, is an asshole? Cool beans.

http://farnorthracing.com/autocross_secrets18.html

[TEC]

Originally Posted by TheAxiom

So everyone who points out how full of shit you are, is an asshole? Cool beans.

http://farnorthracing.com/autocross_secrets18.html

OMG! You linked to Dennis Grants page? Wow... That dude was a DSM legend when it came to making them turn.

On the other hand, I think you may be going a little over board even though I get what you are saying.

[Taskmaster]

Originally Posted by TEC

OMG! You linked to Dennis Grants page? Wow... That dude was a DSM legend when it came to making them turn.

On the other hand, I think you may be going a little over board even though I get what you are saying.

I agreed with most of what he was saying, and I wasn't going to be a dick until I read his post about "good coils are 3k and up" and then I knew I was dealing with one of those guys. The fact that he dug in even deeper pissed me off more.

Take a look here:

http://www.motoiq.com/Projects/Subaru/AutocrossBRZ.aspx

Tested with cheap coils, KW V3s and KW Clubsports.

[Julian2485]

Originally Posted by ajsalida

Where did you get those numbers?

4k = 224 lb/in and 13 k = 728. That latter is pretty stiff for a street car. Are you running coil overs? If not you're going to have to pick something fixed from aftermarket.

This is a great thread for spring rates, all really depends on what you want to do and how stiff you can stand. Good discussion of motion ratios and wheel frequencies later on in it.

http://www.e90post.com/forums/showthread.php?t=85206

Some numbers from that thread

Stock 335i e92:

• Front: 145 lb/in
• Rear: 460 lb/in

Stock M3 e92:

• Front: 160 lb/in
• Rear: 550 lb/in

335i KW v3:

• Front: 260 lb/in (progressive average)
• Rear: 570 lb/in

335i KW Clubsport:

• Front: 400 lb/in
• Rear: 570 lb/in

M3 KW v3:

• Front: 285 lb/in
• Rear: 630 lb/in

M3 KW Clubsport:

• Front: 508 lb/in
• Rear: 800 lb/in

I have sonic tuning s3 coilovers for the xi spring rates are 7k/8k and the 4k/13k is what mfactory told me. They said is very close to the oem ratio. So you don't think they are good rates for a street driven xi? Should I go with a 12k rear instead and I also have a e90 m3 rear swaybar with rsb

[FamilyManTrackSedan]

Jesus why is there blood this thread... I left it so clean only 2 days ago.

[TEC]

Originally Posted by FamilyManTrackSedan

Jesus why is there blood this thread... I left it so clean only 2 days ago.

You were not here to supervise. The peasants have rioted and burned the town.

[sprp85]

Damn, I am loving it let's keep this going!

[NiNeTyOne]

Originally Posted by Julian2485

What spring rates would you guys recommend for xi for street 4k/13k maybe ?

The Eibach Pro kit for the e91 is 348lbs/in(?) in the front and 479lbs/in in the rear.

It's not enough for track use but almost ideal on the street.

I can get you my corner weights so you can do the math for the other chassis.

I'm winning to bet that the e92 front weights are not far off mine, so it's only the rear springs that would matter.

Having had the Pros I would say that a better spring is the Eibach ERS linear springs, but they are a bit more $$$

[NiNeTyOne]

I also wanted to address the hollow vs solid bar point.

Bar rate is what matters here. The thickness of the wall, the length of the lever arm at the various adjustment points, all factor. Measuring thickness is really not telling you much.

These are similar bars to the ones we ran on the Porsche Cup car: Swaybars

Racing bars usually are available in two or three (or more) wall thicknesses, to allow better rate tuning with the blades.

Any fixed bar is a compromise setup which starts with:

• Tire limited grip

• soft under sprung suspension (even the M3 is soft from the factory)

• soft overly comfort oriented bushings

• OE quality dampers (good ones are too expensive for production manufacturing)

etc.

I ran different bars at Laguna than I did at Infineon.

I can tell you after cycling through about 5 variations of bars that there is a wide difference between bars out there, even with identical dimensional specs. Think metallurgy.

The OE bars are not great, for a whole host of reasons.

These cars are heavy as shit and plow into corners. My solution has been to deal with the spring rates, get batter dampers and put some rear bar on. It's loose now, but fast.

Now I was putting a cup car around the old Daytona road course in about 1:54, before 991's were out, and while not pole fast, it's fast. So I know a bit about getting the car to go.

I like it. Your mileage may vary.

Here's what a really fast lap looks like, mind you this is a cool 3 seconds faster than my fastest time ever, and this guy has some pedigree.. (and a better setup) but it's still a fun watch:

[Julian2485]

Originally Posted by NiNeTyOne

The Eibach Pro kit for the e91 is 148lbs/in in the front and 479lbs/in in the rear.

It's not enough for track use but almost ideal on the street.

I can get you my corner weights so you can do the math for the other chassis.

I'm winning to bet that the e92 front weights are not far off mine, so it's only the rear springs that would matter.

Having had the Pros I would say that a better spring is the Eibach ERS linear springs, but they are a bit more $$$

What's the spring rate for the ers ?