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      06-03-2017, 12:12 AM   #67
lowside67
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Front Camber Arm Offset Bushings

Starting to get a little lonely in this thread - it seems all the sane people have sold their 128s and are on to FRS or Corvettes... hmm, those both seem like good ideas! But yet here we are, trucking on.



With my front camber plates maxed hard against the strut tower opening, my car has never been able to achieve over -3 degrees of camber, and at my current ride height, I have -2.9 degrees which is the max I can get. The car is starting to work nicely but I have found it still to be a bit pushy especially on sweepers and my front tires are still wearing a good bit more on the outside, so I decided it was important to try to get a bit more camber in the car.

There are two options to do this - either space the camber plate down low enough that you can get the top of your strut UNDER the opening or make the control arm which controls camber longer. Option #2 is effectively what buying the 1M arms would do, except they are not legal for my class.

Option #1 requires a bunch of fiddling, raises my ride height, and eliminates the possibility of ever running remote reservoir or top-adjusting shocks. Accordingly, enter Option #2 - offset bushings.


Custom delrin offset bushing left, stock non-M bushing right

As you can see - I have gone straight to custom built bushings, in this case, built by John Vitamvas, a top DSP competitor in a heavily modified E46. While off the shelf offset bushings do exist for this car, the few who have run them have had significant issues with them spinning inside the control arm which will cause an unpredictable and terrible feeling car. I sent a new set of control arms (these are stock non-M arms) to John and asked him to machine me a set of bushings and install them for me. Here is what arrived:



Installed, you can see how they effectively lengthen the control arm which will "push out" the bottom of the wheel, adding camber, exactly how the 1M arm would.


Stock 60k mile 128i arm top, new non-M arm with custom delrin bushing bottom

The difference from the bushing bolt hole to the round nub on the ball end side (just chosen for a constant repeatable measuring point) is approximately 1/2". This 1/2" of additional control arm added 0.7 degrees of negative camber per side on my car. Camber after alignment today is -3.6 degrees on each side in the front.

As you can see, I have marked them to make sure after my next event that I can check that they have not moved.

A note about tire clearance:

Generally accepted wisdom on this forum is more camber = more ability to fit tire. I have said until I am blue in the face that adding camber via lengthening the lower control arm actually SUBTRACTS available room for tire clearance and I have experienced this with the above install. I went from tires that were extremely close but never rubbed (255-40-17 extreme summer tires on 9" wider +35 front wheels) to ones that will now rub on large bumps when hit straight on such as a dip in the highway. I don't anticipate this being an issue at autocross but let this serve as a reminder that if you don't need the full amount of camber these bushings would provide, better to clock them at say 10-11pm (assuming they are a clock facing us as posed above) and make sure your camber plate stays maxed.

Lots of seat time coming up in the next few weeks and I am looking forward to running in Packwood at the SCCA National Tour against what I expect to be a great showing of top STX cars.

Until next time,
Mark
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Last edited by lowside67; 06-04-2017 at 12:41 AM..
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      06-03-2017, 09:00 PM   #68
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How does one contact John? Are you trying to reach a certain amount of negative camber?
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      06-04-2017, 12:42 AM   #69
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I would say the goal was simply "more" - I was expecting about a half degree of camber more and these added slightly more than that.

You can find John Vitamvas on Facebook.

Cheers,
Mark
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      06-04-2017, 11:26 AM   #70
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Quote:
Originally Posted by lowside67 View Post
I would say the goal was simply "more" - I was expecting about a half degree of camber more and these added slightly more than that.

You can find John Vitamvas on Facebook.

Cheers,
Mark
What kind of front spring rate are you running?

I have 255/40/17 on 17x9 and I don't seem to need more than the -2.2* that I have right now... wear is right above the wear bar actually... 34psi cold in the front tires... i cant see more camber helping anything. Seems like more camber would actually only serve to reduce grip on the inside tire...
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      06-04-2017, 01:34 PM   #71
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Originally Posted by bNks334 View Post
What kind of front spring rate are you running?

I have 255/40/17 on 17x9 and I don't seem to need more than the -2.2* that I have right now... wear is right above the wear bar actually... 34psi cold in the front tires... i cant see more camber helping anything. Seems like more camber would actually only serve to reduce grip on the inside tire...
From my table of contents:
Front Springs: Swift 7.0kg (392lb-in) / 7" length / 65mm ID
Rear Springs: Swift 12.0kg (672lb-in) / 9" length / 65mm ID


I am running RE71Rs and the car sees basically 100% autocross miles. -2.2 and 34psi are both quite a ways different than my settings - is your car competitive at autocross?

Cheers,
Mark
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      06-05-2017, 10:36 AM   #72
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No offense, but you're either under driving the car or have a drastic setup if you think 2.2* is okay. I was around -3.3* and was chewing front tires.

Yes, law of diminishing return comes into play where you evaluate contact patch on the front tires vs overall wear. But on a BMW you will never be able to satisfy all of these constraints.

Also, minor edit: You can run 1M/3M arms but you have to go back to an OE fixed top hat. Cannot run both a camber plates and lower arms that are longer in length than OE.

Also Also - I still think a 128 can be competitive. But it was time to move on a try something different. Just didn't have the time, or patience to keep on testing waters on the BMW. Now I can't use my car as an excuse for sucking :P
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      06-05-2017, 12:46 PM   #73
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Quote:
Originally Posted by lowside67 View Post
From my table of contents:
Front Springs: Swift 7.0kg (392lb-in) / 7" length / 65mm ID
Rear Springs: Swift 12.0kg (672lb-in) / 9" length / 65mm ID


I am running RE71Rs and the car sees basically 100% autocross miles. -2.2 and 34psi are both quite a ways different than my settings - is your car competitive at autocross?

Cheers,
Mark
I am new to autocross, so I think a better driver would be more competitive than I've been so far. I think I'll need to re-assess tire wear when we get some warmer weather. 60-70f doesn't seem warm enough to generate any real grip with RS3's. I can't seem to get ANY heat into them with the short ~40s courses we are limited to around here. I come off course and my tires and race pads are still cold lol no fun...

I can tell you that last season at HPDE's I was seeing as high as 1.3 g's with stock suspension, 27mm front bar, M3 arms, and -1.7* camber. Front tires were scrubbing as far as the bottom of the wear triangle (still not that bad at all). same tire temps in the range of 34psi cold to 38-40psi hot.

Mods are in sig (fenders and M3 arms put me into Modified classing with the evo's )

Last edited by bNks334; 06-05-2017 at 01:18 PM..
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      06-05-2017, 01:31 PM   #74
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Quote:
Originally Posted by bNks334 View Post
I am new to autocross, so I think a better driver would be more competitive than I've been so far. I think I'll need to re-assess tire wear when we get some warmer weather. 60-70f doesn't seem warm enough to generate any real grip with RS3's. I can't seem to get ANY heat into them with the short ~40s courses we are limited to around here. I come off course and my tires and race pads are still cold lol no fun...

I can tell you that last season at HPDE's I was seeing as high as 1.3 g's with stock suspension, 27mm front bar, M3 arms, and -1.7* camber. Front tires were scrubbing as far as the bottom of the wear triangle (still not that bad at all). same tire temps in the range of 34psi cold to 38-40psi hot.

Mods are in sig (fenders and M3 arms put me into Modified classing with the evo's )
If they're RS3v2s depending on how long you've had them they're probably heat cycled out already (Lots of people, including me threw away tires that had 5/32nds of tread on them yet 80 autocross runs cause the tires are dead)

Also, a lot more than just fenders and M3 arms bumps you out of STU (Intercooler, Stage 2+ Tune, DP with no Cat, Clutch...etc etc)
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      06-05-2017, 03:14 PM   #75
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Quote:
Originally Posted by Kgolf31 View Post
If they're RS3v2s depending on how long you've had them they're probably heat cycled out already (Lots of people, including me threw away tires that had 5/32nds of tread on them yet 80 autocross runs cause the tires are dead)

Also, a lot more than just fenders and M3 arms bumps you out of STU (Intercooler, Stage 2+ Tune, DP with no Cat, Clutch...etc etc)
Yeah, you're right. I was thinking for street prepared, but I am beyond that too now with the clutch which I forgot about. Mods were done for HPDE not to be competitive in AX. I am still trying to learn as much as I can. AX is a big help with car control and getting suspension dialed in.

I agree with you on the tires. They seem pretty shot (bought last spring). Going to order a set of RSR-RR's this week to see how they do seeing as how cheap they are. RE-71 cant seem to be touched in the category...

Can't blame the tires entirely though. It's probably my driving style as well which has also steered me in a much different direction suspension wise than the people I am trying to use as comparison data points... definitely makes me wonder about people needing 3*+
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      06-05-2017, 04:05 PM   #76
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Yeah, you're right. I was thinking for street prepared, but I am beyond that too now with the clutch which I forgot about. Mods were done for HPDE not to be competitive in AX. I am still trying to learn as much as I can. AX is a big help with car control and getting suspension dialed in.

I agree with you on the tires. They seem pretty shot (bought last spring). Going to order a set of RSR-RR's this week to see how they do seeing as how cheap they are. RE-71 cant seem to be touched in the category...

Can't blame the tires entirely though. It's probably my driving style as well which has also steered me in a much different direction suspension wise than the people I am trying to use as comparison data points... definitely makes me wonder about people needing 3*+
My FRS I run -3.5* with a car that is 300 lbs lighter than my 128i was. I could probably go to -4* if I wanted to...
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      06-05-2017, 05:29 PM   #77
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Quote:
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My FRS I run -3.5* with a car that is 300 lbs lighter than my 128i was. I could probably go to -4* if I wanted to...
You're right, plenty of people run that. I'm still trying to wrap my head around it with street tires

Here is where my tires wore to after last ax:
https://ibb.co/gyMutF

Current Rs3 might be pretty shitty, but I must still be doing something terribly wrong behind the wheel lol especially since everything I've done to the suspension since running 6k12k should've put more stress on the front tires.

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      06-06-2017, 08:51 AM   #78
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Quote:
Originally Posted by bNks334 View Post
You're right, plenty of people run that. I'm still trying to wrap my head around it with street tires

Here is where my tires wore to after last ax:
https://ibb.co/gyMutF

Current Rs3 might be pretty shitty, but I must still be doing something terribly wrong behind the wheel lol especially since everything I've done to the suspension since running 6k12k should've put more stress on the front tires.
That's a pretty seriously rear-biased setup. Especially out of a 135, I'm surprised you can ever get power down, particularly on RS3s.

I'm doing some light-ish prep bringing my car back to STX-ish setup. I've been running a Corvette all year and highly prefer it in just about every way other than street driving, and for that they're pretty close...

I still have all the power stuff off my old car, so still 24(2)?/221 for power. Still have the diffsonline diff, and H&R rear bar.

After Jeff Wong's success developing Megan Racing shocks for the FRS, I'm picking up a set for my car. This mostly just started with me wanting to keep the Forgestars on the car, and I needed camber to do so, and a lower ride height to not look ridiculous. I'll be pretty much full weight (3050 or so). Keeping the SuperPro 27mm bar up front, 450/850 or so for springs, and shooting for 3.5F/2.5R camber with around 1/8 toe in rear to start.
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      06-06-2017, 08:33 PM   #79
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Just to confirm what everyone else has been saying about the offset arms... I threw on a set two days ago and gained almost exactly 1* of neg camber from offset delrin bushings. I picked them up from a buddy that gave up on his STU 135i I have no idea what brand they were or where he got them. Did yours have a set screw to prevent rotation?

I also pressed out the liquid filled bushings from a set of new front lower arms and will be throwing those on the next time I get bored.

I had the same tire rub issues that you did on the inner fender and had to bring the front end up a few MM. So much for the corner balance.

I totally forgot that the OE bushings were liquid filled and the 2nd one I was pressing out exploded like a vile water balloon full of filth. Remember kids... safety glasses.

Sitting at -3.2* up front -2* in back with .125" toe out on the front and about .0625" toe in on the rear.
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      06-07-2017, 06:19 AM   #80
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Quote:
Originally Posted by jvb6806 View Post
Just to confirm what everyone else has been saying about the offset arms... I threw on a set two days ago and gained almost exactly 1* of neg camber from offset delrin bushings. I picked them up from a buddy that gave up on his STU 135i I have no idea what brand they were or where he got them. Did yours have a set screw to prevent rotation?

I also pressed out the liquid filled bushings from a set of new front lower arms and will be throwing those on the next time I get bored.

I had the same tire rub issues that you did on the inner fender and had to bring the front end up a few MM. So much for the corner balance.

I totally forgot that the OE bushings were liquid filled and the 2nd one I was pressing out exploded like a vile water balloon full of filth. Remember kids... safety glasses.

Sitting at -3.2* up front -2* in back with .125" toe out on the front and about .0625" toe in on the rear.
If yours are the SuperPro ones that can physically adjust the offset of them, get rid of them NOW. Like, NOW.



Parts problems were a BIG source of my lack of success last year, and these were most of it... This is why I commissioned Vitamvas to make a set (which are now being run by both of the 128s still being seriously campaigned that I'm aware of, and I'm going to buy another set from him as I rebuild my car...).
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      06-07-2017, 06:53 AM   #81
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Quote:
Originally Posted by RyanDavies View Post
If yours are the SuperPro ones that can physically adjust the offset of them, get rid of them NOW. Like, NOW.


Parts problems were a BIG source of my lack of success last year, and these were most of it... This is why I commissioned Vitamvas to make a set (which are now being run by both of the 128s still being seriously campaigned that I'm aware of, and I'm going to buy another set from him as I rebuild my car...).
If only someone warned you of these issues beforehand, would have really helped.
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      06-07-2017, 07:09 AM   #82
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I saw that video... that is terrifying.

The ones I received look very similar to the ones that you used. The only difference is the delrin covers the sleeve as well. I am not sure who made them, but the guy I got them from is the AutoX chair for the chicago region and looking at his current and past builds he doesn't cheap out. I am sure he had them custom made from a reputable place. Him giving up on his STU 135 was the best thing that ever happened to me! He had a few pieces that either came off his car before he sold it, or never made it onto the car including these arms, HPA 1M strut brace, and a few other odds and ends.



I am going to mark them this week before heading to the full course at Autobahn CC on Friday. If the hold up to that I think they will survive autoX.

I might as well throw a picture of the front arms up as well.



sorry... I know this is your build thread.
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      06-07-2017, 09:22 AM   #83
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Not worried about other people posting in my thread! It's nice to see that I am not the only ... well, idiot seems a strong term ... enthusiast trying to make a BMW work. I keep having these terrible thoughts about a hyper-competitive out of the box Corvette.

I have two big events coming up - Canadian Nationals (which is a lot smaller than US Nationals but has a good ST* showing usually) and Packwood SCCA NT. Those two events are going to give me a quick reminder of where I am at and I will make the decision after that what's next for the car.

It's proven to be an STX winner locally and I think has a good shot as the top regional car, but I want to head to US Nationals next year and in a car that can get it done.

We will see!

Mark
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      06-07-2017, 09:43 AM   #84
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Quote:
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That's a pretty seriously rear-biased setup. Especially out of a 135, I'm surprised you can ever get power down, particularly on RS3s.
Definitely disappointed in the RS3's.

A 6k/16k setup is actually not over-steer biased at all. It is actually slightly under-steer biased, but is fairly neutral and it drives that way. Effective wheel rates are close to 309/285 (1.99/1.95hz) which is why I also deleted the front sway altogether.

Putting power down hasn't seemed to be effected that much at all. I feel like the car handles much better now that I am no longer dragging around the rear suspension. With 6k/12k and a big front bar I felt like the car plowed like crazy on turn in. The suspension was still rolling even after the front tires had turned in and taken set. The stiff front and soft rear setup just wasn't working for me. I felt like I had to drift the car around the course to get it to turn (slow in fast out).

The extra weight on the outside front tire (less squat with the stiffer rear springs) seems to allow me to drive the car around corners more, albeit with a much more careful left foot on the gas peddle. The car goes where I point it. Having 500wtq makes up for needing to wait a split second longer to get back on power on exit. I appreciate being able to toss the car into corners at higher speeds though. The outside REAR wheel seems to be doing MORE for me now instead of the suspension just rolling over... basically cross weight remains neutral during roll.

Quote:
Originally Posted by RyanDavies View Post
I'm doing some light-ish prep bringing my car back to STX-ish setup. I've been running a Corvette all year and highly prefer it in just about every way other than street driving, and for that they're pretty close...
I was surprised by how nimble a corvette can be on a tight autocross course. If only I could afford one for warm weather driving lol.

I don't think I'll ever de-mod my 135i just to be class competitive in autocross. My first event was a thrill, but the novelty has worn off already. Something about standing around for 6 hours to drive for 4 minutes doesn't do "it" for me. Not to mention the cost/value isn't there either. Latest even was pretty far away requiring bridge tolls, gas, and an entry fee of $90. People only got 5 runs. It's hard to even learn a course in 5 runs lol.

Quote:
Originally Posted by RyanDavies View Post
I still have all the power stuff off my old car, so still 24(2)?/221 for power. Still have the diffsonline diff, and H&R rear bar.
It's pretty awesome to see what people are doing with the 128i. Mine made 214/210 with light mods before I moved to the 135i. I might've been happy had I gotten headers and tune for 23xwhp. In a lot of ways 128i tuning knowledge exceeds what n55 tuners have experimented with.

Quote:
Originally Posted by RyanDavies View Post
After Jeff Wong's success developing Megan Racing shocks for the FRS, I'm picking up a set for my car. This mostly just started with me wanting to keep the Forgestars on the car, and I needed camber to do so, and a lower ride height to not look ridiculous. I'll be pretty much full weight (3050 or so). Keeping the SuperPro 27mm bar up front, 450/850 or so for springs, and shooting for 3.5F/2.5R camber with around 1/8 toe in rear to start.
I thought you were talking about how you plan to setup the FRS LOL That setup would actually make a lot of sense on an FRS.

For the 1-series, I needed over 2* camber to fit my 17x9 setup so I can see how that is a good reason to run more camber. The 27mm bar and 450/850 rates are where a good amount of people are at with there 1-series setups. 850 rear spring is 15k. Not far off at all from my 16k (896 lb/in). The front spring and bar is where I get lost. Your front wheel rate is going to be 153% stiffer than your rear wheel rate. The 27mm bar on top of that is going to effectively add another couple hundred lbs of spring rate. Your cross weight under load is way out...

Last edited by bNks334; 06-07-2017 at 01:54 PM..
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      06-07-2017, 10:42 AM   #85
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It's nice to see that I am not the only ... well, idiot seems a strong term ... enthusiast trying to make a BMW work.
I'm not sure idiot is too strong of a word. If I didn't have 5 years and way too much money into this car I would be running a twin in STX too. Locally I am doing well in this car, but I still know that I am the weak link on any given weekend. I am usually somewhere around top 40 on PAX in Chicago Region (170ish drivers usually) and so far this year have been 1st or 2nd in class going back and forth with a twin. TSSCC I try and shoot for closer to top 20, and Central Illinois top 10 is my goal. I don't always achieve those goals... but I am still getting faster with my new set up this year. I really need to go up to Milwaukee to see how I stack up to national level STX competition.
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      06-08-2017, 02:03 PM   #86
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I'm not sure idiot is too strong of a word. If I didn't have 5 years and way too much money into this car I would be running a twin in STX too. Locally I am doing well in this car, but I still know that I am the weak link on any given weekend. I am usually somewhere around top 40 on PAX in Chicago Region (170ish drivers usually) and so far this year have been 1st or 2nd in class going back and forth with a twin. TSSCC I try and shoot for closer to top 20, and Central Illinois top 10 is my goal. I don't always achieve those goals... but I am still getting faster with my new set up this year. I really need to go up to Milwaukee to see how I stack up to national level STX competition.
Toledo Express Airport is just 4 hours away and the Champ Tour is coming up here July 29/30th. You should find a way to come
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      06-09-2017, 11:07 AM   #87
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Toledo Express Airport is just 4 hours away and the Champ Tour is coming up here July 29/30th. You should find a way to come
I actually don't have any commitments that weekend as of now. I may ask around and see if anyone else is going. It would be fun shoot for not DFL that weekend.
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      06-23-2017, 06:50 AM   #88
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Definitely disappointed in the RS3's.

A 6k/16k setup is actually not over-steer biased at all. It is actually slightly under-steer biased, but is fairly neutral and it drives that way. Effective wheel rates are close to 309/285 (1.99/1.95hz) which is why I also deleted the front sway altogether.

Putting power down hasn't seemed to be effected that much at all. I feel like the car handles much better now that I am no longer dragging around the rear suspension. With 6k/12k and a big front bar I felt like the car plowed like crazy on turn in. The suspension was still rolling even after the front tires had turned in and taken set. The stiff front and soft rear setup just wasn't working for me. I felt like I had to drift the car around the course to get it to turn (slow in fast out).

The extra weight on the outside front tire (less squat with the stiffer rear springs) seems to allow me to drive the car around corners more, albeit with a much more careful left foot on the gas peddle. The car goes where I point it. Having 500wtq makes up for needing to wait a split second longer to get back on power on exit. I appreciate being able to toss the car into corners at higher speeds though. The outside REAR wheel seems to be doing MORE for me now instead of the suspension just rolling over... basically cross weight remains neutral during roll.



I was surprised by how nimble a corvette can be on a tight autocross course. If only I could afford one for warm weather driving lol.

I don't think I'll ever de-mod my 135i just to be class competitive in autocross. My first event was a thrill, but the novelty has worn off already. Something about standing around for 6 hours to drive for 4 minutes doesn't do "it" for me. Not to mention the cost/value isn't there either. Latest even was pretty far away requiring bridge tolls, gas, and an entry fee of $90. People only got 5 runs. It's hard to even learn a course in 5 runs lol.



It's pretty awesome to see what people are doing with the 128i. Mine made 214/210 with light mods before I moved to the 135i. I might've been happy had I gotten headers and tune for 23xwhp. In a lot of ways 128i tuning knowledge exceeds what n55 tuners have experimented with.



I thought you were talking about how you plan to setup the FRS LOL That setup would actually make a lot of sense on an FRS.

For the 1-series, I needed over 2* camber to fit my 17x9 setup so I can see how that is a good reason to run more camber. The 27mm bar and 450/850 rates are where a good amount of people are at with there 1-series setups. 850 rear spring is 15k. Not far off at all from my 16k (896 lb/in). The front spring and bar is where I get lost. Your front wheel rate is going to be 153% stiffer than your rear wheel rate. The 27mm bar on top of that is going to effectively add another couple hundred lbs of spring rate. Your cross weight under load is way out...
Since I'm finally getting around to reading this.

Even with stiff roll rates (such as those created by a 27mm front bar with a 1:1 motion ratio, and 450lb wheel rates), you still need > 3 camber to keep optimum front tire grip. 450lb seems to be about the happy place for front spring (I had tested between 400-600 in 2016). Much less spring rate and you are going to run into travel problems up front at anything resembling optimal ride heights / compromised geometry.

So, that gets around to the rear. It gains a lot more camber in bump, so that part is nice, and you don't need nearly as much static camber (2.2-2.5). However, having gone as high as 1200lb springs in the back, you run into two pretty substantial problems. 1. Ride compliance, and 2. weight transfer on throttle. If you're trying to get all of your roll rate done back there in spring, the car makes quite a bit of power for its rear grip. So it will much more easily overload the tires. I've got a clutch diff, a 20mm rear bar, and 850lb springs. The car still has excellent bump compliance, but won't run into the issue where one has to still be rather careful driving the rear of the car on power w/high lateral loads.

Having been down the road of operating on textbook theory many times myself over the years, ultimately, the clock is what matters most. I want as much compliance out of the rear of a car as I can for the car to still turn. It'll ride better on the street (and over bumps / surface irregularities on course, which exist a LOT on the east coast), and allow for much more aggressive throttle use without "digital" weight transfer. Kyle and I had talked a bunch about this early on in my development of the car originally, and I'd tried REALLY hard to go the textbook route with high rear spring rates and not much rear bar. It was a far disaster. 400/1200 might have worked from a balance perspective laterally, but it would have been HORRIFIC to drive on the street, and hard to drive aggressively.
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