MS6 Suspension Data & DIY Bilstein Coilovers

[phate]

245/40 Rivals. They're just under the wear bars now so I'll likely need another set to finish out the season. They did really well with the longer sessions. It was a 3.5 mile course and it took them just a few corners to come up to temp and have their typical grip. I never felt them drop off as if they got too hot.

@Nliiitend1; and I were discussing on Sunday how the car would behave at the higher speeds since most everything has been focused on autocross and most recently focused on shifting the roll bias to the rear. I was lucky that Sunday was an autocross day on asphalt, because I set hot temps there and didn't touch them again before Monday. The car felt great, really. I could feel it was still pushy in steady state cornering but was able to get the rear around if I tried. This was just another indicator that the car could use more rear stiffness.

There's more grip available in the rear with pressure and alignment changes, too. If the rear were to respond to LCA bushings as well as the front did, I would probably pick up a little bit of grip from them, also. Hopefully it's enough to offset the stiffer rear bar once it's moved into the stiffer settings. I would love to see the car pick up even more front grip from more rear roll bias.

[dagrimey1]

Love that you continue to make the 6 a true race car. With that said I really got to come to Midwest.

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[KevinK2]

Originally Posted by phate .... Nliiitend1 and I were discussing on Sunday how the car would behave at the higher speeds since most everything has been focused on autocross and most recently focused on shifting the roll bias to the rear. I was lucky that Sunday was an autocross day on asphalt, because I set hot temps there and didn't touch them again before Monday. The car felt great, really. I could feel it was still pushy in steady state cornering but was able to get the rear around if I tried. This was just another indicator that the car could use more rear stiffness....

I think you were speaking of the road course showing more rear roll stiffness was need. From my experience when I was both winning my class in autox, and doing well with my old Triumph regularly on the road course, I always ran my fabricated 5 way adjustable rear sway bar in neutral position for the big track, and one step stiff for autox. Be careful when you let the big track suspension behavior influence the autox set-up.

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[Funkster777]

I had to opportunity to do a ride along with @phate;

In short, it was amazing. His car handles dramatically different than mine. I was very impressed with what he could do with it and how it moves.

Thanks again for the ride.

[KevinK2]

New sway bar testing ... I found some text results from when I modeled an Eibach sway bar for one of my cars, using a "simple beam theory" program. It reminded me that for a long slender bar like your new one, there is a contribution to lever-end deflection due to torsion bar slope at tube ends. If you transpose the applied point load to a force and a moment on the axis of the torsion rod section, the bending moment in question is based on the distance between the transposed force and the support bushing center (due to the dogleg in the lever arm). This puts the rod in "second mode" bending, with added deflection due to the slope at the ends:



A simple manual dial indicator at the "hump" in the torsion rod position would capture this effect:
http://i21.geccdn.net/site/images/n-.../TLS_53304.jpg

This effect was small in the more typical bar I had modeled, but your bar is much more prone to this, based on geometry.


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[phate]

Originally Posted by dagrimey1 Love that you continue to make the 6 a true race car. With that said I really got to come to Midwest.

It's fun, man, and epic midwest is an absolute blast. Not as big as some of the other epic meets, but definitely a great down home feel that is really relaxed.

Originally Posted by KevinK2 I think you were speaking of the road course showing more rear roll stiffness was need. From my experience when I was both winning my class in autox, and doing well with my old Triumph regularly on the road course, I always ran my fabricated 5 way adjustable rear sway bar in neutral position for the big track, and one step stiff for autox. Be careful when you let the big track suspension behavior influence the autox set-up. .

I think you've experienced what I've read about and from what Shaikh told me once on the phone. It was that 'big track' setups tend to need less rear stiffness, whereas autocross can handle more rear stiffness. I've never had experience with this, of course, but Shaikh said the over/understeer bias shifts towards oversteer as the speeds increase.

I've thought for a long time that the car needed more rear stiffness for autocross. I was happy to see that the car was still pushy at Autobahn - I interpreted this as being still far away from having enough rear stiffness to see that shift at higher speeds, based on what Shaikh and you have just said.

Originally Posted by KevinK2 New sway bar testing ... I found some text results from when I modeled an Eibach sway bar for one of my cars, using a "simple beam theory" program. It reminded me that for a long slender bar like your new one, there is a contribution to lever-end deflection due to torsion bar slope at tube ends. If you transpose the applied point load to a force and a moment on the axis of the torsion rod section, the bending moment in question is based on the distance between the transposed force and the support bushing center (due to the dogleg in the lever arm). This puts the rod in "second mode" bending, with added deflection due to the slope at the ends: A simple manual dial indicator at the "hump" in the torsion rod position would capture this effect: http://i21.geccdn.net/site/images/n-.../TLS_53304.jpg This effect was small in the more typical bar I had modeled, but your bar is much more prone to this, based on geometry. .

Right, it's just an overhanging load of equal and opposite forces at each end of the bar. I've been meaning to revise my theoretical spring rate calcs (not previously posted) for the bar and arms now that I have everything in hand. The shape of the arms was the big unknown, so I should be able to calculate everything now and see how closely it matches the bench rate.

[Code Monkey]

Originally Posted by phate I think you've experienced what I've read about and from what Shaikh told me once on the phone. It was that 'big track' setups tend to need less rear stiffness, whereas autocross can handle more rear stiffness. I've never had experience with this, of course, but Shaikh said the over/understeer bias shifts towards oversteer as the speeds increase.

I can only confirm this with experience. Your rear setup is already so much stiffer relative to the front and my setup, that every time you post about going even stiffer, my first thought is always wtf, lol. My car is now very nicely balanced for dry conditions; in the wet, on Maxxis RC1's and with traction control on, the rear still slides all over the place.

[phate]

Originally Posted by Code Monkey I can only confirm this with experience. Your rear setup is already so much stiffer relative to the front and my setup, that every time you post about going even stiffer, my first thought is always wtf, lol. My car is now very nicely balanced for dry conditions; in the wet, on Maxxis RC1's and with traction control on, the rear still slides all over the place.

That could also be shock valving at play. Does it still over steer in steady state cornering?

[Code Monkey]

I would say no, but it is very easy for me to lose the rear the moment the track gets just a little bit of rain, or maybe I should try driving the car more like a FWD car.

[Nliiitend1]

Higher vehicle speeds definitely need less rear roll stiffness relative to the front than low vehicle speeds do for proper rotation/balance/good "steady state" behavior.

[aviator79]

Im just going to ask it:
can I run just the rear setup u did? As in just the stiffer springs and perches and adapters on lca. Wish I didnt sell my BC COs for $200 as my rear is too soft on oem springs and koni struts.

[phate]

Originally Posted by aviator79 Im just going to ask it: can I run just the rear setup u did? As in just the stiffer springs and perches and adapters on lca. Wish I didnt sell my BC COs for $200 as my rear is too soft on oem springs and koni struts.

Yep, no reason you can't. The shocks have to be up to whatever you put in or ride quality will suffer. No adapter on LCA is needed with the QA1 or blue springs. Just the upper adjuster and spring.

Originally Posted by Code Monkey I would say no, but it is very easy for me to lose the rear the moment the track gets just a little bit of rain, or maybe I should try driving the car more like a FWD car.

I sort of do. The two big places I utilize the awd is the launch and corner exit. Otherwise it's very similar to fwd.

[phate]

Lots going on recently. Last weekend we autocrossed and it was HOT! I left the SD card in my laptop the first day, so no video. The second day I did get some video. I still haven't gone through accelerometer data, and not sure that I will do much with it. It's an asphalt surface that we autocross on only twice per year.

My fastest with a cone. It would have landed me second in class, but the cone knocked me back to 4th. That's just how it goes some days.

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Johanna's fastest:

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Me spinning after pushing way too hard:

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I got the rear bar bushings from @zenit; over the weekend, also. I put it all together on Wednesday and rate tested it similar to how I did the stock/whiteline bars:



The company who did the bar and arms stocks a few shapes of the arms, and these were the longest arm they carry. I expected them to be a little short after bending - they're ~2" short of what I need them to be, and they also aren't quite as wide as I'd hoped for. That just means that, for now, I can't get a good rate for the softest setting.

For the stiffest setting, I was expecting 188lb/in. The bar tested at 180lb/in. The "softest" setting at the shorter than expected arm length was 107lb/in. That's a little stiffer than I want it to be, starting out. I'm going to do a test fit on the car in just a few minutes. I have some ideas for extending the arms to achieve the softer rate. [With the outboard extension, all of the rates will be softened just slightly due to some bending in whatever assembly I make.]

[Code Monkey]

Fuck those lampposts, you're gonna hit one some day.

[ItsNox]

Originally Posted by Code Monkey Fuck those lampposts, you're gonna hit one some day.

I was thinking this the entire time!!!

[Deldran]

Originally Posted by Code Monkey Fuck those lampposts, you're gonna hit one some day.

Lol, it looks bad from the video. I have never seen anyone hit one of those. I have only seen 2 accidents. One where a wheel popped off. And one where guy got squirly at the end the run and clipped the curb.

Still safer than driving on the road with the hundreds of idiots driving around you.

Sent from my SM-N910V using Tapatalk

[KevinK2]

Clint, that run with one cone was impressive ... you were coming so close to several cones. And there is one big left turn about 30 sec into the run where you have a lot of discretion on what line you will use, any comment on your approach there? Was the run in 2nd gear? What rpm were you maxing at ? Rear Bar looks real good!

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[phate]

Well that didn't take long With pulling the exhaust off, lunch, taking pictures and being really careful double checking everything, it only took about 3 hours. If the exhaust wasn't in the way and I was just throwing it on, I bet it's <1 hour of work.



I stuck these guys up there to make sure the side pieces sit flush with the toe boxes and that the lower brackets were on the correct side.



That all looked good, so I pulled the lower brackets off and lubed up the bushings and the bar. Stuck the lower brackets onto the bar, then set the bar in place. I put the arms on and re-centered the bar, tightened down everything...



Driver side is at normal ride height, here:



Passenger side suspension is at full droop in this pic:







Plenty of clearance with the lower shock bolt:



And with the diff:







Everything turns smoothly, no binding at all. The holes must be aligned pretty closely!



You can sort of tell in this picture how the arms don't extend backward quite far enough.



And in this pic, you can get an idea of how far out the arms need extended:



I think this is going to be easily remedied, and with a better-than-originally thought idea of how to keep the end links vertical at all positions.




The other big question has been the exhaust. I'm going to end up dumping it right before the axle so I can lose weight, but I'm pretty convinced an exhaust shop could loop a section of the exhaust upward in this space:





Seems there's plenty of room, even for a 3" pipe to go through. I may try this first, just to know for sure it could be done.

[MSP611]

this sway bar and brackets look bad ass!! keep up tht work phate... maybe sell me one too lol... u know wat i would roughly cost for a mocked up 304 stainless short exhaust like ur thinkin?

[xfeejayx]

Originally Posted by MSP611 this sway bar and brackets look bad ass!! keep up tht work phate... maybe sell me one too lol... u know wat i would roughly cost for a mocked up 304 stainless short exhaust like ur thinkin?

Get in line ;-)

[phate]

Originally Posted by KevinK2 Clint, that run with one cone was impressive ... you were coming so close to several cones. And there is one big left turn about 30 sec into the run where you have a lot of discretion on what line you will use, any comment on your approach there? Was the run in 2nd gear? What rpm were you maxing at ? Rear Bar looks real good! .

It's tough to tell in the video, but there are 4 surface finishes over the entire course. In that second lot after the Chicago box, there's a strip of unsealed pavement that the whole car is on, then it narrows to only a strip at the right at the start of the braking zone that had decent grip, then ending at some pavement where grip majorly fell off. I tried to keep the car's right side tires on the higher grip surface while still turning, then tip toeing through that low grip braking zone to get the car slowed enough to make the next left hander. After that it was an attempt to cut off as much distance as possible, which I wasn't very successful at that.

After the start, we short shifted into 2nd and left it there. In the straight between the first and second lot, I data logged 6400-6500 rpm (I think that's ~55mph). The short straight coming into the finish saw as high as 7300 rpm.

[phate]

Originally Posted by MSP611 this sway bar and brackets look bad ass!! keep up tht work phate... maybe sell me one too lol... u know wat i would roughly cost for a mocked up 304 stainless short exhaust like ur thinkin?

I have exhaust work scheduled for next Wednesday. I'm going with a loop above the bar, for now. The big reason is not wanting to change the weight of the car too much, and also just to see if it can be done. I'll ask them about the dumped exhaust while it's in the air.

I have everything on the way for arm extensions and end links. I'll probably machine everything on Monday, retest the bar on Wednesday, then install Friday. That's an autocross weekend, so hopefully everything works out and we'll have this bar on for it. Not sure when I'll pull the whiteline bar...

[phate]

I think everything is ready to go for install, tomorrow. I had a small bend put in the exhaust so the bar would be clear of obstruction. I'll get pics when I'm putting the bar on. @MSP611;, I forgot to ask about a dumped exhaust when it was on the rack. I got distracted trying to explain the situation to the exhaust guy.

Anywho, I made some extension that look something like this:



3 positions for the end link to attach...

Then I made some turnbuckles for the rod ends. These will be my end links:



Did some measuring to make sure I was going to cut the arms to give the same positions relative to the bar:



And I cut some slots into the arms so I can fine tune the lever arm length:




Stuck it all together:






^That end link is attached to the wrong side, lol. They'll be attached to the outboard side of the arms.

The holes are separated by the same distance as the length of the slot. Each hole will overlap with another holes position so it can be adjusted to any length in a 7" range. For now, I can't fully utilize it because the upper attachment points for the end links are in two very narrow ranges. I'm planning to make a rail or something up top so I can slide both ends to keep the end link vertical at all positions.

I rate tested the bar with the new additions.

Softest: 72 lb/in
Stiffest: 190 lb/in

I tested at 4 positions. Graphed together, the stiffness vs lever arm length looks like this:

[KevinK2]

Nice work again. With the MR's included, how does your bar rate compare to the Whiteline in the poly bushings? Wheel rate or otherwise.

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[phate]

Originally Posted by KevinK2 Nice work again. With the MR's included, how does your bar rate compare to the Whiteline in the poly bushings? Wheel rate or otherwise. .

Wheel Rates:

WL Soft Setting: 43 lb/in
WL Stiff Setting: 52 lb/in

New Bar Soft: 72 lb/in
New Bar Stiff: 190 lb/in

If I leave the springs the same (850/800), the soft setting shifts the F/R roll bias by 2.4% rearward, and the stiff setting shifts it by 13.6% rearward.

My plan is to go back to a 700 lb/in rear spring. In that case, the soft setting shifts bias by .5% rearward, and the stiff setting by 12.3% rearward.

The soft setting is pretty darn close to what I wanted. I was expecting 73 lb/in for the softest setting.

[MSP611]

wow this is cool... now start sellin em!!! i need to figure out my dumped exhaust sitch but its hard not bein home

[phate]

Bar is on

























Most of the above pics are at full droop; the last couple are at or near ride height. The clearance between the tire and end link is tight, only ~1/8". At normal ride height, it's ~1/2" (plenty!).

I swapped to the 700 lb/in springs while I had everything apart to remove the Whiteline bar. We're driving up right now for an autocross tomorrow and Sunday.

[Code Monkey]

Definitely only a street/autox use, I would bang the shit out of it at the track.

[phate]

Originally Posted by Code Monkey Definitely only a street/autox use, I would bang the shit out of it at the track.

On what?

I'll take a picture of this tomorrow, but... If you look at everything in side view, the low part of the arm is within the area of the wheel and tire. Since the arms move with the wheel, any bumps you encounter at the wheel also raise the arms. It would have to be something the tires straddle to make contact with the arms.


Edit: or it would take dropping a wheel off of the road surface where the bar arm will contact the edge. Not good if that happens, anyway.

[Code Monkey]

Yeah, spinning out and going over the curbing would do it, the LCA has this metal stripe that goes around the bottom, I already bent it in on one side.

[phate]

Originally Posted by Code Monkey Yeah, spinning out and going over the curbing would do it, the LCA has this metal stripe that goes around the bottom, I already bent it in on one side.

It's probably best if you don't do that

[Code Monkey]

I have special, hmmm, "talents".....

[phate]

So...we found that the car can't be driven the same way, or the back end likes to go around the front. Transitionally, the car is sharper and it turns in better/faster. It turns in with a purpose, now. Steady state is nearly the same, there was a long sweeper and the car still pushed in that section. If we lifted off the throttle too much while the car was transitioning weight the back end would get loose very quickly, which is how the spins started. Before, we were having to lift very suddenly to get any rotation out of the car.

Tires were an issue. We ended up flat spotting and cording a tire in one spin. They were pretty much dead, anyway, and overall grip was down. We ended up mid pack in the class despite everything.

Subjectively, the car is more fun like this. I always compare to the speed 3 in this category and the 6 has always had a more serious and settled demeanor on course. The 6 feels light and agile with it.

It's a new day. We were offered a set of wheels with Dunlop Z2's on them. Going to leave the bar at the softest setting to see if tires were the main culprit. Videos and whatnot later.

[MSP611]

good info now u have too much rotation lol

[phate]

Originally Posted by MSP611 good info now u have too much rotation lol

Nah, just gotta get used to it and drive or more effectively. Fresh tires helped immensely. Just got done with our heat and everything was much better.

[MSP611]

Originally Posted by phate Nah, just gotta get used to it and drive or more effectively. Fresh tires helped immensely. Just got done with our heat and everything was much better.

well thts good to know i would like to know how a 6 setup like this drives... i might be a lil bit of a copy cat here soon when i come home...

[KevinK2]

Originally Posted by phate 09-24-2015 04:21 PM ... I rate tested the bar with the new additions. Softest: 72 lb/in Stiffest: 190 lb/in

Originally Posted by phate 09-24-2015 09:06 PM Originally Posted by KevinK2 View Post With the MR's included, how does your bar rate compare to the Whiteline in the poly bushings? Wheel rate or otherwise. Phate: Wheel Rates: WL Soft Setting: 43 lb/in WL Stiff Setting: 52 lb/in New Bar Soft: 72 lb/in New Bar Stiff: 190 lb/in

Thanks for the update from the track!

I know you are busy now, but when you can please clarify the new bar rates ... is 72/190 at the wheels?

Thanks

[phate]

Originally Posted by KevinK2 Thanks for the update from the track! I know you are busy now, but when you can please clarify the new bar rates ... is 72/190 at the wheels? Thanks

That's single wheel bump at the wheels. Since it's a 1.0 MR, there is no reduction in bench rate except for the loss through the angle of the end links.

[phate]

Here's a couple videos from the weekend I edited quickly. The second video is probably a new favorite of mine...Johanna said not to put the camera there...

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[KevinK2]

First, congratulations on some great engineering work, similar to a Tri-Point Engineering product. Very timely since WL's adjustable 24mm bar (23mm oem) is out of production, as is Cork Sports' 25mm, leaving only the $365 24mm non-adjustable Autoxe bar.

I finally plugged in your input numbers for your program, from post # 203, into my old Puhn based calculator, with the Whiteline bar at stiff for starts:


3469 lbs Total Wt
850F/800R springs
24mm OEM front bar
WL rear bar , stiff @ 485 lb/in
MR rear spring = .573
----------------------
Front Total WT Bias = 58.6%
Front Total WT Transfer Bias = 60.8%
Steady State => Slight Understeer
Front Sprung Wt Bias = 59.4%
16280 Fr Roll Rate, in-lbs/in @ Wheel
7984 Rr Roll Rate, in-lbs/in @ Wheel
Rear end link @ 1G = ~240 lbs

How does this compare? I used your sprung wt central CG location and lever arm to the roll axis, as those were inputs to my program for comparing other variables (to be corrected). I could run your current set-up, if that is more convenient.

.