project:BDR 2006 Evo STU build thread
I'm curious on how you came up with 31/31 psi for the Dunlops? I'm running nearly the same camber and toe, and spring rates, and much higher tire pressures. Did you do any testing with a pyro? or data?
Thanks
Thanks
When I first got my car, I ran it a few events on street tires (255/35/18 star specs). I have an adjustable RSB and a shep built rear diff (full rebuild... yay SM!). While trying to balance the car better on corner entry and mid corner, I adjusted the sway from full soft to full stiff. It helped change the balance of the car, obviously, but it also made putting power down on corner exit more interesting. I found the rear really stepped out when the RSB was full stiff. It was catchable if you knew it was coming, but it was definitely a mental exercise. On full soft, the car would not enter the corner as well, but it definitely was easier to drive out.
I think a very stiff RSB helps unload that inside rear tire even more, making it easier for the rear to break loose under power. If your RSB is adjustable, knock it down to the lowest setting and see how that helps. You may need to keep it low and adjust spring rates and damper settings to get the rest of the handling the way you want it.
Note that once switching to purple crack I set the RSB to full stiff and never went back. The grip level is much higher, so oversteer was more managable. I have had a co-driver or two spin the car, though... more than once in a run
Last edited by psushoe; Jan 18, 2012 at 09:42 AM.
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From: Why do they always call the Evo the Dark Side?
When we got there and it was incredibly cold we figured that 31/31 might not be far off. Mike actually liked the car better when the rears were at 29. It got a little warmer for heat 3 (helped by the tire blankets) and the pressures ended up at more like 34/32.
It was not something I would do in normal weather. I usually run 36/36 or a little higher.
When I first got my car, I ran it a few events on street tires (255/35/18 star specs). I have an adjustable RSB and a shep built rear diff (full rebuild... yay SM!). While trying to balance the car better on corner entry and mid corner, I adjusted the sway from full soft to full stiff. It helped change the balance of the car, obviously, but it also made putting power down on corner exit more interesting. I found the rear really stepped out when the RSB was full stiff. It was catchable if you knew it was coming, but it was definitely a mental exercise. On full soft, the car would not enter the corner as well, but it definitely was easier to drive out.
I think a very stiff RSB helps unload that inside rear tire even more, making it easier for the rear to break loose under power. If your RSB is adjustable, knock it down to the lowest setting and see how that helps. You may need to keep it low and adjust spring rates and damper settings to get the rest of the handling the way you want it.
Note that once switching to purple crack I set the RSB to full stiff and never went back. The grip level is much higher, so oversteer was more managable. I have had a co-driver or two spin the car, though... more than once in a run
I think a very stiff RSB helps unload that inside rear tire even more, making it easier for the rear to break loose under power. If your RSB is adjustable, knock it down to the lowest setting and see how that helps. You may need to keep it low and adjust spring rates and damper settings to get the rest of the handling the way you want it.
Note that once switching to purple crack I set the RSB to full stiff and never went back. The grip level is much higher, so oversteer was more managable. I have had a co-driver or two spin the car, though... more than once in a run
I've only done three events at this point with the rear diff fixed. One was at Hershey (rear bar full stiff). Car was a little scary. After that I softened the bar. The next day I ran at Waldorf with it soft, and it seemed pretty controllable but there weren't many high speed transitions (there's almost never a big slalom at Waldorf because of how the lot is shaped). And the 3rd event was last Sunday, where it was miserably cold and we never had much heat in the rear tires.
The WORKS bar on full soft is 13% stiffer than stock:
https://www.evolutionm.net/forums/wo...formation.html
The percentage of stiffness over stock is 13%, 23%, and 55%.
There's a few options here though if the car is too twitchy - keep it and add camber, go back to the OE bar, go back to the OE bar and add a little more spring, etc etc. I'm guessing that in normal conditions I'm going to want to do one of those, especially with the newfound power. But given that it was really cold, and the tires have ~200 runs on them I don't want to draw too many conclusions yet.
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From: MD
It did feel a little better on 29 in the rear, but that was mostly a bandaid to help and calm the rear down a little. Also, keep in mind it was maybe low-mid 30's when I ran. I didn't use the blankets. Martin Kriz, who was gridded in front of me, used them.
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From: Why do they always call the Evo the Dark Side?
You may have also nicknamed the car, since you kept using the adjective "haywire" to describe the handling...
I threw the wheels back on after them sitting in the garage for a couple months. I hadn't planned on autocrossing until March so I just made sure that they still had enough air for the drive down.
When we got there and it was incredibly cold we figured that 31/31 might not be far off. Mike actually liked the car better when the rears were at 29. It got a little warmer for heat 3 (helped by the tire blankets) and the pressures ended up at more like 34/32.
It was not something I would do in normal weather. I usually run 36/36 or a little higher.
Yeah, the rear diff changed everything. I really wish in retrospect that I had done that first. I might not have bothered with the aftermarket rear bar at all.
I've only done three events at this point with the rear diff fixed. One was at Hershey (rear bar full stiff). Car was a little scary. After that I softened the bar. The next day I ran at Waldorf with it soft, and it seemed pretty controllable but there weren't many high speed transitions (there's almost never a big slalom at Waldorf because of how the lot is shaped). And the 3rd event was last Sunday, where it was miserably cold and we never had much heat in the rear tires.
The WORKS bar on full soft is 13% stiffer than stock:
https://www.evolutionm.net/forums/wo...formation.html
I don't have a good sense for whether the car is lifting a wheel right now with the car on the soft setting, going to have to get a spotter at the next event There's a few options here though if the car is too twitchy - keep it and add camber, go back to the OE bar, go back to the OE bar and add a little more spring, etc etc. I'm guessing that in normal conditions I'm going to want to do one of those, especially with the newfound power. But given that it was really cold, and the tires have ~200 runs on them I don't want to draw too many conclusions yet.
When we got there and it was incredibly cold we figured that 31/31 might not be far off. Mike actually liked the car better when the rears were at 29. It got a little warmer for heat 3 (helped by the tire blankets) and the pressures ended up at more like 34/32.
It was not something I would do in normal weather. I usually run 36/36 or a little higher.
Yeah, the rear diff changed everything. I really wish in retrospect that I had done that first. I might not have bothered with the aftermarket rear bar at all.
I've only done three events at this point with the rear diff fixed. One was at Hershey (rear bar full stiff). Car was a little scary. After that I softened the bar. The next day I ran at Waldorf with it soft, and it seemed pretty controllable but there weren't many high speed transitions (there's almost never a big slalom at Waldorf because of how the lot is shaped). And the 3rd event was last Sunday, where it was miserably cold and we never had much heat in the rear tires.
The WORKS bar on full soft is 13% stiffer than stock:
https://www.evolutionm.net/forums/wo...formation.html
I don't have a good sense for whether the car is lifting a wheel right now with the car on the soft setting, going to have to get a spotter at the next event
There's a few options here though if the car is too twitchy - keep it and add camber, go back to the OE bar, go back to the OE bar and add a little more spring, etc etc. I'm guessing that in normal conditions I'm going to want to do one of those, especially with the newfound power. But given that it was really cold, and the tires have ~200 runs on them I don't want to draw too many conclusions yet.
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From: Why do they always call the Evo the Dark Side?
I finally pulled the tire blanket pics off my phone. There can't be too many pics out there of Dunlop cars with tire blankets
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From: Why do they always call the Evo the Dark Side?
The offseason begins
...
Overall though, no big changes planned...
* Hopefully more than 256 whp
* Fresh Dunlops, possibly on 17x9.5 RPF1s
* New camber brackets for the Motons to eke out a little more in front, like -3.3
* Probably a hair more static camber in the rear, like -1.2
* Pads that aren't HP+
...
Overall though, no big changes planned...
* Hopefully more than 256 whp
* Fresh Dunlops, possibly on 17x9.5 RPF1s
* New camber brackets for the Motons to eke out a little more in front, like -3.3
* Probably a hair more static camber in the rear, like -1.2
* Pads that aren't HP+
More than 256 whp
Definitely. Still want to play with a couple header/O2 combinations but the car is definitely in the ballpark.
Fresh Dunlops:
Not yet. I wanted to wait until the weather was a little nicer (Tire Rack says they have tons in stock in our size so no rush)
17x9.5's
Picked up a set of 17x9.5 RPF1s, powdercoated orange last week. They have 255 Dunlops on them currently with 5/32" left - too wide for STU, but I can use them for non SCCA events until I've burned em off or I need them for bigger events.
New camber brackets for the Motons / more negative camber in the front
The nice folks at Moton shipped them out to me pretty quickly after ordering. After making sure I wasn't crazy, I went to do the install tonight. It looked like the "B" / middle brackets were on, but they were installed in a way that looks like it would give you less negative camber (bolt forced to be closer to the wheel):
All I did was put the fresh "B" brackets on, but orient them the other way to move the bolt closer to the engine bay. From eyeballing it, it appears to have had the desired effect (more negative).
One of my bonus goals here was to be able to get more camber at the hub, so I can get less at the plate. Currently my plates look like this:
With the plate more towards the center, and less towards the engine bay, I should have a little more clearance to move the entire plate back and get more positive caster, since the Cirodesign plates are adjustable for caster as well. I currently have +5.0 on one side and +4.9 on the other, so I'm not sure how much I'll be able to pick up.
More camber in the rear
That'll happen when I get the car aligned next...
Pads that aren't HP+
I found a set of unused Hawk HPS cheap, so I'll probably run those for the non-summer months just to make the car less annoying on the street.
Other than all that stuff, it's just fluid changes.
I'm debating whether to go to the Dixie Tour... it's a 12 hour drive and STU is only 3 cars right now, but it might help me get into the 3 run mentality for the rest of the year. It'll probably depend on whether the car is remotely ready...
