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08-28-2018, 11:19 AM | #1 |
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Suspension feedback wanted
I know this is not the best way to solicit feedback about a suspension setup but was wondering if anyone had any feedback based on the picture from a recent autocross about how it appears my suspension is working and if any changes could/should be made. My car is mainly my DD with emphasis on autocross but not prepped for a specific class, my wife and I race in “time only” classes at our local clubs and just compare times to our friends and other cars. Currently my setup is Koni SA shocks, Swift Spec R springs (so 201 lbs front and 503 lbs rear), an E93 M3 front sway bar and control arm bits, Ground Control street front camber plates with 3.3* front camber, a touch of toe out, 1.7* (I believe) camber in the rear with a touch of toe in. The tires 255 RE71s. I like the setup am thinking about “upgrading” to coil-overs in the next year or so. I’ve had my current setup for about 3 ½ years now and have read that the Swift springs sag over time, and I’m thinking about maybe a little more spring rate. As it is, I made ½” spacers when I put the suspension together because I thought the Swift springs made the car too low. Anyway, thanks for any feedback.
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09-01-2018, 06:17 PM | #2 |
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Not surprised the car is rolling like crazy in the front on 200lb-in springs with 255 RE71Rs. I am running with ~400s and have just bought 500s to test with as the car still feels undersprung in the front to me.
-Mark
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09-06-2018, 01:30 PM | #3 |
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That's what I'm thinking as well, just want to find a decent balance for DD and autocross. I didn't realize the car was rolling this much until I saw the pix from this even. Coil-overs and "stiffer" springs are on my list of future upgrades.
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09-06-2018, 06:27 PM | #4 |
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Ditch the M3 bar, it's trash. Get stiffer springs.
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09-07-2018, 08:03 PM | #5 |
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I don't think the front stiffness is the only issue here. Looks like there's no trouble to lift the inside front wheel.
The real problem with the Spec-R front springs, is that due to the lowered height the car is always riding the bump stops. Anyway it seems like a good time to upgrade to coilovers. |
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09-11-2018, 11:53 AM | #6 | |
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This seems to be the next upgrade I'll be doing.
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09-12-2018, 07:15 AM | #7 |
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I don't understand the comment that the E93 M3 front sway bar is trash. That needs a bit more explanation to put it into context.
The situation is going to change a lot with new coilovers, so I don't see how that can be a universal conclusion. |
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09-27-2018, 01:07 PM | #8 |
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As a temporary "fix" I ordered the Hotchkis 33mm front bar which should arrive today, get installed on Saturday and tested Sunday morning at a local autocross event. New springs/shocks are on the "to-do" hopefully over the Winter.
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09-27-2018, 02:54 PM | #9 | |
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OE style struts like Koni paired with mild spring upgrades like swift is going to ride on the bump stops just like the OE setup does. It takes a lot more spring rate to keep off the bumps stops when you only have ~4-5in of total suspension travel to play with. Dial in a lot of rebound for autocross to keep the car down on the bump stops. Swift springs dial in a lot of rake and drop the car lower than I like, personally. That is a lot of what you see in the pic. Does the car handle neutral or not? Coilovers will be a much different ball game to tune since they usually eliminate the "spring supports" of OE struts but don't come with springs stiff enough to stay off the bump stops. Changes from steady state travel to under-steer/over-steer become much more transparent and abrupt when there is no spring supporter in place. My thoughts are that with the sway bar upgrade your next post will be "how do I get rid of all this terrible under-steer." Last edited by bbnks2; 09-27-2018 at 03:17 PM.. |
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10-01-2018, 10:12 AM | #10 |
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Turns out you're wrong. The car didn't have any new/additional under-steer and did well, hard to same if it was any better though. I did co-drive with a national level driver who liked the car and said it was well balanced but felt the boost comes on "a bit aggressively". He also beat my by 3 seconds on a roughly 55 second course. I'm still .1 second slower than the 2 '18 M2's that show up but I'm getting closer to their times.
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10-01-2018, 11:11 AM | #11 | |
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10-01-2018, 02:19 PM | #12 |
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Thanks. I have the JB4 boost control and JB4 BEF, I limit 1 gear boost to 5 lbs when racing and can limit boost in 2nd and 3rd as well, but that doesn't slow down the delivery of the boost. There is a map 6 where you can set max boost in 500 rpm intervals I might play with over the winter. I'll do some reading on the MHD torque reduction also.
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10-05-2018, 03:15 PM | #13 | |
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Last edited by bbnks2; 10-05-2018 at 03:21 PM.. |
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10-18-2018, 01:16 PM | #14 | |
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10-18-2018, 01:33 PM | #15 | |
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JB4 tuning for 2nd gear would definetly help if you want to limit boost (torque) in the lower rpm range. Last edited by bbnks2; 10-19-2018 at 12:44 PM.. |
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10-18-2018, 03:33 PM | #16 |
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Sure front spring seems a tad soft - but depends if the car is compliant and doing what you want it to do.
"Roll" isn't a bad thing, as long as the car is loading and behaving as it should then there is no need to take immediate action on it. I guess IMO I need more information on actual car behavior before for certain I can agree that upgrading suspension is the right way to go. Sure SA Koni's are an entry level shock, but if you don't know what is wrong with the car or what you want to improve throwing $4000 shocks won't fix anything. Just IMO. Just to show that roll isn't always bad: And to more extremes: |
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