04-17-2018, 11:08 AM | #1 |
Drives: E46 S54 race car, 964C2 Join Date: Feb 2017
Location: Southern Indiana
Posts: 912
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SS 1LE/ZL1 MRC strut mod to achieve more negative camber up front
Ok guys, I’ve passed along this DIY instructions to a few guys on the 1LE forum, but I thought it might be helpful to put this DIY out there for everyone.
After burning through my front OE Goodyears in my SS 1LE the first weekend I took it to the track (with front camber maxed out), I decided to look at how I might achieve more negative camber up front. I know there is some variability between cars, but my car maxed out around -2.2-2.3 front camber. After this mod, I’m at -2.9- 3.0 up front (tire wear perfectly even on track now). This mod to the front struts if very straightforward, and should only take about 30-45 minutes. I have a good friend with a lift, which made this easier having everything at eye level when standing. The only tools needed are a carbide bit/Dremel and some flat black spray paint. There are 2 parts to this mod: (Obviously first you need to put the car on jack stands with the front wheels removed, and remove both lower strut mount bolts) 1. Mildly elongate the existing camber adjustment range on the upper hole of the lower strut mount. This is how you are able to achieve more negative camber. Do not remove much material, a little goes a long way here. I used the imprint of where the camber bolt had previously been tightened as a template for material to remove. See top photo. 2. Grind down the ridge above the lower strut mount. If you don’t grind down the ridge on the strut, the inner barrel of the wheel will make contact with the strut ridge with the increased negative camber value. You might need to do a test fit or two to make sure at max negative camber the wheel clears the strut ridge. Also, don’t be alarmed if the strut bottoms out at the knuckle at max negative camber, mine did. I did this mod in April of 2017, have 8k road & track miles/ 25+ days on track. This was the best mod I’ve done to my car, front tires now wear evenly. Last edited by Provoste; 04-17-2018 at 11:24 AM. |
04-17-2018, 12:01 PM | #2 |
Drives: 2017 SS 1LE Join Date: Oct 2015
Location: San Ramon, Ca
Posts: 550
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Thanks for posting this!
With maxed out 2.3 neg camber I've been wearing out the front outside edges. |
04-18-2018, 09:35 AM | #3 |
corner barstool sitter
Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012
Location: Eastern Time Zone
Posts: 6,990
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Nice, thanks.
Guys, you should be able to estimate how much to grind from the center to center distance between the upper and lower holes and using a little trig. They're pretty close together, so a little (like maybe 1.0 mm) really does go a long way (maybe a whole degree). I did a very similar modification on a Mazda 626 that I used to autocross. Norm
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'08 GT coupe 5M (the occasional track toy)
'19 WRX 6M (the family sedan . . . seriously) |
04-18-2018, 12:23 PM | #4 |
Drives: 1LEs Join Date: May 2009
Location: DFW - Texas
Posts: 1,319
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I wonder how much is parts variation vs. alignment rack variation vs. combo. I showed -2.76 / -2.78 up front without elongating the holes. My front wear on both G3's and G3R's show I need more. Rear wear at -1.80 has been very even on both tire types as long as I rotate side-to-side frequently.
I have camber plates laying on the shelf but haven't had the time to install and realign. Thought about doing the old elongating trick before to see if I could get another degree negative out of my fronts. Will post if I do. For the stock ZL1 1LE front wheels on my SS, I had to profile grind like you show. Will have to probably take additional material off if I elongate the struts. I did grind enough to get ~4-5mm clearance without having to use a spacer. Provoste: Appreciate you showing the folks, too. |
07-28-2018, 08:33 PM | #5 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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I'm doing this mod this weekend. What I noticed was the top of the knuckle contacts the strut with almost nothing removed from the elongated holes.
I'm shaving a tiny amount of material from the back of the knuckle just above the threaded adjustment hole (where it contacts the strut restricting the camber). Don't worry. I'm test fitting as I go to ensure the wheel won't rub. I was at -2.2 before. I'll report back once I get the car realigned. I'm thinking anything -3.0 or better will make it worthwhile.
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07-28-2018, 08:58 PM | #6 | |
Drives: E46 S54 race car, 964C2 Join Date: Feb 2017
Location: Southern Indiana
Posts: 912
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Quote:
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07-28-2018, 09:10 PM | #7 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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I'm not sure what the tolerances are on the knuckles, but I don't think that I could have gained anything without removing a little material from the back of the knuckle. My knuckle was basically touching the strut before I started. Maybe there are slight differences which might help to explain why different people get different max camber values in the stock configuration.
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07-30-2018, 01:43 PM | #8 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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I thought I'd add some more pictures to the thread.
Before modification: Here's one of the test fits. Be sure to leave enough room for wheel weights to clear. I removed a little more material from the strut after this test. After the modification: After first coat of paint:
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07-30-2018, 01:50 PM | #9 |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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Provoste, thanks for taking the time to do this write-up. I found it very helpful.
I have an appointment for an alignment on Thursday. I'm switching to R7s so I'd like to get at least -3.0 up front. I'll report back with my results.
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07-30-2018, 08:42 PM | #10 |
Drives: E46 S54 race car, 964C2 Join Date: Feb 2017
Location: Southern Indiana
Posts: 912
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Awesome! Glad you found it helpful, please post alignment #’s when you have them. Very clean job too- looks completely factory!
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07-31-2018, 03:32 PM | #11 | |
Drives: ISO ss 1le Join Date: May 2018
Location: FL
Posts: 764
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07-31-2018, 03:55 PM | #12 | |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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https://www.amazon.com/gp/product/B00004UDJJ To clean it up, I used the Dremel EZ407SA with a 60 grit band followed by a 120 grit band. For the slots/holes I did all of the cutting with the 60 grit band (no cutter). For consistency I checked periodically using a digital caliper to remove 1.5mm of material from each slot. If you don't plan to remove any material from the back of the knuckle, 1mm is probably plenty.
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08-03-2018, 09:43 AM | #13 | |
Drives: '17 ZL1 Join Date: Jul 2016
Location: Fairmont, WV
Posts: 1,558
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So It looks like I needed to remove a little more material from the left strut knuckle. I did my best to get them even, but that's something that's hard to measure without the proper tools. Anyway, assuming the numbers are right, it looks like -3.3 of front camber is completely doable via this mod. I'm sure there's more room left in it, but I'll probably never try to go any further than that. If I ever have the need, I'll be looking into camber plates and/or completely different struts. I drove the car at PittRace yesterday after the alignment and it drove awesome. I was running R7s for the first time and ran a 1:55.26 which is respectable for that track. On street tires, my best time was a mid 1:59.
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08-03-2018, 09:58 AM | #14 | |
Drives: ISO ss 1le Join Date: May 2018
Location: FL
Posts: 764
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I have a question on when you are talking about removing material from the knuckle, what exactly are you talking about, i get the slots and the grinding, but am confused as to where the knuckle is you (and others) are referring to? I am attempting to achieve about a -2.9 - 3 with NT01, so should 1mm of material in the slots be good? Do you recall exactly how much material you removed from the struts? Thanks in advance. |
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