"uofime-2" (uofime-2)
04/26/2017 at 13:53 • Filed to: None
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"uofime-2" (uofime-2)
04/26/2017 at 13:53 • Filed to: None | 7
| 6 |
I discussed in !!!error: Indecipherable SUB-paragraph formatting!!! that I believed that this car was intentionally held back handling wise from the factory in order to provide an easier to control and safer experience. It has been a long term goal of mine to fix that and there have been !!!error: Indecipherable SUB-paragraph formatting!!! of modification and research required to get there.
Lets start from the beginning, below is on the top is how you will recieve the car from the factory (roughly) and below that is what you can do adjusting the alignment equipment that comes stock on the car.
The goal here is to increase the grip at the front of the car relative to the rear of the car. The goal is to loosen the car up, make it corner harder and reduce understeer. In order to increase the front grip during cornering it is beneficial to increase the (-)camber. For a FWD or AWD car it is usually preferable to have the front camber be greater than the rear. For RWD cars that may make the car too unstable, but for understeer prone cars a little instability is good because it will help the car turn-in and it is easily fixed with throttle application to pull you out if the rear starts to step out too much.
I also zeroed the front toe angle, negative toe makes the car want to go straight and positive will make it easier to change direction, very much of either will increase tire wear.
With camber still not balanced the way I would like using the factory equipment, aftermarket parts were required. First I went with the cheap option, a second set of camber bolts in the lower hole of the struts. With those I gained another half a degree, which was still not enough to reach the goal. Short of slotting the hole in the strut the only other option is to move the top of the strut.
The most common way to do that is with adjustable camber plates, you’ll see these on pretty much every set of coilovers you can buy. They’re just two pieces of metal (usually aluminum) that when loosened can slide relative to one another. The inner one has a spherical bearing that the strut rod goes through to attach. The downside of these is that they are harsh and add a lot of NVH to a car due to being solid mounts and also that the spherical bearings will often get contaminated by road salt and grime, wear out, get loose in their housing and the suspension will clunk and make terrible noises.
Instead I went with offset strut tops, they maintain a rubber mounting and a regular shielded and sealed bearing. They provide lower noise and lower maintenance. The down side is they aren’t really adjustable. they only have three positions set by clocking them on the upper mounts to the chassis and you really only want to use one of those three positions.
In the desirable position you gain -negative camber and caster by moving the strut towards the center line of the car and back towards the rear.
All that adds up to -2.5deg of camber for the front which was very nearly the goal the whole time. I wasn’t going to worry about a tenth of a degree difference from my goal of 0.5 degres more front than rear, buuuuuut then t !!!error: Indecipherable SUB-paragraph formatting!!! messaged me saying he was selling his adjustable rear lower control arms... Those are the parts you need to change the rear camber with the multilink rear suspension in this (and the previous) generation WRX.
“So what,” you might say, used performance parts for a WRX, those are certainly not in short supply. Anyone could hop on NASIOC, facebook or craigslist and find dozens of adjustable LCAs for a WRX at any time and you’d be right. However these particular LCA’s are little more special than that, because they have a unique design and were only produced for a very short time.
There are two kind of LCA’s, ones with eccentric holes at the knuckle and ones with turn buckles between the two ends. The eccentric ones are cheaper but less robust and a total pain to adjust. The turn buckle style are more expensive and almost always use spherical rod ends. As we discussed before spherical bearings on a daily driven car have some serious downsides. That brings us to these LCAs, these LCAs are turn buckle style but instead of rod ends they use a housing with a large bushing. These are perfect for my application and darn hard to get! So of course I bought them and with the help of a !!!error: Indecipherable SUB-paragraph formatting!!! installed them that night.
They were only a minor pain to install, but by the time we were done it was getting late. Therefore, when we threw a measuring tape across the tires and found that the toe was way off I wasn’t about to get the car back in the air to try to fix it. So a careful drive home and then to work the next day was called for. Fortunately I was able to get an alignment appointment on 4 hours notice at the dealer near where I work to get it all straightened out before the drive home.
Looking at the top you can see just how bad it was. Next, looking at the bottom you can see just how “bad” it is now that I’m finished and have it where I want (gasp, redness) . Pretty much perfect -2.5 camber front, -2.0 camber rear, nearly zero toe at both ends.
Looking forward to my next track day on memorial day weekend to see how well it works when driving in anger. I do still have a couple more projects I’d like to finish before then though...
fourvalleys
> uofime-2
04/26/2017 at 13:56 |
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Oh hi.
I’m very pleased with how easy these were to install. Thank you for not bringing (more) rusty garbage into my garage. And also thank you for not keeping my neighbors awake because something went wrong.
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uofime-2
> fourvalleys
04/26/2017 at 14:07 |
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Thanks for volunteering to help, its a good thing I didn’t wait, the front was pretty screwed up too.
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fourvalleys
> uofime-2
04/26/2017 at 14:20 |
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Of course, always happy to lend my tiny garage.
I’m sure you’ll have an opportunity to help me out soon anyway... tiny brakes!
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uofime-2
> fourvalleys
04/26/2017 at 14:22 |
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not tiny, tactical!
Oh yeah, I’ll pump your brakes, if you know what I’m saying!
Justin Hughes
> uofime-2
04/26/2017 at 15:13 |
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Well there’s your problem -you’ve got three flat tires! You know what happened to that M3 with one tire just 1.5psi off... :D
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uofime-2
> Justin Hughes
04/26/2017 at 15:30 |
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Ha, they always do that, disconnect the hoses after the start and the machine forgets that they measured at the start.
Similar thing on the earlier alignment last year