The Tarett arms are adjustable for roll center on the ball joint side as well as camber and caster. Camber is adjustable via shims at the chassis end of the arm just like the Porsche factory cup car parts. In fact, the same shims are used.
The caster and wheelbase is adjustable via this red eccentric that the tension rod in the front and the trailing arm in the rear bolt to. The arm pivots on spherical bearings eliminating all rubber that can flex and cause the alignment to deflect and to cause rubber feeling and slow response.
These are the shims used to adjust camber by spacing out the lower arm between the man body of the arm and the spherical bearing inner pivot.
We replaced the OEM front suspension tension rod and rear suspension trailing arm with these adjustable spherical pieces from Tarett Engineering. The Tarett parts give full adjustability for the caster int the front of the car and wheelbase in the rear. You can also adjust the anti-squat and anti-dive to a degree, something that is not often exploited and should be considered in a lowered car.
A spherical bearing is used at the chassis end of the of the Tarett arms. You can see the spacers and washers that you can stack to adjust the anti-squat and anti-dive by moving the bearing up and down. The stock front tension and rear trailing arms also use a spherical bearing but when going to a lot of negative camber the wheel goes forward in the wheel well and the adjustable length lets you center it again. The tension arms also give the ability to adjust caster precisely.
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Ok, I really like the idea of using the HLS to do rake; will be cool if that works well. Do you know what the roll centers end up like on these things when lowered and strut inclination? I was looking at a bunch of more modern McPherson strut cars and trying to figure out what they’re doing for geometry lately.
I am waiting for the right springs to come in so I can figure stuff out and get it all set up. Next article.
Cool, looking forwards to it. I’m in the middle of some some relatively weird design work for an SCCA car so wanted to sanity check some stuff before I start machining a bunch of NLA parts; I’m basically mulling over changing steering axis inclination on 1st gen RX-7 knuckles.
Whole project is going to be going relatively slowly because I have a one month old daughter now, but I figure if I’m going to the extent of having shock pistons made for struts and doing cambered floater hubs on a live axle, might as well be thorough.
You can look to off road and circle track parts for camber floating live axle hubs. Some Mustang guys run that stuff on drift cars too. I am in the middle of figuring out how to control scrub on a strut suspension with really wide tires. My first idea got banned by FD before we could even make it.
I’m cribbing design of it from circle track practice certainly, but scaling down – the circle track stuff with the right features all tends to be 5×5″ bolt pattern and all the affordable good 15×7 wheels (yay SCCA rules) are 4x100mm.
I assume you’ve seen the Revoknuckle, Superstrut, and the dual pivot lower control arm solutions… I’ve been thinking of the same thing and how to get something like that through the rules. Only about 9.5″ of tread width, but on slicks, and I’m not sure power steering is in the weight budget.
What about something like the Chevy Cruze WTCC front strut – they had a big bracket moving the strut around the tire which could let you sink the knuckle deeper into the wheel.
“The anti-corrosive construction is one of the reasons why KW Clubsports have a limited lifetime guarantee.” The KW Clubsports do not carry a warranty as stated by KW’s web site, unlike the other models. Unless you’re referring to another guarantee, thought I’d point that out for those in the market.
Nice program !
I like the pinch bolts instead of jam nuts to lock the alignement settings ! Far more convenient and precise.
The Rennline brace doesn’t look that well engineered though, it’s more for show than actual stiffness.
I’ve had a really good result with tightening the front end with a triangle brace on the front subframe, where there is usually just two stamped steel braces, I have a solid piece that triangulates the whole subframe instead and the difference is quite noticeable ! Should be even more so with full spherical bearings suspensions !
Did you fabricate the brace or is it commercially available?
It’s a Ultra Racing brace. I’m sure you can easily fabricate one like it. But it was very cheap.
It protrudes a bit underneath the car, but no big deal on mine, it never touched anything (and I’m lowered).
Check out their strut brace too, looks much stronger than the rennline 😉
I’ve been running Tarett parts for 15+ years on my aircooled cars, top notch stuff that is built to last. We recently added the Tarett cockpit adjustable sway bars to our 987.1 Cayman racecar and they are awesome too. It’s so nice to be able to make adjustments on the fly without losing time on track or having to roll around on 100+ degree asphalt between sessions.
We agree and that’s why we chose them as well!
Is this project still going on, I’m building up my 2009 Cayman S and looking for ideas.
So far I have JRZ RS’s front and rear, Tarett lower control arms front and camber plates up top. Rennline tie-downs and rear support. Adjustable Rear toe links and I have a Tarett 22mm rear anti-swaybar and adjustable swaybar links.
My car is a PDK and I live in Arizona so I just had a BGB transmission cooler installed. Next, I have Sparco EVO race seats and harness bar going in as soon as I get my BBI mounting brackets, any day now.
It’s an ongoing prosses so I’d like to see how this build is going.
We are about to do a bunch of engine and cooling stuff.
Mike, Two of us own a 987.2 and are about to embark on suspension upgrades. We are both instructors with BMW and PCA and Audi. We have stock suspension, albeit low mileage car. 18″ wheels and 200 R comp type tires. We have experienced understeer, wheel hop and lack of ease to slip angle the car and get on throttle. As we research we are leaning to the Tarett and have watched your video on the suspension work you did on the 987.2. We are wondering if the work you did to lower the tension/thrust arms, etc. (to reduce anti dive and anti squat) actually worked to reduce hop? Stephan and Zafer
Billy Johnson tested the car at Buttonwillow and he did not complain about wheel hop, there is an aero imbalance that we need to fix. that was causing understeer. Billy said the back of the car was very planted. It was turning 1:57 laps which is ok for the type of tires. I think the car has another 2 seconds in it easily with some more suspension and aero tuning. I was not there that day and I could have worked it better working with Billy.