viper501

http://www.vividracing.com/catalog/p...oducts_id/8370

v.

http://www.paragon-products.com/prod...ap-996-200.htm

v.

http://www.theracersgroup.com/shop/trgracing.php

v.

http://www.tarett.com/items/996-prod...lnk-detail.htm

?????

JimB

I guess I can try. I wish I had some pictures but I don't have any handy. On the back of a stock 996 you have three primary parts that hold things in place.

1) The first is usually refered to as the "lower control arm. It is the large arm that runs from the chassis to the bottom of the hub. On the car side it is held in place with an excentric (sp?) bolt that allows you to adjust camber. On the hub side, it connects with a bolt that comes out of a ball joint. This is the bolt that I've had break a couple of times. Not a good deal. This is the part that many replace with GT3 or cup car parts. The GT3 part splits in the middle which allows you to make it longer with shims. Longer means more camber.

2) The top of the hub is connected to the chassis by two "upper control arms". These are not adjustable although they can be replaced by aftermarket adjustable versions.

3) Toe is controled by a "rear tie rod". This is another weak link. It has an excentric on the chassis side and a ball joint on the hub side. The ball joint tends to go bad.

Other rear suspension parts include the coilover, drop links and sway bars.

The front is actually is similar. 1) It has the same lower control arm and can be replaced by the same GT3 or cup parts.

2) Rather than upper control arms, the front hub is held in place by the coilover which bolts through the fender. The coilover bolts into slots in the fender which allow some camber adjustment.

3) Obviously the front also has tie rods which allow the car to steer. The stock versions actually keep you from adding too much camber although they can easily be replaced with longer motorsport parts.

Like the back you have a coilover, a drop link and a swaybar. Oh and a diagonal arm that contols caster.

I think that's pretty much everything. I'm doing this from memory.

I hope this helps.
Jim

JimB

The first two links here show the rear upper contol arms. Personally I'd look at the ones from ERP or Motorsports rather than Agency.

The second two links are the rear tie rods I refered to.

karlooz

+1 on ERP. things may have changed but the AP parts i got were sub par. cheap heim joints that rusted and binded and steel bolts that also rusted... all within a few months.

one thing about the tie rods. be sure to lock out the eccentrics with the locking plates offered by tarett otherwise they are still susceptible toe changes.

JimB

I agree although many race series make you keep the eccentrics so the next best option it to "center" or "zero" them which is really nothing more than setting them to the middle position and not using them. Make sure to mark all your settings so you can correct them in case they move.

viper501

So I can fix the toe using just the adjustable rear tie rods? Is that the best solution?

karlooz

first make sure that you are at the bare minimum toe. it's just very odd that you have a factory sport suspension which produces excessive toe in.

the toe arms control the majority of toe adjustment. if you are at minimum then you should try out the tie rods before the upper control arms.

one thing though. you never mentioned what your alignment specs are. maybe you have too much camber and your toe is fine. it's just hard for me to believe that x74 caused excessive toe in.

10 GT3

I was surprised to see this come back.

Were you using GT3 control arms in back? I only used them in front as we NEVER had an issue getting enough camber out back. Only the fronts on these cars are really limited. We could get only -1.0 in front before the control arms, we could get almost -2.5 on my car out back with my ROW M030 which is no where as low as an X74 can go (the lower, the greater the maximum camber). After trying a few different alignments at the track, I settled on -1.9 out back. At this setting with 295/30 MPSCs on 11.0" wheels with 34-35 psi hot pressures, I get only a variance of 3 degrees across my rear tires hot (inner, center and outer). I am getting dead even wear out back with absolutlely no toe issues (I run minimal toe-in). Any more or less camber out back would result in less grip. My front is still camber limited, so I will be adding more shims on the next alignment; but the rear will be left untouched.

If you are using GT3 control arms out back, why? What was the camber limit with your car? Most likely if you are using them, you don't need them. If so, how much of a shim pack are you using? If you were to try to run a rediculous amount of camber and run a big shim pack then you would have the problem you are describing and would have to elongate the toe links to correct it. On the front on my car with a 7mm shim pack, we had to take 5 full turns out of the tie rod ends to correct the toe when we put the GT3 control arms on. The only reason why we would ever need more would be to run some of the soft sidewall road racing slick (not DOT tires) that require -3+ in camber for optimal grip. There is no point going to these without going to a very stiff full race suspension that can use them.

I have nothing against Vivid as a sponsor, but be weary of Agency Power links. They do work fine on the street. I highly advise against them for track use. The spherical ends are not up to track standards and fail commonly. I would look at TRG or Fabcar for race worthy pieces for track use.

MagnusB

Thanks JimB et al., excellent info. Now I have to run out and jack up the car to look :-)
I still don't get the toe link for the rear.
The lower and upper control arms should "fix" the toe as well. How is the toe link connected?
(I guess we need pictures, I'll try to take some tomorrow morning)

JimB

OK it's 5:30 in the morning here and I'm taking suspension pictures. What's wrong with that picture.

Anyway, here's a pretty good picture of what is probably about as good as 996 suspensions get. In the picture the two smaller upper contol arms are pretty clear connecting the top of the hub to the chassis. The stock parts are not adjustable. These are ERP parts and allow you to push the top of the tire out or pull it in.

The large contol arm on the bottom (with the part number marked on it) is the lower control arm. It's a little hard to see where the lower control arm splits but it's near the chassis. The eccentric bolt is pretty clear.

You can see the rear tie rod (closest to you) running from the hub to the chassis. It's eccentric is somewhat covered by the swaybar. This part is the Porsche Motorsport version but yours look similar.

The tie rod is what you use to adjust toe. Changing camber changes toe but you then use the tie rod to correct it. If you are happy with the amount of camber you have and can't get enough toe then your tie-rods are not long enough. Like others, I'm a little preplexed by that. We had problems with the front tie rods not being long enough but the only problem we had with the rears was the very weak ball joints.

Does that help?

LVDell

The toe arm does just that, changes toe. Here is a pic of the TRG toe arm installed on my GT3. The control arms are NOT your toe adjustment places.

LVDell

Jim, looks like we just tried to post the same info at the same time. You're right....wtf are we doing talking suspension bits at this time of the morning?

JimB

Carrera,
There are several very good reasons to use upgraded rear control arms. First, the stock ones break and when they do it gets real ugly in a hurry. Second, you can control camber without using the eccentric. Third, I don't agree with your assessment of rear camber. 2.5 degrees may be enough for most but many track junkies will want more.

BTW, you can't use tire temps to determine optimal grip. Optimal grip will result in excessive wear and excessive heat on the inside edge. Why? Because when the camber is optimal for corners it's overheating the inside edges going down the straights. If you have even temps and even wear you are leaving lots of corner grip on the table.
Jim

JimB

You better get used to getting up at strange hours.

LVDell

You ain't kidding! My wife's ob/gyn was telling us that the getting up several times a night to use the bathroom is GREAT practice for when the baby comes. But, I don't want to practice